Jeep Engines - Oljeep

--Part Number: P5007161$30.00,

Many part numbers are listed in this book for reference. They may notbe currently available. For part numbers with the letter P prefix, referto the latest Mopar Performance F’arts Catalog. For part numberswithout the letter P prefix, contact your local Chrysler-Plymouth-Dodge-Jeep dealer.Mopar Performance Parts Technical Assistance Hotline1-248-969-1 690Monday through Friday8:OO a.m. - 12:OO p.m.1:00 p.m. - 5:OO p.m. (EST).. . T - 117

AcknowledgementsThe information presented in this book was compiled from various sources. Much of it has come fromDaimlerChrysler Engineering, the DaimlerChrysler Service Manual Department, and the Walter P. ChryslerMuseum, and reflects not only our experience with performance research and development, but our racinginvolvement as well. To this I must add my appreciation for the tremendous job that our independenttesting facilities have done relative to the information contained in this manual.I would also like to acknowledge my coworkers at Mopar Performance Parts, as well as our friends atArrow Racing Engines, McCormack Motorsports, modis Solutions, and the Adair Printing Company.Without them, this manual would not be possible.Finally, I give my sincere thanks to our many Mopar racers, race teams, and enthusiasts for their loyaltyand continued support. This book has been created especially for you.- L. S. Shepardl- -lI1

1990. 4.2L Engine Specifications ........3361990. 4.2L Engine TorqueSpecifications ..................... 340Chapter 6: 4.7L Power Tech V-8Introduction ....................... 343Block .......................... 344Crankshaft ....................... 344Timing Drive System ............... 344Piston and ConnectingRod Assembly .................... 345Cylinder Heads ................... 346Camshaft and Valve Gear ............ 346Oiling System .................... 348Cooling System ................... 350Starting System .................... 355Charging System .................. 357Intake Manifold ................... 358Fuel Delivery System ............... 358Powertrain ControlModule (PCM) .................... 361Positive CrankcaseVentilation (PCV) System ............ 364Exhaust System ................... 365Ignition System ................... 365Troubleshooting ................... 3661999, 4.7L Engine Specifications ........3701999. 4.7L Engine TorqueSpecifications ..................... 372Chapter 7: 360 AMC V-8Introduction ....................... 375Block ........................... 377Crankshaft ....................... 380Piston and Connecting Rod Assembly .... 388Cylinder Heads .................... 394Camshaft and Valve Gear ............ 397Oiling System ..................... 406Cooling System .................... 413Induction System ...................414Fuel Delivery System ................ 421Exhaust System ................... 424Ignition System .................... 425Engine Assembly .................. 4351971. 304-360 AMC V-8 EngineSpecifications ..................... 4351971. 304-360 AMC V-8 Engine TorqueSpecifications ..................... 4381981. 304-360 AMC V-8 EngineSpecifications ..................... 4401981. 304-360 AMC V-8 Engine TorqueSpecifications ..................... 4421990. 360 AMC V-8 EngineSpecifications ..................... 4441990. 360 AMC V-8 Engine TorqueSpecifications ..................... 448Chapter 8: Off-Roading and RacingOff-Road Driving ................... 451Tread Lightly! ..................... 453Jeep Jamborees ................... 455Camp Jeep ....................... 460Getting Started in Racing ............. 464Contingency ...................... 468Safety and the Performance Advantage ... 469Personal Safety .................... 471Body and Chassis Safety ............. 471Engine and Drivetrain Safety .......... 474Safety Checklist ................... 476Drag Racing ...................... 477Building Your PerformanceVehicle in Stages .................. 482Mopar Performance Parts Engine PackageRecommendations ..................482Suspension Upgrades ............... 484Tires ........................... 485Mopar Performance PartsInformation and Sources ............. 487Additional Sources ..................491Chapter 9: Additional InformationRacing Formulas ................... 494Chrysler-Plymouth-Dodge-JeepBody and Engine Types .............. 496Metric to EnglishConversion Table .................. 497..T - 7 1 .

CONTENTSiContentsIntroductionWELCOME .............................. 3OVERVIEW ............................. 3Chapter 1: Jeep HistoryJEEP HISTORY............ 7............ 7.................... 10The Great Out .................... 11Beyond the Quad ..................... 12Kaiser-Jeep .......................... 13Birth of the Sport Utility Vehicle ...... 15American Motor Corporation (A ...... 161984 Cherokee Redefines the SUV ........ 18Enter the Wrangler ..................... 20Chrysler Corporation Buys AMC ......... 21DaimlerChrysler and Beyond ............ 23Additional Jeep Information ............. 24Chapter 2: 2.5L Power Tech In-line 4IntroductionBlock2.5L ENGINE GENERALSPECIFICATIONS ............ ........ 27DISASSEMBLY AND ASSEMBLYPROCEDURES ........... 29Crankshaft........... 30Cylinder Bore Reconditioning ............ 31Short Block Assembly .................. 32INTRODUCTION ....................... 33CRANKSHAFT MAIN BEARINGS ......... 33Removal ........... . . 33............. 34.................... 34Main Bearing-to-Journal ClearanceCrankshaft Installed .................... 34Main Bearing Journal DiameterCrankshaft Removed ................... 35Installation ........ ......... 35Crankshaft End Play ................... 36ENGINE DAMPER ....................... 36Removal ............................ 36Installation ........................... 36VIBRATION DAMPER .................... 37Removal ............................ 37Installation .......................... 37TIMING CASE CRemoval ...Installation ........................... 38TIMING CHAIN AND SPROCKETS ......... 39Removal ............................ 39Installation .......................... 39TIMING CASE COVER OILSEAL REPLACEMENT ................... 40Timing Case Cover Removed ............ 40Timing Case Cover Installed ............. 41REAR MAIN OIL SEAL ................... 41Removal ...... .................. 41Installation ........................... 41Connecting RodsINTRODUCTION ........................ 42BASIC PREPARATION ................... 42RODRATIO . . ............ 42INSPECTION ........................... 42MEASURING BEARING-TO-JOURNALMEASURING SIDE CLEARANCE ........... 44Pistons and RingsPISTONS ................ ........... 45Piston Fitting (Non-Coated PPiston Fitting (Coated Pistons Only) ....... 45PISTON AND CONNECTING RODASSEMBLY ............................ 46Removal ............................ 46Installation .......................... 47Piston Ring Fitting(Non-Coated Pistons Only) .............. 48Piston Ring Fitting (Coated Pistons Only) . . SORing Gap Orientation ................ soPISTON PIN ........................... 51Removal . ................... 51Inspection ........................... 51Installation ........................... 5244.. ..T ..ll 1.

iiMOPAR PERFORMANCE PARTSCylinder HeadINTRODUCTION ............. .53REMOVAL AND INSTALLATIONPROCEDURES ........................ .53.................... 53tion ................54.................... 54CYLINDER HEAD COVER . .Removal ..................Inspection .......................... .56Installation ...... ......... .56Camshaft and Valve GearCAMSHAFT ........................... .57Removal ............................ 58Inspection .......................... .58Installation ..................... 58CAMSHAFT PIN REPLACEMENT ..........60Removal ............................ 60Installation ..................... 60VALVES AND VALVE SPRINGSRemoval -Cylinder Head Removed .......61Removal - Cylinder HeadNOT Removed ............ ........62Cleaning ......... ........... .62Inspection .......................... .63Valve Refacing .... ............. 63Valve Spring Tension Test .............. .63Installation-Cylinder Head Removed ......63Installation - Cylinder HeadNOT Removed ......... ............64VALVE TIMING ........................ .65VALVE STEM OIL SEALS ................ .65VALVE GUIDES ........................ .65Valve Stem-to-GuideClearance Measurement ................66VALVE SEATS ................ .66Valve Seat Refacing ...................66ROCKER ARMS ..................... 67..................... 67Cleaning and Inspection .................68Installation ... .................... 68PUSHRODS .... ...................... 68HYDRAULIC LIFTERS (TAPPETS) ..........68Removal ................Disassembly and Cleaning .... .......69Assembly ....... ......... .69Installation .......................... .69Oiling SystemINTRODUCTION ....................... .70Oil Pressure Requirements ..............70........................Removal .... ................ 72....................... 72OILPUMP ............................. 73Removal ....................Gear End Clearance MeasurementsGear-to-Body Clearance MeasuremeDisassembly ...................Assembly ....................Installation ...................Fuel Delivery and Fuel Injection SystemsMULTI-POINT FUEL INJECTION (MPI)SYSTEM .............................. .76Powertrain Control Module (PCM) ........76PCM Inputs ........................ .77PCM Outputs ...........Modes of Operation ...........Throttle Body .............Fuel RaiVFuel Damper ..................78Fuel Pressure Regulator .................78Racing Modifications ...................79Crankcase Ventilation System ............79THROTTLE BODY (SINGLE POINT)FUEL INJECTION (TBI) ...... .........79Electronic Control Unit (ECU) ...........80ECU Inputs ... .............. 80ECU Outputs ........................ .80Modes of Operation ................... .81Throttle Body ........................ .81FUEL PUMP .................. .......81TBI Fuel Pump ...................FUEL FILTER .......................... .8 1INTAKE MANIFOLD .................... .81Removal ............................ 81Installation .... ................. 82AIR FILTERS .... .............. 83Exhaust SystemEXHAUST SYSTEM ...............Exhaust Gas Recirculation (EGR) ...Exhaust System Troubleshooting Chart .....85Exhaust System Torque Specifications ......85EXHAUST MANIFOLD .............. 86Removal ............................ 86Installation .......................... .86._l- -1-1

CONTENTSiiiIgnition SystemTHROTTLE BODY FUEL INJECTION (TBI)IGNITION SYSTEM ..................... .87MULTI-POINT FUEL INJECTION (MPI)IGNITION SYSTEM .........Camshaft Position Sensor .Distributor ..... ..........Distributor Cap ............. 88Distributor RotorIgnition Coil ........................ .89SPARK PLUGS . ...........89Gap Adjustment ...................... .89Installation .......................... .90STARTER MOTOR ..............Operation ...........Removal ....................Installation .......................... .9 1MOPAR PERFORMANCE PARTSELECTRONIC IGNITION COMPONENTS ... .92Engine Assembly1990,2.5L ENGINE SPECIFICATIONS . .1990,2.5L ENGINE TORQUESPECIFICATIONS ...................... .961999,2.5L ENGINE SPECIFICATIONS ...... .971999,2.5L ENGINE TORQUESPECIFICATIONS ..................... .lo0Chapter 3: 2.46L In-Line 4Block ................................... 104Crankshaft ............... .......... .lo5INTRODUCTION .......................lo5CRANKSHAFT MAIN BEARINGS ........ .lo5Removal . ...................... 105Installation .... .............. 105CRANKSHAFT (FRONT) OIL SEALREPLACEMENT-COVER INSTALLED .... ,105REAR MAIN BEARING OIL SEAL ........ .lo6Removal ...................... 106Installation ...... ........ .lo6VIBRATION DAMPER .................. .lo6Removal ........................Installation ......................... .lo6TIMING CASE COVER ............................ 106...................... 106TIMING CHAIN ....................... .lo7Removal ........................... 107Installation ......................... .lo7Connecting RodsPISTON AND CONNECTINGROD ASSEMBLY ...................... ,109Removal ........................... 109Installation ......................... .lo9CONNECTING ROD BEARINGS .........,110Removal ........................... .I 10Installation ......................... .l 10Pistons and Rings ........................ .l 11Cylinder HeadREMOVAL AND REPLACEMENTPROCEDURES ..........Cleaning and Inspection ....CYLINDER HEAD COVER ...... .115Removal ..............Installation ..... ...Camshaft and Valve GearCAMSHAFT .......... ..........,116Installation ...VALVE SPRING AND OIL DEFLECTOR .....118Removal.. .... .... 118Installation ....... ........ 118ROCKER ARM ASSEMBLY ............... 118Removal ........ ....Cleaning and Inspection ......Installation ... ................... 119HYDRAULIC VALVE TAPPETS(LIFTERS) . ......................... 119Removal ............................ 119Installation .......................... 119Oiling SystemOILPAN .............................. 120Removal ........................... 120Installation ......................... .120OIL PUMP ....................120Removal ........................... 120Installation ................... ...,120._T-7 n

ivMOPAR PERFORMANCE PARTSEngine Assembly2.46L ENGINE GENERALSPECIFICATIONS ....................... 12 12.46L ENGINE GENERAL TORQUESPECIFICATIONS ....................... 124Chapter 4: 4.0L Power Tech In-line 6Introduction .............................. 129BlockINTRODUCTION ....................... 130Build Date Code ..................... 130Oversize and UndersizeComponent Codes .................... 131Block Harness ....................... 131Rough Bored Blocks .................. 131CYLINDER BLOCK PREPARATION ....... 131Block-to-Head Distortion ............... 131Stress Relieving ...................... 132Sonic Testing ........................ 132Core Shift .......................... 132Surfacing (“Decking”) ................. 133Honing ............................. 133Boring and Milling Specifications ........ 134Cylinder Bore Measurements ............ 134CYLINDER BLOCK ASSEMBLYHead Bolts ...............Bottoming Taps ...........Main Bearing Bores ........Deck Height ..............Dowel Pins ..............Rear Main Bearing Oil Seal . .Camshaft Bearings .........Deburring ................Tappet Bores .............Notching the Cylinder Bore forConnecting Rod Clearance ...CC’ing the Block ................... 134......... 134......... 134......... 134......... 135......... 135......... 135......... 135......... 135......... 135......... 135......... 135ADDITIONAL CYLINDER BLOCKPREPARATION AND ASSEMBLY TIPS ..... 135MAINCAPS ........................... 136FREEZE PLUGS ........................ 136CrankshaftINTRODUCTION ....................... 137Balanced and Unbalanced Crankshafts ..... 137Crank Bolt .......................... 137BASIC PREPARATION ................... 137SPECIAL CRANKSHAFT PROCEDURES ... 138Measuring Main Bearing Clearances ...... 138Top Dead Center (TDC) ................ 139Mallory Metal ..... ............... 140Tuff-Triding and Nitriding .............. 1414.2L Engine Crankshaft Installation ....... 141MAIN JOURNALS ...................... 141MAIN BEARINGS ...................... 141Main Bearing Material ....Removal ..............Inspection .......................... 142Fitting ............................. 142Installation .......................... 142Main Bearing Fitting Chart ............. 144Crankshaft End Play .................. 145REAR MAIN OIL SEAL .................. 145Removal ........................... 145Installation .......................... 145VIBRATION DAMPER ................... 145Vibration Damper Failure ............... 146Vibration Damper Performance Tips ...... 146Removal ........................... 146Installation .......................... 147TIMING CHAIN AND SPROCKETS ........ 147Installation Tips ...................... 147Connecting RodsINTRODUCTION ....................... 148BASIC CONNECTING ROD PREPARATIONAND INSTALLATION TIPS ............... 148SPECIAL CONNECTING RODINSTALLATION PROCEDURES ........... 149Rod Ratio ........................... 149Measuring Side Clearance .............. 149Cap Alignment ............ ........ 149Connecting Rod Bolt Protectors .......... 150ALUMINUM CONNECTING RODS ........ 150CONNECTING ROD BEARINGS .......... 151Installation ..... .................. 151Measuring Connecting RodBearing Clearance .................... 151Pistons and RingsPISTONS .............................. 152Piston Compression Ratio Ratings ........ 152Piston Shape ........................ 153Piston-to-Head Clearance ............... 153Valve-to-Piston Clearance .............. 153Piston Race Preparation ................ 153Reversing Pistons With Offset Pins ....... 154CC’ing the Block ..................... 154..l- - 1 1

CONTENTSVCOMPRESSION RATIO .................. 154Measuring 1/2" Down Fill Volume ........ 155PISTON RINGS ........................ 155Basic Piston Ring Preparation ........... 156PISTON PIN ........................... 156Removal ........................... 156Inspection .......................... 156Installation .......................... 156Offset Pins .......................... 157Pin Coatings ......................... 157Pin Oiling .......................... 157PISTON AND CONNECTINGROD ASSEMBLY ....................... 158Removal ........................... 158Inspection .......................... 159Cylinder Bore Measurement ............. 159Fitting Pistons-Bore Gauge Method ......159Piston Size Chart ..................... 159Fitting Rings ........................ 159Installation .......................... 160Cylinder HeadINTRODUCTION ....................... 162SELECTION ........................... 162CYLINDER HEAD REMOVAL ANDINSTALLATION PROCEDURES ........... 163Removal ........................... 163Cleaning and Inspection ................ 164Preparation .......................... 164Installation .......................... 165CYLINDER HEAD PERFORMANCEAND ASSEMBLY TIPS ................... 166Alignment .......................... 166Piston-to-Head Clearance ............... 166Oil Restriction ....................... 166Valve-to-Valve Clearance ............... 166Measuring Cylinder Head CombustionChamber Volume ..................... 166Block-to-Head Distortion ............... 167Spring Seats and Valve Guides ........... 168Diagnosing Valve Seat Insert Failure ...... 168Aluminum Head Threads ............... 169Weeping ............................ 169PORTED CYLINDER HEAD .............. 170Swirl Ports .......................... 170Porting ............................. 171Flow Bench ......................... 171Evaluating Cylinder Head Air Flow ....... 172Oversize Valve Seats and Guides ......... 174CYLINDER HEAD COVER ............... 175Removal ........................... 175Cleaning and Inspection ................ 175Installation .......................... 175Camshaft and Valve GearCAMSHAFT ........................... 176CAMSHAFT SELECTION ................ 177Racing Camshaft Selection .............. 177CAMSHAFT REMOVAL ANDINSTALLATION PROCEDURES ........... 178Removal ........................... 178Inspection .......................... 178Installation .......................... 178CAMSHAFT INSTALLATION TIPS ......... 179CAMSHAFT INSTALLATIONTROUBLESHOOTING ................... 180SPECIAL CAMSHAFT THEORIES ......... 180Camshaft Duration .................... 180Camshaft Centerline ................... 181Calculating Duration at Fifty ............ 184Base Circle ......................... 184VALVE GEAR .......................... 185General Valve Gear ................... 186Valve Gear Selection .................. 186VALVE GEAR PERFORMANCE ANDASSEMBLY TIPS ....................... 186SPECIAL VALVE GEAR THEORIES ........ 187Valve Gear Oiling .................... 187Valve Train Geometry ................. 188Dynamics ........................... 188VALVES ............................... 188Stainless Steel Valves .................. 190Valve Grinding (Valve Job) ............. 190Valve Timing ........................ 192Polished Valve Stems .................. 193Valve Stem Lash Caps ................. 193VALVE STEM OIL SEALS ................ 193VALVE GUIDES ........................ 194Valve Stem-to-Guide ClearanceMeasurement ........................ 194VALVE SEATS .......................... 194Valve Seat Refacing ................... 194VALVE SPRINGS ....................... 195Big Camshaft ValveSpring Considerations ................. 196Valve Spring InstallationPerformance Tips ..................... 196... l- - T I 7.

viMOPAR PERFORMANCE PARTSVALVE AND VALVE SPRINGREMOVAL AND INSTALLATION . . . . . . . . . . I97Removal . . . . . . . . . . . .I97Cleaning ............... 198Inspection . . . . . . . . . . . . . . . . . . . . . . . . . .I98Valve Clearance . . . . . . . . . . . . ,198Valve Refacing . . . . . . . . . . . . . . . . . . . . . . ,199Valve Spring Tension Test . . . . . . . . . . . . . . I99Installed Height and GuideI99Installation . . . . . . . . . . . . . . . . . . . . . . . . . .I99VALVE SPRING RETAINERSAND KEEPERS (LOCKS) . . . . . . . . . . . . . . . . ,2008" Versus 10" Retainers andKeepers (Locks) . . . . . . . . . . . . . . . . . . . . . .20 IROCKER ARMS . . . . . . . . . . . . . . . . . . . . . . . .20 1RemovalCleaning aInstallation . . . . . . . . . . . . . . . . . . . . . . .202PUSHRODS . . . . . . . . . . . . .Hydraulic Pushrods . . . . . . . . . . . . . . . . . . ,203LIFTERSRAPPETS . . . . . . . . . . . . . . . . . . ,203Hydraulic LiftersRappets . . . . . . 203Oiling SystemPreliminary Check . . . . . . . . . . . . . . . . ,203Tappet Noise Diagnosis . . . . 204Removal . . . . . . . . . . . . . . . . . . . . . . . 204Disassembly, Cleaning andInspection . , . . . . . .Hydraulic Tappet Installation Tips . . . . . . . .2OSMushroom Liftersflappets . . . . . . . . . . . . . .205INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . ,206Troubleshooting . . . . . . . . . . . . . . . . . . . . . .206OILING SYSTEM PERFORMANCECONSIDERATIONS .. . . . . . . . . . . . . . . . . . . ,208Choosing the Correct Oiling System . . . . . ,208Oiling System Passage Requirements 208Oil Flow to Connecting Rod Bearings 208Oil Restriction . . . . . . . . . . . . . . . . ,208OIL PUMP ....... . . . . . . . ,208High Volume Oil Pump Assembly . . . . . . . ,208Oil Pressure Requirements . . . . . . . . . . . . . .209Oil Pump Priming . . . . . . . . . . . . . . . . . . . .209OIL PUMP SERVICE PROCEDURES 209Removal . . . . . . . . . . . . . . . . . . . . . . . . . . .209Gear End Clearance Measurement . . . . . . . ,209Gear-to-Body Clearance Measurement . . . . ,210Assembly . . . ..... 210Installation . . . . . . . . . . . . . . . . . . . . . . . . . .2 10OILPICK-UPS .......................... 210OILPAN . ................. 210OIL PAN PERFORMANCECONSIDERATIONSStock (Production) Oil PanModifications . . . . . . . . . . . . . . . . . . . . . . . .211DRY SUMP OIL SYSTEM . . . . . . .211OIL COOLERS . . . . . . . . . . . . . . . . . . . . . . . . .2 12OIL ................................... 212. . .212Oil Level Inspection . . . . . . . . . . . . . . . . . . .2 12Engine Oil Change . . . . . . . . . . . . . . . . . . . .2 12ENGINE OIL FILTER . . . . . . . . . . . .RemovalInstallation . . . . . . . . . . . . . . . . . . . . . . . . . .213Cooling SystemINTRODUCTION . . . . . . . . . . . . . . . . . . . . . . .214Cooling System Capacity . . . . . . . . . . . . . . ,214Coolant Reservoir/Overflow System . . . . . .214Troubleshooting . . . . . . . . . . . . . . . . . . . . . .215COOLING SYSTEM HOSES . . . . . . . . . . . . . . .215SERPENTINE DRIVE BELT . . . . . . . . . . . . . . .2 ISDiagnosis ........................... 215WATERPUMP .......................... 218Performance Tips . . . . . . . . . . . . . . . . . . . . .2 18Water Pump Flow Test . . . . . . . . . . . . . . . . .2 18Water Pump Inspection . . . . 218WATER NECK . . . . . . . . . . . . . . . . . . . . . . . . . .21890 Degree Water Neck Outlet . . . . . . . . . . . .219THERMOSTAT ............ 219COOLANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220FANS ................................. 220Viscous Fan Drive . . . . . . . . . . . . . . . . .220Mopar Performance Parts ViscousFan Package ............... 220Electric Fans... . . . . . . .22 IInduction SystemINTAKE MANIFOLD . . . . . . . . . . . . . . . . . . . .222Removal and Installation . . . . . . . . . . . . . . .222MULTI-POINT FUEL INJECTION (MPI) . . . . .222Powertrain Control Module (PCM) . . . . . . .222PCM InputsPCM Outputs . . . . . . . . . . . . . . . . . . . . . . . .223Modes of Operation . . . . . . . . . . . . . . . . . . .223..T - l l 1

CONTENTSviiThrottle Body ........................ 223Fuel Rail ........................... 223Fuel Pressure Regulator ................ 224Racing Modifications .................. 224AIRFILTERS ........................... 224TURBOCHARGING ...........SUPERCHARGING ...................... 225Sources ............................ 226Fuel Delivery SystemINTRODUCTION ....................... 227Drag Racing Fuel System ............... 227Oval Track Fuel System ................ 227FUEL PUMP ........................... 228MPI Fuel Pump ...................... 228MPI Fuel Pump Controls ............... 228FUEL TANKS AND FUEL CELLS .......... 228FUEL LINE ............. ............ 229FUEL FILTER .......................... 229FUEL HOSES AND CLAMPS .............. 229Quick Connect Fuel Tube Fittings ........ 229FUEL ................................. 229Fuel Definitions ...................... 229FUEL ECONOMY ....................... 230Engine ............................. 231Tune-up and Check-Out ............ 231Rework (Simple Modifications) ...... 232Rebuild (Major Modifications) ....... 232Chassis ............................. 232Cost Effectiveness .................... 233Driving ............................ 233Exhaust SystemINTRODUCTION ....................... 234Catalytic Converter ................... 234Heat Shields ......................... 235Exhaust Gas Recirculation .............. 235EXHAUST AND INTAKE MANIFOLDS ..... 235Removal ........................... 235Installation .......................... 236EXHAUST SYSTEM MODIFICATIONS ...... 237Headers ............................ 237Mufflers ............................ 237Ignition SystemINTRODUCTION ....................... 238Ignition Energy ...................... 238ELECTRONIC IGNITION SYSTEM ......... 238Powertrain Control Module (PCM) ....... 239239Ignition Coil ......................... 239Distributor .......................... 239Ignition Control Module (ICM) ..........Mopar Performance Parts ElectronicIgnition Components .................. 240DISTRIBUTORLESSIGNITION SYSTEM ..................... 241Powertrain Control Module (PCM) ....... 241...................... 241Automatic Shutdown (ASD) Relay ....... 242Crankshaft Position Sensor .............. 242Camshaft Position Sensor ............... 242SPARK PLUGS ......................... 242Spark Plug and Ignition Wire Removal .... 245Inspection .......................... 245Specifications ........................ 245Gap Adjustment ...................... 245Installation .......................... 245SPARK PLUG CABLES(IGNITION WIRES) ..................... 245Accessories ......................... 246IGNITION SWITCH ..................... 246GENERAL IGNITION SYSTEMPERFORMANCE TIPS ................... 246Starting SystemINTRODUCTION ....................... 247Operation ........................... 247STARTER MOTOR ...................... 247Operation ........................... 247STARTER RELAY ....................... 248BATTERY ............................. 248Battery Relocation .................... 249Engine AssemblyINSPECTION AND TESTING .............. 250Cylinder Compression Pressure Test ...... 250Cylinder Head Gasket Failure Diagnosis ... 250Cylinder-to-C ylinder Leakage Test ........ 250Cylinder-to-Water Jacket Leakage Test ..... 250Cylinder Combustion PressureLeakage Test ........................ 250Oil Leak Inspection ................... 251Air Leak Detection Test Method ......... 252Inspection for Rear Seal Area Leaks ...... 252BUILDING A NEW ENGINE .... ....... 252What Parts to Use .................... 253Engine Torque vs . Horsepower ........... 253... . .r - T - T

viiiMOPAR PERFORMANCE PARTSBefore You Start ..... ..........254Reference Material ........ .....254Equipment ............. ..........254Records ................. .....254ENGINE BLUEPRINTING ............... .254Dynamic BalancingNominal Numbers ...............Dynamometers (Dynos) ..........DISASSEMBLY ........................ ,256Things to Check . . ...........Part Identification ...........INSPECTION AND PREPARATION ........,257..........Crankshaft ...... ................ 258Rod Bearing Clearances ...........Cylinder Head .................Pistons and Rings ...............Seal and Cover .................SUB-ASSEMBLY OF BASIC GROUPSPreliminary Assembly ...........Cylinder Head and Intake Manifold .......26 ICamshaft and Valve Gear ....Notes Before Final Assembly ......FINAL ASSEMBLY ................Camshaft into BlockCylinder Head onto Block .......Valve Gear onto EngineIntake Manifold ............Carburetion System (ifOiling System .......Accessory Drives ............Valve Clearances .... ............. 264Boring and Milling SpEngine Paint. ............ .........265Seal and Cover ...................... .265Engine Building Checklist .Engine Start-up ...........TRACK TESTING ................Before Testing ...... .........261Preparation ...............ENGINE SPECIFICATIONS ...............268At the Track ................ ......268BASIC TUNE-UP ANDTROUBLESHOOTING ...................268Basic Tuning ............. ......268Basic Troubleshooting ................,269PERFORMANCE TROUBLESHOOTING .... .269...........Leak Checking .........Bl0w-B~ .................In Storage ..............Out of Storage .......1989,4.0L ENGINE SPECIFICATIONS ..... ,2721989,4.0L ENGINE TORQUESPECIFICATIONS ....... .....2761999,4.0L ENGINE SPECIFlCATIONS ..... .2771999,4.0L ENGINE TORQUESPECIFICATIONS ...............Chapter 5: 4.2L In-line 6. . ,280Introduction ... ........................ 283Block...........Cylinder Bore Resurfacing ............. ,285Assembly ..................285ENGINE MOUNTS . . ................ 285CrankshaftCRANKSHAFT .............,286CRANKSHAFT MAIN BEARINGS ........ .286Removal ........... ......,286Inspection ........... 281Fitting ... ........... 287Main Bearing-to-JournalClearance-Crankshaft Installed ..... 287Main Bearing JournalInstallation ................Crankshaft End Play ..........REAR MAIN OIL SEAL ...Removal ...........Installation .......... ...........289VIBRATION DAMPER ...........................Installation ..............TIMING CASE COVER .........Removal ...... ...........Installation ..........Installation ....... .............. 291.. T -1-1

CONTENTSixPiston and Connecting Rod AssemblyREMOVAL AND INSTALLATIONPROCEDURES .................Removal ...... ............. 292Inspection . ................. 292Bearing-to-Journal ClearanceMeasurement .................Side Clearance Measurement .....Installation .................... 293CONNECTING RODS ................... ,294Connecting Rod Installation Tips ........ ,294CONNECTING ROD BEARINGS ...........294Removal and Inspection ................294Installation .................. 295PISTONS .....Piston Fitting ............................ 29sPISTON RINGS ....... ........ ,295Piston Ring Fitting ...........PISTON PIN. ..............Removal ............Inspection .............Installation .............Cylinder Head................... 298................Cleaning and Inspection ............... ,299Installation .................. .299CYLINDER HEAD COVER .............. .300Camshaft and Valve GearCAMSHAFT ..... .............. 302Removal ...... ............. 302Inspection ..........Installation ............Measuring Cam Lobe LiftVALVES AND VALVE SPRINGSCleaning ........... ........,303Inspection .......... ........ 304Valve Refacing ........... .....304Valve Seat Refacing .............. 304Valve Spring Tension Test ..........Installation-Cylinder Head Removed ....,304VALVE STEM OIL DEFLECTOR ........Replacement ............ .....304VALVE GUIDES . ............... 305Preferred Method .... .........,305Alternate Method ..... .........305VALVE TIMING ....................... ,305ROCKER ARMS ....................... .306Removal ..........Cleaning and InspectInstallation ....... ............ 306HYDRAULIC TAPPETS............... 306Removal ....... ...........306Oiling SystemAssembly ................... 307Installation ......................... ,307SYSTEM OVERVIEW ................... .308OILPAN .............................. 310..................... 310.................. 310Installation ......................... .310OIL PUMP ...... .................. 310Removal .................... 310Gear End Clearance Measurement ........311Gear-to-Body Clearance Measurement .....311Disassembly ........................ .311Assembly ...................... 311Installation ......................... .311Oil Pressure Relief Valve ...............311Induction SystemINDUCTION SYSTEM ...................312Fuel Pump ................... 312Computerized Emission Control(CEC) Fuel Feedback System ............312JEEP 4.2L MULTI-POINT FUEL INJECTIONCONVERSION KIT INSTALLATIONINSTRUCTIONS ................ ....,313Disassembly ........................ 313Assembly ..................Troubleshooting Notes ....Ignition SystemSOLID STATE IGNITION SYSTEM .........327System Operation . ................ 327Ignition Advance . ................ 327IGNITION SYSTEM COMPONENTS ....... .327Micro-Computer Unit (MCU) .......... .327Ignition Module ..................... .327Ignition Coil .......... .......... ,328

~~ ~~ ~XMOPAR PERFORMANCE PARTSIgnition Coil ConnectResistance Wire ....Distributor ........Pickup Coil and Trigger WCap and Rotor .....IGNITION SYSTEM TIMINGMagnetic Timing Probe ...Ignition Timing ProcedureAlternate Timing ProcedureSPARK PLUG SPECIFICATlONSSSI DISTRIBUTOR AND IGNITIONCOIL SPECIFICATIONS .................. 33 IMOPAR PERFORMANCE PARTSELECTRONIC IGNITION COMPONENTS .... 332Engine Assembly1981,4.2L ENGINE SPECIFICATIONS ...... 3331981,4.2L ENGINE TORQUESPECIFICATIONS . . .................. 3351990,4.2L ENGINE SPECIFICATIONS ...... 3361990,4.2L ENGINE TORQUESPECIFICATIONS 340Chapter 6: 4.7L Power Tech V-8INTRODUCTIONGeneral SpecificationsEngine Firing Order ........Engine IdentificationFuel RequirementsBLOCKStructural Dust Cover ................. 344CRANKSHAFTTIMING DRIVE SYSTEMPISTON AND CONNECTINGROD ASSEMBLY ....................... 345CYLINDER HEADS ..................... 346Valve Guides ........................ 346Cylinder Head Covers ................ 346Engine Gasket Surface Preparation ........ 346CAMSHAFT AND VALVE GEAR ......Rocker Arms ....................Valves ............................. 346Valve Springs ........................ 347Hydraulic Lash Adjusters ............... 347Valve Stem Seals ..................... 347Engine Timing Verification .... .... 347OILING SYSTEM ....................... 348Engine Oil .......................... 349Engine Oil Level Inspection ............. 349Engine Oil Change .......Engine Oil Filter Change . .Oil Pan . . ......... ......... 350COOLING SYSTEM ........ ......... 350Cooling System Capacity . .Cooling System Components ............ 351Water Pump Bypass ................... 352Coolant Reservoir/Overflow System ...... 352Accessory Drive Belt Tension ........... 352Radiator Pressure Cap ....Viscous Fan Drive .................... 354Serpentine Drive Belt Diagnosis . . ..... 355STARTING SYSTEM .... .............. 355Starter Motor ........................ 356Starter Relay ........................ 357CHARGING SYSTEM ................... 357Generator ........................... 357Battery Temperature Sensor . . . 358Electronic Voltage Regulator ............ 358INTAKE MANIFOLD . 358FUEL DELIVERY SYSTEM ............... 358Fuel Pump Module .......Fuel Pump .............Fuel Gauge Sending Unit ............... 359Fuel FilterFuel Pressure Regulator ....... 359Fuel Tank ........................... 360Fuel Injectors ..... .............. 360Fuel Injector Rail . . .............. 360Fuel Tank Filler Tub .............. 360POWERTRAIN CONTROLMODULE (PCM) ........... ....... 361Modes of Operation .............. 361Ignition Switch (Key-On) Mode .......... 362Engine Start-up Mode .....Cruise Mode ........................ 363Acceleration Mode .................... 363Deceleration Mode .................... 363Wide Open Throttle Mode .............. 363Ignition Switch Off Mode .............. 364POSITIVE CRANKCASEVENTILATION (PCV) SYSTEM ........... 364... .. l- -1.1.

CONTENTSxiEXHAUST SYSTEM ........... 365Exhaust Manifolds ......... 36.5Oxygen Sensors ..................... ,365Muffler and Tailpipe ................. ,365IGNITION SYSTEMSpark Plugs ...... ........,365Ignition Coils ..... .........365TROUBLESHOOTINCylinder Compression Pressure Test ......366Engine Cylinder Head GasketFailure Diagnosis .................... ,367Cylinder-to-Cylinder Leakage TestCylinder-to-Water JacketLeakage Test ....................... 367Cylinder Combustion PressureLeakage Test ...................Engine Oil Leak Inspection ........Air Leak Detection Test Method ...Inspection for Rear Seal Area Leaks1999,4.7L ENGINE SPECIFICATIONS1999,4.7L ENGINE TORQUESPECIFICATIONS ..................... ,372Chapter 7: 360 AMC V-8IntroductionEngine Description ................... 375BlockINTRODUCTION ...........Short Block Assembly .....Cylinder Bore Measurement .Cylinder Bore ReconditioningShort Block Assembly ................ ,378ENGINE MOUNTS .... ..... ,379CrankshaftCRANKSHAFT ........................ .3 80CRANKSHAFT MAIN BEARINGS ........,380.................. 380.................. 380......................... 380Main Bearing-to-JournalClearance -Crankshaft Installed ...,381TIMING CASE COVER . . ... . 384Removal ................ 384Oil Seal Replacement ................. ,384Installation .......................TIMING CHAIN AND SPROCKETS .....Timing Chain Wear Measurements ........386Removal . ...................... 386Installation ...................... 386REAR MAIN orL SEAL ................. .387Removal ........................... 387Installation . ................. 387Piston and Connecting Rod AssemblyPISTONS . ............... 388CONNECTING RODS AND BEARINGS .... .388Rod Ratio ...................Basic Preparation .............Inspection ................Connecting Rod Bearing Fitting ......... ,389Measuring Bearing-to-JournalClearance ...........Measuring Side Clearance ......PISTON PIN ............ .........391Removal ..........Inspection ...............Installation .........PISTON AND CONNECTING RODASSEMBLY . . ..................... 391Removal ........................... 391Piston Fitting ....................... ,391Piston Ring Fitting ....Installation ..........Cylinder HeadsMain Bearing - Journal Diameter -Crankshaft Removed.................,382Installation ......................... .382I Camshaft and Valve GearCrankshaft End Play ................. 382VIBRATION DAMPER .................. .383Removal ........................... 383Installation ......................... ,383INTRODUCTION ...................... 394Removal . . ................ 394Cleaning and ................ 394htallation ......................... .394CYLINDER HEAD SHIMS ............... 395CYLINDER HEAD COVERS ............. 395................. 395Installation ......... ,396...CAMSHAFT .......................... 397Cam Lobe Lift Measurements .......... .397Removal ........................... 397Inspection ......................... .398Installation ......................... .398

xiiMOPAR PERFORMANCE PARTSBREAKING CAMSHAFTS 399 ICAMSHAFT BEARINGS ................. 399VALVES AND VALVE SPRINGS ........... 400Removal - Cylinder Head Removed ....... 400Cleaning ........................... 40 1Inspection .......................... 401lnstallation-Cylinder Head Removed ..... 401VALVE STEM OIL DEFLECTOR ........... 40 1Removal - Cylinder HeadNOT Removed ................ 401Installation . Cylinder HeadNOT Removed ....................... 402VALVE GUIDES ........................ 402Valve Stem-to-Guide ClearanceMeasurements ............ 402VALVE SEATS .......................... 403Valve Seat Refacing ................... 403VALVE TIMING ................ 403ROCKER ARMS ............... 403.................. 404............... 404Installation .......................... 404PUSHRODS ............... 404HYDRAULIC LIFTERS (TAPPETS) 404Removal -Cylinder HeadNOT Removed ....................... 405Disassembly, Cleaning and Inspection ..... 405....... 405Oiling SystemNOT Removed .................. 405INTRODUCTION ....................... 406OIL PAN ......Removal ...........Cleaning .......Installation ..........Stock (Production)Oil Pan Modifications ................. 406CUSTOM DRAG RACING OIL PANFABRICATION ................Pro Stock Pan ..............Oil Pan Capacity and Swinging PiCheck-Out .......................... 408DRY SUMP OILING SYSTEM ............. 409OILPUMP ............................. 410Oil Pressure Relief ValveRemoval .............................. Cleaning and Inspection ................ 411Gear End Clearance Measurement ........ 411Gear-to-Body Clearance MeasurementImtallation .......................... 412Oil Pressure Requirements .............. 412Oil Pump Priming .................... 412Cooling SystemINTRODUCTION ....................... 413Induction SystemINTRODUCTION ....................... 414CARBURETION SYSTEM ................ 414.............. 415SPECIAL CARBURETORCONS1 DERATIONS ..................... 416Headers vs . Carburetors ................ 416Carburetor cfm ....................... 416Lean Carburetor .............. 416Lean Idle Fuel M ................ 417STANDARD PRODUCTION2 150 CARBURETORADJUSTMENTS/OVERHAULTroubleshooting .........Cleaning ............... 418INTAKE MANIFOLD .................... 418Vacuum Leak\AIR CLEANERS .........AIR FILTERS .......................... 420Fuel Delivery SystemFUEL PUMPS .......................... 421360 AMC V-8 Mechanical Fuel Pump ..... 422FUEL FILTER .......................... 422FUEL HOSES AND CLAMPS .............. 422FUEL ................................. 422Gasoline ............................ 422Gasoline Additives .................... 423Octane Booster Effectiveness ............ 423Exhaust System .......................... 424Ignition SystemINTRODUCTION ....................... 425Spark Advance ....................... 425Lean Burn Ignition .................... 428Magnetos ........................... 428SOLID STATE IGNITION (SSI)IGNITION SYSTEM ..................... 428

CONTENTSxiiiSSI IGNITION COMPONENTS ............. 428Ignition Module ...................... 428Distributor .......................... 428Ignition Advance .................. 428Pickup Coil and Trigger Wheel ....... 429Distributor Cap ................... 429Distributor Rotor .................. 429Ignition Switch ....................... 430Ignition Wires ....................... 430Ignition Coil Connector ................ 430Resistance Wire ...................... 430Vacuum Advance Control System ........ 431Spark Plugs ......................... 431Removal ........................ 431Inspection ....................... 431Specifications .................... 431Gap Adjustment .................. 431Installation ...................... 431Battery ............................. 431VOLTAGE REGULATOR ................. 433IGNITION SYSTEM TIMING .............. 433Magnetic Timing Probe ................ 433Ignition Timing Procedures ............. 433MOPAR PERFORMANCE PARTSELECTRONIC IGNITION COMPONENTS ... 433Engine Assembly1971,30 4-360 AMC V-8 ENGINESPECIFICATIONS ....................... 4351971,30 4-360 AMC V-8 ENGINE TORQUESPECIFICATIONS ....................... 4381981,30 4-360 AMC V-8 ENGINESPECIFICATIONS ....................... 4401981,30 4-360 AMC V-8 ENGINE TORQUESPECIFICATIONS ....................... 4421990, 360 AMC V-8 ENGINESPECIFICATIONS ....................... 4441990, 360 AMC V-8 ENGINE TORQUESPECIFICATIONS ....................... 448Chapter 8: Off-Roading and RacingOFF-ROAD DRIVING .................... 451Preparation .......................... 451General Advice ...................... 45 1Off-Road Techniques .................. 452Additional Information ................. 453TREAD LIGHTLY ! ...................... 453Mission ............................ 454Off-Highway Vehicle (OHV)Trip Preparation ...................... 454Things to Remember ..................Reading Travel Maps ..................454455JEEP JAMBOREES ...................... 455A Typical Jeep Jamboree Weekend ....... 456Frequently Asked Questions ............. 457CAMPJEEP ............................ 460Events and Activities .................. 460GETTING STARTED IN RACING .......... 464Recognize Your Limitations ............. 465Where Do I Start? .................... 465Obtaining Publicity ................... 466Governing Body Problem ............... 467CONTINGENCY ........................ 468Mopar Performance PartsContingency Program .................. 469SAFETY AND THE PERFORMANCEADVANTAGE .......................... 469PERSONAL SAFETY .................... 471Clothing ............................ 471Helmets ............................ 471BODY AND CHASSIS SAFETY ............ 471Fire ............................... 471Roll Cage ........................... 472Steering Lock ........................ 473WheelLoss ......................... 474Brakes and Brake Lines ................ 474ENGINE AND DRIVETRAIN SAFETY ...... 474Fuel Filters .......................... 474Electric Fuel Pump .................... 474Stuck Throttles ....................... 474Driveshaft Loop ...................... 475Automatic Transmission Safety .......... 475SAFETY CHECKLIST .................... 476DRAGRACING ......................... 477Bracket Racing ....................... 477Bracket Racing Build-Up Strategy ........ 477Stock Eliminator Trucks ................ 478How to Build a Stock Eliminator Truck .... 478Super Street ......................... 479Consistency ......................... 479BUILDING YOUR PERFORMANCEVEHICLE IN STAGES .................... 482Stage 1: Induction, Exhaust and Timing .... 482Stage 2: Cams, Valve Train and Chassis .... 482Stage 3: Advanced Engine and ChassisModifications ........................ 482Stage 4: All-out CompetitionModifications ........................ 482. . .. T - T 1.

l- -1-1xivMOPAR PERFORMANCE PARTSMOPAR PERFORMANCE PARTS ENGINEPACKAGE RECOMMENDATIONS . ,4822.SL Jeep 4-Cylinder Engine PackageRecommendations . . . . . . . . . . . . . . . 482Stage I ............... 482Stage II ......................... 483Stage III . . . . .. . . ,4834.01, Jeep In-Line 6 Engine PackageRecommendations . . . . . . .Stage I . . . . . . . . . . . .Stage 11 . . . . . . . . . . .Stage 111 . . . . . . . . . .360 AMC V-8 Engine PackRecommendations . . . . . . . . . . . . . . . . . . . .483. . . . . .483. . . . . ,483Stage I11 . . . . . . . . . . . . . . . . . . . . . . . ,483SUSPENSION UPGRADES . . . . . . . . . . . . . . . ,484Shock Absorbers ................ 484Installation Tips . ................ 484RS5000 Cellular Gas Shocks . . . . . . . . . . . ,485Heavy Duty UrethaneSuspension Bushings . . . . . . . . . . . . . . . . . ,485Steering Stabilizers . . . . . . .. 485TIRES ................................ 485Choosing Tires for On or Off-Road . . .General Performance Strategies . . . . . . . . . ,487MOPAR PERFORMANCE PARTSINFORMATION AND SOURCES . . . . . . . . . . .487Mopar Performance Parts Race Team . . . . . ,487Mopar Performance Parts Racing Books . . ,488Mopar Performance Parts Catalogs . . . . . . . ,490Mopar Performance Parts‘Technical Assistance . . . . . . . . . . . . . .Mopar Performance Parts Website . . . . . . . .49 1Mopar Car Club Directory . . . . . . . . . . . . . .49 IMopar National Events . . . . . . . . . . . . .ADDITIONAL SOURCES . . . . . . . . . . . . . . . . ,491DaimlerChrysler Sources . . . . . . . . . . . . . . .49 1Newspapers and Magazines . . . . . . . . . . . . ,492Drag Racing Organizations . . . . , . . . . . . . ,492Oval Track Racing Organizations . . . . . .Sports Car Racing Organizations . . . . . .Chapter 9: Additional InformationRACING FORMULAS . . . . . . . . . . . . . . . . . . . ,494Cylinder Volume . .Cy1 i nder Displaceme.................. 494.................. 494Compression Ratio . . . . . . . . . . . . . . . . . . . ,494Chamber Volume . . . . . . . . . . . . . . . . . . . . ,494Displacement Ratio . . . . . . . . . . . . . . . . . . ,494Horsepower ................ 494Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,495................... 495Quarter Mile Gear Ratio . . . . . . . . . . .Quarter Mile E.T. Estimate . . . . . . . . .Quarter Mile mph Estimate . . . . . . . .CHRY SLER-PLY MOUTH-DODGE- JEEPBODY AND ENGINE TYPES . . . . . . . . . . . . . ,496METRIC TO ENGLISHCONVERSION TABLE . . . . . . . . . . . . . . . . . . .497

Introduction

2 MOPAR PERFORMANCE PARTSWelcome ................................................................................ 3Overview ................................................................................ 3l- ‘ 1 1.

INTRODUCTION 3IntroductionWELCOMEWelcome to Jeep Engines-3rd Edition.This performance book has been prepared as a guide forthose enthusiasts who are interested in everything frommild performance gains to building highly competitiveracing vehicles and is intended to compliment the servicemanual for your particular vehicle and/or engine.Therefore, to avoid any possible problems and/orheadaches, Mopar Performance Parts highly recommendsthat the proper service manual for your vehicle and/orengine be obtained.This performance book builds on the service manualinformation. Service manuals tell you how to take yourengine apart and put it back together; Jeep Engines-3rdEdition tells you how to modify your engine and increaseits performance. If you find that you need further assistanceor have any performance and/or modification questions youwould like to ask, you can contact Mopar PerformanceParts Technical Assistance.Mopar Performance Parts Technical AssistanceP.O. Box 597Oxford, Michigan 4837 1-05971-248-969-1690(fax) 1-248-969-3342Mopar Performance Parts hopes that this book satisfies anyneeds andlor desires that you have pertaining to your Jeepengine. We firmly believe that the performance tipsenclosed within these pages will prove to be trulyinvaluable to you.OVERVIEWThe primary emphasis of this book is on the 4.0L PowerTech In-Line 6 cylinder engine, the 4.2L In-Line 6 cylinderengine, the 2.5L Power Tech In-Line 4 cylinder engine, andthe 360 AMC V-8 engine. The 2.46L In-Line 4 cylinderengine is also covered, but because of the limited numberof performance parts available, it is discussed only briefly.We have also included a special chapter which highlightsour new all-aluminum 4.7L V-8 engine that debuted in1999. This new engine is certain to play an important rolein our future Jeep performance parts program. Magnumengines have their own book; therefore, they are notcovered in this book.Note: For complete Magnum V-10, V-8, V-6, and 4-cylinder engine information, refer to Magnum Engines(P4876668), as well as the appropriate service manual.The total amount of information we possess regarding all ofthese Jeep engines could have easily filled a book many timesthe size of this one, so we had to prioritize based on what ourracers and enthusiasts were requesting. If there is anything thatyou need to know or have questions about that is not coveredin this book or your service manual (or you simply can’t findthe answer), call Mopar Performance Parts TechnicalAssistance. They will be glad to help you any way they can.Jeep Engines-3rd Edition is divided into nine distinctchapters, as follows:Chapter 1: Jeep HistoryChapter 1 presents a brief history of Jeep, from the early1940s through today. However, because this chapter couldeasily fill an entire book of its own, not every event orperson involved in the Jeep program is discussed.Because so much information has already been publishedregarding the history of Jeep, we chose to include lesserknowninformation that could only come fromDaimlerChrysler. Photographs from deep within ourarchives highlight this history of arguably the mostsuccessful off-road vehicles ever built.Chapter 2: 2.5L Power Tech In-Line 4Chapter 2 is the most comprehensive and detaileddiscussion of the 2.5L Power Tech In-Line 4 cylinderengine ever published by DaimlerChrysler. Both race-onlyand dual purpose engine build-up strategies andperformance modifications are covered. The information ispresented along with hundreds of detailed figures,photographs, tables, and charts. When used in conjunctionwith the appropriate service manual, this chapter providesthe most up-to-date technical information on the 2.5Lengine available anywhere.Please note that much of the information contained inChapter 4 is generic to all Jeep performance engines.Therefore, in addition to this chapter, 2.5L engine ownersshould read Chapter 4 in its entirety. The appropriateservice manual should also be consulted.Chapter 3: 2.46L In-Line 4Chapter 3 presents a summary of selected features of the2.461, In-Line 4 cylinder engine. Due to the limited numberof performance parts available, the chapter is very brief.However, much of the information contained in Chapter 2applies directly to the 2.46L engine. In addition, much ofthe information contained in Chapter 4 is generic to all Jeepperformance engines. Therefore, in addition to this chapter,2.46L engine owners should read Chapters 2 and 4 in theirentirety. The appropriate service manual should also beconsulted.

4 MOPAR PERFORMANCE PARTSChapter 4: 4.0L Power Tech In-Line 6Chapter 4 is the centerpiece of Jeep Erzginrs-3rd Edition. Itis the most comprehensive and detailed discussion of the4.0L Power Tech In-Line 6 cylinder engine ever publishedby DaimlerChrysler. Both race-only and dual purposeengine build-up strategies and performance modificationsare covered. The information is presented along withhundreds of detailed figures, photographs, tables, andcharts. When used in conjunction with the appropriateservice manual, this chapter provides the most up-to-datetechnical information on the 4.0L engine availableanywhere. The authoritative source for all your 4.0L engineracing needs.Chapter 5: 4.2L In-Line 6Chapter 5 presents a summary of selected features of the 4.2Lengine, as well as a great deal of information on our popularmulti-point fuel injection conversion kit. Please note that muchof the information contained in Chapter 4 applies directly tothe 4.2L engine. Therefore, in addition to this chapter, 4.2Lengine owners should read Chapter 4 in its entirety. Theappropriate service manual should also be consulted.Chapter 6: 4.7L Power Tech V-8Chapter 6 highlights our new 4.7L Power Tech V-8 enginewhich was introduced in 1999. This technologicallyadvanced, all-aluminum powerplant represents the future ofDaimlerChrysler V-8 engine technology, and will play animportant part in our future Jeep performance partsdevelopment program.Due to the present lack of performance parts available for thisbrand-new engine, this chapter is brief. However, much of theinformation contained in Chapter 4 is generic to all Jeepperformance engines. Therefore, in addition to this chapter,4.7L V-8 engine owners should read Chapter 4 in its entirety.The appropriate service manual should also be consulted.Chapter 7: 360 AMC V-8Chapter 7 presents the most comprehensive and detaileddiscussion of the 360 AMC V-8 engine ever published byDaimlerChrysler. The information is presented along withdozens of detailed figures, photographs, tables, and charts,providing the most up-to-date technical information on the360 AMC V-8 engine available anywhere.Please note that much of the information contained inChapter 4 is generic to all Jeep performance engines.Therefore, in addition to this chapter, 360 AMC V-8 engineowners should read Chapter 4 in its entirety. Theappropriate service manual should also be consulted.For additional information on small block engineperformance modifications, refer to Srriall Block ‘A’Engines (P4876826).Chapter 8: Off-Roading and RacingChapter 8 is for everyone interested in off-roading andorracing their Jeep-powered vehicle. It contains informationon our ever-popular Jeep Jamboree and Camp Jeep events,as well as the basics of off-roading, how to get started inracing, safety, driving tips, performance engine packagerecommendations, and more. Chapter 8 also includes alisting of all the books and catalogs currently availablethrough Mopar Performance Parts, along with how andwhere to contact various DaimlerChrysler/Mopar sources.A must read for anyone interested in off-roading or racing aJeep-powered vehicle.Chapter 9: Additional InformationChapter 9 provides racing (mathematical) formulas and aMetric-to-English conversion table we thought might comein handy.

Chapter 1Jeep History

6 MOPAR PERFORMANCE PARTSWillys-Overland .......................................................................... 7Birthofthe"Quad" ........................................................................ 7AJeepBy Any OtherName .................................................................. 9CivilianLife ............................................................................ 10The Great Outdoors ....................................................................... 11BeyondtheQuad ......................................................................... 12Kaiser-Jeep .............................................................................. 13Birth of the Sport Utility Vehicle ............................................................. 15American Motors Corporation (AMC) ......................................................... 161984CherokeeRedefinestheSUV ........................................................... 18Enterthewrangler ........................................................................ 20Chrysler Corporation Buys AMC ............................................................. 21DaimlerChryslerandBeyond ................................................................ 23Additional Jeep Information ................................................................. 24. B ri .

JEEP HISTORY 7Jeep HistoryThe Jeep has evolvedfrom utilitarianmilitary vehicle, tosun-and-fun off-roader, topopular boulevard cruiser.It has been producedfor better than 50 years,exported worldwide andis arguably one of themost recognizable vehiclesever made. It is soughtafter by collectors and Walter I?fans, and widely regardedas a leader in thesporthtility and off-road markets. Compact andfull-size pickup trucks and SUVs have carriedhowcarry the Jeep nameplate, placing Jeep in many differentcategories in the industry. But were it not for theintervention of Walter Chrysler to aid thc Willys-Overland Company, and events relating to the SecondWorld War, the Jeep may never have existed.Willys-OverlandIn 1929, John North Willys sold his interest in the Toledo,Ohio-based Willys-Overland Company to become U.S.Ambassador to Poland. He returned to Willys-Overland thenext year as active head of the company. Unfortunately, hiscompany was now facing the same financial hardship thathad befallen many other companies following the 1929Stock Market Crash.By 1933, the Willys-Overland Company was in seriousfinancial trouble and might have shut down operationswere it not for the generosity of John North Willys’good friend, Walter P. Chrysler. Chrysler allowedWillys to use the Chrysler-created “floating power”principles for engine balance.“Floating power” had firstappeared in late 1932 onthe 1933 Plymouth SeriesPA, but had originallybeen developed by Chryslerengineers during the firstfew years of the company’sexistence. Floating powerreduced noise and vibrationby adding a third mainbearing to the crankshaft.A floating platform springsupported the front of theengine while rubber padsand bushings helped to absorb shock and eliminate themetal-on-metal contact at the rear. This innovation was oneof the earliest uses of rubber to reduce engine vibration, andallowed a four or six cylinder engine to maintain operatingsmoothness comparable to an eight cylinder engine.Chrysler (pictured here with his original1924 Chrjysler Six)Chrysler patented the floating power principle, but allowedWillys-Overland to use the system in the 1933-36 Willys 77.This was a small, four cylinder economy car whose saleshelped to keep Willys-Overland in business, as they had goneinto receivership in 1933. John North Willys died shortlyafter the production of the Willys 77 in 1937, at the age of 64.Birth of the “Quad”Dating back to World War I, the US. Army had been lookingfor a fast, lightweight all-terrain reconnaissance vehicle. Thehorse cavalry and sidecar motorcycles used before were nowantiquated. In addition, the Axis powers were beginning toscore victories in Europe and Northern Africa. The Armynow needed rapid development of this vehicle. In thesummer of 1940, automobile manufacturers were calledupon to produce a running prototype for such a vehicle in just49 days, and 70 production vehicles in 75 days.

8 MOPAR PERFORMANCE PARTSWillys-Overland MA (Prototype)Additionally, the Army had very tight specifications for their vehicle:Cooling System: Able to allow a sustained low speed without overheating the engineWeight: Approximately 1,300 lbs.Four-wheel-driveEngine (power): 85 Ib-ft of torqueTread: Not more than 47“Payload: 600 lbs.Wheelbase: Not more than 80”Ground Clearance: Minimum of 6.25“Manufacturers scrambled to put together mock-ups in effort to secure the contract. Many different vehicleswere submitted for approval ranging from a rolling platfcirm to heavily armored trucks. Due to theconstrictive 49-day development deadline, many manufacturers were eliminated. Ultimately, only Willys-Overland, the Bantam Car Company, and to an extent Ford Motor Company were involved in the project.The Bantam Car Company had worked to supply reconnaissance vehicles to the Army in the past andfelt able to meet the deadline (Willys-Overland requested additional time for completion). With the helpof engineer Karl Probst, Bantam developed a prototype which would later evolve into the Jeep. TheArmy forwarded plans for the Bantam prototype to Willys-Overland and Ford, who submitted theirown prototypes based on the Bantam design. Willys-Overland’s vehicle, the “Quad,” came in over theweight limits (at 2,400 pounds), due in large part to its more powerful engine, the “Go Devil.” The GoDevil had been tried and tested in the Willys Americar, and its torque rating of I 05 eclipsed that of theBantam and Ford engines at 83 and 85 respectively.With all three prototypes in hand, the Army ordered 1,500 vehicles from each of the manufacturers tobe field tested. Probably due to their pleasure with the power of the Go Devil, the Army raised theweight requirement to 2,160 pounds. This meant the Quad still needed to shed weight.Knowing that the engine, as heavy as it was, was the streng,th of the Quad, Willys-Overland decided tokeep the same engine under the hood and trim the weight elsewhere. The Quad was completelydisassembled, part by part, and evaluated for possible use of lighter materials. Bolts were shortened,material was trimmed, and the final product came in 7 oz. under the weight limit.Delivery of the first 4,500 vehicles (1,500 each from Willys-Overland, Bantam and Ford) came in June,1941. After careful study and testing, the Army decided to standardize one basic design. Based on itslower bid and Bantam’s shaky financial and manufacturing position, the Army awarded an all-ornothingcontract to Willys-Overland to produce 16,000 vehicles at the rate of 125 per day. Securing thecontract allowed continued business operation for Willys-Overland.As the war grew in intensity, the demand for the Quad also grew. Willys-Overland was ordered to turn overdesigns to Ford so they could produce 15,000 of the same vehicle. During World War 11, Willys-Overlandand Ford produced more than 600,000 Jeep vehicles, with Willys-Overland accounting for 330,000 units.

JEEP HISTORY 9A Jeep By Any Other Name ...Sometime after Willys-Overland began production of this all-purpose military vehicle, the name Jeepcame on board. At first, the vehicle was designated the MA, and later in 1941 the MB. The name Jeepbecame synonymous with it at that time and soon became a household word. Although no one reallyknows the name’s true origin for certain, everyone has a favorite theory.Some say the Jeep name came from the slurring of the acronym G.P. which was a Ford engineeringterm, “G’ for a government contract vehicle, “P’ for 80-inch wheelbase reconnaissance car. Anotherexplanation is that the name was used in Oklahoma as early as 1934. to designate a truck equipped withspecial equipment for drilling oil wells. Others claim the vehicle was called a Jeep in reference to thecharacter “Eugene the Jeep” in the 1936 Popeye comic strip by E.C. Edgar. Eugene the Jeep was asmall, impish looking animal that had the power to travel back and forth between dimensions and couldsolve all sorts of problems. Yet another version is that Irving “Red” Haussman, a Willys-Overland testdriver who tested the first pilot model picked up the Jeep name that some soldiers at Camp Holabirdhad been using. Shortly thereafter, Red gave a demonstration ride to a group of dignitaries inWashington, D.C. Among the group was Katherine Hillyer, a reporter for the Washington Daily Newswho wrote an article about the vehicle that was published in February, 1941 with the photo captionheadline, “Jeep Creeps Up Capitol Steps.” This was perhaps the first reference to the vehicles’ Jeepname by the media. In 1950, Willys-Overland obtained a U.S. Trademark Registration for the Jeeptrademark. There are currently over 1,100 registratlions for the Jeep@ trademark throughout the world.From their inception, Jeep vehicles have captured I he attention and admiration of people everywhere.They served their country in the war in Europe and the Pacific, helping to defeat the Axis powers andbring peace to the world. The strength and durability of the Jeep was soon realized. War correspondentErnie Pyle characterized the Jeep vehicle in this way. “I don’t think we could continue ... without the Jeep.It’s as faithful as a dog, as strong as a mule and agile as a goat. It constantly carries twice what it wasdesigned for and still keeps going.” Jeep vehicles were used by every division of the U.S. military, andlarge numbers were also shipped to the Allied Forces of Canada, Britain, Australia and New Zealand.Jeep vehicles became a vital part of all action on land. They were used to lay telephone communications,to transport the wounded, and as taxis to carry battle commanders, generals, prime ministers andpresidents. They were crated and freighted, broken down and built-up, modified, converted and movedabout by sea, rail, road and air. Transport crews could load a complete Jeep vehicle into a C-47 cargoplane to be easily and rapidly deployed on the front lines where they were needed most.Willys-Overland MB

10 MOPAR PERFORMANCE PARTSJeep in actionCivilian Life1946 Jeep CJ-2A (Prototype) 1953 Jeep CJ-3BAs early as 1942, long before the war in Europe or the Pacific came to an end, Willys-Overlandrecognized that the popular Jeep vehicles could serve the civilian market as well. The phrase “the Jeepin Civvies” often appeared in Willys-Overland magazine and newspaper ads published on thehomefront during and just after World War 1I:Other ads touted the heroic exploits of the Jeep vehiclesin the war, declaring “the power and the stamina of the versatile Jeep will serve many needs in the yearsof reconstruction ahead.” Willys-Overland began to promote the versatility of the Jeep vehicle as adelivery, work and recreational vehicle with quotes like “When I get back I’ll get a Jeep. It’ll make aswell delivery car,” “A Jeep can beat a team of horses all hollow,” and “Gee, wouldn’t it be swell tohave a Jeep at the lake after the war‘? Are you Jeep planning too?” The first civilian Jeep (CJ) vehicle,the CJ-2A, was produced in 1945. Advertisements proclaimed it to be “A Powerhouse on Wheels,”again selling it as a work vehicle for farmers and construction workers. The CJ-2A came with a tailgate,side-mounted spare, larger headlanips, an external fuel cap, chrome trim, and many more items that itsmilitary predecessors did not include. Intended primarily as a work vehicle, it maintained a spartanprofile including round military-type gauges and instrumentation.The postwar U.S. economy and industries afforded many opportunities for the Jeep. It was capable ofhauling workers and materials to remote worksites, through desert gullies, even knee-high water,further proving the Willys-Overland design. Farmers and ranchers found a multitude of agriculturaluses for the small, powerful 4x4. The rugged design of the CJ-2A was obvious. It had a durable enginewith good low-end torque, a rear axle designed for much larger trucks, and a transmission and transfercase sufficient to pull heavy loads through varying terrain...- --I n

JEEP HISTORY 11Perhaps one of the most common and recognizable uses for the Jeep was U.S. mail delivery. Postalofficials, impressed by the performance of Jeeps during the war, decided to harness that strength for maildelivery. These strong, agile vehicles could stand up to the rigors of delivering the mail in any weatherand on any road. The postal service purchased both left and right-hand drive Jeeps for their carriers.Unlike previous postal vehicles, which were painted a drab shade of olive green, Jeeps and other vehiclespurchased in the 1950s were painted red, white, and blue. The PostaUDispatch Jeep was made in twobasic models, the DJ-3A and the DJ-5. The DJ-3A ‘was a flat fender Jeep similar to the CJ model exceptit was two-wheel-drive and had a side sliding door for ease of loading/unloading. It was produced from1956 until 1965 (manufactured by Kaiser-Jeep who1 purchased Willys-Overland in 1953). The DJ-5 wasintroduced in 1965 which is the postal Jeep most people are familiar with today. Also produced from1965- 1968 was a long version, the DJ-6. The DJ-5 vvas made by Jeep into the early 1970s and productioncontinued under AM General (AMC purchased Kaiser-Jeep in 1970). For over 40 years Postal workershave delivered mail through “rain, sleet and snow” with the aid of their trusty Jeep.The Great OutdoorsAmong the public attracted to Jeep 4x4s were a growing number of outdoor enthusiasts. Alreadyproven capable of handling the outdoors, the CJ-2A and surplus MBs brought primitive back countryfishing, hunting, rock collecting and exploring easily within reach. They gave families access to remotecamping and numerous other outdoor activities. There was a zest for life in postwar Americacontrasting the lean Depression and World War I1 years. This created a greater interest in recreation.Additionally, fuel costs were low, and the cost of liiving was relatively inexpensive. The Jeep provideda means for those weekend getaways.The recreation aspect caught on quickly and has flourished. Today, there are many organizations whichhost activities and events for Jeep owners, fans, and aficionados. The Camp Jeep and Jeep Jamboreegroups for example, set up off-roading events, car shows, picnics, clinics, etc., to bring together Jeeplovers worldwide. These events are wildly popular and attended religiously by some owners.But Jeep’s growing popularity was not limited to the U.S. The popular 4x4 was sought by manyworldwide no doubt due to its high visibility in wartime activities. It maintains a healthy worldwideappeal today, and there exist many clubs, societies, and groups dedicated to ownership, history, racing,etc., of the Jeep.Getting a way!

12 MOPAR PERFORMANCE PARTSBeyond the Quad1948-51 Willys-Overland JeepsterIn 1946, Willys-Overland introduced the auto industry’s first all-steel station wagon and sedan deliveryvehicles. These two-wheel-drive vehicles featured seven-passenger capacity and reached a top speed of65 mph. When four-wheel-drive and a Willys six cylinder engine were added in 1949, the Jeep All-Steel Station Wagon truly became the forerunner of the modern-day Jeep Cherokee. The new Jeepstation wagon had pressed-steel framing and three-tone paintwork which simulated the natural woodlook. It used the Jeep running gear and MB-style front sheel. metal and was designed to compete againstthe “real” wood wagons still being manufactured by Detroit’s Big Three. The new vehicle chassis wasalso available in a sedan delivery truck. Four-wheel-drive would become available in these models in1949 along with the 148 cubic-inch “Lightning” six cylinder engine.From 1948- I95 I , Willys-Overland produced probably its most stylish vehicle to that point - theJeepster VJ-2 and VJ-3. A two door, two-wheel-drive, low-slung convertible, the Jeepster was uniquein styling to other American vehicles of the time. Unfortunately, the Jeepster was also underpoweredwith a four cylinder engine, and less desirable to the public without four-wheel-drive. It posted onlymodest sales and was never able to find a market niche. Popular opinion holds that if a larger sixcylinder engine had been offered, the Jeepster may well have survived longer. Interestingly enough, asimilar version was released during the sixties under Kaiser ownership, and enjoyed good success.The CJ model was updated in 1953, becoming the CJ-3B. It was the first Jeep CJ with noticeable bodychanges from its military predecessor. It had a taller body grille and hood to accommodate the newHurricane F-Head four cylinder engine. Although it had the same displacement as the original “GoDevil” engine, the “Hurricane” featured a revised valve train. It first appeared in the 1951 M38A1military model. The CJ-3B remained in production until 1968, and a total of 155,494 weremanufactured in the U.S.

JEEP HISTORY 131953 Jeep CJ-3BKaiser-JeepIn April, 1951, Willys-Overland was sold to the H[enry J. Kaiser interests for $60 million. The namewas changed to Willys Motors. This would be the beginning of Kaiser’s influence on the future of 4WDsport utility as the company began extensive research and development that would seek to broaden Jeepproduct appeal in this area.Kaiser introduced the 1955 CJ-5 whose production and popularity would reach all the way into the1980s. It was slightly longer and wider than the Jeep CJ-3B, as it had an increased wheelbase. Constantimprovements in power plants, axles, transmissims and seating comfort made the Jeep CJ-5 the idealvehicle for the public’s increasing interest in off-road activities. Although very similar to the CJ-2A thatit replaced, it featured softer styling lines, including rounded body contours.Model year 1956 saw the introduction of the CJ-6 work truck. Though there were many fans of the CJ-5,it was limited by its 81 inch wheelbase. The CJ-6 maintained the CJ-5 powertrain (F-head 134), but hada wheelbase which was a full 20 inches longer, and ,sheetmetal inserts ahead of the rear wheel openings.This made it even more attractive as a work vehicle. Kaiser continued to produce both models mirroringpowertrain changes and upgrades.For 1957, Kaiser released two cab-forward control models, the FC150, and the FC170. Styling wassimilar between the two, but the 170 was slightly larger with a longer wheelbase. It also featured a sixcylinder engine. The 150 received the F-head 134 four cylinder. The powertrains were spun off fromearlier Jeep models, but styling was unique and was aimed at the utility market. Unfortunately, bothmodels yielded only modest customer interest and were soon discontinued.Throughout the fifties production continued on the “Hurricane” engine which was then the mosteconomical and powerful engine in its class. This was the standard engine on the wagon with the“Lightning,” the optional V-6.Also during this time, Kaiser expanded the production Jeep CJ into a truly international symbol. In the16 years of Kaiser ownership, manufacturing facilities were established in some 30 foreign countries,and Jeep vehicles were marketed in more than 150 countries around the world.By March 1963, Kaiser saw fit to change the company name to Kaiser-Jeep. For that same model yearKaiser-Jeep released its first full-sized vehicles.

14 MOPAR PERFORMANCE PARTS1956 Jeep CJ-61949 Jeep All-Steel Station WagonT--I n

JEEP HISTORY 15Birth of the Sport Utility VehicleIn anticipation of burgeoning growth in the crossover four-wheel-drive truck market, Kaiser-Jeep madebold advances in this area. Targeting rural and suburban markets, they introduced the full size GladiatorJ-trucks and Wagoneers. These models were built to the wheelbase specifications of other U.S. truckmanufacturers. This was a major departure from the lighter, smaller vehicles produced under Willys-Overland and Willys Motors.The Wagoneer, powered by the first modern, mass-produced, overhead-cam six cylinder truck engine(known as the “Tornado-OHC” six), could also be had with an industry-first automatic transmission ona four-wheel-drive vehicle and independent front suspension. A larger V-8 engine produced byAmerican Motors Corporation (AMC) was also available by 1965. The Wagoneer was offered in twoand four-wheel-drive versions. This vehicle was bigger than the station wagon and the first of whatcould properly be called a sport-utility vehicle. The second-generation Wagoneer also included a SuperWagoneer Station Wagon that featured three-tone body striping, vinyl roof, chrome roof rack, fullwheel hubcaps and white-walled tires. It came with four-wheel-drive and power supplied from a 327cubic inch V-8 engine, and, said Kaiser-Jeep, “conslituted a unique and dramatic approach to the stationwagon market ... designed for the prestige buyer who is rapidly becoming aware of the advantages offour-wheel-drive. While being the ultimate in detailed elegance, the new vehicle still has all thetraditional versatility and ability of Jeep vehicles to go on or off-road.’’This, along with the J-series “Gladiator” pickup, was the first fresh non-military design from thecompany since the all-steel station wagon and sporty two-wheel-drive Jeepster. Both the Wagoneer andthe Gladiator found a huge market with construction, agricultural and military buyers, and evolved intoa niche with everyday retail buyers who wanted a good looking all-terrain vehicle for fishing, skiing,hunting, hauling and off-highway adventuring.Ford, Chevrolet, and Dodge lagged far behind Jeep in this market, unable to offer any directcompetition until the late sixties. At the time, they only offered cumbersome work-oriented 4x4pickups, and Chevrolet’s bland Suburban. Kaiser-Jeep had advanced in all areas of design with theWagoneer and Gladiator. Power accessory options never seen on a “truck” were now available, as wellas luxury appointments and a high style factor.In the fall of 1965, the new “Dauntless” V-6 engine was introduced as an option on both the 81-inchwheelbase CJ-5 and 101-inch wheelbase CJ-6. The (55 horsepower engine almost doubled the output ofthe standard Hurricane four cylinder engine. It was the first time a Jeep CJ could be equipped with a V-6,but would be only the beginning of available six cylinder engines that would come in the years to follow.1972 Jeep Commando

16 MOPAR PERFORMANCE PARTS1989 Jeep Grand Wagoneer LimitedFor 1967, the Jeepster was reintroduced, and (as mentioned earlier) enjoyed much success. The timingwas right for a small sport-utility vehicle, as other manufacturers were shifting focus to this newmarket. The Jeepster was built on the CJ-6 wheelbase and offered four-wheel-drive and the DauntlessV-6 (rated at an impressive 160 hp).The original Jeep had always enjoyed little or no direct competition until International produced thefirst Scout model, and Ford produced its Bronco in the mid--sixties. Both of these models however wereconsiderably more expensive, so Jeep sales were not severlAy impacted.Similarly, the Wagoneer and Gladiator models were alone in their niche market until GM producedupscale versions of the Suburban, Blazer and Jimmy models in 1969. Chrysler would produce theRamcharger and Trailduster, but not until 1974.American Motors Corporation (AMC)In 1970, after two decades of growth and international expansion, Kaiser-Jeep was bought by AMC.Recognizing the value of the Jeep trademark, AMC created a division for it-the Jeep Corporation.They also split civilian and military vehicle production, proving to be a wise decision as four-wheeldrivevehicles became more popular than ever in the civilian market. By 1978, total Jeep vehicleproduction was up to 600 vehicles a day, over three times lwhat it had been at the start of the decade.AMC’s connection to Jeep dates back to 1965 when they produced engines for Kaiser-Jeep (the 327cubic inch V-8 and the 232 cubic inch in-line six). They would go on to eliminate the Dauntless V-6and previously available GM 350 cubic inch V-8 from their lineup. In their place would come a 258cubic inch (4.2L) in-line 6, and 304 and 360 cubic inch V-8s.Through 1971, AMC/Jeep models remained largely unchanged from Kaiser designs. However, AMCengineering changes appeared on 1972 models as shifts in engine technology and styling changes wereimplemented to meet marketing goals.AMC chose to market the CJ and Commando (Jeepster) vehicles from a strength and durability angleusing tag lines such as “with the guts to come on stronger than ever,” and “if a new Jeep vehicle can’ttake you there, maybe you ought to think twice about going.” All Jeep CJs came equipped with AMCbuiltengines, and all were available with 304 or 360 cubic inch V-8 engines. More stringent emissionsstandards in 1972, along with the availability of high torque in-line six engines, ended production ofthe F-head 134. AMC also equipped both the CJ-5 and CJ-6 with heavier axles, brawnier brakes, awider track, and higher-capacity heater/defrosters. Of particular interest was the CJ-5 “Renegade”package. It boasted a standard 304 cubic inch V-8, rollbar, full gauges, and identification trim. It alsocame with its own tag line -“Jeep-The toughest four-letter word on wheels.”

-r -1 r7JEEP HISTORY 17The Wagoneer continued to endure competition from Ford and GM and maintain a sizeable hold on thesport-utility market. Trim and accessory optionis were on par with luxury automobiles, and theWagoneer’s reputation garnered many repeat buyers. In 1972, the Wagoneer was outfitted with thelargest standard engine in the 4WD station wagon field -a 258 cubic-inch, AMC-built OHV 6-cylinder.In 1974, the Cherokee became the two-door version of the Wagoneer, and there was also the largerCustom Wagoneer. A four-door model of the Cherokee would be available by 1977. Also introducedto the Wagoneer line during the 1970s was Quadra-Traco, an automatic full-time 4WD system. Thiswas another industry first.In 1976, 35 years after the production of the original Jeep, AMC introduced the seventh generation ofthe civilian Jeep, the CJ-7. For the first time, the CJ-7 offered an optional molded plastic top and steeldoors and came standard with a fully boxed frame to bolster chassis strength.The full size J-trucks progressed during this time iiS well to stay competitive with the Big Three. The401 cubic inch V-8 was offered in 1976. Prior to that engine availability ranged from the 232 cubic inchin-line six up to the 360 cubic inch V-8. The big 401 was healthy on torque and horsepower and easilykept pace with the other manufacturer’s offerings of the time.By the mid-seventies, the family of big V-8s was available across the entire Jeep line. Two and fourbarrel carburetor options were also available, giving the customer a choice based on application ordesire. However this availability, would be short-lived. Toward the late-seventies, emissionsregulations became considerably stricter, rendering large displacement engines impractical to produce.The 401 was discontinued, and heavy duty/towing applications had to be reconfigured with 360 cubicengines. In addition to this, taller rear axle ratios were used to meet EPA/CAFE standards.Subsequently, full size truck performance diminished across the board with all manufacturers.During this time, AMC released the CJ-8 Scrambler for the 1981 model year. It was a small pickuptruck based on the CJ-7, and would compete against the new compact pickups being produced by GMand various foreign automakers.Full-size trucks and sport-utilities were not the only victims of the new emissions regulations. In 1982,AMC was forced to drop the 304 cubic inch V-8 option for CJ models as they were not able to achieveacceptable performance levels under the new regulations.With all the new restrictions in place, light truck engineering was heavily impacted. Across the board,manufacturers had to utilize weight-saving body panels, lighter powertrain components and taller rearaxle ratios. This resulted in lowered engine performance and durability. The lighter parts met therestrictions, but did not last in service. The “rough, powerful” image of the American truck suffereddamage, and the late-seventies/early eighties proved to be an awkward time for US. truck makers.1988 Jeep Cherokee Limited

18 MOPAR PERFORMANCE PARTSBeyond the weight-saving measures, and low-performance enginedgearing CJ models suffered further.The CJ-5, noted for its off-road prowess and tight maneuverability, came under media scrutiny duringthe 1983 model year. Initially designed for all-terrain use, the CJ-5 had a high overall ground clearanceand center of gravity. Additionally, its short wheelbase offered a good tight turning radius-allconsidered desirable in an off-road situation. During a period of impassioned consumer advocacy andpublic resentment toward American automobiles and manufacturers, the CJ- 5 was attacked for allegedrollover vulnerability. While the allegations were never reasonably proven, AMC chose not to becomeinvolved in a large-scale, high-visibility legal battle over the issue. Instead, they opted to discontinue theCJ-5, and continue production of the longer wheelbase, lower center of gravity CJ-7 and CJ-8 models.1984 Cherokee Redefines the SUVA market research program undertaken by American Motors Corporation culminated in the birth of themodem Cherokee. Their research found that future markets lay in compact sport-utility vehicles. AMCthen invested $250 million into the design and production of the new compact Cherokee and Wagoneersport wagons for the 1984 model year. They were introduced to the press in late 1983 and immediatelyreceived rave reviews. Additionally, despite the backlash directed toward the now-discontinued CJ-5, thenew Cherokee exceeded all sales and marketing expectations. In retrospect, AMC’s decision to abandonthe CJ-S proved wise. Further controversy would likely have detracted from the new Cherokee. Instead,despite the impassioned pleas of hard-core back country four wheelers who protested the CJ-S’spassing, hordes of recently converted four wheelers rushed to buy the new compact wagon.The new Cherokee was a unique and revolutionary vehicle. It measured in 21 inches shorter, 6 inchesnarrower, 4 inches lower and weighed 1,000 pounds less than the Jeep Wagoneer (SJ) first introducedin 1962. It was the only compact sport utility to offer two-door and four-door models at that time. Itwas built as a uniframe body rather than using a traditional chassis and frame construction. Differentfour-wheel-drive systems, including Command-Traco and Selec-Traco, offered either part-time or fulltimefour-wheel traction. Various interior and exterior styling, comfort and off-road performancepackages were also offered. The model line continued largely unchanged into the 199Os, although manyrevisions and improvements were made during that time.

JEEP HISTORY 19Interior appointments were on par with the new competition (GM’s S Blazer and Ford’s Bronco 11). TheCherokee was ultimately named “4x4 of the Year” by three magazines in 1984.Consumers immediately liked the new package, especially the four doors. American tastes andpurchasing trends had changed and were now geared toward a more practical vehicle. The awkward rearseat entry was a complaint of the two door utility models for some time. With four doors, the Cherokeeallowed for easier access, and supplanted many family station wagons. Four-wheel-drive was alsopopular for its perceived added safety and ability to better navigate poor roads and winter conditions.The Cherokee’s standard powerplant was the 150 cubic inch in-line four cylinder. This engine had beenused previously in CJ models. Given the Cherokee’s relatively light curb weight of around 3,000pounds, this engine offered decent performance. The optional 2.8L V-6 engine offered modesthorsepower gains, but with a negative trade-off.The V-6 was plagued with a marginal performance carburetor and a poorly designed rear main seal thatwas prone to leaks. Worse than the leak, the cure for the main seal involved engine removal and blockmachining to properly seat the upgraded seal. Even with these setbacks, Cherokee sales were still high,and it became AMC’s premier model. Recognizing the need for better performance and to stay on parwith the competition’s growing powerplants, a 4.01- in-line six cylinder engine was made available forthe 1987 Cherokee.A direct descendant of the carbureted 4.2L in-line six introduced in 197 1, the new 4.0L engine offeredmulti-point fuel injection and produced a healthy 177 horsepower. AMC also offered this powerplantin their new for 1987 Comanche pickup. Based on the Cherokee, it was built on the same platform. Thepowerful six cylinder proved to be both an engineering and marketing success for AMC. Salesincreased and AMC claimed a majority market share from GM and Ford.The Cherokee and Comanche had also gained wide popularity in racing circles. As part of JeepMotorsports, the two vehicles (and to a limited extent the CJ models) participated in both on and offroadracing events. Jeep vehicles were posting wins in thousand mile long desert Baja-typecompetitions, as well as 24-hour endurance challenges. Of course, it might be expected for Jeep to havea good showing in these events because of their inherent off-road design, but they performed well onstreet courses as well.1989 Jeep Wagoneer Limited.* . ..

20 MOPAR PERFORMANCE PARTS1987 Jeep WranglerEnter The WranglerThe 1987 model year also saw the redesign of the CJ model. While the growing market for compact4WD vehicles still sought the utilitarian virtues of the Jeep CJ series, consumers also were seekingmore of the “creature features” associated with the typical passenger car. AMC responded to thismarket demand by discontinuing the CJ series and by introducing the 1987 Jeep Wrangler (YJ). TheWrangler had nearly the same wheelbase of the CJ-7 and shared its familiar open-body profile.Similarities to the CJ ended there, as the Wrangler contained few common parts with its famouspredecessor. In fact, mechanically, the Wrangler had more in common with the Cherokee (XJ) than theCJ. Due to the CJ-5 controversy, the Wrangler was given a wider stance and a lower center of gravity.This caused low ground clearance and inhibited trail use to a degree, but did not seriously impact sales.With the Wrangler, AMC was able to improve the comfort, ride quality and appearance whilepreserving the durability and unrivaled off-road prowess of the Jeep CJ model. It now appealed to anentirely new buyer. Relying on the CJ heritage and off-road image, the new Wrangler was still a backcountry rover, but now also an urban sportster. A typical Wrangler, while still off-road capable, spentmore time on the highway and in the city. It could serve all transportation needs, and found a new nichewith active youthful customers. Like the Cherokee, Wrangler had a long list of options offering morethan the austere stark style of the earlier CJs. Its upscale interior, solid doors, full instrumentation, andfull power options reflected the tastes of the modern Jeep buyer.

JEEP HISTORY 21Chrysler Corporation Buys AMCWhile the 1987 model year saw changes in AMC's, vehicle lineup, the 1987 calendar year saw greaterchanges at the corporate level. Jeep trucks were thse success story at AMC. Despite awkward mergersand partnerships with foreign automakers, the Jeep division provided great profit and worldwiderecognition. On August 5, 1987, a little more than a year after the introduction of the Wrangler,American Motors Corporation was sold to Chrysler Corporation and the popular Jeep brand became apart of the JeepEagle Division of Chrysler. Jeep vehicles now benefited from a worldwide dealernetwork and support, as well as a highly advanced parts network (Mopar).Ironically, if Walter P. Chrysler had not allowed John North Willys the use of floating power to build hisWillys 77, Willys-Overland probably would have folded and AMC would not have had Jeep to buy in 1970.Without Jeep, perhaps there would have been no incentive for Chrysler Corporation to purchase AMC.The Jeep models underwent minor changes and revisions under Chrysler in the late eighties and earlynineties. The Wrangler benefited from the large 4.0L in-line six as an option, giving it one of the mostpowerful engines in its class. New interior and exterior trim levels were offered. As a result, Jeep salesremained steady under the new ownership.In the early nineties Jeep engineers developed ii right-hand drive version of the Cherokee. Thisproduced a model that made it possible to sell to domestic mail fleets and to export markets in Britain,Australia and Japan. Jeep engineers had one more model to add to this winning new range: the GrandWagoneer Limited. It was introduced as the ultimate luxury performance model, powered by anelectronically fuel-injected 360 cubic inch V-8 engine. But with the introduction of the 1993 GrandCherokee, the Grand Wagoneer Limited was discontinued.I1988 Jeep ComancheI

T -1722 MOPAR PERFORMANCE PARTSLoosely based on the modem Cherokee (XJ), the Grand Cherokee was slightly larger, with a more ruggedappearance. A practical four-door model, it offered varying trim levels, powertrain options, and fourwheel-driveconfigurations. It also inherited the SUV- pioneering uniframe construction. The 4.0L sixcylinder remained the standard powerplant, with a large displacement 5.2L V-8 as an option. A 5.9L V-8 was even offered as a limited edition, giving the Grand Cherokee loads of performance and horsepower.Wrangler and Cherokee styling were redesigned and refined for the 1997 model year (production onthe 1996 Wrangler was cancelled due to the reworking). As a result, Petersen’s 4-Wheel & Off-Roadnamed Wrangler its “4x4 of the Year,” and Four Wheeler Magazine named Cherokee its “Four Wheelerof the Year” in 1997.The current (1999) Grand Cherokee has received some upgrades as well. Subtle exterior stylingchanges give it a more rounded, smooth look. A new V-8 engine, the 4.7L Power Tech, offers increaseddurability, greater horsepower, faster acceleration, and better fuel economy increased durability than its5.2L predecessor. It even weighs less by approximately 54 pounds. New steering linkage, a newsteering gear, and optimized steering geometry improve ride and handling and afford more precisesteering response and improved vehicle control.I

JEEP HISTORY 231994 Jeep Grand Cherokee1999 Jeep Grand CherokeeDaimlerChrysler and BeyondIn 1998, Chrysler Corporation merged with Daimler-Benz to become DaimlerChrysler. It’s difficult toguess what direction Jeep models may head towiird in the future, but they continue to be sales andindustry leaders. The current versions combine better than 50 years of engineering and technologicalexcellence with classic styling and practicality. Whatever the future may hold, it’s safe to say that Jeep’splace in automotive history has already been assured... ...

24 MOPAR PERFORMANCE PARTSAdditional Jeep InformationFor more information on Jeep history, as well as information helpful when shopping for your first (orsecond?) Jeep, visit the Jeep website at www.jeepunpaved.com or consult the following publication:Jeep Owner’s BibleAutomotive writer Moses Ludel has assembled a 335 page ‘bible’ of Jeep information, includingeverything from the history and development of the legendary Jeep, to tune-up, maintenance andrepair procedures. Ludel’s manual also covers high performance tuning and off-road driving tips.P524943 1 Jeep Owner :s BibleJeep Commander Concept Vehicle1998 Jeep Wrangler Sahara

Chapter 22.5L Power Tech In=Line 4

26 MOPAR PERFORMANCE PARTSIntroduction ............................................................................. 27Block .................................................................................. 29Crankshaft ..... ... ...... 33Connecting Rods ......................................................................... 42PistonsandRings ......................................................................... 45CylinderHead ........................................................................... 53Camshaft and Valve Gear ................................................ 57Oiling System ........ ................................................ 70Fuel Delivery and Fuel Injection System ....................................................... 76Exhaustsystem .......................................................................... 84Ignition System . ........... 87EngineAssembly ......................................................................... 93...l- - T ’ T.

~~2.5L POWER TECH IN-LINE 4 (INTRODUCTION) 27Note: The following procedures for the 2.5L Power Tech In-Line 4 cylinder engine are intended to be performed invehicle,on a dynamometer, or as an individual change/modilication.In addition to the information contained in this chapter, much of the information contained in Chapter 4, 4.0L Power TechIn-Line 6, is generic to all Jeep engines (including the 2.5L). Therefore, in addition to this chapter, we highly recommendthat all 2.5L engine owners read Chapter 4 in its entirety.For additional 2.5L engine general service information, refer to the proper service manual.IntroductionThe Jeep 2.5 liter (150 cubic inch displacement) engine is acast iron, overhead valve, In-Line 4 cylinder design. It has astandard bore and stroke of 98.45 x 80.97 mm (3.876 x3. 188"), and a 9.2:l compression ratio.The 2.5L has a liquid cooled, forced circulation cooling systemwith a capacity of 9.5L (10 quarts-MJKJ vehicles); 8.5L (9quarts - YJ vehicles). The cylinders are numbered 1 through 4from front to rear. The firing order is 1-3-4-2 (Figure 2-1).For more information, refer to 2.5L Engine Specifications,'Engine Assembly' section of this chapter.2.5L Engine General SpecificationsNote: The following information has been reprinted fromthe 1999 Jeep Wrangler Service Manual.Engine Type ........... In-Line 4-cylinderBore and Stroke ........ 98.4 x 81.0 mm (3.88 x 3.19")Displacement .......... 2.5L (1 50 CID)Compression Ratio ...... 9.1 :IFiring Order ........... 1-3-4-2Lubrication ............ Pressure Feed-FullFlow FiltrationCooling System ........ Liquid Cooled-ForcedCirculationCylinder Block ......... Cast IronCrankshaft. ............ Cast Nodular IronCylinder Head. ......... Cast IronCamshaft ............. Cast IronPistons ............... Aluminum AlloyCombustion Chamber .... Dual-QuenchConnecting rods ........ Cast Malleable Iron.* ...

28 MOPAR PERFORMANCE PARTS

Flywheel Attaching PackageBolts required to attach flywheel and clutch to new engineassembly. Includes 6 flywheel bolts, 6 clutch bolts, and apilot bearing.P4529667Flywheel attaching package.Drive Plate Attaching PackageBolts required to attach torque converter drive plate to thecrankshaft and to attach the torque converter to the driveplate. Includes 6 flywheel bolts and 4 torque converter bolts.P4529249Drive plate attaching package.Block2.5L POWER TECH IN-LINE 4 (BLOCK) 299. Remove the camshaft (Figure 2-6).10. Remove the oil pan, gaskets and scals.11. Remove the timing chain tensioner (Figure 2-7).12. Remove the front and rear oil galley plugs.13. Remove the connecting rods and the pistons. Removethe connecting rod and piston assemblies through thetop of the cylinder bores14. Remove the crankshaft.FIRING ORDER:1 3 4 2aocKwisEROTATIONJ9009-20Figure 2 - 2Figure 2 - 1DISASSEMBLY AND ASSEMBLY PROCEDURESShort Block DisassemblyTIMINGCASE\ COVERCAMSHAFT/1.2.3.4.5.6.7.8.Drain the engine oil. Remove and discard the oil filter.Remove the water pump and distributor from thecylinder block.Remove the vibration damper using vibration damperremoval tool (Figure 2-2).Remove the timing case cover (Figure 2-3) and layupside down.Position a drift punch into the slot (Figure 2-4) in theback of the cover and tap the old seal out.Remove the timing chain bumper (Figure 2-4).Remove the oil slinger from the crankshaft.Remove the camshaft retaining bolt and remove thesprockets and chain as an assembly (Figure 2-5).Figure 2 - 3..

~~30 MOPAR PERFORMANCE PARTSS L ~ T J8909-116/TIMING CHAINTENSIONER\J8909-117Figure 2 - 4Figure 2 - 7CleaningCAMSHAFTTThoroughly clean the oil pan and engine block gasketsurfaces.Use compressed air to clean out:The galley at the oil filter adapter hole, the filter bypasshole (Figure 2-8)The front (Figure 2-9) and rear (Figure 2-10) oilgalley holesThe feed holes for the crankshaft main bearingsJ9009-26Once the block has been completely cleaned, apply LoctitePST pipe sealant with Teflon 592 to the threads of the oilgalley plugs and tighten them to 41 Nom (30 ft-lbs) torque.Figure 2 - 5FILTER BYPASSHOLEOIL FI'LTERADAPTOR HOLE J9009-50CRAN'KSHAFTJ9009-31Figure 2 - 8Figure 2 - 6

T --I ri2.5L POWER TECH IN-LINE 4 (BLOCK) 31Figure 2 - 9OILHOLEJ9009-514. Determine taper by subtracting the smaller diameterfrom the larger diameter.5.Rotate measuring device 90" and repeat steps above.6. Determine out-of-roundness by comparing thedifference between each measurement.7. If cylinder bore taper does not exceed 0.025 mm(0.001") and out-of-roundness does not exceed 0.025mm (0.001"), the cylinder bore can be honed. If thecylinder bore taper or out-of-round condition exceedsthese maximum limits, the cylinder must be bored andthen honed to accept an oversize piston. A slightamount of taper always exists in the cylinder bore afterthe engine has been in use for a period of time.10mm -(3/8 IN.)-MIDDLEwBORE13/8 10mm OF 1N.I-.-. - .USE FORSIZINGPISTONww9509-27Figure 2 - 11Cylinder Bore ReconditioningFigure 2 - 10Cylinder Bore Measurement1. It is mandatory to use a dial bore gauge to measureeach cylinder bore diameter (Figure 2-1 1). To correctlyselect the proper size piston, a cylinder bore gaugecapable of reading in 0.003 mm (.0001")INCREMENTS is required. If a bore gauge is notavailable, DO NOT use an inside micrometer.2.3.Measure the inside diameter of the cylinder bore atthree levels below top of bore. Start perpendicular(across or at 90 degrees) to the axis of the crankshaftand then take two additional readings.Measure the cylinder bore diameter crosswise to thecylinder block near the top of the bore. Repeat themeasurement near the middle of the bore, then repeatthe measurement near the bottom of the bore.Caution: DO NOT use rigid type hones to removecylinder wall glaze.1. Use an expanding type hone on the cylinder bore toremove glaze for faster piston ring seating. Move thehone down and up (stroke) at sufficient speed to producea uniform 60" angle crosshatch pattern on the cylinderwalls. DO NOT use more than ten (10) strokes percylinder (one stroke is one down-and-up movement).2.3.Scrub the cylinder bores clean with a wlution of hotwater and detergent.Immediately apply light engine oil to the cylinderwalls. Wipe with clean, lint-free cloth.

T "7732 MOPAR PERFORMANCE PARTSShort Block Assembly1. Install the crankshaft.2. Install the connecting rods and the pistons through thetop of the cylinder bores.3.4.Install the front and rear oil galley plugs.Install the timing chain tensioner.5. Install the camshaft.6.7.8.9.Install the sprockets and chain as an assembly.Install the oil slinger to the crankshaft.Install the timing chain bumper.Install the timing case cover seal.IO. Install the timing case cover.1 1. Install the oil pan gasket and oil pan.12. Install the vibration damper.13. Install the water pump. Tighten the mounting bolts to31 Nom (270 in-lbs) torque.14. Remove the distributor from the cylinder block.15. Lubricate the oil filter seal with clean engine oil.Tighten oil filter to 18 Nem (1 3 ft-lbs) torque.16. Install the engine into the vehicle.17. Fill the engine with clean lubrication oil.18. Fill the cooling system.

~T --TriINTRODUCTIONThe 2.5L engine uses a cast nodular iron crankshaft thatrotates within five (5) main bearings and has a standardbore and stroke of 98.45 x 80.97 mm (3.876 x 3.188").Crankshaft rotation is clockwise, when viewed from thefront of the engine.The crankshaft has a main bearing journal diameter of63.489-63.502 mm (2.4996-2.5001"), and main bearingjournal widths of (No. 1) 27.58-27.89 mm (1.086-1.098"),(No. 2) 32.28-32.33 mm (1.27 1-1.273"), and (Nos. 3,4 and5) 30.02-30.18 mm (1.182-1.188").The crankshaft has a connecting rod journal diameter of53.17-53.23 mm (2.0934-2.0955") and a connecting rodjournal width of 27.18-27.33 mm (1.070- 1.076").For more crankshaft specifications, refer to 2.5L EngineSpecifications, 'Engine Assembly' section of this chapter.~~High Performance CrankshaftFactory engineered high performance crankshaft iscarefully inspected and magna-fluxed. Includes bearings.Stock stroke length. For 2.5L engine only.P4529646High performance crankshaft.C ran ks haf t2.5L POWER TECH IN-LINE 4 (CRANKSHAFT) 338.Bend the cotter pin as illustrated to fabricate the tool(Figure 2-13). With the cotter pin tool in place, rotatethe crankshaft so that the upper bearing insert willrotate in the direction of its locking tab.Note: Because there is no hole in the No. 2 mainjournal, use a tongue depressor or similar soft-facedtool to remove the bearing insert (Figure 2-1 3). Aftermoving the insert approximately 25 mm (I"), removeit by applying pressure under the tab.Using the same procedure just described, remove theremaining bearing inserts (one at a time) for inspection.CONNECTINGROD JOURNALCRANKSHAFT MAIN BEARINGSStreet Performance BearingsVMAIN BEARING CAPSJ8909-144These production style main bearings are made from AL6aluminum. Package includes complete engine set.Standard size. For 2.5L engine only.IFigure 2 - 12P4529648Street performance bearings.CollEuIRemoval1.Disconnect the battery negative cable.I2. Remove the spark plugs.3. Raise the vehicle.4.Remove the oil pan and oil pump as outlined in the'Oiling System' section of this chapter.5.Remove only one main bearing cap and lower insert ata time (Figure 2- 12).6.Remove the lower insert from the bearing cap.7.Remove the upper insert by loosening (DO NOTremove) all of the other bearing caps and inserting asmall cotter pin tool in the crankshaft journal oil hole.IFigure 2 - 13

34 MOPAR PERFORMANCE PARTSInspection0 Wipe inserts clean and inspect for abnormal wearpatterns and for metal or other foreign materialimbedded in the lining. Normal main bearing insertwear patterns are shown in Figure 2-14.000Note: If any of the crankshaft journals are scored,remove the engine for crankshaft repair.Inspect the back of the inserts for fractures, scrapings,or irregular wear patterns.Inspect the upper insert locking tabs for damage.Replace all damaged or worn bearing inserts.Refer to the Main Bearing Fitting Chart (refer to the properservice manual) to select the proper bearing inserts toobtain the specified bearing clearance. Refer to 2.5L EngineSpec(fificutions, 'Engine Assembly' section of this chapter,for the correct main bearing clearances.When required, upper and lower bearing inserts of differentsizes may be used as a pair. A standard size insert issometimes used in combination with a 0.025 mm (0.00l'')undersize insert to reduce the clearance by 0.013 mm(0.000S"). Refer to Figure 2-15.Note: Never use a pair of bearing inserts with greater thana 0.025 mm (0.001") difference in size.Example: When replacing inserts, install the odd sizeinserts either all on the top (in cylinder block) or all on thebottom (in main bearing cap).lower0.025 mm (0.001 in.)Undersize0.051 mm (0.002 in.)Undersize~__ ~FittingHEAVIER WEARPATERN ONLOWER INSERT J9009-90Figure 2 - 14The main bearing caps, numbered (front to rear) from 1through 5 have an arrow to indicate the forward position.The upper main bearing inserts are grooved to provide oilchannels while the lower inserts are smooth. Crankshaftend play is controlled by the thrust bearing which is flangedand installed at the No. 2 main bearing position.Each bearing insert pair is selectively fit to its respectivejournal to obtain the specified operating clearance. Inproduction, the select fit is obtained by using various sized,color-coded bearing insert pairs as listed in the MainBearing Fitting Charr (refer to the proper service manual).The bearing color code appears on the edge of the insert.Note: The size is not stamped on bearing inserts used forengine production.The main bearing journal size (diameter) is identified inproduction by a color-coded paint mark on the adjacentcheek toward the flanged (rear) end of the crankshaft,except for the rear main journal. The paint mark thatidentifies the rear main journal diameter is on thecrankshaft rear flange.I I I19109-179Figure 2 - 15Main Bearing-to-Journal Clearance- CrankshaftInstalledWhen using Plastigauge, check only one bearing clearanceat a time.1.2.3.4.5.Install the grooved main bearings into the cylinder blockand the non-grooved bearings into the bearing caps.Install the crankshaft into the upper bearings dry.Place a strip of Plastigauge across full width of thecrankshaft journal to be checked.Install the bearing cap and tighten the bolts to 108 Nom(80 ft-lbs) torque.Note: DO NOT rotate the crankshaft. This will causethe Plastigauge to shift, resulting in an inaccuratereading. Plastigauge must not be permitted to crumble.If it is brittle, obtain fresh stock.Remove the bearing cap. Determine the amount ofclearance by measuring the width of the compressedPlastigauge with the scale on the Plastigauge envelope(Figure 2-16). The correct clearance is 0.0254 to0.0635 mm (.0010 to ,0025") for all main bearingjournals, with 0.05 1 mm (0.002") preferred... .

2.5L POWER TECH IN-LINE 4 (CRANKSHAFT) 35Plastigauge should indicate the same clearance across theentire width of the insert. If clearance varies, it may indicate atapered journal or foreign material trapped behind the insert.If the specified clearance is indicated and there are noabnormal wear patterns, replacement of the bearing inserts isnot necessary. Remove the Plastigauge from the crankshaftjournal and bearing insert. Proceed to Installation.If the clearance exceeds specification, install a pair of 0.025mm (0.00 1") undersize bearing inserts and measure theclearance as described in the previous steps. The clearanceindicated with the 0.025 mm (0.001") undersize insert pairinstalled will determine if this insert size or some othercombination will provide the specified clearance.Example: If the clearance was 0.0762 mm (0.003")originally, a pair of 0.0254 mm (0.001") undersize insertswould reduce the clearance by 0.0254 mm (0.00 1 "). Theclearance would then be 0.05 1 mm (0.002") and within thespecification. A 0.05 I mm (0.002") undersize bearing insertand a 0.0254 mm (0.001 ") undersize insert would reduce theoriginal clearance an additional 0.0127 mm (0.0005") andthe clearance would then be 0.0381 mm (O.OOl5").Caution: Never use a pair of inserts that differ more thanone bearing size as a pair. For example, DO NOT use astandard size upper insert and a 0.051 mm (0.002")undersize lower insert.If the clearance exceeds the specification using a pair of0.05 I mm (0.002") undersize bearing inserts, measure thecrankshaft journal diameter with a micrometer. If thejournal diameter is correct, the crankshaft bore in thecylinder block may be misaligned, which requires cylinderblock replacement or machining to true bore.If the diameter for journals 1 through 5 is less than 63.4517mm (2.4981"), replace the crankshaft or grind the crankshaftdown to accept the appropriate undersize bearing inserts.Once the proper clearances have been obtained, remove thecrankshaft and proceed to Iristullution.COMPRESSED'PLASTIGAGEPLASTIGAGESCALEIFigure 2 - 16J9009-42Main Bearing Journal Diameter - CrankshaftRemovedClean the main bearing journal of oil.Determine the maximum diameter of journal with amicrometer. Measure at two locations 90" apart at each endof the journal.The maximum allowable taper and out of round is 0.01 3 mm(0.0005"). Compare measured diameter with the journaldiameter specification listed in the Main Bearing FittingChart (refer to the proper service manual) and select insertsrequired to obtain the specified bearing-to-journal clearance.Installation1. Lubricate the bearing surface of each insert withengine oil.2.3.4.5.6.7.8.9.Loosen all the main bearing caps. Install the mainbearing upper insert(s).Install the lower bearing inserts into the main bearing caps.Install the main bearing cap(s) and lower insert(s).Clean the rear main bearing cap (No. 5) mating surfaces.Apply Mopar Gasket Maker (or equivalent) to the rearbearing cap (Figure 2-17). The bead should be 3 mm(0.125 in) thick. DO NOT apply Mopar Gasket Maker(or equivalent) to the lip of the seal.Install the rear main bearing cap. DO NOT strike thecap more than twice for proper engagement.Tighten the bolts of caps 1, 3, 4 and 5 to 54 Nom(40 ft-lbs) torque. Now tighten these bolts to 95 Nom(70 ft-lbs) torque. Finally, tighten these bolts to 108Nom (80 ft-lbs) torque.Push the crankshaft forward and backward. Load thecrankshaft front or rear and tighten cap bolt #2 to 54 Nom(40 ft-lbs) torque. Then tighten to 95 Nom (70 ft-lbs)torque, and finally tighten to 108 Nom (80 ft-lbs) torque.

36 MOPAR PERFORMANCE PARTS10. Rotate the crankshaft after tightening each mainbearing cap to ensure the crankshaft rotates freely.11. Check crankshaft end play. Refer to Crankshaft EndPlay, in this section, for the procedure.12. If the crankshaft was removed, install the crankshaftinto the cylinder block.13. Install the oil pan.14. Install the drain plug. Tighten the plug to 34 N-m(25 ft-lbs) torque.15. Install new rear main seal.16. Lower the vehicle.17. Install the spark plugs. Tighten the plugs to 37 N-m(27 ft-lbs) torque.18. Fill the oil pan with engine oil to the safe mark onthe dipstick.19. Connect the battery negative cable.5. If end play is not within specification, inspect crankshaftthrust faces for wear. If no wear is apparent, replace thethrust bearing and measure end play. If end play is stillnot within specification, replace the crankshaft.DIALINDICATORFigure 2 - 18SEUERLOCITlONSEUEROCATIONSENGINE DAMPER(Refer to Figure 2-19.)RemovalCYLINDER BLOCK1.2.3.4.5.Disconnect the battery negative cable.Remove the top and bottom damper nuts.Remove the outer retainers and bushings.Remove the top damper bracket nut and bolts.Remove the bracket, inner retainers, bushings andthe damper.Crankshaft End PlayFigure 2 - 17Attach a magnetic base dial indicator to the cylinderblock at either the front or rear of the engine.Position the dial indicator rod so that it is parallel to thecenterline of the crankshaft.Pry crankshaft forward and position dial indicator to zero.Pry the crankshaft forward and backward. Note the dialindicator readings. End play is the difference betweenthe high and low measurements (Figure 2-18). Correctend play is 0.038 to 0.165 mm (0.0015 to 0.0065").The desired specifications are 0.051 to 0.064 mm(0.002 to 0.0025").Installation1.2.3.4.5.6.7.8.Install the damper on the lower bracket with the lowerinner retainer and bushing in place.Install the upper inner retainer and bushing on the topof the damper.Position the upper damper bracket over the damper andinstall the stud nut and bolts.Tighten the stud nut to 23 N*m (17 ft-lbs) torque andtighten the bracket bolts to 61 N-m (45 ft-lbs) torque.Install the bushing, upper outer retainer and damper nut.Install the bushing, lower outer retainer and damper nut.Tighten the upper and lower damper nuts.Connect the battery negative cable.

UPPERSHOCKI2.5L POWER TECH IN-LINE 4 (CRANKSHAFT) 37Installation1. With the key in position, align the keyway on thevibration damper hub with the crankshaft key and tapthe damper onto the crankshaft.2.3.Install the vibration damper retaining bolt and washer.Torque the damper retaining bolt to 108 Nom(80 ft-lbs).4. If equipped with a crankshaft pulley for the accessorydrive belts, install the crankshaft pulley and retainingbolts.5. Tighten the bolts to 27 Nem (20 ft-lbs) torque.6. Install the drive belt(s) and tighten to the specifiedtension.7. Connect the battery negative cable.TIMING CASE COVER(Refer to Figure 2-20.)LOWERSHOCK ABSORBERBRACKETVIBRATION DAMPERVibration DamperFigure 2 - 19J8909-3Production-type replacement vibration damper compatiblewith production crankshaft and piston-rod weight. For2.5L engine only.P4529669Vibration damper.~~ ~ ~Damper Attaching PackageIncludes bolt, washer, oil slinger, and three keys. For 2.5Land 4.0L engines only.P4529677Removal1.2.3.4.5.Damper attaching package.Disconnect the battery negative cable.Remove the drive belt(s) and fan shroud, if equipped.If equipped with a crankshaft pulley for accessorydrive belts, remove the retaining bolts and separate thecrankshaft pulley from the vibration damper.Remove the vibration damper retaining bolt and washer.Use a vibration damper removal tool to remove thedamper from the crankshaft (Figure 2-2).RemovalI.2. Remove accessory drive belts.3.4.Disconnect the battery negative cable.Remove the accessory drive brackets that are attachedto the timing case cover.Remove the fan and hub assembly and remove thefan shroud.5. Remove the A/C compressor (if equipped) andalternator bracket assembly from the cylinder head andmove to one side.6.7.8.9.Use a vibration damper removal tool to remove thedamper from the crankshaft (Figure 2-2).Remove the oil pan-to-timing case cover bolts andcover-to-cylinder block bolts.Remove the timing case cover front seal and gasketfrom the engine.Cut off the oil pan side gasket end tabs and oil panfront seal tabs flush with the front face of the cylinderblock and remove the gasket tabs (Figure 2-21).10. Clean the timing case cover, oil pan and cylinder blockgasket surfaces.11. Remove the crankshaft oil seal from the timing casecover (Figure 2-20).

38 MOPAR PERFORMANCE PARTSVIBRATIONDAMPERPULLEYIOIL PANSIDECRANKSHAFTOIL SEALFigure 2 - 20TIMING80abdZblOIL PAN FRONT'SEAL TABS J9009-22InstallationFigure 2 - 276.7.8.9.Position the timing case cover on the cylinder block.Insert timing case cover alignment and seal installationtool in the crankshaft opening in the cover (Figure 2-22).Install the cover-to-cylinder block bolts and the oilpan-to-cover bolts.'Tighten the cover-to-cylinder block bolts to 7 Nom (62in-lbs) torque and the oil pan-to-cover bolts to 13 Nom(11 ft-lbs) torque.10. Remove the cover alignment tool and position areplacement oil seal on the tool with the seal lip facingoutward. Apply a light film of Perfect Seal orequivalent on the outside diameter of the seal. Lightlycoat the crankshaft with engine oil.11. Position the tool and seal over the end of the crankshaftand insert a draw screw tool into the seal installationtool (Figure 2-23).12. Tighten the nut against the tool until it contacts the cover.13. Remove the tool and apply a light film of engine oil onthe vibration damper hub contact surface of the seal.14. With the key inserted in the keyway in the crankshaft,install the vibration damper, washer and bolt. Lubricateand tighten the bolt to 108 Nom (80 ft-lbs) torque.15. Install the crankshaft pulley. If equipped with aserpentine drive, the pulley is integral with the damperand they are installed as a unit. Tighten the bolts to 27Nom (20 ft-lbs) torque.16. Install the A/C compressor (if equipped) and thealternator bracket assembly.17. Install the engine fan and hub assembly and shroud.18. Install the drive belt(s) and tighten to obtain thespecified tension.19. Connect the battery negative cable.I. Install a new seal in the timing case cover using a sealinstal 1 ati on tool (Figure 2-22).2.3.4.5.Apply sealing compound (Mopar Gasket-in-a-Tube, orequivalent) to both sides of the replacement timingcase cover gasket and position the gasket on thecylinder block.Cut the end tabs off the replacement oil pan sidegaskets corresponding to those cut off the originalgasket (Figure 2-21). Attach the end tabs to the oil panwith cement.Coat the front cover seal end tab recesses generously withRTV sealant (Mopar Gasket-in-a-Tube, or equivalent)and position the seal on the timing case cover.Apply engine oil to the seal-to-oil pan contact surface.

T -1n2.5L POWER TECH IN-LINE 4 (CRANKSHAFT) 39Figure 2 - 22J9009-23Jeep Gear DrivesReplace conventional Jeep timing chain and gear sets andeliminate chain induced cam timing fluctuations with thisMopar Performance Parts dual idler gear drive camshaftcenterlining drive system. Rugged and durable for offroadapplications. Fits all 4.0L, 4.2L, and 2.5L Jeepengines.P5249009Jeep gear drives.All-out Race Chain and SprocketsCloyes matched sprockets and double roller chain for alloutrace applications. Has three matched keyways toadjust cam timing. Kit includes Magna-fluxed sprocketsand roller timing chain. For 2.5L and 4.0L engines only.P52495 19All-out race chain and sprockets.SEALINSTALIATIONTOOLFigure 2 - 23TIMING CHAIN AND SPROCKETSThe timing chain tensioner reduces noise and prolongs timingchain life. In addition, it compensates for slack in a worn orstretched chain and maintains the correct valve timing.Timing Chain and Sprockets SetThis kit is the ideal service replacement package for Jeep2.5L 4-cylinder engines. The package includes singleroller timing chain and sprockets.P4529822Timing chain and sprockets set.Removal1.2.Disconnect the battery negative cable.Remove the fan and shroud.3. Remove the drive belt(s).4. Remove the crankshaft vibration damper and thepulley (Figure 2-2).5.6.7.8.9.Remove the timing case cover.Rotate the crankshaft until the zero timing mark on thecrankshaft sprocket is closest to and on a centerline withthe timing mark on the camshaft sprocket (Figure 2-24).Remove the oil slinger from the crankshaft.Remove the camshaft retaining bolt and remove thesprockets and chain as an assembly.To replace the timing chain tensioner, the oil pan mustbe removed. Refer to Oil Pun Removal, ‘OilingSystem’ section of this chapter for the procedure.Installation1. Turn the tensioner lever to the unlock (down) position(Figure 2-25).2.3.Pull the tensioner block toward the tensioner lever tocompress the spring. Hold the block and turn thetensioner lever to the lock (up) position (Figure 2-25).Apply Mopar Silicone Rubber Adhesive Sealant to thekeyway in the crankshaft and insert the key. With thekey in the crankshaft keyway, install thecrankshafdcamshaft sprockets and timing chain.Ensure the timing marks on the sprockets are properlyaligned (Figure 2-26).

40 MOPAR PERFORMANCE PARTS4.Install the camshaft sprocket retaining bolt and washerand tighten the bolt to 108 Noin (80 ft-lbs) torque.5.6.7.‘To verify correct installation of the timing chain, turnthe crankshaft to position the camshaft sprocket timinginark at approximately the one o’clock position (Figure2-26). This positions the crankshaft sprocket timing[nark where the ad.jacent tooth meshes with the chain atthe three o’clock position. Count the number of chainpins between the timing marks of both sprockets.There must be 20 pins.Turn thc chain tensioner lever to the unlocked (down)position (Figure 2-25).Install thc oil slinger.Replace the oil seal in the timing case cover./TENSIONERLEVERBLOCKJ9009-278.Install the timing case cover and gasket.Figure 2 - 259.With the key inserted in the keyway in crankshaft,install the vibration damper, washer and bolt. Lubricateand tighten the bolt to 108 Nom (80 ft-lbs) torque.CAMSHAFTSPROCKET10 . Install the fan and shroud.I I . Connect negalive cable to battery.:RANKSHAFT;PROCKET J9009-28Figure 2 - 26TIMING CASE COVER OIL SEAL REPLACEMENTTiming Case Cover Removed\ J9009-251.Disconnect the battery negative cable.Figure 2 - 242.3.Pry oil seal out of cover from front with a large pry tool.Install the replaccment seal so that the open end of theseal is toward the inside of the cover.4.Support the cover at the seal area while installing theseal and force it into position with seal installation tool(Figure 2-22 and Figure 2-23).5.Connect the battery negative cable.

~~ ~2.5L POWER TECH IN-LINE 4 (CRANKSHAFT) 41Timing Case Cover Installed1.2.3.4.5.6.7.8.9.10.11.12. Install the A/C compressorkalternator bracket assembly.13.Disconnect the battery negative cable.Remove the drive belts.Remove the vibration damper (Figure 2-2).Remove the radiator shroud.Remove the oil seal using oil seal removal tool(Figure 2-27).Position the replacement oil seal on the timing casecover alignment and seal installation tool (Figure 2-22)with seal lip facing outward. Apply a light film ofPerfect Seal, or equivalent, on the outside diameter ofthe seal. Lightly coat the crankshaft with engine oil.Position tool and seal over the end of the crankshaftand insert a draw screw tool into seal installation tool(Figure 2-23). Tighten the nut against the tool until itcontacts the cover.Remove the tools. Apply a light film of engine oil onthe vibration damper hub contact surface of the seal.With the key inserted in the keyway in the crankshaft,install the vibration damper, washer and bolt. Lubricateand tighten the bolt to 108 Nom (80 ft-lbs) torque.Install the crankshaft pulley. Tighten the bolt to 27Nom (20 ft-lbs) torque.Install the drive belt(s) and tighten to the specifiedtension. If equipped with a serpentine drive, the pulley isintegral with the damper and they are installed as a unit.Connect the battery negative cable.REAR MAIN OIL SEALRemovalTo replace the rear main oil seal, the transmission must beremoved. Refer to service manual for the proper procedure.I. Remove flywheel or torque converter drive plate.Discard the old bolts.2.Pry out seal from around crankshaft flange (Figure 2-28).InstallationCoat the outer lip of the replacement rear main bearingseal with engine oil.Carefully position the seal into place. Use rear mainseal installer tool to install the seal flush with the block.Caution: The felt lip must be located inside theflywheel mounting surface. If the lip is not positionedcorrectly the flywheel could tear the seal.Install the flywheel or torque converter drive plate.New bolts MUST be used when installing the flywheelor torque converter drive plate. Tighten the new boltsto 68 Nom (50 ft-lbs) torque. Turn the bolts anadditional 60".Install the transmission. Refer to service manual for theproper procedure.CRANKSHAFT'\CRANKSHAFTOIL SEALFigure 2 - 28IFigure 2 - 27

42 MOPAR PERFORMANCE PARTSINTRODUCTIONThe 2.5L engine's connecting rods are made of castnodular iron with a total weight (less the bearings) of 657-665 grams (23.2-23.5 oz.), and a total length(center-to-center) of 155.52-155.62 mm (6.123-6.127").Connecting rod journal diameter is 53.17-53.23 mm(2.0934-2.0955"). Connecting rod journal width is 27.18-27.33 mm (1.070-1.076").For connecting rod removal and installation procedures,refer to Piston and Connecting Rod Assembly, 'Pistons andRings' section of this chapter.Connecting RodThese heavy duty forgings are shot-peened and Magnafluxed.Includes high strength bolts. Can be used as heavyduty stock replacement. For 2.5L and 4.0L engines only.(Sold individually.)P4529209Connecting rod.Connecting Rod BearingsThese connecting rod bearings are made of productionstylematerial. Available in standard and two undersizes.For Jeep 2.5L and 4.0L engines only. (Sold individually.)P4529208Connecting RodsConnecting rod bearings, standard size.P4529236 Connecting rod bearings, .001"undersize.P4529238 Connecting rod bearings, ,010"undersize.Basic Preparation1.2.3.4.5.6.Rods should be checked for alignment; bores should beparallel. Check big and small ends for size. Use only aSunnen rod reconditioner for this purpose.Using a small file, deburr rods, paying particularattention to the mating surfaces and the tab groove.You need the clamping effect of a 60 micro bore. Thesides should be polished by hand on a flat plate using#600 paper.In an engine that is to used in a high rpm situation, therods and rod bolts should be Magna-Glo checked forcracks or forging flaws.A race engine should use the heavy duty rod bolts and nuts.The rod bearing clearances should be 0.03-0.06 mm(0.001 -0.0025").The rod bolt head should be seated against the flat,machined surface in the rod.7. For a race engine, the big end rod should be sized tothe minimum diameter to get the maximum crush fromthe bearing.8.9.Shot-peening the rods is recommended if they haven'tbeen already.Clean all parts before proceeding.Rod RatioFor all-out modified race engines, it is recommended that arod ratio (length of the rod divided by the stroke) of 1.75 to1.85 be maintained (if possible) for best performance. (Thestock 2.5L engine has a rod ratio of I .92 - this is consideredlong.) Side clearance should be 0.25-0.48 mm (0.010-0.019").Inspection1. Connecting Rod BearingsInspect connecting rod bearings for scoring and bentalignment tabs (Figure 2-29 and Figure 2-30). Checkthe bearings for normal wear patterns, scoring,grooving, fatigue and pitting (Figure 2-3 1). Replaceany bearing that shows abnormal wear.Inspect connecting rod journals for signs of scoring,nicks and burrs.2. Connecting RodsMisaligned or bent connecting rods can causeabnormal wear on pistons, piston rings, cylinder walls,connecting rod bearings and crankshaft connecting rodjournals. If wear patterns or damage to any of thesecomponents indicates the probability of a misalignedconnecting rod, inspect it for correct rod alignment.Replace misaligned, bent or twisted connecting rods.WALONI LO~ER J8909- 27LFigure 2 - 29.~..- .T-l

2.5L POWER TECH IN-LINE 4 (CONNECTING RODS) 43ABNORMAL CONTACT AREACAUSED BY LOCKING TABS NOTFULLY SEATED OE BEING BENTJ8909- 1 29J8909-128Figure 2 - 31Figure 2 - 30UPPOC Insert SizeLower Insert SizeYellow- 53.2257-53.2079 mm2.0955-2.0948 inchStandardYellow - Standard Yellow - StandardOrange- 53.2079-53.1 901 mm2.0948-2.0941 inchUndersize (0.01 78 mmor 0.0007 inch)Yellow- StandardBlack- Undersize0.025 mm0.001 inchBlack- 53.1901-53.1723 mrn2.0941-2.0933 inchUndersize (0.0356 mmor 0.0014 inch)Black- Undersize0.025 mm0.001 inchBlack- Undersize0.025 mm0.001 inchRed- 53.971 7-53.9539 mm2.0855-2.0848 inchUndersize (0.254 mmor 0.01 0 inch)Red- Undersize0.254 mm0.001 inchRed- Undersize0.254 mm0.001 inchFigure 2 - 32J9009-43

44 MOPAR PERFORMANCE PARTSMeasuring Bearing-to-Journal Clearance1.2.3.4.5.6.7.8.9.Wipe the journal clean of oil.Use short rubber hose sections over rod bolts duringinstallation. (For more information, refer toConnecting Rod Bolt Protectors, 'Connecting Rods'section of Chapter 4.)Lubricate the upper bearing insert and install inconnecting rod.Use piston ring compressor to install the rod and pistonassemblies with the oil squirt holes in the rods facing thecamshaft and the arrow on the piston crown pointing tothe front of the engine (Figure 2-37). Verify that the oilsquirt holes in the rods face the camshaft and that thearrows on the pistons face the front of the engine.Install the lower bearing insert in the bearing cap. Thelower insert must be dry. Place a strip of Plastigaugeacross the full width of the lower insert at the center ofbearing cap. Plastigauge must not crumble in use. Ifbrittle, obtain fresh stock.Install bearing cap and connecting rod on the journaland tighten nuts to 45 Nom (33 ft-lbs) torque. DO NOTrotate crankshaft. Plastigauge will smear, resulting ininaccurate indication.Remove the bearing cap and determine the amount ofbearing-to-journal clearance by measuring the width ofcompressed Plastigauge using the scale on thePlastigauge envelope (Figure 2- 16). The correctclearance is 0.0381 to 0.0635 mm (0.0015 to 0.0025").Note: Plastigauge should indicate the same clearanceacross the entire width of the insert. If the clearancevaries, it may be caused by either a tapered journal,bent connecting rod, or foreign material trappedbetween the insert and cap or rod.If the correct clearance is indicated, replacement of thebearing inserts is not necessary. Remove thePlastigauge from crankshaft journal and bearing insert.Proceed with installation.If bearing-to-journal clearance exceeds thespecification, install a pair of 0.0254 mm (0.001")undersize bearing inserts and measure the clearance asdescribed in the previous steps.10. The clearance measured with a pair of 0.0254 mm(0.001 ") undersize bearing inserts installed willdetermine if two 0.0254 mm (0.001") undersize insertsor another combination is needed to provide the correctclearance (see the Connecting Rod Bearing FittingChart, Figure 2-32).Example: If the initial clearance was 0.0762 mm(0.003"), 0.0254 mm (0.001") undersize inserts wouldreduce the clearance by 0.0254 mm (0.001"). Theclearance would be 0.002" and within specification. A0.0508 mm (0.002") undersize insert would reduce theinitial clearance an additional 0.0127 mm (O.000St1).The clearance would then be 0.0381 mm (0.0015").Measuring Side ClearanceSlide snug-fitting feeler gauge between the connecting rodand crankshaft journal flange. The correct clearance is 0.254to 0.482 mm (0.010 to 0.019"). Replace the connecting rodif the side clearance is not within specification.Note: Too much side clearance will cause the engine tohave a high oil demand, resulting in either low or very lowoil pressure..., . ..l- .. T -1

2.5L POWER TECH IN-LINE 4 (PISTONS AND RINGS) 45Pistons and RingsCast Pistons and Rings for Jeep 2.5L EnginesPart NumberPS249902Bore Stroke Rod CR Dome Rings3.905" 3.19" 6.125" 9.2: 1 Dish P4876962PISTONSThe 2.SL engine uses aluminum alloy pistons (with struts)that weigh (less pin) 563-567 grams (19.86-20.00 oz.) each.The piston combustion cavity is a single quench design.For more piston (and piston ring) specifications, refer to2.5L Engine Specifications, 'Engine Assembly' section ofthis chapter.Piston Fitting (Non-Coated Pistons Only)I. Micrometer Methoda. Measure the inside diameter of the cylinder bore at apoint 58.725 mm (2-5/16") below the top of the bore.b.Measure the outside diameter of the piston. Becausepistons are cam ground, measure at right angle topiston pin at centerline of pin (Figure 2-33).Note: The difference between cylinder bore diameterand piston diameter is piston-to-bore clearance.ABD - EFGROOVE HEIGHT2.0193-2.0447 mim (0.0795-0.0805 in)4.7752-4.8 133 mm (0.1880-0.1895 in)GROOVE DIAMETER87.78-87.90 mm 3.456-3.461 in87.50-87.75 mm 13.445-3.455 in/MEASURE PISTONAT THIS AREAFOR FITTING2. Feeler Gauge Method(Not recommended for racing.)a.b.C.d.e.Remove the rings from the piston.Insert a long 0.025 mm (0.001") feeler gauge intothe cylinder bore.Insert the piston, top first, into cylinder borealongside the feeler gauge. With entire pistoninserted into cylinder bore, the piston should notbind against feeler gauge.Repeat steps with a long 0.051 mm (0.002") feelergauge. The piston should bind.If the piston binds on a 0.025 mm (0.001 ") feelergauge, the piston is too large or the cylinder boreis too small. If the piston does not bind on a 0.05 1mm (0.002") feeler gauge, the piston is too smallfor cylinder bore. Pistons up to 0.102 mm(0.004") undersize may be enlarged by knurling.Replace pistons that are 0.102 mm (0.004") ormore undersize.Piston Fitting (Coated Pistons Only)1. Bore Gauge MethodTo correctly select the proper size piston, a cylinderbore gauge capable of reading in 0.003 mm (.000l")INCREMENTS is required. If a bore gauge is notavailable, DO NOT use an inside micrometer.a. Measure the inside diameter of the cylinder boreat a point 49.5 mm (1-15/16") below top of bore.Start perpendicular (across or at 90 degrees) to theaxis of the crankshaft at point A and then take anadditional bore reading 90 degrees to that at pointB (Figure 2-34).b.Coated pistons, piston pins and connecting rods arepre-assembled. The coated piston and connectingrod assembly can be used to service previouslybuilt engines; however, they MUST be replaced ascomplete sets. Tin-coated pistons should not beused as replacements for coated pistons.Figure 2 - 33.. ...

~46 MOPAR PERFORMANCE PARTSc. The coating material is applied to the piston afterthe final piston machining process. Measuring theoutside diameter of a coated piston will notprovide accurate results. Therefore measuring theinside diameter of the cylinder bore with a dialbore gauge is MANDATORY. To correctly selectthe proper size piston, a cylinder bore gaugecapable of reading in 0.003 mm (.0001")increments is required.d.Piston installation into the cylinder bore requiresslightly more pressure than that required for noncoatedpistons. The bonded coating on the pistonwill give the appearance of a line-to-line fit withthe cylinder bore.ABORE GAUGEFigure 2 - 342. Coated Piston Size ChartCvlinder Bore SizeCYLINDERBOREPiston Letter Size98.438 to 98.448 mm A(3.8755 to 3.8759")98.448 to 98.458 mm B(3.8759 to 3.8763")98.458 to 98.468 mm C(3.8763 to 3.8767")98.468 to 98.478 mm D(3.8767 to 3.877 1 ")98.478 to 98.488 mm E(3.877 1 to 3.8775")98.488 to 98.498 mm F(3.8775 to 3.8779")PISTON AND CONNECTING ROD ASSEMBLYRemoval1.2.3.4.5.6.7.8.9.1011Remove the cylinder head cover. Refer to CylinderHead Cover, 'Cylinder Head' section of this chapterfor the procedure.Remove the rocker arms, bridges and pivots. Refer toRocker Arms, 'Camshaft and Valve Gear' section ofthis chapter for the procedure.Remove the pushrods. Refer to Pushrods, 'Camshaft andValve Gear' section of this chapter for the procedure.Remove the cylinder head. Refer to Cylinder HeadRemoval, 'Cylinder Head' section of this chapter forthe procedure.Position the pistons one at a time near the bottom of thestroke and use a ridge reamer to remove the ridge fromthe top end of the cylinder walls. Use a protective clothto collect the cuttings.Raise the vehicle.Drain the engine oil.Remove the oil pan, gaskets and seals. Refer to Oil Pun,'Oiling System' section of this chapter for the procedure.Remove the connecting rod bearing caps and insertsand retain in the same order as removed to facilitateinstallation in the original locations. The connectingrods and caps are stamped with the correspondingcylinder number (Figure 2-35).Lower vehicle until it is about two (2) feet from the floor.Have an assistant push the piston and connecting rodassemblies up and through the top of the cylinder bores(Figure 2-36).Caution: Ensure that the connecting rod bolts don'tscratch the crankshaft journals or cylinder walls. Shortpieces of rubber hose slipped over the rod bolts willprevent damage to the cylinder bores and crankshaftjournals.

2.5L POWER TECH IN-LINE 4 (PISTONS AND RINGS) 47The rod journal is identified during engine production by acolor-coded paint mark on the adjacent cheek orcounterweight toward the flanged (rear) end of thecrankshaft. The color codes used to indicate journal sizesare listed in the Connecting Rod Bearing Fitting Chart(Figure 2-32).InstallationCONNECTING ROD J9009-40Figure 2 - 35Figure 2 - 3619509-86Each bearing insert is selectively fit to its respective journalto obtain the specified operating clearance between thebearing and the journal. In production, the select fit isobtained by using various sized, color-coded bearing insertsas listed in the Connecting Rod Bearing Fitting Chart(Figure 2-32). The color code appears on the edge of thebearing insert. The size is not stamped on inserts used forproduction of engines.When required, upper and lower bearing inserts of differentsizes may be used as a pair (see Connecting Rod BearingFitting Chart, Figure 2-32). A standard size insert issometimes used in combination with a 0.025 mm (0.001")undersize insert to reduce clearance 0.013 mm (0.00OS").Caution: DO NOT intermix bearing caps. Eachconnecting rod and its bearing cap are stamped with theassociated cylinder number on a machine surface adjacentto the oil squirt hole that faces the camshaft side of thecylinder block (Figure 2-35).1.2.3.4.5.6.7.8.9.Clean the cylinder bores thoroughly. Apply a light film ofclean engine oil to the bores with a clean lint-free cloth.Install the piston rings on the pistons if removed.Refer to Piston Ring Fitting, this section, for theproper procedure.Lubricate the piston and rings with clean engine oil.Use a piston ring compressor to install the connectingrod and piston assemblies through the top of thecylinder bores (Figure 2-36).Caution: Ensure that connecting rod bolts DO NOTscratch the crankshaft journals or cylinder walls. Shortpieces of rubber hose slipped over the connecting rodbolts will provide protection during installation.Ensure the arrow on the piston top points to the frontof the engine (Figure 2-37).Note: For racing applications, refer to ReversingPistons with Oflset Pins, 'Pistons and Rings' section ofChapter 4.Raise the vehicle.Install the connecting rod bearing caps and inserts inthe same positions as removed.Caution: Verify that the oil squirt holes in the rodsface the camshaft and that the arrows on the pistonsface the front of the engine.Install the oil pan and gaskets as outlined in theinstallation procedure.Lower the vehicle.10. Install the cylinder head, pushrods, rocker arms,bridges, pivots and cylinder head cover as outlined inthe installation procedures in this chapter.11. Fill the crankcase with engine oil.

l- -1-148 MOPAR PERFORMANCE PARTS9. The top compression ring (the scraping edge is gray incolor) has a chamfer on the TOP of the inside edge(Figure 2-43). This ring may also have one dot locatedon the top surface.10. Using a ring installer, install the top ring with thechamfer facing up. If the ring has a dot, the dot will befacing up.11. Position the ring end gaps on the piston as shown(Figure 2-44).Figure 2 - 37J9009-41Piston Ring Fitting (Non-Coated Pistons Only)1.2.3.4.5.6.7.8.Carefully clean the carbon from all ring grooves. Oildrain openings in the oil ring groove and pin boss mustbe clear. DO NOT remove metal from the grooves orlands. Doing so will change ring-to-groove clearancesand will damage the ring-to-land seating.Measure the ring side clearance with a feeler gauge fitsnugly between the ring land and ring (Figure 2-38).Rotate the ring in the groove. It must move freelyaround the circumference of the groove.Place ring in the cylinder bore and push down withinverted piston to position near lower end of the ringtravel. Measure ring gap with a feeler gauge fit snuglybetween ring ends (Figure 2-39). The correctcompression ring end gap is 0.25-0.51 mm (0.010-0.020"). The correct oil control ring end gap is0.381-1.397 mm (0.01s-0.0S5").Refer to Figure 2-44 for position of ring gaps wheninstalling piston rings.Install the oil control rings according to instructions inthe package. It is not necessary to use a tool to installthe upper and lower rails. Insert expander ring first,then side rails.The two compression rings are different and cannot beinterchanged (Figure 2-40). The top ring is a moly ring(the scraping edge is gray in color). The second ring isa black cast iron ring (the scraping edge is black incolor when new).The second compression ring (black cast iron) has achamfer on the BOTTOM of the inside edge (Figure 2-41). This ring may also have two dots located on thetop surface.Using a ring installer, install the ring with the chamferfacing down (Figure 2-42). If the ring has dots, the dotswill be facing up..._Edrllirnetorr InchorNo. 1 Compression 0.025-0.08 1 0.001-0.0032(0.043 Prdwred) (0.0017 Preferred)No. 2 Compression 0.025-0.081 0.00 1-0.0032(0.043 Preferred) (0.0017 Preferred).Oil Control 0.02520.241 0.001 -0.0095(0.08 Preferred) (0.003 Preferred)Figure 2 - 38Figure 2 - 39FEELERGAUGEE8909402

2.5L POWER TECH IN-LINE 4 (PISTONS AND RINGS) 49IJ9009-48Figure 2 - 43Figure 2 - 40TOP COMPRESSION RINGSECOND COMPRESSION RING(BLACK CAST IRON)\ CHAMFERCOMPRESSIONCONTROL RAILOIL RAILTWODOTS J9009-46Figure 2 - 41ONTROL RAILGINARY LINETHROUGH CENTEROF PISTON SKIRTIMAGINARY LINEPARALLEL TOVARY k20° FROMJ8909- 143Figure 2 - 44RECOMMENDED J9009-47Figure 2 - 42

T - 1 150 MOPAR PERFORMANCE PARTSPiston Ring Fitting (Coated Pistons Only)1. Carefully clean the carbon from all ring grooves. Oildrain openings in the oil ring groove and pin boss mustbe clear. DO NOT remove metal from the grooves orlands. This will change ring-to-groove clearances andwill damage the ring-to-land seating.2.3.Be sure the piston ring grooves are free of nicksand burrs.Measure the ring side clearance with a feeler gauge fitsnugly between the ring land and ring. Rotate the ring inthe groove. It must move freely around circumference ofthe groove.8. Using a ring installer, install the second compressionring with the dot facing up (Figure 2-47).9.Using a ring installer, install the top compression ring(either side up).Ring Gap OrientationPosition the gaps on the piston as shown in Figure 2-48.Oil spacer - Gap on center line of piston skirt.Oil rails - gap 180" apart on centerline of piston pin bore.No. 2 Compression ring - Gap 180" from top oil rail gap.No. 1 Compression ring - Gap 180" from No. 2compression ring gap.RinaTop Compression Ring(0.0017 to 0.0033")Second Compression Ring(0.0017 to 0.0033")Oil Control Ring(0.0024 to 0.0083")Side ClearanceMeasurement0.042 to 0.084 mm0.042 to 0.084 mm0.06 to 0.21 mm\ TOP COMPRES4. Place ring in the cylinder bore and push down withinverted piston to position near lower end of the ringtravel. Measure ring gap with a feeler gauge fittingsnugly between ring ends (Figure 2-39).Figure 2 - 4580a72311RinaTop Compression RingSecond Compression RingOil Control RingGapMeasurement0.229 to 0.610 mm(0.0090 to 0.0240")0.483 to 0.965 mm(0.0190 to 0.0380")0.254 to 1.500 mm(0.010 to 0.060")5. The oil control rings are symmetrical, and can beinstalled with either side up. It is not necessary to usea tool to install the upper and lower rails. Insert oil railspacer first, then side rails.6.7.The two compression rings are different and cannot beinterchanged. The top compression ring can be identifiedby the shiny coating on the outer sealing surface and canbe installed with either side up (Figure 2-45).The second compression ring has a slight chamfer onthe bottom of the inside edge and a dot on the top forcorrect installation (Figure 2-46).Figure 2 - 46

2.5L POWER TECH IN-LINE 4 (PISTONS AND RINGS) 51TOP COMPRESSIONSECONDCOMPRESSIONRINGPISTONThe piston pins are press-fit into the connecting rods andDO NOT require a locking device.Removal1. Position the piston and connecting rod assembly on anarbor press.2.Apply force to a piloted driver and press the pincompletely out of the connecting rod and pistonassembly (Figure 2-49). Note position of the pinthrough the gauge window of removal support tool.InspectionFigure 2 - 47TOP COMPRESSION RINGCONTROL RAILBOlTOM OILCONTROL RAILInspect the piston pin and bore in the connecting rodfor nicks and burrs. Remove as necessary. Never reusea piston pin after it has been installed in and removedfrom a connecting rod.With the pin removed from the piston and connectingrod, clean and dry the piston pin bore and thereplacement piston pin.Position the piston so that the pin bore is in the verticalposition. Insert the pin in the bore. At roomtemperature, the replacement pin should slidecompletely through the pin bore in piston by force ofgravity.Replace piston if pin jams in the pin bore.IMAGINARY LINEPARALLEL TOPILOTEDI/THROUGHIMAGINARY LINECENTEROF PISTON SKIRTPOSITION ILLUSTRATED80a72339Figure 2 - 48PISTON PINThe 2.5L engine’s piston pins have a diameter of 23.632-23.645 mm (0.9304-0.9309”) and piston-to-pin clearance of0.010-0.015 mm (0.0004-0.0006”) (preferred-loose 0.015mm [loose 0.000611]).1 SU+ORT J 8909- 133Figure 2 - 49

52 MOPAR PERFORMANCE PARTSPISTON\CONNECTING2.3.4.Position the pin pilot, piston and connecting rod on asupport with the squirt hole ol'the connecting rod to theleft-hand side (Figure 2-50),Insert the piston pin through the upper piston pin boreand into the connecting rod pin bore (Figure 2-49).Position the piloted driver inside thc piston pin(Figure 2-49).J9009-445.Using an arbor press, press the piston pin through theconnecting rod and piston bores until the pin pilotindexes with the mark on the support. The piston pinrequires an 8900 N (2,000 pounds) press-fit. If littleeffort is required to install the piston pin in theconnecting rod, or if the rod moves laterally on the pin,the connecting rod must he replaced.InstallationFigure 2 - 506.Remove the piston and connecting rod assembly fromthe press. The pin should be centered in the connectingrod (rt0.792 min or rtO.03 12").1. Insert the piston pin pilot through the piston andconnecting rod pin bores. Ensure that the arrow on thepiston crown is pointing up (Figure 2-SO).T ----n

INTRODUCTIONThe 2.5L engine uses a cast nodular iron cylinder head witha combustion chamber volume of 49.9-52.9 cc (3.04-3.23cu. in.). The cylinder head has dual quench-typecombustion chambers that create turbulence and fastburning of the aidfuel mixture, which results in good fueleconomy. Valve lengths are (for intake) 124.435- 125.070mm (4.899-4.924”), and (for exhaust) 125.120-1 25.755 mm(4.927-4.952”).One of the most important parts of any engine assembly isthe cylinder head. It holds the key to making power. It alsooffers the opportunity to make more horsepower.Camshafts, headers, and carburetion can only go so farmaking horsepower without the cylinder head. Cylinderheads can be expensive; however, this may be one place inthe engine where spending the extra money is worth it.For more cylinder head specifications, refer to 2.5L EngineSpecijications, ‘Engine Assembly’ section of this chapter.Heavy Duty Head GasketThis heavy duty head gasket is designed for the 2.5L(only). Can be used as replacement for production.Factory approved and engineered for durability.P4529662Heavy duty head gasket.REMOVAL AND INSTALLATION PROCEDURESRemoval(Refer to Figure 2-5 1 .)I.Disconnect negative cable from battery.Warning! DO NOT remove the cylinder block drain plugs orloosen the radiator drain cock with the system hot andpressurized because serious bums from the coolant can occur.Drain the coolant and disconnect the hoses at theengine thermostat housing. DO NOT waste reusablecoolant. If the solution is clean and is being drainedonly to service the engine or cooling system, drain thecoolant into a clean container for reuse.Remove the air cleaner assembly.Remove the engine cylinder head cover. (Refer toprocedure in this section.)Remove the capscrews, bridge and pivot assembliesand rocker arms.2.5L POWER TECH IN-LINE 4 (CYLINDER HEAD) 53Cy1 i nder Head6. Remove the pushrods. Retain the pushrods, bridges,pivots and rocker arms in the same order as removed.7.8.Loosen the accessory drive belt at the power steeringpump bracket (if equipped) or at the idler pulley bracket.If equipped with air conditioning, perform the following:a. Remove the bolts from the A/C compressormounting bracket and set the compressor aside.b.c.Remove the air conditioner compressor bracketbolts from the engine cylinder head.Loosen the through bolt at the bottom of the bracket.9. If equipped, disconnect the power steering pumpbracket. Set the pump and bracket aside. DO NOTdisconnect the hoses.10. Perform fuel pressure release procedure (refer to theproper service manual for procedures).11. Remove the latch clip and disconnect the fuelsupply hose.12. Remove the intake and engine exhaust manifolds fromthe engine cylinder head (refer to ‘Fuel Delivery andFuel Injection Systems’ and ‘Exhaust System’ sectionsof this chapter for procedures).13. Number and disconnect the ignition wires and removethe spark plugs.14. Disconnect the coolant temperature sending unitconnector.15. Remove the engine cylinder head bolts.16. Remove the engine cylinder head and gasket.17. If this was the first time the bolts were removed, put apaint dab on the top of the bolt. If the bolts have a paintdab on the top of the bolt or it isn’t known if they wereused before, discard the bolts.18. Stuff clean lint free shop towels into the cylinder bores.Note: If valves, springs, or seals are to beinspectedreplaced at this time, refer to Valves and ValveSprings, ‘Camshaft and Valve Gear’ section of this chapterfor proper procedures.

T -7-754 MOPAR PERFORMANCE PARTS1Cleaning and InspectionFigure 2 - 51CYLINDER HEADCYLINDERJ8909-lo9Stuff clean lint free shop towels into the cylinder boreswhile the head is removed.Thoroughly clean the cylinder head and cylinder blockmating surfaces. Clean the intake and exhaust manifold andcylinder head mating surfaces. Remove all gasket materialand carbon.Check to ensure that no coolant or foreign material hasfallen into the tappet bore area.Remove carbon deposits from the combustion chambers.InstallationThe cylinder head gasket is a composition gasket. Thegasket is to be installed DRY. DO NOT use a gasket sealingcompound on the gasket.If the cylinder head is to be replaced and the original valvesused, measure the valve stem diameter. Only standard sizevalves can be used with a service replacement cylinder headunless the replacement head valve stem guide bores arereamed to accommodate oversize valve stems. Remove allcarbon buildup and reface the valves.1. Fabricate two engine cylinder head alignment dowelsfrom used head bolts (Figure 2-52). Use the longesthead bolt. Cut the head of the bolt off below the hexhead. Then cut a slot in the top of the dowel to alloweasier removal with a screwdriver.2. Install one dowel in bolt hole No. 10 and the otherdowel in bolt hole No. 8 (Figure 2-53).3. Remove the shop towels from the cylinder bores. Coatthe bores with clean engine oil.4.Place the engine cylinder head gasket (with thenumbers facing up) over the dowels.5. Place the engine cylinder head over the dowels.Caution: Engine cylinder head bolts should be reused onlyonce. Replace the head bolts if they were used before or ifthe:y have a paint dab on the top of the bolt.6. Coat the threads of bolt No. 7, only, with Loctite PSTsealant (or equivalent).7. Install all head bolts, except No. 8 and No. 10.8. Remove the dowels.9. Install No. 8 and No. 10 head bolts.Caution: During the final tightening sequence, bolt No. 7will be tightened to a lower torque than the rest of the bolts.DO NOT over tighten bolt No. 7.10. Tighten the engine cylinder head bolts in sequenceaccording to the following procedure (Figure 2-54):a. Tighten all bolts in sequence (1 through 10) to 30Nom (22 ft-lbs) torque.b. Tighten all bolts in sequence (1 through 10) to 61Nom (45 ft-lbs) torque.c. Check all bolts to verify they are set to 61 Nom(45 ft-lbs) torque.d. Tighten bolts (in sequence):Bolts 1 through 6 to 149 Nom (110 ft-lbs) torque.Bolt 7 to 136 Nom (100 ft-lbs) torque.Bolts 8 through 10 to 149 Nom (110 ft-lbs)torque.e. Check all bolts in sequence to verify thecorrect torque.f. If not already done, clean and mark each bolt witha dab of paint after tightening. Should youencounter bolts which were painted in an earlierservice operation, replace them.11. Connect the coolant temperature sending unitconnector.12. Install the spark plugs and tighten to 37 Nom (27 ft-lbs)torque. Connect the ignition wires.13. Install the intake and exhaust manifolds (refer to ‘FuelDelivery and Fuel Injection Systems’ and ‘ExhaustSystem’ sections of this chapter for properprocedures).

2.5L POWER TECH IN-LINE 4 (CYLINDER HEAD) 55I14. Install the fuel supply line. Push until a “click” isheard. Reinstall latch clip.15. If equipped, attach the power steering pump and bracket.16. Install the pushrods, rocker arms, pivots and bridges inthe order they were removed.nUSEDCYLINDERHEADBOLT17. Install the engine cylinder head cover.18. Attach the air conditioning compressor mountingbracket to the engine cylinder head and block. Tightenthe bolts to 40 Nom (30 ft-lbs) torque.19. Attach the air conditioning compressor to the bracket.Tighten the bolts to 27 Nom (20 ft-lbs) torque.SLOTCaution: The accessory drive belt must be routed correctly.Incorrect routing can cause the water pump to turn in theopposite direction causing the engine to overheat.20. Install the accessory drive belt and correctly tension thebelt (refer to proper service manual for the procedure).21. Install the air cleaner and ducting.I ALIGNMENTFigure 2 - 52J9009-1322. Connect the hoses to the thermostat housing and fill thecooling system to the specified level (refer to properservice manual for the procedure).23. Install the coolant temperature sending unit connector.24. Connect negative cable to battery.25. Connect the upper radiator hose and heater hose at thethermostat housing.26. Fill the cooling system. Check for leaks.Warning! Use extreme caution when the engine isoperating. DO NOT stand in direct line with the fan. DONOT put hands near the pulleys, belts or fan. DO NOTwear loose clothing.Figure 2 - 534 1 5 927. Operate the engine with the radiator cap off. Inspect forleaks and continue operating the engine until thethermostat opens. Add coolant, if required.7 3 2 6 10J9009-15Figure 2 - 54. ..

56 MOPAR PERFORMANCE PARTSCYLINDER HEAD COVERThe following procedure can be performed with the enginein or out of the vehicle.Crankcase BreatherA universal high performance re-usable crankcasebreather (must have stand pipe on valve cover). Washesclean with P4529392 cleaning fluid for extra miles ofservice.P4529394Removal1.2.3.4.5.Crankcase breather.Disconnect the battery negative cable.Disconnect the Crankcase Ventilation (CCV) vacuumhose (MJ and XJ Vehicles - Figure 2-55) or the PositiveCrankcase Ventilation (PCV) vacuum hose (YJVehicles - Figure 2-56) from the cylinder head cover.Disconnect the CCV (Figure 2-55) or the PCV (Figure2-56) fresh air inlet hose from the cylinder head cover.Remove the cylinder head cover mounting bolts.Remove the cylinder head cover.InspectionInspect the cylinder head cover for cracks. Replace if cracked.InstallationThe cylinder head cover has a cured gasket attached to it.1. Thoroughly clean the sealing surface of the cylinderhead and the seal on the cylinder head cover.2.3.4.Install cylinder head cover. Tighten the mounting boltsto 8 Nom (70 in-lbs) torque.Connect the CCV hose (Figure 2-55) or the PCV hose(Figure 2-56).Connect the battery negative cable.Figure 2 - 56Figure 2 - 55. ..

CAMSHAFT2.5L POWER TECH IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 57Camshaft and Valve GearThe Jeep 2.5L engine uses a cast nodular iron camshaftwith intake and exhaust valve lifts of 10.770 mm (0.424"),intake and exhaust cam lobe lifts of 6.731 mm (0.265"), andintake and exhaust durations of 270".The camshaft rotates within four steel-shelled, Babbit-linedbearings that are pressed into the cylinder block and thenline reamed. The camshaft bearing bores and bearingdiameters are not the same size. They are stepped down in0.254 mm (0.010") increments from the front bearing(largest) to the rear bearing (smallest). This permits easierremoval and installation of the camshaft. The camshaftbearings are pressure lubricated.Note: It is not advisable to attempt to replace camshaftbearings unless special removal and installation toolsare available.Camshaft end play is maintained by the load placed on thecamshaft by the oil pump and distributor drive gear. Thehelical cut of the gear holds the camshaft sprocket thrustface against the cylinder block face.To advance or retard camshaft centerline, the 2.5L engineuses offset bushings. For more information on centerliningas well as offset bushings, refer to the 'Camshaft and ValveGear' section of Chapter 4.For more camshaft specifications, refer to 2.5L EngineSpecifications, 'Engine Assembly' section of this chapter.Camshaft Bearing SetMade of production material. Complete engine set forJeep 2.5L and 4.0L engines.P4529226Camshaft bearing set.Timing Chain and Sprockets SetThis kit is the ideal service replacement package for Jeep2.5L engines. The package includes single roller timingchain and sprockets.P4529822Timing chain and sprockets set.Jeep Gear DrivesReplace conventional Jeep timing chain and gear sets andeliminate chain induced cam timing fluctuations with thisMopar Performance Parts dual idler gear drive camshaftcenterlining drive system. Rugged and durable for off-roadapplications. Fits all 4.0L, 4.2L, and 2.5L Jeep engines.P5249009Jeep gear drives.All-out Race Chain and SprocketsCloyes matched sprockets and double roller chain for alloutrace applications. Has three matched keyways toadjust cam timing. Kit includes Magna-fluxed sprocketsand roller timing chain. For 2.5L and 4.0L engines only.P52495 19All-out race chain and sprockets.~Camshaft Offset Bushing SetFor centerlining camshafts, all engines. Includes fivebushings: 2, 4, 6, and 8 degree offset, plus one on-centerbushing. Installs in camshaft sprocket. For all Jeep 4.0Land 2.5L engines.P3690936Camshaft offset bushing set.0-90-1 80-90-0 Degree WheelDurable Mopar Performance Parts aluminum plate degreewheel for centerlining camshafts, finding TDC, etc.Features step-by-step instructions printed on the back side.P44529900-90- 1 80-90-0 degree wheel.. ..

58 MOPAR PERFORMANCE PARTSIPart No.P4529656P4529657P4.529658Jeep 2.5L Hydraulic Camshaft Specifications ChartAdvertised Duration Overlap Centerline Lift Recom. Spring Applications & Comments2401240" 24" 108" .4301.430" P4S292 14 Mild Cornu.2481248" 32" 108" .4401.440" P45292 14 Mild Comp.2561256" 40" 108" .4501.450" P5249464 Mild Comp.II :P;;;:IPerformanceLevelStockP4.529656Best Choice4x4 Street RodManual Automatic Auto 81 Man Auto & Man1Stock Stock - -P4529656P4529657 P4529657 P4529656~ ~ : ' ~ ~ ~ f i1 1 1I I 1Phase I11 P4.529658 P4529658 P4529657 P4529657Removal1.Disconnect the battery negative cable.Warning! The coolant in a recently operated engine is hotand pressurized. Release the pressure before removing thedrain cock, cap and drain plugs.2. Drain the cooling system. DO NOT waste reusablecoolant. If the solution is clean, drain it into a cleancontainer for reuse.3. Remove the radiator or radiator and condenser, ifequipped with AIC.4.5.6.7.Scribe a mark on the distributor housing in line withthe lip of the rotor.Scribe a mark on the distributor housing near the clampand continue the scribe mark on the cylinder block inline with the distributor mark.For ease of installation, note the position of the rotorand distributor housing in relation to adjacent enginecomponents.Remove the distributor and ignition wires.8. Remove the engine cylinder head cover.9. Remove the rocker arms, bridges and pivots.10. Remove the pushrods.11. Remove the hydraulic valve tappets from the enginecylinder head.12. Remove the vibration damper.13. Remove the timing case cover.14. Remove the timing chain and sprockets.15. Remove the camshaft (Figure 2-6).Inspection1.2.3.4.5.Inspect the cam lobes for wear.Inspect the bearing journals for uneven wear patternor finish.Inspect the bearings for wear.Inspect the distributor drive gear for wear.If the camshaft appears to have been rubbing againstthe timing case cover, examine the oil pressure reliefholes in the rear cam journal. The oil pressure reliefholes must be free of debris.InstallationNote: When installing a new camshaft, ALWAYS usenew lifters.1. Lubricate the replacement camshaft with MoparEngine Oil Supplement, or equivalent.2. Carefully install the camshaft to prevent damage to thecamshaft bearings (Figure 2-6).3. Turn the tensioner lever to the unlocked (down) position4. Pull the tensioner block toward the tensioner lever tocompress the spring. Hold the block and turn thetensioner lever to the lock (up) position (Figure 2-25).5. lnstall the timing chain, crankshaft sprocket and(camshaft sprocket with the timing marks aligned.. . ..

- -1 n~~~~2.5L POWER TECH IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 596. Install the camshaft sprocket retaining bolt and washer.Tighten the bolt to 108 Nom (80 ft-lbs) torque.7.8.Release the timing chain tensioner by moving the leverto the unlocked (down) position (Figure 2-25).Install the timing case cover with a replacement oil seal(Figure 2-3).9. Install the vibration damper10. Install the hydraulic valve tappets.11. Install the pushrods.12. Install the rocker arms, bridges and pivots.13. Install the cylinder head cover.14. Install the distributor and ignition wires.15. Properly position the distributor rotor as follows:Note: Always rotate the crankshaft clockwise (thedirection of normal rotation). DO NOT rotate thecrankshaft backward to align the timing marks.a.b.C.d.e.f.Remove No. 1 spark plug. Hold your finger overthe spark plug hole and rotate the crankshaft untilcompression pressure is felt. Slowly continue torotate the crankshaft until the timing index on thevibration damper pulley aligns with the top deadcenter (TDC) mark (0") on the timing degree scale.Using a flat blade screwdriver, rotate the oilpump gear so that the gear slot on the oil pumpshaft is slightly past the three (3) o'clock position(Figure 2-57).Turn the distributor shaft until the rotor tip pointsin the direction of No. I terminal in the distributorcap. Turn the rotor 1/8 turn counterclockwise pastthe position of No. 1 terminal.With the distributor cap removed, start thedistributor into they cylinder block with the rotorlocated at the five (5) o'clock position (Figure 2-58).Slide the distributor shaft down into the engineand position the distributor vacuum advancemechanism housing in approximately the samelocation (in relation to adjacent enginecomponents) as when removed. Align the scribemark on the distributor housing with thecorresponding scribe mark on the cylinder block.It may be necessary to rotate the oil pump shaftwith a long flat-blade screwdriver to engage theoil pump drive tang, but the rotor should alignwith the position of No. 1 terminal when thedistributor shaft is down in place.Install the distributor hold-down clamp and bolt,but DO NOT tighten the bolt.g. When the distributor is fully engaged in its correctlocation, the rotor should be at the six (6) o'clockposition (Figure 2-59).h.If the distributor is not properly installed, or if it isremoved later, then the complete installationprocedures must be repeated.16. Install the radiator and condenser (if equipped with NC).17. Fill the cooling system.18. Connect the battery negative cable.1FRONT FACE OF3 O'CLOCKOIL PUMPPOSITIONGEAR SLOTI J9009-32II tIFigure 2 - 57IFRONT FACE OFENGINE BLOCK-L I I5 APPROX. O'CLOCK-/IFigure 2 - 58J9009-33

60 MOPAR PERFORMANCE PARTSIIFRONT FACE OFENGINE BLOCKROTOR POSITION WHEN1 PROPERLY INSTALLEDIJ9009-34Figure 2 - 59CAMSHAFT PIN REPLACEMENTRemoval1.Warning! DO NOT loosen the radiator draincock with thesystem hot and pressurized because serious burns fromcoolant can occur.2.3.4.Disconnect the battery negative cable.Drain the radiator. DO NOT waste reusable coolant. Ifsolution is clean, drain it into a clean container for reuse.Remove the fan and shroud.Disconnect the radiator overflow tube, radiator hoses, andautomatic transmission fluid cooler pipes (if equipped).5. Remove the radiator.6. If equipped with air conditioning:a.b.Caution: DO NOT loosen or disconnect any airconditioner system fittings. Move the condenser andreceiveddrier aside as a complete assembly.c.Remove the A/C compressor drive belt idler pulley.Disconnect and remove the alternator.Remove the A/C condenser attaching bolts andmove the condenser and receiveddrier assemblyup and out of the way.7. Remove the drive belt(s).8.Remove the crankshaft vibration damper and pulley.9. Remove the timing case cover. Clean the gasketmaterial from the cover.10. Rotate the crankshaft until the zero degree (0") timingmark on the crankshaft sprocket is closest to and on thecenterline with the timing mark on the camshaft sprocket.1 1. Remove camshaft sprocket retaining bolt.12. Remove the crankshaft oil slinger.13. Remove the sprockets and chain as an assembly(Figure 2-60).Caution: The following procedural step must beaccomplished to prevent the camshaft from damaging therear camshaft plug during pin installation.14. Inspect the damaged camshaft pin.15. If the pin is a spring-type pin, remove the broken pinby inserting a self-tapping screw into the pin andcarefully pulling the pin from the camshaft.16. If the pin is a dowel-type pin, center-punch it. Ensure theexact center is located when center-punching the pin.Caution: Cover the opened oil pan area to prevent metalchips from entering the pan.17. Drill into the pin center with a 4 mm (5/32") drill bit.18. Insert a self-tapping screw into the drilled pin andcarefully pull the pin from the camshaft.I\IInstallation1.2.3.4.Figure 2 - 60(Clean the camshaft pin hole.CRANKSHAFTSPRTKET SPRQCKETCompress the center of the replacement spring pin withvise grips.Carefully drive the pin into the camshaft pin hole untilit is seated.Install the camshaft sprocket, crankshaft sprocket andtiming chain with the timing marks aligned.. .. .. T -17

2.5L POWER TECH IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 615. To verify correct installation of the timing chain, turnthe crankshaft to position the camshaft sprocket timingmark at approximately the one o'clock position. Thispositions the crankshaft sprocket timing mark wherethe adjacent tooth meshes with the chain at the three(3) o'clock position. Count the number of chain pinsbetween the timing marks on both sprockets. Theremust be 20 pins.6.7.Install the crankshaft oil slinger.Tighten the camshaft sprocket bolt to 108 Nom (80 ft-lbs)torque8. Check the valve timing.9. Coat both sides of the replacement timing case covergasket with gasket sealer. Apply a 3 mm (I/S'l) bead ofMopar Silicone Rubber Adhesive Sealant, orequivalent to the joint formed at the timing case coverand cylinder block.10. Position the timing case cover on the oil pan gasket andthe cylinder block.11. Place timing case cover alignment and seal installationtool in the crankshaft opening of the cover (Figure 2-22).12. Install the timing case cover-to-cylinder block bolts.Install the oil pan-to-timing case cover bolts.13. Tighten the 1/4" cover-to-block bolts to 7 Nom (60 in-lbs)torque. Tighten the 5/16" front cover-to-block bolts to 22Nom (192 in-lbs) torque. Tighten the oil pan-to-cover1/4" bolts to I4 Nom (I 20 in-lbs) torque. Tighten the oilpan-to-cover 5/16" bolts to 18 Nom ( 156 in-lbs) torque.14. Remove the cover alignment tool and install areplacement oil seal into the cover.15. Install the vibration damper on the crankshaft.16. Lubricate and tighten the damper bolt to 108 Nom(80 ft-lbs) torque.Note: If the crankshaft turns before the damper bolttorque value is attained, the crankshaft can beprevented from turning by placing two, 5/16 x 1-1/2"bolts into the damper front pulley holes and wedging abar between them. Rotate the bar until it contacts theframe member to prevent the crankshaft from turning.17. Install the damper pulley, if applicable.18. If equipped with air conditioning:a. Install the A/C compressor drive bell idler pulley.b. Install the alternator.c. Install the A/C condenser and receiveddrier assembly.19. Install the drive belt(s) on the pulleys and tighten.20. Install the radiator. Connect the radiator hoses andautomatic transmission fluid cooler pipes, if equipped.Fill the cooling system.21. Install the fan and shroud.22. Connect the battery negative cable.VALVES AND VALVE SPRINGSRemoval -Cylinder Head RemovedThis procedure is for the removal/installation of the valvesand valve springs with the cylinder head removed from thecylinder block.1. Remove the cylinder head from the cylinder block (referto 'Cylinder Head' section of this chapter for procedure).2. Use valve spring compressor tool and compress eachvalve spring (Figure 2-61).3. Remove the valve locks, retainers, springs and valvestem oil seals. Discard the oil seals.4. Use an Arkansas smoothstone or a jewelers file toremove any burrs on the top of the valve stem,especially around the groove for the locks.5.Remove the valves, and place them in a rack in thesame order as removed.SPRINGCOMPRESSORTOOL \I J8909-87Figure 2 - 61

62 MOPAR PERFORMANCE PARTSRemoval -Cylinder Head NOT RemovedThis procedure is for the removal of valve springs and oilseals with the cylinder head installed on the cylinder block.Each valve spring is held in place around the valve stem bya retainer and a set of conical valve locks. The locks can beremoved only by compressing the valve spring.1.Remove the cylinder head cover (refer to 'CylinderHead' section of this chapter for procedure).2.Remove capscrews, bridge and pivot assemblies androcker arms (Figure 2-62) for access to each valvespring to be removed. Alternately loosen eachcapscrew one turn at a time to avoid damaging thebridge.3.4.5.6.Remove pushrods (Figure 2-62). Retain the pushrods,bridges, pivots and rocker arms in the same order andposition as removed.Inspect the springs and retainer for cracks and possiblesigns of weakening.Remove the spark plug(s) adjacent to the cylinder(s)below the valve springs to be removed.Install a 14 mm (1/2") (thread size) air hose adapter inthe spark plug hole. An adapter can be constructed bywelding an air hose connection to the body of a sparkplug with the porcelain removed.rFigure 2 - 62J8909-87.Connect an air hose to the adapter and apply airpressure slowly. Maintain at least 621 kPa (90 psi) ofair pressure in the cylinder to hold the valves againsttheir seats. For vehicles equipped with an airconditioner, use a flexible air adapter when servicingthe No. 1 cylinder.8.Tap the retainer or tip with a rawhide hammer to loosenthe lock from the retainer. Use valve spring compressortool to compress the spring and remove the locks(Figure 2-61). Use an old rocker arm pivot and thesupplied bolt to attach the tool.9.10.Remove valve spring and retainer (Figure 2-63).Remove valve stem oil seals (Figure 2-63). Note thevalve seals are different for intake and exhaust valves.The top of each seal is marked either INT or EXH. DONOT mix the seals.ICleaningFigure 2 - 63J8909-861. Clean all carbon deposits from the combustionchambers, valve ports, valve stems, valve stem guidesand cylinder head.2.Clean all grime and gasket material from the cylinderhead machined gasket surface.....-r --I 1

2.5L POWER TECH IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 63Inspection1. Inspect for cracks in combustion chambers andvalve ports.2.3.4.5.Inspect for cracks on exhaust seats.Inspect for cracks in the gasket surface at eachcoolant passage.Inspect valves for burned, cracked or warped heads.Inspect for scuffed or bent valve stems, especially thegrooves. An Arkansas smoothstone should be used toremove nicks and high spots. Replace valvesdisplaying any damage.CONICALVALVESPRINGValve Refacing1. Use a valve refacing machine to reface the intake andexhaust valves to the specified angle. After refacing, atleast a 0.787 mm (1/32") margin must remain (Figure2-64). If not, replace the valve.2.The valve stem tip can be resurfaced and rechamberedwhen worn. DO NOT remove more than 0.25 mm(0.010").VALVE MARGINFigure 2 - 65J9009-17VALVE SPRINGTESTER TOOLVALVE SPRINGCORRECT VALVE FACINGNO MARGINJ9009-18Figure 2 - 66INCORRECT VALWE FACINGFigure 2 - 64Valve Spring Tension TestJ9009-69The 2SL engines use a conical valve spring (Figure 2-65).Use a valve spring tester and a torque wrench (Figure 2-66)to test each valve spring for the specified tension value.(Refer to 2.5L Engine Specifications, 'Engine Assembly'section of this chapter, for valve spring tension values.)Replace valve springs that are not within specification.Installation - Cylinder Head RemovedInstall replacement valve stem oil seals over the valvestems and onto the valve guide boss.Note: If valves with 0.381 mm (0.015") oversizestems are used, oversize oil seals are required.Position the valve spring and retainer on the cylinderhead and compress the valve spring with valve springcompressor tool (Figure 2-61). Install valve locks andrelease the tool.Lightly tap the valve spring from side-to-side with arubber hammer to ensure the spring is properly seatedon the cylinder head.Install the cylinder head to the cylinder block (refer toCylinder Head Installation, 'Cylinder Head' section ofthis chapter, for the procedure).1.2.Thoroughly clean the valve stems and valve guide bores.Lightly lubricate the stem and install the valve in theoriginal valve guide bore.....T - 1 1

T -1-764 MOPAR PERFORMANCE PARTSInstallation -Cylinder Head NOT RemovedCaution: Install oil seals carefully to prevent damage fromthe sharp edges of the valve spring lock groove.1.2.3.4.Lightly push the valve seal over the valve stem andvalve guide boss. Be sure the seal is completely seatedon the valve guide boss.Install valve spring and retainer.Compress the valve spring with valve springcompressor tool (Figure 2-61) and insert the valvelocks. Release the spring tension and remove the tool.Tap the spring from side-to-side with a rubber hammerto ensure that the spring is seated properly on thecylinder head.Release air pressure and disconnect the air hose.Remove the adapter from the spark plug hole andinstall the spark plug.1 1 1 1 1 -pJeep 2.5L Valve Specifications Chart~_______Part Number I Location I Diameter I Length I Material I ModificationP4529212 Intake std. Std.Std. M: Back-cut, 8 mmP4S292 13 Exhaust Std. Std. Back-cut, 8 mmP.5249879P5249880Exhaust 1 .SO" 4.93" Stainless 8 mm stemExhaust 1.56"5.6.7.8.9.Repeat these procedures for each remaining valvespring to be removed.Install the pushrods. Ensure the bottom end of each rodis centered in the plunger cap seat of the hydraulicvalve tappet.Install the rocker arms, pivots and bridge at theiroriginal location.Tighten the bridge capscrews alternately, one at a time,to avoid damaging the bridge. Tighten the capscrews to28 N*m (21 ft-lbs) torque.Install the cylinder head cover (refer to Cylinder HeudCover Installation, 'Cylinder Head' section of thischapter, for the procedure).PS24987S Intake 1.92" 4.91" Stainless 8 mm stemI P5249877 I Intake I 1.97" I 4.91" I Stainless I 8 mm stemJeep 2.5L Valve Spring Specifications ChartPart NumberP4529214~45292 15P5249464Installed Ht. Description O.D. Wire Diameter Lift Range Material1.64" Cylindrical 1.31" 177" .350/.430" Prod.1.64" Conical Prod. Prod. .350/.430" Prod.1.64" Single w/damper 1.42" ,187" .400/.525" Chrome-si1Jeep 2.5L Valve Spring Retainer Specifications ChartRetainerP4529217MaterialSingle-Std.Conical

~~~ ~r ~~~2.5L POWER TECH IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 65Jeep 4 and 6 Cylinder Engine Keepers (Locks)Part Number Valve Stem Size Angle Hardened Groove Use With Retainers SetsP45292 18 8 mm 8" Std. Sinele P45292 16, P4529217 24 PiecesVALVE TIMING1.2.3.4.5.6.7.8.9.10.Disconnect the spark plug wires and remove thespark plugs.Remove the engine cylinder head cover.Remove the capscrews, bridge and pivot assembly, androcker arms from above the No. 1 cylinder.Alternately loosen each capscrew, one turn at a time, toavoid damaging the bridge.Rotate the crankshaft until the No. 4 piston is at topdead center (TDC) on the compression stroke.Rotate the crankshaft counterclockwise (viewed fromthe front of the engine) 90".Install a dial indicator on the end of the No. 1 cylinderintake valve pushrod. Use rubber tubing to secure theindicator stem on the pushrod.Set the dial indicator pointer at zero.Rotate the crankshaft clockwise (viewed from the frontof the engine) until the dial indicator pointer indicates0.305 mm (0.012") travel distance (lift).The timing notch index on the vibration damper should bealigned with the TDC mark on the timing degree scale.If the timing notch is more than 13 mm (1/2") awayfrom the TDC mark in either direction, the valvetiming is incorrect.If the valve timing is incorrect, the cause may be abroken camshaft pin. It is not necessary to replace thecamshaft because of pin failure. A spring pin isavailable for service replacement.VALVE STEM OIL SEALSViton Valve Stem Oil Seal SetViton heavy duty umbrella seals are specially designed towithstand high temperatures. Helps prevent oil seepagedown valve guides. Good for dual purpose highperformance engines. Includes 4 intake and 4 exhaustseals. Not recommended for dual valve springs. Fits 2.5Lengine valves with 8 mm stems only.P452966 1Viton valve stem oil seal set.Race Valve Stem Oil Seal SetsPerfect Circle valve stem oil seals for use with dual valvesprings in race applications. Set of 16 seals. Includesinstallation tool.P3690963P4876099P4876 100VALVE GUIDESRace valve stern oil seal set, 3/8" insidediameter.Race valve stem oil seal set, 11/32!'inside diameter.Race valve stem oil seal set, 5/16" insidediameter.The valve guides are an integral part of the cylinder headand are not replaceable. When the valve stem guideclearance is excessive, the valve guide bores must bereamed oversize. Service valves with oversize stems areavailable in 0.076 mm (0.003") and 0.381 mm (0.015")increments. Corresponding oversize valve stem seals arealso available and must be used with valves having 0.381mm (0.0 15") oversize stems.Note: If the valve guides are reamed oversize, the valveseats must be reground afterwards to ensure that the valveseat is concentric to the valve guide.Valve stem seals are installed over each valve stem andvalve guide boss preventing oil from entering thecombustion chamber through the valve guides. There areseparate seals for intake and exhaust valve stems. Sealsmarked INT are for intake valve stems, seals marked EXHare for exhaust valve stems. Replace valve stem seals whenservice is performed or if the seals have deteriorated.

-7-766 MOPAR PERFORMANCE PARTSValve Stem-to-Guide Clearance MeasurementValve stem-to-guide clearance may be measured by eitherof the following two methods.1. Preferred MethodRemove the valve from the head.Clean the valve stem guide bore with solvent andbristle brush.Insert a telescoping gauge into the valve stem guidebore approximately 9.525 mm (3/8") from the valvespring side of the head with contacts crosswise tothe cylinder head (Figure 2-67). Remove andmeasure telescoping gauge with a micrometer.Repeat the measurement with contacts lengthwiseto cylinder head.Compare the crosswise to lengthwisemeasurements to determine out-of-roundness. Ifthe measurements differ by more than 0.0635 mm(0.0025"), ream the guide bore to accommodatean oversize valve stem.Compare the measured valve guide bore diameterwith specifications (7.95-7.97 mm or 0.3 13-0.314"). If the measurement differs fromspecification by more than 0.076 mm (0.003"),ream the guide bore to accommodate an oversizevalve stem.Note: Valve seats must be reground after reamingthe valve guides to ensure that the valve seat isconcentric to the valve guide.2. Alternate MethodVALVE SEATSUse a dial indicator to measure the lateralmovement of the valve stem (stem-to-guideclearance). This must be done with the valveinstalled in its guide and just off the valve seat(Figure 2-68).Correct clearance is 0.025-0.0762 mm (0.001-0.003"). If indicated movement exceeds thespecification, ream the valve guide toaccommodate an oversize valve stem.Note: Valve seats must be reground after reamingthe valve guides to ensure that the valve seat isconcentric to the valve guide.Figure 2 - 68ICYLINDERHEADFigure 2 - 67VALVE. STEMGUIDEJEW-92With cast iron cylinder heads, all the valve seats aremachined into the head material. (Aluminum heads usevalve seat inserts.) One of the most important items in ahigh output engine is the valve job.Valve Seat Refacing1. Install a pilot of the correct size in the valve guide boreand reface the valve seat to the specified angle with agood dressing stone (Figure 2-69). Remove onlyenough metal to provide a smooth finish.2.3.Use tapered stones to obtain the specified seat widthswhen required.Control valve seat run-out (Figure 2-70) to a maximumof 0.0635 mm (0.0025").

l- -7 ‘72.5L POWER TECH IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 67SEAT WIDTH TOP ANGLE -\INTAKE - 30°EXHAUST - 15’SEAT ANGLE - 44So-A5ORoller Rocker Arm SetIOAT ANGLE -INTAKE - 60°EXHAUST - 50°Figure 2 - 69NO USED INSE~TON I@,,,INTAKE 19009-79Fits all 2.SL and 4.0L engines. (Must use a spacer forvalve cover clearance.)0Contains one cylinder set of two rockers, two supportstands, rocker shaft and screws.Extruded aluminum rockers, anodized blue.0 Can be used with hydraulic, mechanical or rollercamshafts.00Roller tip and center pivot to reduce internal friction.Provides exact geometry; 1.6: I ratio.Adjustable, oil through pushrod style.P4529885Roller rocker arm set.Aluminum Rocker Assembly LubeWhen you use aluminum roller rockers, don’t take achance with a substandard lubricant. Mopar PerformanceParts assembly lube is a must to complete the job right.P5249099Aluminum rocker assembly lube.1ROCKER ARMSHeavy Duty Rocker ArmFigure 2 - 70Heavy duty stamped rocker arms for use with hydrauliccams (only). Right and left rockers are the same. Can beused to service stock engines. For all 2.SL and 4.0L Jeepengines. (Sold individually.)P452922 1Heavy duty rocker arm.RemovalThe following procedure can be performed with the enginein or out of the vehicle.1. Remove the cylinder head cover (see Cylinder HeadCover Removal, ‘Cylinder Head’ section of thischapter, for the procedure).2.Remove the two capscrews at each bridge and pivotassembly. Alternately loosen the capscrews one turn ata time to avoid damaging the bridges.3. Check for rocker arm bridges which are causingmisalignment of the rocker arm-to-valve tip area.4.5.Remove the bridges, pivots and corresponding pairs ofrocker arms and place them on the bench in the sameorder as removed.Remove the pushrods and place them on the bench inthe same order as removed.

l- ‘ T - l~~ ~68 MOPAR PERFORMANCE PARTSCleaning and Inspection1.2.3.4.5.6.Clean all the components with cleaning solvent and usecompressed air to blow out the oil passages in therocker arms and pushrods.Inspect the pivot surface area of each rocker arm.Replace any that are scuffed, pitted, cracked orexcessively worn.Inspect the valve stem tip contact surface of each rockerarm and replace any rocker arm that is deeply pitted.Inspect each pushrod end for excessive wear andreplace as required. If any pushrod is excessively wornbecause of lack of oil, replace it and inspect thecorresponding hydraulic tappet for excessive wear.Inspect the pushrods for straightness by rolling themon a flat surface or by shining a light between thepushrod and the flat surface.A wear pattern along the length of the pushrod is notnormal. Inspect the cylinder head for obstruction if thiscondition exists.Installation1.2.3.4.5.Lubricate the ball ends of each pushrod with MoparSuper Oil Conditioner (or equivalent) and installpushrods in their original locations. Ensure that thebottom end of each pushrod is centered in the tappetplunger cap seat.Lubricate the area of the rocker arm that the pivot contactswith Mopar Super Oil Conditioner (or equivalent) andinstall rocker arms, pivots and bridge above each cylinderfrom where they were originally removed.Loosely install capscrews through each bridge.At each bridge, tighten the capscrews alternately, oneturn at a time, to avoid damaging the bridge. Tightenthe capscrews to 26 Nom (19 ft-lbs) torque.Install the cylinder head cover (see Cylinder HeadCover Installation, ‘Cylinder Head’ section of thischapter, for the procedure).PUSHRODSThe valve train of the Jeep 2.SL engine is oiled through thepushrods. Jeep engine pushrods (all Jeep engines) are hollowso that oil can pass through them to oil the valve train.Warning! Because the 2.SL engine valve train is oiledthrough its hollow pushrods, SOLID SHAFT PUSHRODSCANNOT BE USED.Standard Length PushrodThis is a fully assembled, stock diameter hydraulicpushrod. It is hollow to provide valve train oiling (same asproduction pushrod). Factory approved and engineered forrebuild or repairs. For all 2.SL and 1987-2000 4.0Lengines. (Sold individually.)P45 292 19Standard length pushrod.Standard Length Pushrod SetComplete set of factory original pushrods for 2.5L engines(only). These are fully assembled, stock diameterpushrods. They are hollow to provide valve train oiling(same as production). Complete set of eight (8).P4S29674Standard length pushrod set.HYDRAULIC LIFTERS (TAPPETS)Note: The following removal and installation procedures canbe performed with the cylinder head installed on the engine.Hydraulic TappetFor use with general purpose, high performance hydrauliccamshafts. Can be used as a production replacement.(Sold individually.)P4529220Removal1.2.3.4.5.Hydraulic tappet.Remove the cylinder head cover (refer to CylinderHead Cover Removal, ‘Cylinder Head’ section of thischapter, for the procedure).Remove the bridge and pivot assemblies and rockerarms by removing the two capscrews at each bridge.Alternately loosen each capscrew one turn at a time toavoid damaging the bridge.Remove the pushrods. Place them on a workbench inthe same order as removed to facilitate installation intheir original locations.Remove the tappets through the pushrod openings inthe cylinder head with a hydraulic valve tappetremoval/installation tool (Figure 2-7 1). Place them ona workbench in the same order as removed to facilitateinstallation in their original locations.Inspect the tappets for wear. If worn, check the camlobes for wear. Replace if wear is found.

2.5L POWER TECH IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 69HYDRAULIC VALVE TAPP€lREMOVAL/ INSTALLATIONSNAPRING-RUNGER CAPETERING VALVPLUNGEROILINLETHOLE\J8909-96Figure 2 - 71Disassembly and Cleaning1. Release snap ring and remove the plunger cap, meteringvalve, plunger, check valve assembly and plungerreturn spring from the tappet body (Figure 2-72). Retaincomponents of each tappet separately.2.3.4.Clean the components of each tappet assembly incleaning solvent to remove all varnish, gum and sludgedeposits.Inspect for indications of scuffing on the side and baseof each tappet body.Inspect each tappet base for concave wear with astraightedge positioned across the base. If the base isconcave, the corresponding lobe on camshaft is alsoworn. Replace the camshaft and defective tappets.Assembly1. Install the plunger return spring, check valveassembly, plunger, metering valve and plunger cap inthe tappet body.2.Compress the plunger assembly by exerting force on theplunger cap with the pushrod and install the snap ring.InstallationNote: It is not recommended to fill the tappets with oil asthis may make the engine difficult to start. The tappets willcharge themselves within three to eight minutes once theengine has been started.I. Coat each tappet assembly in Mopar Super OilConditioner, or equivalent.2.3.4.5.6.7.TAPPO \/BODY J8909-97Figure 2 - 72Use a hydraulic valve tappet removal/installation toolto install each tappet in the same bore from where itwas originally removed.Install the pushrods in their original locations.Install the rocker arms and bridge and pivot assembliesat their original locations. Loosely install thecapscrews at each bridge.Tighten the capscrews alternately, one turn at a time, toavoid damaging the bridges. Tighten the capscrews to26 N*m (1 9 ft-lbs) torque.Pour the remaining Mopar Super Oil Conditioner (orequivalent) over the entire valve actuating assembly.The Mopar Super Oil Conditioner (or equivalent) mustremain with the engine oil for at least I600 km ( 1,000miles); however, it does not need to be drained until thenext scheduled oil change.Install the cylinder head cover. Refer to Cylinder HeudCover Installation, ‘Cylinder Head’ section of thischapter, for the procedure.

70 MOPAR PERFORMANCE PARTSINTRODUCTION(Refer to Figure 2-73.)The 2.SL engine uses a pressure feed, full flow filtrationoiling system utilizing a positive displacement, gear-typeoil pump driven by the distributor shaft. The oiling systemhas a capacity of 3.8L (4 quarts). (For more oiling systemspecifications, refer to 2.5L Engine Spec@ations, ‘EngineAssembly’ section of this chapter.)A gear-type positive displacement pump is mounted at theunderside of the block opposite the No. 4 main bearing, Thepump draws oil through the screen and inlet tube from thesump at the rear of the oil pan. The oil is driven between thedrive and idler gears and pump body, then forced throughthe outlet to the block. An oil galley in the block channelsthe oil to the inlet side of the full flow oil filter. Afterpassing through the filter element, the oil passes from thecenter outlet of the filter through an oil galley that channelsthe oil up to the main galley which extends the entire lengthof the block.Galleries extend downward from the main oil galley to theupper shell of each main bearing. The crankshaft is drilledinternally to pass oil from the main bearing journals (exceptNo. 4 main bearing journal) to the connecting rod journals.Each connecting rod bearing cap has a small squirt hole. Oilpasses through the squirt hole and is thrown off as the rodrotates. This oil throw off lubricates the camshaft lobes,distributor drive gear, cylinder walls, and piston pins.Oiling SystemThe hydraulic valve tappets receive oil directly from themain oil galley. Oil is provided to camshaft bearingsthrough galleys. The front camshaft bearing journal passesoil through the camshaft sprocket to the timing chain. Oildrains back to the oil pan under the No. I main bearing cap.The oil supply for the rocker arms and bridged pivotassemblies is provided by the hydraulic valve tappets whichpass oil through hollow pushrods to a hole in thecorresponding rocker arm. Oil from the rocker armlubricates the valve train components, then passes downthrough the pushrod guide holes in the cylinder head pastthe valve tappet area, and returns to the oil pan.Oil Pressure RequirementsOil pressure requirements for the 2.5L engine are as follows:At Idle Speed (800 rpm) . . . , 25-35 psi . . . . 172-241 kPaAt 1,600+ rpm. . . . . . . . . . . . 37-75 psi . . . .255-517 kPaOil Pressure Relief . . . . . . . . 75 psi. . . . , . . 517 kPa

2.5L POWER TECH IN-LINE 4 (OILING SYSTEM) 71TAPPETGALLERYTAPPETGALLERYCAMKRANKCAMSHAFTSPROCKET80ae8366Figure 2 - 73

72 MOPAR PERFORMANCE PARTSOIL PANOil Pan Gasket SetIncludes both sides and the ends. For 2.5L engines only.P4.529664 Oil pan gasket set.Removal1.2. Raise the vehicle.3.4.Disconnect the battery negative cable.Remove the oil pan drain plug and drain the engine oil.Disconnect the exhaust pipe at the exhaust manifold (ifnecessary - check clearances first).5. Disconnect the exhaust hanger at the catalyticconverter and lower the pipe (if necessary -checkclearances first).6. Remove the starter motor.7.Remove the converter/flywheel housing access cover.8. Position a jack stand directly under the enginevibration damper.9.Place a piece of wood (2 x 2) between the jack standand the engine vibration damper.10. Remove the engine mount through bolts.11. Using the jack stand, raise the engine until adequateclearance is obtained to remove the oil pan.12. Remove transmission oil cooling lines (if equipped).13. Remove the oxygen sensor wiring supports that areattached to the oil pan studs (if equipped).14. Remove the oil pan bolts and carefully remove the oilpan and gasket.Cleaning4. Slide the one-piece gasket over the dowels and onto theblock and timing case cover.5.6.7.8.9.Position the oil pan over the dowels and onto the gasket.Install the 1/4" oil pan fasteners (Figure 2-77). Tightenthese fasteners to 9 Nom (7 ft-lbs) torque. Install the5/16" oil pan fasteners (Figure 2-77). Tighten thesefasteners to 15 N*m (1 1 ft-lbs) torque.Remove the dowels. Install the remaining 1/4" oil panfasteners and tighten to 9 Nom (7 ft-lbs) torque.Lower the engine until it is properly located on theengine mounts.Install the through bolts and tighten the nuts to 65 N*m(48 ft-lbs) torque.10. Lower the jack stand and remove the piece of wood.11. Install the flywheel/torque converter housing access cover.12. Install the starter motor.13. Connect the exhaust pipe (if removed) to the hangerand the exhaust manifold.14. Install transmission oil cooling lines (if removed) andoxygen sensor wiring supports that attach to the oil panstuds (if removed).15. Install the oil pan drain plug using a new gasket (Figure2-77). Tighten the plug to 34 Nom (25 ft-lbs) torque.16. Lower the vehicle.17. Connect the battery negative cable.18. Fill the oil pan with engine oil to the specified levelWarning! Use extreme caution when the engine isoperating. DO NOT stand in direct line with the fan. DONOlT put your hands near the pulleys, belts or fan. DO NOTwear loose clothing.19. Start the engine and inspect for leaks.1. Clean the block and pan surfaces to remove gasketmaterial and sealant.2.Remove all sludge and grime from the oil pan sump.Installation1. Fabricate 4 alignment dowels from 1/4" x 1-1/2" bolts.Cut the head off the bolts and cut a slot into the top ofthe dowel. This will allow easier installation andremoval with a screwdriver (Figure 2-74).2.3.Install two dowels in the timing case cover. Install theother two dowels in the cylinder block (Figure 2-75).Apply Mopar Silicone Rubber Adhesive Sealant oncylinder block to rear main bearing cap corners andcylinder block-to-front cover joints (four places).(Refer to Figure 2-76.)

~~2.5L POWER TECH IN-LINE 4 (OILING SYSTEM) 731/4" x 1 1/2" BOLTDDOWEL(A) 5/16" BOLTS - 15N.m (1 1 FT-LBS)1 /4" BOLTS - 9NSbTJ9209-6~Figure 2 - 74OIL PANOIL PAN DRAINPLUG GASKETOIL PAN DRAIN J9009-37PLUGm DOWELCYLINDERFigure 2 - 77OIL PUMPw J9209- 18Figure 2 - 75The positive displacement, gear-type oil pump is driven bythe distributor shaft which is driven by a gear on thecamshaft. Oil is siphoned into the pump through an inlettube and strainer assembly that is pressed into the pumpbody. The pump incorporates a non adjustable pressurerelief valve to limit maximum pressure to 75 psi (5 17 Wa).In the relief position, the valve permits oil to bypass througha passage in the pump body to the inlet side of the pump.Oil pump removal or replacement will not affect distributortiming because the distributor drive gear remains in meshwith the camshaft gear.Removal1. Remove the oil pan as outlined in the removalprocedure in this section.Caution: If the oil pump is not to be serviced, DO NOTdisturb position of oil inlet tube and strainer assembly inpump body. If the oil inlet tube is moved within the pumpbody, a replacement tube and strainer assembly must beinstalled to assure an airtight seal.2. Remove the pump-to-cylinder block attaching bolts andremove the pump assembly with gasket (Figure 2-78).Figure 2 - 76

T ll --l74 MOPAR PERFORMANCE PARTSOIL FILTER /-OIL PUMPGEARBLOCKSTRAINERASSEMBLYATTACHI NGBOLTSJ9509-85Figure 2 - 78Gear End Clearance MeasurementRemove the cover retaining screws and cover from thepump body.1. Preferred Methoda. Place a strip of Plastigauge across the full width ofeach gear (Figure 2-79).b.Install the pump cover and tighten the bolts to 8Nom (70 in-lbs) torque.c. Remove the pump cover and determine theamount of clearance by measuring the width ofcompressed Plastigauge with scale on thePlastigauge envelope.Correct clearance by this method is 0.05 1-0.152 mmwith 0.051 mm preferred (0.002-0.006" with 0.002"preferred). If gear end clearance is excessive, replacethe oil pump assembly.-STRIP OF P~ASTIGAGE J8909- 202. Alternate MethodFigure 2 - 79a. Place a straightedge across the ends of the gearsand the pump body.b.Select a feeler gauge that fits snugly but freelybetween the straightedge and the pump body(Figure 2-80).Correct clearance by this method is 0.051-0.152 mmwith 0.05 1 mm preferred (0.002-0.006" with 0.002"preferred). If gear end clearance is excessive, replacethe oil pump assembly.Figure 2 - 80

2.5L POWER TECH IN-LINE 4 (OILING SYSTEM) 75Gear-to-Body Clearance MeasurementWith both gears in place, measure the gear-to-bodyclearance by inserting a feeler gauge between the gear toothand the pump body inner wall, directly opposite the point ofgear mesh (Figure 2-81). Select a feeler gauge which fitssnugly but freely. Rotate gears to measure each tooth-tobodyclearance in this manner.Correct clearance is 0.051-0.102 mm with 0.051 mmpreferred (0.002-0.004" with 0.002" preferred). If the gear-tobodyclearance is more than specified, replace the oil pump.2. If the position of inlet tube in the pump body has beendisturbed, install a replacement inlet tube and strainerassembly. Apply a light film of Permatex No. 2 sealant,or equivalent, around the end of the inlet tube. Use anoil pump inlet tube installation tool to drive the inlettube into body (Figure 2-82). Ensure the supportbracket is properly aligned.3.4.5.6.Install the idler gear and drive gear assembly.Spin the drive gear shaft to assure a binding conditiondoes not exist before installing the oil pump.To assure self-priming of the oil pump, fill pump withpetroleum jelly before installing the oil pump cover.DO NOT use grease.Apply a thin bead of Loctite 5 15 (or equivalent) to thetop of the pump housing and install the pump coverscrews with 8 Nom (70 in-lbs) torque.OIL PUMP INLET TUBE" 'A INSTALLATION TOOLFigure 2 - 81J8909-122COVERm-39DisassemblyRemove the cotter pin and slide the spring retainer, springand oil pressure relief valve plunger out of the pump body.Inspect for binding condition during disassembly. Clean orreplace as necessary.Note: The oil inlet tube and strainer assembly must bemoved to allow removal of the relief valve. Install areplacement inlet tube and strainer assembly.AssemblyTwo relief valve plunger sizes (standard and oversize) areavailable. When replacing the valve, assure correctreplacement valve, standard size or 0.254 mm (0.010")oversize plunger diameter, is obtained and installed.1. Install the oil pressure relief valve plunger, spring,retainer and cotter pin.InstallationFigure 2 - 821. Install the oil pump on the cylinder block using areplacement gasket. Tighten the short bolt to 14 Nom(10 ft-lbs) torque and the long bolt to 23 Nom (17 ftlbs)torque. (Refer to Figure 2-78.)2.3.Install the oil pan. (Refer to Oil Pan Installation, in thissection, for the procedure.)Fill the oil pan with oil to the specified level.T - 1 1

76 MOPAR PERFORMANCE PARTSFuel Delivery and Fuel Injection SystemsNote: Older, carbureted versions of the 2.5L engine will not be discussed in this chapter. However, service parts for theseolder carbureted models are still available through your local Chrysler-Plymouth-Dodge-Jeep dealer. If you have an old 2.5Lcarbureted engine, refer to the ‘Induction System’ section of Chapter 7, 360 AMC V-8, for general carburetor information, aswell as the correct service manual for your vehicle/engine.MULTI-POINT FUEL INJECTION (MPI) SYSTEMNewer 2.5L engines use a sequential Multi-Point FuelInjection (MPI) system (vehicle specific -refer to yourservice manual). Fuel is injected into the intake manifoldbefore the intake valve in precise metered amounts throughelectrically operated injectors. The injectors are fired in aspecific sequence by the Powertrain Control Module (PCM).The PCM constantly adjusts the amount of fuel injected tomeet changing operating conditions by controlling injectorpulse width (the length of time the injector is energized). ThePCM also adjusts ignition timing by controlling the ignitioncoil operation through the Ignition Control Module (ICM).The PCM determines air-fuel mixture and ignition timingbased on inputs it receives from various sensors that monitorengine operating conditions.The PCM receives inputs from sensors that react to exhaustgas oxygen content, coolant temperature, manifold absolutepressure, engine speed (crankshaft position), throttleposition, battery voltage, intake manifold air temperature,engine knock and transmission gear selection. These inputsrepresent the engine’s instantaneous operating conditions.Air-fuel mixture and ignition timing calibrations forvarious driving and atmospheric conditions are preprogrammedinto the PCM. The PCM monitors andanalyzes its various inputs, computes engine fuel andignition timing requirements based on these inputs, andcontrols fuel delivery and ignition timing accordingly. TheEngine Control System is comprised of (1) the sensors andswitches that provide input to the PCM, (2) the PCM itself,and (3) the PCM outputs (engine control devices that thePCM constantly adjusts). The Engine Control Systemconsists of:Battery VoltageManifold Absolute Pressure (MAP) SensorCoolant Temperature SensorManifold Air Temperature (MAT) SensorExhaust Oxygen (02) SensorEngine Speedcrankshaft Position SensorThrottle Position SensorInjector Synchronization SignalA/C Select Signal0 A/C Request Signal0 Neutral Safety Switch0 Knock Sensor0 Fuel Pump Relay0 Fuel Injectors0 Idle Speed Stepper Motor0 B+ Latch RelayOxygen Sensor Heater RelayEGR Valve SolenoidIgnition Control ModuleShift Indicator Light (manual transmissions only)0 A/C Clutch RelayPowertrain Control Module (PCM)The Powertrain Control Module (PCM) is a digitalmicroprocessor. Air-fuel mixture calibrations for variousdriving and atmospheric conditions are pre-programmedinto the PCM. The PCM monitors and analyzes its variousinputs, computes engine fuel and ignition timingrequirements based on these inputs, and controls fueldelivery and ignition timing accordingly. As operatingconditions change, the PCM adjusts injector pulse width andignition timing for optimum performance and fuel economy.T --I -1

2.5L POWER TECH IN-LINE 4 (FUEL DELIVERY AND FUEL INJECTION SYSTEMS) 77PCM InputsThe PCM is powered by the vehicle’s battery. When theignition is turned to the ON or START position, thefollowing inputs are supplied to the PCM:000000000000Battery VoltageManifold Absolute Pressure (MAP) SensorCoolant Temperature SensorManifold Air Temperature (MAT) SensorExhaust Oxygen (02) SensorEngine Speedcrankshaft Position SensorThrottle Position SensorInjector Synchronization SignalA/C Select SignalNeutral Safety Switch (gear selection - automatictransmission)Knock SensorStart SignalPCM OutputsBased upon signals from various input sensors andswitches, the PCM adjusts the following components(PCM outputs):0 Fuel Pump RelayB+ Latch Relay0 Oxygen Sensor Heater Relay0 A/C Clutch Relay0 Fuel Injectors0 Idle Speed Stepper Motor0 EGR Valve Solenoid0 Ignition Control Module (ICM)Shift Indicator Light (manual transmission only)Modes of OperationAs input signals to the PCM change, the PCM adjusts itsresponse to the output devices. For example, the PCM mustcalculate a different injector pulse width and ignition timingfor idle than it does for wide open throttle. There are eightdifferent modes of operation that determine how the PCMresponds to the various input signals.Modes of operation are of two different types: OPENLOOP and CLOSED LOOP.During OPEN LOOP modes the PCM receives inputsignals and responds only according to preset PCMprogramming. Input from the oxygen (0,) sensor is notmonitored during OPEN LOOP modes.During CLOSED LOOP modes the PCM does monitor the0, sensor input. This input indicates to the PCM whether ornot the calculated injector pulse width results in the idealair-fuel ratio (14.7 parts air to 1 part fuel). By monitoring theexhaust oxygen content through the 0, sensor, the PCM can‘fine tune’ the injector pulse width to achieve optimum fueleconomy combined with low emission engine performance.The MPI system has the following modes of operation:Ignition Switch ONEngine Start-up (Crank)0 Engine Warm-up0 Idle0 CruiseDeceleration0 Wide Open Throttle0 Ignition Switch OFFThe ignition switch ON, engine start-up (crank), enginewarm-up, deceleration, and wide open throttle modes areOPEN LOOP modes. The idle and cruise modes, with theengine at operating temperature, are CLOSED LOOP modes.Throttle BodyFiltered air from the air cleaner enters the intake manifoldthrough the throttle body. Fuel does not enter the intakemanifold through the throttle body. Fuel is sprayed into themanifold by the fuel injectors. This throttle body, mountedon the intake manifold, contains an air bypass passage thatis used to supply air for idle conditions, and a throttle valvefor above idle conditions.The throttle position sensor and idle speed stepper motorare attached to the throttle body. The accelerator cable isconnected to the throttle valve through a bellcrank andlinkage mounted to the intake manifold.There are different throttle bodies for automatic and manualtransmission equipped vehicles. The throttle valve is notcontrolled by the PCM.

78 MOPAR PERFORMANCE PARTSFuel RaWFuel DamperThe fuel rail supplies the necessary fuel to each individualfuel injector and is mounted to the intake manifold (Figure2-83). A fuel damper is located at the front of the fuel rail(Figure 2-83). The damper is used only to help control fuelpressure pulsation. This pulsation is the result of the firingof the fuel injectors. It is not used as a fuel pressureregulator. The fuel pressure regulator is not mounted to thefuel rail on any engine. It is located on the fuel tankmounted fuel pump module.Depending on vehicle modellengine, the fuel rail may/maynot be equipped with a fuel pressure test port. Refer to theproper service manual for additional information.The fuel rail is not repairable.NUMBEREDFUEL 11 \\ FUEL TAGBOLTWNUTSFigure 2 - 838w61034Fuel Pressure RegulatorThe fuel pressure regulator used with the MPI fuel systemis a vacuum assisted, non-adjustable type. The regulator ismounted on the output end of the fuel rail and is connectedto intake manifold vacuum. The regulator is calibrated tomaintain fuel system pressure at approximately 214 kPa (31psi) with vacuum applied while the engine is at idle. Fuelpressure will be 55-69 kPa (8-10 psi) higher if vacuum isnot applied to the regulator.The pressure regulator contains a diaphragm, calibratedspring and fuel return valve. Fuel pressure operates on thebottom side of the diaphragm while spring pressure andintake manifold vacuum operate on the top side of thediaphragm. Spring pressure tries to force the return valveclosed. Fuel pressure, with assistance from manifoldvacuum on the spring side, acts against the spring pressureto open the return valve. Thus, system fuel pressure is theamount of fuel pressure required to force against springpressure and unseat the fuel return valve.Without vacuum applied to the spring side of the regulator,the spring is calibrated to open the fuel return outlet whenthe pressure differential between the fuel injectors and theintake manifold reaches approximately 269 Wa (39 psi).Since manifold vacuum varies with engine operatingconditions, the amount of vacuum applied to the spring sideof the diaphragm varies. For this reason, fuel pressurevaries depending upon intake manifold vacuum. With lowvacuum, such as during wide open throttle conditions,minimal vacuum assistance is available and full springpressure is exerted to seal the fuel outlet causing systempressure to increase. With high vacuum, such as during idle,._

2.5L POWER TECH IN-LINE 4 (FUEL DELIVERY AND FUEL INJECTION SYSTEMS) 79fuel pressure on the bottom of the diaphragm is assisted byintake manifold pressure on the spring side of thediaphragm, resulting in lower system fuel pressure. Thefuel pressure regulator is not controlled by the PCM.IAIRccvRacing ModificationsBy their nature, unlike carbureted engine set-ups, fuelinjection systems deliver fuel equally among all fourcylinders. It’s because of this excellent fuel distributioncharacteristic that fuel injection is preferred over carburetors,even over high performance 2 and 4-Bbl. carburetors.And don’t disconnect those stock fuel injection sensors!Today’s engines run a lot hotter because they run a lotleaner; because of this, fuel injection temperature is verycritical. It is something that has to be constantly monitoredand stabilized to keep the fuel injection and the power levelin their proper places. Mopar Performance Partsrecommends the use of all sensors, even in highperformanceracing set-ups. These sensors constantly inputvital information to the PCM, and the PCM corrects themixture accordingly.And don’t abandon that oxygen sensor, either. Since racingset-ups don’t use catalytic converters, use an EGT probe tolocate the hottest spot in the exhaust system and install theoxygen sensor there.Crankcase Ventilation SystemAll 2.5L 4-cylinder engines are equipped with a CrankcaseVentilation (CCV) system (Figure 2-84). The CCV systemperforms the same function as a conventional PCV system,but does not use a vacuum controlled valve.A fitting on the driver’s side of cylinder head (valve)cover contains the metered orifice. It is connected tomanifold vacuum.A fresh air supply CCV tube (hose) from the air cleaner isconnected to the rear cover.When the engine is operating, fresh air enters the engine andmixes with crankcase vapors. Manifold vacuum draws thevapor/air mixture through the fixed orifice and into the intakemanifold. The vapors are then consumed during combustion.Figure 2 - 84ccv PTUBETHROTTLE BODY (SINGLE POINT) FUELINJECTION (TBI)aQa4a5d8Throttle Body Fuel Injection (TBI) is a single point, pulsetime system that injects fuel through an electricallyoperated fuel injector into the throttle body above thethrottle plate.The fuel injection pulse width (period of time that theinjector is energized causing fuel to be released into thethrottle body) is controlled be the engine’s ElectronicControl Unit (ECU). The ECU accomplishes this byopening and closing the ground path to the injector. Bycontrolling fuel injector pulse width, the ECU is able tometer the amount of fuel to the engine and constantly adjustthe air-fuel ratio.The ECU receives inputs from sensors that react to exhaustgas oxygen content, coolant temperature, manifold absolutepressure, engine speed (crankshaft position), throttleposition, battery voltage, and air-fuel temperature. Theseinputs represent the engine’s instantaneous operatingconditions. Based on these inputs, the ECU adjusts air-fuelratio and ignition timing for the current operatingconditions. The engine control system is comprised of (1)the sensors and switches that provide input to the ECU, (2)the ECU itself, and (3) the ECU outputs (engine controldevices that the ECU constantly adjusts).1- - ll ’1

80 MOPAR PERFORMANCE PARTSThe engine control system consists ofCoolant Temperature Sensor (CTS)Manifold Air Temperature (MAT) SensorManifold Absolute Pressure (MAP) SensorEngine Speed /Crankshaft Position Sensor (CPS)Throttle Position Switch (TPS)Exhaust Oxygen (02) SensorBattery Voltage (B+)A/C Select SignalA/C Request SignalWide Open Throttle Switch (model specific-checkyour service manual)Closed Throttle SwitchNeutral Safety SwitchPower Steering High Pressure SwitchStarter Motor RelayElectronic Control Unit (ECU)Fuel Pump RelayB+ Latch RelayIdle Speed Actuator (ISA)Ignition Control ModuleFuel InjectorEGREvaporative Canister Purge Solenoid (modelspecific -check your service manual)EGR Valve Vacuum Solenoid (model specific -checkyour service manual)A/C Compressor Clutch Relay (model specific - checkyour service manual)Air-fuel mixture calibrations for various driving andatmospheric conditions are programmed into the ECU. TheECU monitors and analyzes its various inputs, computesengine fuel and ignition timing requirements based on theseinputs, and controls fuel delivery and ignition timingaccordingly. As operating conditions change, the ECUadjusts injector pulse width and ignition timing foroptimum performance and fuel economy.Electronic Control Unit (ECU)The ECU controls the fuel injector pulse width and ignitiontiming based on inputs received from sensors that react toexhaust gas oxygen content, air-fuel temperature, coolanttemperature, manifold absolute pressure, battery voltage,crankshaft position (engine speed), throttle position andinputs from switches that are triggered by power steeringpump output pressure, wide open throttle conditions, andtransmission gear selection (automatic transmissions only).Battery voltage is also monitored to determine injectorpulse width. These sensors and switches are consideredECU inputs.ECU InputsThe ECU is powered by the vehicle's battery. When theignition is turned to the ON or START position, thefollowing inputs are supplied to the ECU:Start SignalEngine Coolant TemperatureIntake Manifold Air-Fuel TemperatureIntake Manifold Absolute PressureEngine Speed (Crankshaft Position)Throttle PositionExhaust Gas Oxygen ContentBattery VoltageAIC Select and RequestWide Open Throttle Switch (model specific -checkyour service manual)Closed Throttle SwitchNeutral Safety SwitchPower Steering Pressure SwitchECU OutputsThe following are controlled by the ECU:Electric Fuel Pump RelayB+ Latch RelayA/C Compressor Clutch RelayIdle Speed Actuator (ISA) MotorIgnition Power ModuleFuel InjectorEGRBvaporative Canister Purge Solenoid (modelspecific -check your service manual)EGR Valve Vacuum Solenoid (model specific-checkyour service manual)Shift Indicator Lamp - Manual Transmission Only

-7-2.5L POWER TECH IN-LINE 4 (FUEL DELIVERY AND FUEL INJECTION SYSTEMS) 81Modes of OperationAs input signals to the ECU change, the ECU adjusts itsresponse to the output devices. For example, the ECU mustcalculate a different injector pulse width and ignition timingfor idle than it does for wide open throttle.Modes of operation are of two different types: OPENLOOP and CLOSED LOOP.During OPEN LOOP modes, the ECU receives inputsignals and responds only according to preset ECUprogramming. Input from the oxygen (0,) sensor is notmonitored during OPEN LOOP modes.During CLOSED LOOP modes the ECU does monitor the0, sensor input. This input indicates to the ECU whether ornot the calculated injector pulse width results in the idealair-fuel ratio (14.7 parts air to 1 part fuel). By monitoring theexhaust oxygen content through the 0, sensor, the ECU can‘fine tune’ the injector pulse width to achieve optimum fueleconomy combined with low emission engine performance.The TBI system has the following modes of operation:Ignition Switch ONEngine Start-upEngine Warm-upCruiseDecelerationWide Open ThrottleIgnition Switch OFFThe Ignition Switch ON, Engine Start-up (crank), EngineWarm-up, Deceleration, and Wide Open Throttle modesare OPEN LOOP modes. The Deceleration and Cruisemodes, with the engine ut operuring temperurure, areCLOSED LOOP modes.Throttle BodyThe throttle body is mounted on top of the intake manifoldand contains the fuel injector, fuel pressure regulator, andthrottle valve. The fuel inlet and return tubes are connectedto the throttle body by pressure fittings. The ISA motor andthrottle position sensor (TPS) are also mounted to thethrottle body.FUEL PUMPThe fuel pumps used for carbureted and fuel injectedvehicles are different. Carbureted vehicles have amechanical fuel pump driven by an eccentric lobe on theengine’s camshaft. Fuel injected engines (such as the 2SL)have a gearlrotor type pump driven by a permanent,magnetic 12 volt electric motor that is immersed in the fueltank. This electric pump is integral with the fuel sender unitand is also installed inside the fuel tank.Note: Electric fuel pumps used for Throttle Body Injection andMulti-Point Injection systems, though similar in appearanceand function, are different and CANNOT be interchanged.TBI Fuel PumpThe TBI fuel pump has a check valve at the outlet end thatconsists of a steel ball held against a seat by force appliedfrom a spring. When the pump is operating, fuel pressureovercomes spring pressure and forces the ball off its seat,allowing fuel to flow. When the pump is not operating,spring pressure forces the ball back against the seatpreventing fuel back flow through the pump.Voltage to operate the TBI fuel pump is supplied throughthe fuel pump relay when the relay is grounded by theengine’s Electronic Control Unit (ECU).TBI system fuel pressure is 97-103 kPa (14-15 psi)while the pump is operating, and zero (0) when thepump is not operating.FUEL FILTERThe fuel filter protects the fuel injector(s) from dirt, waterand other foreign matter. The filter is located under thevehicle along the driver’s side frame rail. Replace filter atintervals specified on the Maintenance Schedule in theservice manual.Caution: Fuel filters designed for carbureted systems areNOT interchangeable with filters designed for fuel injectionsystems. Using fuel filters designed for carbureted systemson fuel injection systems will cause damage to systemcomponents andor fuel system shut down. For proper fuelinjection system fuel filter availability and pricing, contactyour local Chrysler-Plymouth-Dodge-Jeep dealer.INTAKE MANIFOLDRemoval1.2.3.4.5.6.Disconnect the battery negative cable.Remove the air inlet hose and resonator from thethrottle body and air cleaner housing (Figure 2-84).Loosen the accessory drive belt tension and remove thebelt from the power steering pump. (Refer to the properservice manual for correct procedure.)Remove the power steering pump and brackets fromthe water pump and intake manifold. Support powersteering pump and bracket with wire attached to theradiator upper crossmember.Perform the fuel pressure release procedure. (Refer tothe proper service manual for correct procedure.)Disconnect fuel supply tube from the fuel rail. (Referto the proper service manual for correct procedure.)

82 MOPAR PERFORMANCE PARTS7. Disconnect the accelerator cable from the throttle bodyand cable bracket.Caution: When disconnecting the speed control connectorat the throttle body, DO NOT pry the connector off withpliers or screwdriver. Use finger pressure only. Prying theconnector off could break it.8. Disconnect the speed control and transmission linepressure cable from the throttle body and cable bracket(if equipped).9.Disconnect the following electrical connectors. Pullthe harnesses away from the manifold.Throttle Position SensorIdle Air Control motorCoolant Temperature Sensor at the thermostathousingManifold Air Temperature sensor at the intakemanifoldFuel injector(s)0 Oxygen (0,) sensor10. Disconnect the crankcase ventilation (CCV) vacuumhose and Manifold Absolute Pressure sensor vacuumhose connector at the intake manifold.11. Disconnect HVAC supply vacuum hose from theintake manifold.12. Disconnect the CCV hose at the cylinder head cover(Figure 2-84).13. Remove the molded vacuum harness.14. Disconnect the vacuum brake booster hose at theintake manifold.15. Remove bolts 2 through 5 securing the intake manifoldto the cylinder head (Figure 2-85). Loosen but DO NOTremove exhaust manifold bolt No. 1 and nuts 6 and 7.16. Remove the intake manifold and gaskets. Drain thecoolant from the manifold.IInstallationI.2.3.4.5.6.7.8./EXHAUSTMANIFOLDCYLINDER HEAD DOWELSFigure 2 - 85J92115Clean the intake manifold and cylinder head matingsurfaces. DO NOT allow foreign material to enter eitherthe intake manifold or the ports in the cylinder head.Install the new intake manifold gasket over the locatingdowels.Position the manifold in place and finger-tighten themounting bolts.Tighten the fasteners in sequence and to the specifiedtorque (Figure 2-85).Fastener No. I-Tighten to 41 Nom (30 ft-lbs)torque.Fastener No. 2 through No. 7-Tighten to 31 Nom(23 ft-lbs) torque.Before connecting the fuel line to the fuel rail, inspectthe fuel line O-rings and replace them if necessary.Connect the fuel supply tube to the fuel rail inlet. Pushtube until a click is heard.Pull on fuel supply line to verify that it is properlyconnected. Install latch clip.Connect the molded vacuum hoses to the vacuum porton the intake manifold and the cylinder head cover.Connect the electrical connectors.Throttle Position Sensor0 Idle Air Control motorCoolant Temperature Sensor at the thermostathousingManifold Air Temperature sensor at the intakemanifoldFuel injector(s)Oxygen (0,) sensor..T-lI-7

2.5L POWER TECH IN-LINE 4 (FUEL DELIVERY AND FUEL INJECTION SYSTEMS) 839. Connect the brake booster vacuum supply hose.10. Connect the CCV hose and MAP sensor vacuum hoseconnectors to the throttle body.11. Install the power steering pump and bracket assemblyto the water pump and intake manifold. Torque powersteering pump bolts to 28 Nom (21 ft-lbs). Torquebracket to water pump bolts to 47 Nmm (35 ft-lbs).Caution: Ensure that the accessory drive belt is routedcorrectly. Failure to do so can cause the water pump to turnin the opposite direction resulting in engine overheating.(Refer to the proper service manual for correct procedure.)12. Install and tension the accessory drive belt. (Refer tothe proper service manual for correct procedure.)13. Connect the accelerator cable to the bracket and thethrottle lever.14. Connect the speed control and transmission line pressurecable (if equipped) to the bracket and throttle lever.15. Install the air inlet hose and resonator to the throttlebody and the air cleaner.16. Connect the battery negative cable.17. Start the engine and check for leaks.AIR FILTERS~~High Performance Air Filter ElementSpecial reusable filter element for high performance.Increases air flow versus stock filters which increasesengine output.PS2499 18P4876273P4876272Air Filter Cleaning FluidHigh performance air filter element,1986-96 Jeep Wrangler 2.5L only.High performance air filter element,1997-98 Jeep Wrangler 2.5L only.High performance air filter element,1987-96 Jeep Cherokee 2.5L only.Mopar Performance Parts long-life high performance airfilters are reusable. This cleaning fluid is designed toremove dirt to extend the life of the filter.P4529392Air Filter OilAir filter cleaning fluid.Long life, high performance air filters trap dirt with aspecial oil on the filter. After cleaning air filters, re-oilthem with this special fluid.P4529393Air filter oil.

~~84 MOPAR PERFORMANCE PARTSEXHAUST SYSTEMThe basic exhaust system on all vehicles consists of anexhaust manifold, front exhaust pipe, catalytic converter,heat shield(s), muffler and tailpipe (Figure 2-86).Vehicles with the 2.5L engine use a single muffler exhaustsystem with a single, monolithic-type catalytic converter.The exhaust system must be properly aligned to preventstress, leakage, and body contact. If the system contacts anybody panel, it may amplify objectionable noises originatingfrom the engine or body.When inspecting an exhaust system, critical items toinspect for are cracked or loose joints, stripped screw orbolt threads, corrosion damage, and worn, cracked orbroken hangers. Replace all components that are badlycorroded or damaged. DO NOT attempt to repair. Whenreplacement is required, use original equipment parts (ortheir equivalent). This will assure proper alignment andprovide acceptable exhaust noise levels.All exhaust systems should be checked for leaks. A leak inthe exhaust system is unsafe and will cost you power.Caution: Avoid application of rust prevention compoundsor undercoating materials to exhaust system floor pan heatshields. Light overspray near the edges is permitted.Application of coating will result in excessive floor pantemperatures and objectionable fumes.Exhaust SystemIntake/Exhaust Manifold Attaching PackagePackage of factory original nuts and bolts to attach intakeand exhaust manifolds. Includes five bolts, seven washers,four studs, two pins, two spacers, and three plugs. ForJeep 2.5L carbureted engines only.P4529679Intake/Exhaust manifold attachingpackage.Intake/Exhaust Manifold GasketThe 2.5L engine uses a common intake and exhaustmanifold gasket. This gasket is designed for originalreplacement. For Jeep 2.5L engine only.P452’9663 Intake/Exhaust manifold gasket.Exhaust Gas Recirculation (EGR)To assist in the control of oxides of nitrogen (NO,) inengine exhaust, all engines are equipped with an exhaustgas recirculation (EGR) system (Figure 2-87). The use ofgas to dilute incoming aidfuel mixtures lowers peak flametemperature during combustion, thus limiting theformation of NOx.Exhaust gases are taken from openings in the exhaust gascrossover passage in the intake manifold. Refer to theservice manual for a complete description, diagnosis andproper service procedures.HEAT SHIELDDOWNPIPEHEAT SHIELD(BOllOM)figure 2 - 86Figure 2 - 87

~~~ ~~ ~~~2.5L POWER TECH IN-LINE 4 (EXHAUST SYSTEM) 85Exhaust System Troubleshooting ChartCOndHlonEXCESSIVE EXHAUSTNOISE(a) Leab at pipe ioints.(b) Burned or blown-out muffler.(c) Burned or d-aut exhaust pipe.(d) Exhaust pips leaking at manifold flange.(a) Tighten clamps at leaking pink(b) Replace muffler assembly.(c) Replace exhaust pip.(d) Tighten connection attoching nuts.LEAKING EXHAUSTGASESENGINE HARD TO WARMUP OR WlLL NOT RETURNTO NORMAL IDLEHEAT CONTROL VALVENOISY(e) Exhaust manifold crocked CH broken.(t) Leak between manifdd and cylinder head.(g) Restriction in muffler or tailpipe.(a) Leaks at pipe joints.(b) Damaged or improperly indolled gaskets.(a) Heat control valve frozen in the open podion.(b) Blocked crossover posKlge in intake manifdd.(a) Thermostat broken.(b) Broken, weak or missing anti-de spring.(e) Replace manifold.(t) Tighten manifdd to cylinder head stud nuts orbok.(g) Remove resttiction, if possible, or replace, asnecessary.(a) Tighten U-bolt nuts at looking joints.(b) Replace gaskets as necessary.(a) Free-up manifold heot control valve using asuitable solvent.(b) Remove restriction or replace intake manifold.(0) Replace thennortat.(b) Replace spring. 1891 1.2Exhaust System Torque SpecificationsCOMPONENTSENGINESTORQUESAir Injection Monifold FittingsAir Pump Adjustment StropAir Pump Mounting BoltsCarburetor Mounting NutsCotalytic Converter-to-MufflerClamp NutsDownpipe-to-Catalytic Converter NutsDownpipe-to-Cotalytic ConverterClomp NutsDownpipe-to-Exhaust Manifold NutsDownpipe-to-Exhausi Manifold NutsDownstream Tube-to-CatalyticConverter ClompExhoust Monifold Bolts/NutsExhoust Manifold Middle NutsExhaust Monifold Outside NutsExhaust Monifold Center Two BoltsExhoust Manifold Outer Four BoltsEGR Tube NuisEGR Tube Boltslntoke Monifold BoltsIntoke Manifold BoltsOxygen Sensor5.9L5.9L5.9L5.9L4.ZL 8 5.9L4.2L5.9L2.511 & 4.0L4.211 a 5.9~4.2L2.5L4.011 a 4.2~4.011 a 4.215.9L5.9L~SL, 4.o~ a 4.2~2.5L2SL, 4.OL & 4.2L5.912.6L, 4.OL 8 4.2L52 N-m 38 ft-lbs27 N-rn 20 ft-lbs27 N-rn 20 ft-lbs19 Nom 14 ft-lbs61 N-m 45ft-lbs34 N*rn 25 ft-lbs61 Nvn 45ft-lbs31 Nom 23ft-lbs27 N-m 20 ft-lbs5 N-m (44 in-lbs]41 N-m 30ft-lbs41 N-m 30ft-lbs31 N*m 23ft-lbs34 N-m 25 ft-lbs20 N-m 15 ft-lbs41 N-rn 30ft-lbs19 N-m 14 ft-lbs31 N-m 23ft-lbs58 N*rn 43 ft-lbs48 N*rn 35 ft-lbs1- - T -I

86 MOPAR PERFORMANCE PARTSEXHAUST MANIFOLDRemoval1.2. Raise the vehicle.3. Disconnect the exhaust pipe from the engineexhaust manifold.4. Lower the vehicle.5.6.7.Disconnect the battery negative cable.Remove the intake manifold. (Refer to Intake ManifoldRemoval, ‘Fuel Delivery and Fuel Injection Systems’section of this chapter.)Remove fasteners 2 through 5 and remove the intakemanifold (Figure 2-85).Remove fasteners 1, 6 and 7 and remove the engineexhaust manifold (Figure 2-85).Installation1. Clean the intake and engine exhaust manifolds andcylinder head mating surfaces. DO NOT allow foreignmaterial to enter either the intake manifold or the portsin the cylinder head.2.Install a new intake manifold gasket over the alignmentdowels on the cylinder head.3.4.5.61.-1I .8.‘3.Install the engine exhaust manifold assembly. Exhaustmanifold must be centrally located over the end studsand spacer (Figure 2-85).Tighten bolt No. 1 to 41 Nom (30 ft-lbs) torque (Figure2-85).Install the intake manifold on the cylinder head dowels(Figure 2-85).Install bolts 2 through 5 (Figure 2-85). Tighten thesebolts to 31 Nom (23 ft-lbs) torque.Install new engine exhaust manifold spacers over theengine exhaust manifold mounting studs in thecylinder head (Figure 2-85).Tighten nuts 6 and 7 to 31 Nem (23 ft-lbs) torque(Figure 2-85).Install all components to the intake manifold.10. Raise the vehicle.11. Connect the exhaust pipe to the engine exhaustmanifold. Tighten the bolts to 3 I Nom (23 ft-lbs) torque.12. Lower the vehicle.13. Connect the battery negative cable.14. Start the engine and check for leaks.

2.5L POWER TECH IN-LINE 4 (IGNITION SYSTEM) 87Ignition SystemTHROTTLE BODY FUEL INJECTION (TBI)IGNITION SYSTEMThe 2.5L engine TBI ignition system is controlled by theElectronic Control Unit (ECU). The ignition systemconsists of0 Ignition Control Module (ICM)The solid-state Ignition Control Module (ICM)consists of a solid-state ignition circuit and anintegrated ignition coil that can be removed andserviced separately if necessary.Ignition advancehetard is controlled electronically bythe Electronic Control Unit (ECU). Electronic signalsfrom the ECU to the ICM determine the amount ofignition timing advance or retard needed to meetvarious engine load requirements.The ECU provides an input signal to the ICM. TheICM has only two outputs:- Tachometer signal to the tachometer anddiagnostic connector- High voltage from the coil to the distributor cap0 Electronic Control Unit (ECU)The ECU controls the fuel injector pulse width andignition timing based on inputs received from sensorsthat react to exhaust gas oxygen content, air-fueltemperature, coolant temperature, manifold absolutepressure, battery voltage, crankshaft position (enginespeed), throttle position and inputs from switches thatare triggered by power steering pump output pressure,wide open throttle conditions, and transmission gearselection (automatic transmissions only). Batteryvoltage is also monitored to determine injector pulsewidth. These sensors and switches are considered ECUinputs. For more information, refer to ‘Fuel Deliveryand Fuel Injection Systems’ section of this chapter.0 DistributorThe 2.5L engine distributor does not have built-incentrifugal or vacuum assisted advances. Ignitiontiming/advance is controlled by the Electronic ControlUnit (ECU). Because ignition timing is controlled bythe ECU, base ignition timing is not adjustable on anyof these engines. The distributor is locked in place byan ear on the distributor housing that a hold down boltpasses through when the distributor is installed.Because the distributor position is locked wheninstalled, its rotational position cannot be changed. DONOT attempt to modify the distributor housing to geltdistributor rotation.Distributor Cap and Rotor SetDistributor cap and rotor for 2.5L engines only.P4.529685 Distributor cap and rotor set.MULTI-POINT FUEL INJECTION (MPI) IGNITIONSYSTEMThe 2SL engine MPI ignition system is controlled by thePowertrain Control Module (PCM).The MPI ignition system consists ofSpark PlugsIgnition CoilSecondary Ignition CablesDistributor (contains rotor and camshaft position sensor)Powertrain Control Module (PCM)Crankshaft Position, Camshaft Position, ThrottlePosition and MAP SensorsCamshaft Position SensorThe camshaft position sensor is located in the distributor.The sensor contains a hall effect device called a sync signalgenerator to generate a fuel sync signal. This sync signalgenerator detects a rotating pulse ring (shutter) on thedistributor shaft. The pulse ring rotates 180 degrees throughthe sync signal generator. Its signal is used in conjunctionwith the crankshaft position sensor to differentiate betweenfuel injection and spark events. It is also used to synchronizethe fuel injectors with their respective cylinders.When the leading edge of the pulse ring (shutter) enters thesync signal generator, the interruption of magnetic fieldcauses the voltage to switch high resulting in a sync signalof approximately 5 volts.When the trailing edge of the pulse ring (shutter) leaves thesync signal generator, the change of the magnetic fieldcauses the sync signal voltage to switch low to 0 volts.l- - 1 1

aaMOPAR PERFORMANCE PARTSDistributorAll MPI engines are equipped with a camshaft drivenmechanical distributor containing a shaft driven distributorrotor. All distributors are equipped with an internal camshaftposition (fuel sync) sensor (Figure 2-88). This sensor providesfuel injection synchronization and cylinder identification.The distributor does not have built in centrifugal or vacuumassisted advance. Base ignition timing and all timing advanceis controlled by the Powertrain Control Module (PCM).Because ignition timing is controlled by the PCM, baseignition timing is not adjustable on any of these engines.The distributor is locked in place by a fork with a slotlocated on the distributor housing base. The distributor holddown clamp bolt passes through this slot when installed.Because the distributor position is locked when installed, itsrotational position can not be changed. DO NOT attempt tomodify the distributor housing to get distributor rotation.Distributor position will have no effect on ignition timing.The position of the distributor will determine fuelsynchronization only.All distributors contain an internal oil seal that preventsoil from entering the distributor housing. The seal is-not serviceable.CAMSHAFTFigure 2 - 89DISTRIBUTORCAPCARBONPATHJ918D-9SYNCSIGNAL-GENERATORFigure 2 - 90J918D-10Distributor RotorDISTRIBUTORASSEMBLYDistributor CapFigure 2 - 88Remove the distributor cap and wipe it clean with a dry lintfree cloth. Visually inspect the cap for cracks, carbon paths,broken towers or damaged rotor button (Figure 2-89 andFigure 2-90). Also check for white deposits on the inside(caused by condensation entering the cap through cracks).Replace any cap that displays charred or eroded terminals.The machined surface of a terminal end (faces toward rotor)will indicate some evidence of erosion from normaloperation. Examine the terminal ends for evidence ofmechanical interference with the rotor tip.Visually inspect the rotor (Figure 2-91) for cracks, evidenceof corrosion or the effects of arcing on the metal tip. Alsocheck for evidence of mechanical interference with the cap.Some charring is normal on the end of the metal tip. Thesilicone-dielectric varnish compound applied to the rotortip for radio interference noise suppression will appearcharred. This is normal. DO NOT remove the charredcompound. Test the spring for insufficient tension. Replacea rotor that displays any of these adverse conditionsT - 1 1

2.51. POWER TECH IN-LINE 4 (IGNITION SYSTEM) 89INSUFFICIENTSPRINGTENSIONROTIP \CORRODED EVIDENCE OFPHYSICALCONTACTWITH CAPIgnition CoilFigure 2 - 91J908D-48The ignition coil is an epoxy filled type. If the coil isreplaced, it must be replaced with the same type.1. RemovalThe ignition coil is mounted to a bracket on side ofengine (to rear of distributor) (Figure 2-92).a. Disconnect ignition coil secondary cable fromignition coil.b. Disconnect engine harness connector fromignition coil.c.Remove ignition coil mounting bolts (nuts areused on back side of bracket on some coils).d. Remove coil from vehicle.2. Installationa. Install ignition coil to bracket on cylinder blockwith mounting bolts (and nuts if equipped). Ifequipped with nuts and bolts, tighten to 11 Nom(100 in-lbs) torque. If equipped with bolts only,tighten to S Nom (50 in-lbs) torque.b.c.Connect engine harness connector to coil.Connect ignition coil cable to ignition coil.SPARK PLUGSFigure 2 - 92Spark Plug and Ignition Wire RemovalRemove the ignition wire by grasping it at the spark plugboot, and then turn (1/2 turn) and pull it straight back in onesteady motion.Prior to removing the spark plug, spray compressed airaround the spark plug hole and the area around thespark plug.Remove the spark plug using a quality socket with arubber or foam insert.Inspect the spark plug. Refer to 'Ignition System'section of Chapter 4 for information.SpecificationsSpark Plug Electrode TighteningEnuine Type Gap Torque1 2.5L RC-12 LYC 0.89 mm 37 Nom(0.035") (27 ft-lbs)Gap AdjustmentCheck the spark plug with a gap (feeler) gauge. If the gapis not correct, adjust it by bending the ground electrode.The gap for 2.SL engines is 0.89 mm (0.035").T -7-1

90 MOPAR PERFORMANCE PARTSInstallationSTARTER MOTOR0 Start the spark plug into the cylinder head by hand toavoid cross threading.0Tighten the spark plug to 37 Nom (27 ft-lbs) torque.Install ignition wires over spark plugs.Always tighten spark plugs to the specified torque. Overtightening can cause distortion resulting in a change in thespark plug gap. Tighten all spark plugs to 37 Nom (27 ft-lbs).When replacing the ignition wires, route the wirescorrectly and secure them in the proper retainers. Failure toroute the wires properly can cause ignition noise radioreproduction, cross ignition of spark plugs, or short-circuitthe wires to ground.Pack PINP4876939P4876940P487694 1P4876942P4876943P4 8 76944P4876945Pack PINP4876928P4876929P4876930P487693 1P4876932P4876933P4876934P4876935Cross ReferenceC 63CC 61C to C 5‘3CC 57c to C 55cc 53c to c 51cC 51CC 61C to C 59cC 57c to c s5cCross ReferenceC 61C to C 59CC 57c to c 55cC 53C to C 51CC 51CS 61C to S 59Cs 57c to s 57cs 53c to s 51cs 51cThe starter motor is mounted with two screws to the rightrear corner of the engine block.The starter motor incorporates several features to create areliable, efficient, compact, lightweight and powerful unit.The electric motor of the starter has four brushes contactingthe motor commutator. The starter motor uses fourpermanent magnets for the field poles, and is rated at 1.2kilowatts (about 1.6 horsepower) output at 12 volts.The starter motor is serviced only as a unit with its startersolenoid, and cannot be repaired. If either component isfaulty or damaged, the entire starter motor and startersolenoid unit must be replaced.I 1I Mopar Performance Parts Spark Plugs IIIINEW! These spark plugs are specifically designed for lhe optimum performance of your Moparengine. Each package contains 4 spark plugs.Race & Tuning Application Plugs (J-Strap Type)Professional Race PlugsApplicationAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesApplicationAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsIII

-I- -1-72.5L POWER TECH IN-LINE 4 (IGNITION SYSTEM) 91OperationThe starter motor is equipped with a planetary gearreduction (intermediate transmission) system. Theplanetary gear reduction system consists of a gear that isintegral to the output end of the electric motor armatureshaft that is in continual engagement with a larger gear thatis splined to the input end of the starter pinion gear shaft.This feature makes it possible to reduce the dimensions ofthe starter. At the same time, it allows higher armaturerotational speed and delivers increased torque through thestarter pinion gear to the starter ring gear.The starter motor is activated by an integral heavy dutystarter solenoid switch mounted to the overrunning clutchhousing. This electromechanical switch connects anddisconnects the feed of battery voltage to the starter motorand actuates a shift fork that engages and disengages thestarter pinion gear with the starter ring gear.The starter motor uses an overrunning clutch and starter piniongear unit to engage and drive a starter ring gear that is integralto the flywheel (manual transmission) or torque converterdrive plate (automatic transmission) mounted on the rearcrankshaft flange. Shims are available and can be used toadjust the starter motor mounting position to correct forimproper starter pinion gear-to-starter ring gear engagement.Removal1.2.3.4.5.6.7.Disconnect and isolate the battery negative cable.Raise and support the vehicle.While supporting the starter motor with one hand, usethe other hand to remove the two screws that secure thestarter motor to the engine block (Figure 2-93).Lower the starter motor from the engine block farenough to access and remove the nut that secures thesolenoid wire harness connector eyelet to the solenoidterminal stud. Always support the starter motor duringthis process. DO NOT let the starter motor hang fromthe wire harness.Remove the nut that secures the battery cable harnessconnector eyelet to the solenoid battery terminal stud.Always support the starter motor during h s process. DONOT let the starter motor hang from the wire hamess.Remove the battery cable and solenoid wire connectoreyelets from the solenoid terminal studs.Remove the starter motor and any starter motor shims(if used) from the engine compartment.6 SCREWInstallation1.2.3.4.5.Figure 2 - 93BOaWPosition the starter motor in the engine compartment.Install the battery cable and solenoid wire connectoreyelets onto the solenoid terminal studs.Install and tighten the nut that secures the battery cableharness connector eyelet to the solenoid battery terminalstud. Tighten the nut to 10 Nom (90 in-lbs). Alwayssupport the starter motor during this process. DO NOTlet the starter motor hang from the wire harness.Install and tighten the nut that secures the solenoidwire harness connector eyelet to the solenoid terminalstud. Tighten the nut to 6 Nam (55 in-lbs). Alwayssupport the starter motor during this process. DO NOTlet the starter motor hang from the wire harness.Position the starter motor and any starter motor shimsthat were removed to the engine block and looselyinstall both of the mounting screws.Note: Shim thickness available is 0.381 mm (0.015").Refer to the proper service manual for more information.6. Tighten both of the starter motor mounting screws to45 Nom (33 ft-lbs).7. Lower the vehicle.8. Reconnect the battery negative cable.

l- -7792 MOPAR PERFORMANCE PARTSMOPAR PERFORMANCE PARTS ELECTRONICIGNlTlON COMPONENTSHigh Performance Electronic Control UnitsFor a hotter spark and more rpm capability, use one ofMopar Performance Parts’ high performance ECUs. Forgeneral high performance and usage up through 6,000rpm, use the Orange Box ECU. For higher rpm outputrequirements up through 8,000, select the Chrome BoxECU.P4 120505P4120534Orange Box ECU.Chrome Box ECU.Super Gold Electronic Control UnitThe Super Gold Electronic Control Unit is the culminationof eight years of high performance ignition systemsdevelopment. Designed to out perform any ignition unitpreviously offered to Mopar racers, it will handle the highcurrent demand by the P3690560 (Accel) highperformance coil, while keeping dwell variation to lessthan 1 O from 1,000 to 10,000 rpm. Dwell is set formaximum spark output at low and high engine speeds.The Super Gold ECU provides outstanding performancefrom idle to 12,000 rpm.P4 120600Super Gold ECU -race only.Ballast Resistor - Electronic DistributorP244464 1PS206436Use with mechanical advance distributorusing P3690560 coil. 1/4 Ohm.Use with electronic ignition systemsusing P4 12050.5 Orange Box ECU andproduction coil, or with P4120889 coil.1 Ohm.~ ~Ignition CoilsP4120889P3690560Accel Super Coil for all 12-voltapplications. Not recommended forengine speeds over 6,500 rpm. (Use withballast resistor PS206436.)Accel Race Coil specifically designed tobe used with race electronic ignitionkits. Designed for racing applicationsonly. Not recommended for continuedoperation at speeds below 3,000 rpm formore than 30 minute periods. (Use withballast resistor P2444641.)Control Wiring Harness Kit for Electronic IgnitionsKit used to convert to a new electronic ignition system.P3690 152Chrome Ignition Coil BracketControl wiring harness kit for electronicignitions.Another underhood piece to dress-up your enginecompartment. Includes special clamp screw.P4286728Tach AdapterChrome ignition coil bracket.Designed for applications when high capacitive dischargecoils interfere with tachometer or fuel injection signals.Thi:j device provides a clear 12 volt square wave signaloutput with a 30% duty cycle.P4876738Tach adapter.

2.5L POWER TECH IN-LINE 4 (ENGINE ASSEMBLY) 93Engine AssemblyNote: For engine assembly information, performance modifications and tips, refer to 'Engine Assembly' section of Chapter4. 4.0L Power Tech In-Line 6.1990,2.5L ENGINE SPECIFICATIONSNote: The following information has been reprinted from the I990 Jeep Wrangler Service Manual.Cylinder BlockDeck HeightDeck ClearanceCylinder Bore Diameter (Standard)Maximum TaperMaximum Out-of-Roundlappet Bore DiameterCylinder Block FlatnessMain Bearing Bare Diameter236.7.3 mm0.000 mm98.42-98.48 mm0.025 mm0.025 mm23.000-23.025 mm0.03 per 25 mm0.05 per 152 mm68.35-68.38 mm9.320 in.0.000 in.3.8751 -3.8775 in.0.001 in.0.001 in.0.9055-0.9065 in.0.001 per 1 in.0.002 per 6 in.2.691 -2.692 in.Combustion Chamber VolumeValve ArrangementValve Guide ID (Integral)1 Valve Stem-to-Guide ClearanceIntake Valve Seat AngleExhaust Valve Seat AngleValve Seat WidthValve Seat RunoutCylinder Head Flatness49.9-52.9 ccE-I-I-I-E-I-I-E7.95-7.97 mm0.02-0.07 mm44%'4490'1.02-1.52 mm0.06,4 mm0.03 per 25 mm0.05 per 152 mm3.04-3.23 cu. in.0.313-0.31 4 in.0.001 -0.003 in.0.040-0.060 in.0.0025 in.0.001 per 1 in.0.002 per 6 in.Oil PressureIAt Idle Speed (800 rpm). .......................At 1600+ rpm.. ..............................Oil Pressure Relief .............................172-241 kPa255..517 kPa517 kPa25-35 psi37-75 psi75 psiOil PumpGear-to-Body Clearance (Radial) ................Preferred ...................................Gear End Clearance - Plastigage. ...............Preferred ...................................Gear End Clearance - Feeler Gouge ............Preferred ..................................0.051 -0.102 mm0.051 mm0.051 -0.1 52 mm0.051 mm0.1 016-0.2032 mm0.1778 mm0.002-0.004 in.0.002 in.0.002-0.006 in.0.002 in.0.004-0.008 in.0.007 in.IRocker Arms, Push Rods and TappetsRocker Arm RatioPush Rad lengthPush Rod DiameterHydraulic Tappet DiameterTappet-to-Bore Clearance1.6:l241.300-241 BO8 mm7.5'2-8.00 mm22.962-22.974 mm0.03-0.05 mm9.500-9.520 in.0.312-0.315 in.0.904-0.9045 in.0.001 -0.0025 in.IJ8909-66

94 MOPAR PERFORMANCE PARTSEarnshaftTappet ClearanceEnd Ployearing ClearanceBaring Journol DiameterNo. 1No. 2No. 3No. 4base Circle Runout:om Lobe LiftIntakeExhaustValve LifiIntakeExhaustIntoke Valve TimingOpensClosesExhaust Valve TimingOpensClosesVolve OverlapIntake DurationExhaust DurationZero lash (hyd.) tappetsZero (engine operation)0.025-0.076 mm51.54-51.56 mm51.28-51.31 mm51.03-51.05 mm50.78-50.80 mm0.03 mm max.6.731 mm6.731 mm10.770 mm10.770 mm12" BTDC78" ABDC56" BBDC34" ATDC46"270"270"0.001 -0.003 in.2.029-2.030 in.2.019-2.020 in.2.009-2.010 in.1.999-2.000 in.0.001 in. mox.0.265 in.0.265 in.0.424 in.0.424 in.Eonnecting Rods657-665 grams 23.2-23.5 oz.Total Weight (Less Bearings)Total Length (Center-to-center)155.52-155.62 mm6.10.9288-0.929823-6.1 27 in.in.23.59-23.62 mmPiston Pin Bore Diameter56.08-56.09 mm2.2080-2.2085 in.Connecting Rod Bore (Less Bearings) 0.03-0.08 mm 0.001 -0.0025 in.Bearing ClearancePreferredSide ClearanceMoximum TwistMaximum Bend0.044-0.050 mm0.25-0.48 mm0.001 mm per mm0.001 mm per mm0.001 5-0.0020 in.0.01 0-0.01 9 in.0.001 in. per in.0.001 in. per in.CrankshaftsEnd PloyMain Bearing Journal DiameterMain Bearing Journol WtdthNo. 1No. 2NO. 3-4-5Main Bearing ClearancePreferredConnecting Rod Journal DiameterConnecting Rod Journal WtdthMaximum Out-of-Round (All Journals)Maximum Toper (All Journals)0.038-0.1 65 mm63.489-63.502 mm27.58-27.89 mm32.28-32.33 mm30.02-30.1 8 mm0.03-0.06 mm0.051 mm53.17-53.23 mm27.1 8-27.330.01 3 mm0.01 3 mm0.001 5-0.0065 in.2.4996-2.5001 in.1.086-1.098 in.1.271 -1.273 in.1.1 82-1.1 88 in.0.001 -0.0025 in.0.002 in.2,0934-2.0955 in.1.070-1.076 in.0.0005 in.0.0005 in.J8909411

~ Exhaust2.5L POWER TECH IN-LINE 4 (ENGINE ASSEMBLY) 95PistonsIcWeight (Less Pin)Piston Pin BoreCenterline-to-Piston TopPiston-to-Bore ClearancePiston Ring Gop Clearonce -Compression (Both)Piston Ring Gap Clearance -Oil Control Steel RailsPiston Ring Side ClearanceNo. 1 CompressionNo. 2 CompressionOil ControlPiston Ring Groove HeightCompression (Both)Oil ControlPiston Ring Groove DiameterNo. 1 ond No. 2Oil ControlPiston Pin Bore DiometerPiston Pin DiometerPiston-to-Pin ClearancePreferredPiston Pin-to-Connecting RodValvesValve length (Tip-to-Gauge Dim. Line)IntakeExhaustValve Stem DiameterStem-to-Guide ClearanceIntake Valve Head Diometer1 Intake Valve Face AngleValve Head DiameterExhaust Valve Face Angle1 Maximum AllowoMe Removed forTip RefinishingValve Springs Free LengthValve Spring Tension ClosedValve Spring Tension Open563-567 grams40.67 mm0.033-0.053 mm0.25-0.51 mm19.86-20.00 01.1.601 in.0.001 3-0.0021 in.0.01 0-0.020 in.0.381 -1.397 mm 0.01 5-0.055 in.0.0254-0.081 3 mm0.254-0.241 mm0.254..0.2032 mm2.01 9-2.045 mm4.78-4.80 mm87.78..87.90 mm87.50.,87.75 mm23.624-23.655 mm23.632-23.645 mm0.01 0-0.01 5 mmLoose 0.015 mm8.9 kN Press-fit124.435-1 25.070 mm125.1 20-1 25.755 mm7.89-7.98 mm0.02-0.05 mm48.38-48.6 mm45”37.97-38.6 mm45”0.25 mm49.962 mm355-400 N @ 41.656 mm890 N @ 30.886 mm0.001 -0.0032 in.0.001 -0.0032 in.0.001-0.0085 in.0.0795-0.0805 in.0.1 88-0.1 895 in.3.456-3.461 in.3.445-3.455 in.0.9308-0.931 3 in.0.9304-0.9309 in.0.0004-0.0006 in.Loose 0.0006 ir,.2000 Ibs.-f Press-fit4.899-4.924 in.4.927-4.952 in.0.31 1-0.31 2 in.0.001 -0.003 in.1.905-1.91 5 in.1.495-1 SO5 in.0.01 0 in.1.967 in.80-90 Ibs (u 1.640 in.200 Ibs (u 1.21 6 in.1E 3909 4 3f

96 MOPAR PERFORMANCE PARTS1990, 2.5L ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1990 Jeep Wrungler Service Manual.ComponentTorqueNC Bracket-to-Block/Head BoltsNC Compressor-to-Bracket BoltsAlternator Adjusting BoltAlternator Pivot Bolt/NutAlternator Mounting Bracket-to-Engine BoltsAlternator Mounting-to-Head Bolts40 N.m27 Nm27 N.m38 N.m38 N.m45 N.m30 ft-lbs20 ft-lbs20 ft-lbs28 ft-lbs20 ft-lbs33 ft-lbsIBlock Heater Nut1.8 N.m16 in-lbsCamshaft Sprocket BoltConnecting Rad Bolt NutsConverter Plate BoltsCrankshaft Main Bearing BoltsCrankshaft Pulley-to-Damper NutCrossmember-to-Sill - Front Bolts- Rear NutsCylinder Block Oil Galley PlugsCylinder Head Bolts (#1-7 & #9-10)(#8)Cylinder Head Cover Bolts108 N.m45 Nm68 N-m +60'108 N.m27 N.m88 Nm41 N.m41 N.m149 Nvn136 N.m8 N.m80 ft-lbs33 ft-lbs50 ft-lbs +60'80 ft-lbs20 ft-lbs65 ft-lbs30 ft-lbs30 ft-lbs1 10 ft-lbs100 ft-lbs70 in-lbsDrive Plate-to-Torque Converter Bolts54 N.m40 ft-lbsEngine Shock Damper Stud NutExhaust Manifold-to-Downpipe Nuts23 N.m31 N.m17 ft-lbs23 ft-lbsFlywheel BoltsFront Support Bracket-to-Cylinder BlockFront Support Cushion-to-Mount (Thru Bolt)Front Support Cushion-to-Sill BracketFuel Pump Bolts68 N-m +60"61 N.m65 N.m40 N.m22 N.m50 ft-lbs +60'45 ft-lbs48 ft-lbs30 ft-lbs16 ft-lbsOil Pan Bolts - 1 /4-20- 5/16-18Oil Pan Drain PlugOil Pan-to-Timing Cose Cover BoltsOil Pump Attaching Bolts (Short)Oil Pump Attaching Bolts (Long)Oil Pump Cover Bolts9 Nm15 N.m34 N.m13 N-m14 N.m23 N.m8 N.m7 ft-lbs11 ft-lbs25 ft-lbs11 ft-lbs10 ft-lbs17 ft-lbs70 in-lbsPower Steering Pump Pressure Hose Nut52 N.m38 ft-lbsRear Support Cushion-to-Brocket BoltsRocker Arm Assembly-to-Cylinder Head43 N.m26 N.m32 ft-lbs19 ft-lbsSpark PlugsStarting Motor-to-Cylinder Block Bolts37 N-m45 N.m27 ft-lbs33 ft-lbsTiming Case Cover-to-Block Bolts7 N.m62 in-lbsVibration Damoer Bolt [Lubricated)108 N.m80 ft-lbsJ9009-5:

2.5L POWER TECH IN-LINE 4 (ENGINE ASSEMBLY) 971999, 2.5L ENGINE SPECIFICATIONSNote: The following information has been reprinted from the I999 Jeep Wrangler Service Manual.Engine Type ................. In-line kylinderBore and Stroke ... 98.4 x 81.0 mm (3.88 x 3.19 in.)Displacement ................... 2.5L (150 c.i.)Compression Ratio ...................... 9.1: 1Firing Order. ..................... 1- 342Pressure Feed-Full Flow FiltrationCooling System ................ Liquid Cooled-Forced CirculationCylinder Block ..................... Cast IronCrankshaft ................. Cast Nodular IronCylinder Head. ..................... Cast IronCamshaft ......................... Cast IronAluminum AlloyLubrication ...................Pistons ......................Combustion Chamber ............. Dual-QuenchConnecting rods ............ Cast Malleable IronEngine SpecificationsCamshaftHydraulic Tappet Clearance ......... Zero LashBearing Clearance .......... 0.025 to 0.076 mm(0.001 to 0.003 in.)Bearing Journal DiameterNo. 1 ..... 51.54 to 51.56 mm (2.029 to 2.030 in.)No. 2 ..... 51.28 to 51.31 mm (2.019 to 2.020 in.)No. 3 ..... 51.03 to 51.05 mm (2.009 to 2.010 in.)No. 4 ..... 50.78 to 50.80 mm (1.999 to 2.000 in.)Base Circle Runout ........... 0.03 mm - max.(0.001 in. - max.)Camshaft Lobe LiftExhaust ................ 6.579 mm (0.259 in.)Intake ................. 6.477 mm (0.255 in.)Valve LiftExhaust .............. 10.528 mm (0.4145 in.)Intake. ............... 10.350 mm (0.4075 in.)Intake Valve TimingOpens ........................ 15.4" BTDCCloses .......................... 58" ABDCExhaust Valve TimingOpens ......................... 52.8 BBDC26.2" ATDCCloses .........................Valve Overlap ........................ 41.6"Intake Duration ..................... 253.3"Exhaust Duration ..................... 259."CrankshaftEnd Play ................... 0.038 to 0.165 mm(0.0015 to 0.0065 in.)Main Bearing JournalDiameter ............... 63.489 to 63.502 mm(2.4996 to 2.5001 in.)Main Bearing JournalWidth No. 1 .............. 27.58 to 27.89 mm(1.086 to 1.098 in.)Main Bearing JournalWidth No. 2 .............. 32.28 to 32.33 mm(1.271 to 1.273 in.)Main Bearing JournalWidth No. 3-4-5 ........... 30.02 to 30.18 mm(1.182 to 1.188 in.)Main Bearing Clearance ....... 0.03 to 0.06 mm(0.001 to 0.0025 in.)Main Bearing Clearance (Preferred) ... 0.051 mm(0.002 in.)Connecting Rod JournalDiameter. ................ 53.17 to 53.23 mm(2.0934 to 2.0955 in.)Connecting Rod JournalWidth ................... 27.18 to 27.33 mm(1.070 to 1.076 in.)Out-of-Round (Max. All Journals) ..... 0.013 mm(0.0005 in.)Taper (Max. - All Journals) ......... 0.013 mmCylinder BlockDeck Height ............ 236.73 mm (9.320 in.)Deck Clearance .......... 0.000 mm (0.000 in.)Cylinder Bore Diameter-Standard. ................ 98.45 to 98.48 mm(3.8759 to 3.8775 in.)Cylinder Bore Diameter-Taper (Max.) ............ 0.025 mm (0.001 in.)Cylinder Bore Diameter-(0.0005 in.)Out-of-Round (Max.) ...... 0.025 mm (0.001 in.)Tappet Bore Diameter ..... 23.000 to 23.025 mm(0.9055 to 0.9065 in.)Flatness ................ 0.03 mm per 25 mmFlatness(0.001 in. per 1 in.)............... 0.05 mm per 152 mm(0.002 in. per 6 in.)Flatness Max. ......... 0.20 mm for total length(0.008 in. for total length)Main Bearing Bore Diameter ........ 68.3514 to68.3768 mm (2.691 to 2.692 in.)...

98 MOPAR PERFORMANCE PARTSConnecting RodsTotal Weight (Less Bearing) ... 657 to 665 grams(23.17 to 23.45 02.)Length (Center-to-Center) . . 155.52 to 155.62 mm(6.123 to 6.127 in.)Piston Pin Bore Diameter .... 23.59 to 23.62 mm(0.9288 to 0.9298 in.)Bore (Less Bearings) ........ 56.08 to 56.09 mm(2.2080 to 2.2085 in.)Bearing Clearance .......... 0.025 to 0.076 mm(0.001 to 0.003 in.)Bearing Clearance (Preferred) . 0.044 to 0.050 mm(0.0015 to 0.0020 in.)Side Clearance .............. 0.25 to 0.48 mm(0.010 to 0.019 in.)Twist (Max.). .............. 0.001 mm per mm(0.001 in. per inch)Bend Max.) ............... 0.001 mm per mm(0.001 in. per inch.)Cylinder Compression PressureRatio ............................... 9.1: 1Pressure Range ............. 827 to 1,034 Wa(120 to 150 psi)Max. Variation Between Cylinders ..... 206 kPaCylinder Head(30 psi)Combustion Chamber. .......... 49.9 to 52.9 cc(3.04 to 3.23 cu. in.)Valve Guide I.D. (Integral) ..... 7.95 to 7.97 mm(0.313 to 0.314 in.)Valve Stem-to-Guide Clearance ........ 0.025 to0.076 mm (0.001 to 0.003 in.)Intake Valve Seat Angle ................ 44.5"Exhaust Valve Seat Angle .............. 44.5"Valve Seat Width. ............ 1.01 to 1.52 mm(0.040 to 0.060 in.)Valve Seat Runout ....... 0.064 mm (0.0025 in.)Flatness ................ 0.03 mm per 25 mm(0.001 in. per 1 in.)Flatness ............... 0.05 mm per 152 mm(0.002 in. per 6 in.)Flatness Max. ......... 0.15 mm for total length(0.006 in. for total length)Rocker Arms, Push Rods & TappetsRocker Arm Ratio ..................... 1.6: 1Push Rod Length ....... 241.300 to 241.808 mm(9.500 to 9.520in.lPush Rod Diameter ........... 7.92 to 8.00 mm(0.312 to 0.315 in.)Hydraulic Tappet Diameter . 22.962 to 22.974 mmTappet-to-Bore Clearance(0.904 to 0.9045 in.).... 0.025 to 0.063 mm(0.001 to 0.0025 in.)ValvesLength (Tip-to-Gauge Dimension Line)Intake ............... 124.435 to 125.070 mm(4.899 to 4.924 in.)Length (Tip-to-Gauge Dimension Line)Exhaust .............. 125.120 to 125.755 mm(4.927 to 4.952 in.)Valve Stem Diameter ........ 7.899 to 7.925 mm(0.311 to 0.312 in.)Stem-to-Guide Clearance. .... 0.025 to 0.076 mm(0.001 to 0.003 in.)Valve Head Diameter-Intake ........ 48.387 to48.641 mm (1.905 to 1.915 in.)Valve Head Diameter-Exhaust ....... 37.973 to38.227 mm (1.495 to 1.505 in.)Valve Face Angle-Intake ................ 45"Valve Face Angle-Exhaust ............... 45"Tip Refinishing (Max. Allowable) ...... 0.25 mmValve Springs(0.010 in.)Free Length (Approx.) ..... 47.65 mm (1.876 in.)Spring Tension-Valve Closed. ... 316 to 351 N 841.656 mm (71 to 79 lbf. 8 1.64 in.)Spring Tension-Valve Open. ... 898.6 to 969.7 N30.89 mm (202 to 218 lbf 8 1.216 in.)Inside Diameter ......... 21.0 mm to 21.51 mm(0.827 to 0.847 in.)PistonsWeight (Less Pin) ........... 417 to 429 grams(14.7 to 15.1 oz.)Piston Pin Bore (Centerline toPiston Top) ... 40.61 to 40.72 mm (1.599 to 1.603in.)Piston-to-Bore Clearance ..... 0.018 to 0.038 mm(0.0008 to 0.0015 in.)Ring Gap Clearance-Top Compression Ring ...... 0.229 to 0.610 mmRing Gap Clearance-2nd(0.0090 to 0.0240 in.)CompressionRing ... 0.483 to 0.965 mm (0.0190 to 0.0380 in.)Ring Gap Clearance-Oil Control SteelRails ..... 0.254 to 1.500 mm (0.010 to 0.060 in.)Ring Side Clearance-CompressionRings . . 0.042 to 0.084 mm (0.0017 to 0.0033 in.)Ring Side Clearance-Oil ControlRing ..... 0.06 to 0.21 mm (0.0024 to 0.0083 in.)Piston Ring Groove HeightCompressionRings ... 1.530 to 1.555mm (0.0602 to 0.0612 in.)Piston Ring Groove Height-Oil ControlRing ... 4.035 to 4.060 mm (0.1589 to 0.1598 in.)Piston Ring Groove Diameter-No. 1 CompressionRing ....... 88.39 to 88.65 mm (3.48 to 3.49 in.)...

~~~2.5L POWER TECH IN-LINE 4 (ENGINE ASSEMBLY) 99Piston Ring Groove Diameter-No.2 CompressionRing ....... 87.63 to 87.88 mm (3.45 to 3.46 in.)Piston Ring Groove Diameter-Oil ControlRing ....... 89.66 to 89.92 mm (3.53 to 3.54 in.)Piston Pin Bore Diameter . . 23.650 to 23.658 mm(0.9312 to 0.9315 in.)Piston Pin Diameter ...... 23.637 to 23.640 mm(0.9306 to 0.9307 in.)Piston-to-Pin Clearance .... 0.0102 to 0.0208 mm(0.0005 to 0.0009 in.)Piston-to-Pin Connecting Rod (Press Fit) . . 8.9 kNOil Pump(2000 lbf.)Gear-to-Body Clearance (Radial) ....... 0.051 to0.102 mm (0.002 to 0.004 in.)Gear-to-Body Clearance (Radial)(Preferred) .............. 0.051 mm (0.002 in.)Gear End Clearance-Plastigage . 0.051 to 0.152 mm (0.002 to 0.006 in.)Gear End Clearance-Plastigage(Preferred) .............. 0.051 mm (0.002 in.)Gear End Clearance-Feeler Gauge. ... 0.1016 to0.2032 mm (0.004 to 0.008 in.)Gear End Clearance-Feeler Gauge(Preferred) ............. 0.1778 mm (0.007 in.)Oil PressureMin. Pressure (600 rpm) ...... 89.6 kPa (13 psi)At Idle Speed (800 rpm) ........ 172 to 241 kPa(25 to 35 psi)At 1600 rpm & Higher ......... 255 to 517 kPa(37 to 75 psi)Oil Pressure Relief ........... 517 Pa(75 psi)

100 MOPAR PERFORMANCE PARTS1999,2.5L ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1999 Jee,n Wrangler Service Manual.DESCRIPTIONTORQUEA/C Compressor Bracket-to-Engine34 N-m (25 R. lbs.)Bolts ....................A/C CompressorMounting Bolts ............ 27 N-m (20 R. lbs.)Block HeaterNut ....................Camshaft SprocketBolt ....................Clutch Cover to FlywheelBolts ....................Connecting Rod CapNuts ....................Cylinder BlockCylinder Head1.8 N-m (16 in. lbs.)108 N.m (80 R. lbs.)31 N.m (23 R. lbs.)45 N.m (33 R. lbs.)Drain Plugs ............... 41 N-m (30 R. lbs.)Bolts #1-10 & #12-14 ..... 149 N-m (110 R. lbs.)Bolt #11. ............... 135 N-m (100 R. lbs.)Cylinder Head CoverBolts ................... 13 N-m (115 in. lbs.)Dipstick Tube Bracket to Cylinder BlockBolt ................... 19 N.m (168 in. lbs.)Distributor Hold-Down ClampBolt ................... 23 N.m (204 in. lbs.)Engine Mounts-FrontInsulator Bracket Bolts ...... 81 N-m (60 R. lbs.)Insulator Bracket Nuts ...... 47 N-m (35 ft. lbs.)Insulator Thru-Bolt ......... 81 N-m (60 R. lbs.)Engine Mounts-RearSupport CushiodCrossmember Nuts .... 22 N.m(192 in. lbs.)Support CushiodBracket Nuts ......... 46 N.m(34 R. lbs.)Transmission Support Bracket Bolts. .... 43 N-m(32 ft. lbs.)Transmission Support Bracket/Cushion Bolt ............. 75 N-m (55 R. lbs.)Transmission Support AdaptorBracket Bolts ............. 75 N.m (55 R. lbs.)Exhaust ManifoldPipeNuts ....................FlywheeUConverter HousingBolts ....................Flywheel to Crankshaft27 N.m (20 R. lbs.)38 N.m (28 R. lbs.)Bolts .................. 143 N.m (105 R. lbs.)Front Cover to BlockBolts 1/4-20 ............... 7 N-m (60 in. lbs.)Bolts 5/16-18 ............ 22 N-m (192 in. lbs.)GeneratorAdjusting Bolt. ............ 24 N-m (18 R. lbs.)Pivot BoltMut ............. 38 N.m (28 R. lbs.)Mounting Bracket-to-Engine Bolts ...... 38 N.m(28 R. lbs.)Mountinmead Bolts ....... 45 N-m (33 R. lbs.)DESCRIPTIONTORQUEMain Bearing CapBolts ................... 108 N.m (80 R. lbs.)Oil FilterAdaptor Bolt ............. 102 N-m (75 R. lbs.)Connector ................ 68 Nom (50 ft. lbs.)Filter. ................... 18 N-m (13 R. lbs.)Oil GalleyPlug .................... 41 N.m (30 R. lbs.)Oil Pan1/4-20 Bolts. ............. 9.5 N-m (84 in. lbs.)5/16-18 Bolts ............ 15 N.m (132 in. lbs.)Drain Plug ............... 34 N-m (25 R. lbs.)Oil Pressure Sending UnitSending Unit ............ 15 N.m (130 in. lbs.)Oil PumpShort Attaching Bolts ...... 23 N.m (204 in. lbs.)Long Attaching Bolts ...... 23 N.m (204 in. lbs.)Cover Bolts ............... 8 N-m (70 in. lbs.)Power Steering Pump Pressure HoseNut ..................... 52 N.m (38 R. lbs.)Rocker Arm Assembly to Cylinder HeadCapscrews ................ 28 N.m (21 R. lbs.)Spark PlugsPlugs .................... 37 Nem (27 R. lbs.)Starter MotorMounting Bolts ............ 45 N-m (33 R. lbs.)Tensioner Bracket ot Cylinder BlockBolts ................... 19 Nom (168 in. lbs.)Thermostat HousingBolts. .................. 18 N.m (156 in. lbs.)Throttle BodyBolts. ................... 10 N-m (90 in. lbs.)Vibration DamperBolt.. .................. 108 N-m (80 R. lbs.)Water Pump to BlockBolts ....................31 Nom (23 ft. lbs.)..r -11

Chapter 32.46L In-Line 4

102 MOPAR PERFORMANCE PARTSBlock ................................................................................. 104Crankshaft ............................................................................. 105Connecting Rods ........................................................................ 109PistonsandRings ........................................................................ 111Cylinder Head .......................................................................... 112Camshaft and Valve Gear .................................................................. 116Oiling System ........................................................................... 120EngineAssembly ........................................................................ 121... "l- - T - T.

T- T - T2.46L IN-LINE 4 (BLOCK) 103Note: Due to the similarity of 2.46L and 2.5L Jeep engines, only those procedures specific to the 2.46L engine will becovered in this chapter. All other 4-cylinder procedures, techniques and modification tips can be found in Chapter 2, 2.5LPower Tech In-Line 4.In addition to the information contained in this chapter and Chapter 2, much of the information contained in Chapter 4, 4.0LPower Tech In-Line 6, is generic to all Jeep engines (including the 2.46L). Therefore, in addition to this chapter and Chapter2, we highly recommend that all 2.46L engine owners read Chapter 4 in its entirety.For additional 2.46L engine general service information, refer to the proper service manual.

104 MOPAR PERFORMANCE PARTSBlock2.46L CYLINDER BLOCK (EXPLODED VIEW)fa- *t A 3131. Oil Level Gauge(Dipstick) and Tube2. Ring Set3. Piston4. Pin Set5. Connecting Rod6. Plugs7. Cylinder Block8. Flywheel and Ring Gear(WlManual Transmission)9. Pilot Bushing (WithManual Transmission)10. Bushing Oil Wick (WithManual Transmission)11. Main Bearing Cap SealKit (Rear)12. Main Bearing Cap(Rear)13. Connecting RodBearing14. Connecting RodBearing Cap15. Gasket16. Timing Case Cover17. Seal18. Vibration Damper19. Vibration Damper Pulley20. Washer21. Main Bearing Caps22. Main Bearings23. Crankshaft Sprocket24. Oil Shedder (Slinger)25. Washer26. Timing Chain27. Camshaft Sprocket28. Timing ChainTensioner29. Keys30. Crankshaft31. Pin32. Camshaft33. Oil Channel Plug8401 24

INTRODUCTIONThe Jeep 2.46L (258 CID) engine uses a cast nodular ironcrankshaft that rotates within seven (7) main bearings andhas a standard bore and stroke of 3.750-3.753" x 3.895".Crankshaft rotation is clockwise, when viewed from thefront of the engine.The crankshaft has a main bearing journal diameter of2.4986-2.5001", and main bearing journal widths of (No. 1)1.086-1.098", (Nos. 2, 4, 5, 6, and 7) 1.182-1.188", and(NO. 3) 1.271-1.273".The crankshaft has a connecting rod journal diameter of2.0934-2.0955" and a connecting rod journal width of1.073 .For more crankshaft specifications, refer to 2.465 EngineSpecifications, 'Engine Assembly' section of this chapter.CRANKSHAFT MAIN BEARINGSRemoval1. Remove the spark plugs.2. Disconnect the battery cables.3. Raise and support the vehicle.4. Drain the engine oil.5. Remove the oil pan. Refer to Oil Pan Removal, 'OilingSystem' section of this chapter.6.7.8.9.Remove the oil pump. Refer to Oil Pump Removal,'Oiling System' section of this chapter.Remove the first main bearing cap and lower insert.Remove the lower bearing insert from the bearing cap.Remove the upper bearing insert by loosening all of theother bearing caps and inserting a small cotter pin toolin the crankshaft journal oil hole.10. Bend a cotter pin as illustrated in Figure 2-13 tofabricate the tool.Note: A tongue depressor may also be used to removethe bearing insert.11. With the cotter pin tool in place, rotate the crankshaftso that the upper bearing insert will rotate in thedirection of its locking tab.Note: Because there is no hole in the No. 3 mainjournal, use a tongue depressor or similar soft-facedtool to remove the bearing insert. After moving theinsert approximately 25 mm (1 'I), it can be removed byapplying pressure under the tab.C ran ks haf t2.46L IN-LINE 4 (CRANKSHAFT) 10512. Using the same procedure described above, remove (asnecessary) the remaining bearing inserts one at a timefor inspection.Installation1.2.3.4.5.6.7.8.9.Lubricate the bearing surface of the inserts withengine oil.Loosen all the main bearing caps. Install the mainbearing upper insert.Install the main bearing cap and lower insert.Tighten the bolts with 54 Nom (40 ft-lbs) torque. Then,tighten with 95 Nom (70 ft-lbs) torque. Finally, tightenwith 108 Nom (80 ft-lbs) torque.Rotate the crankshaft after tightening each mainbearing cap to ensure that the crankshaft rotates freely.Note: When installing a crankshaft kit (crankshaftplus bearing inserts), measure each bearing-to-journalclearance with Plastigauge to ensure a proper fit.Install the oil pump with a replacement gasket. Referto Oil Pump Installation, 'Oiling System' section ofthis chapter.Install the oil pan with replacement seals and gaskets.Tighten the drain plug securely. Refer to Oil PanInstallation, 'Oiling System' section of this chapter.Fill the oil pan with engine oil to the FULL MARK onthe dipstick.CRANKSHAFT (FRONT) OIL SEALREPLACEMENT- COVER INSTALLED1.2.3.4.5.6.7.8.Remove the drive belt(s) and fan shroud.Remove the vibration damper with vibration damperremoval tool (Figure 2-2).Remove the vibration damper and key.Remove the crankshaft oil seal with timing cover oilseal remover tool.Position a replacement oil seal on timing case coveralignment and seal installation tool with the seal lipfacing outward.Apply a light film of Perfect Seal, or equivalent, on theoutside diameter of the seal.Lightly coat the crankshaft oil seal contact surface withengine oil.Position the timing case cover alignment and sealinstallation tool with seal over end of crankshaft(Figure 2-22).

106 MOPAR PERFORMANCE PARTS9. Install seal into timing chain cover by gently tappingwith rubber or plastic mallet.10. Remove the timing case cover alignment and sealinstallation tool.11. Apply a light film of engine oil on the vibrationdamper hub contact surface of the seal.12. With the key inserted in the keyway on the crankshaft,install the vibration damper, washer and bolt.13. Lubricate and tighten the bolt with 108 Nom (80 ft-lbs)torque.Note: If the crankshaft turns before the damper bolttightening torque value is attained, the crankshaft canbe prevented from turning by placing two 5/16 x 1-1/2”bolts into the damper pulley holes and wedging a barbetween them. Rotate the bar until it contacts the framemember to prevent the crankshaft from turning.14. Install the damper pulley. Tighten the bolts with 27Nom (20 ft-lbs) torque.15. Install the drive belt(s) and tighten to the specified tension.REAR MAIN BEARING OIL SEALThe crankshaft rear main bearing oil seal is a one piece,single-lip seal that fits tightly between the cylinder blockand the crankshaft.Note: When replacing the rear main bearing oil seal, thetransmission must be removed. Refer to your servicemanual for installation procedures.Removal1.2.Remove the flywheel or torque converter drive plate.Remove the seal from the crankshaft flange by pryingaround the crankshaft flange.Installation1. Coat the inner lip of the replacement rear main bearingseal with engine oil.2.3.4.Carefully insert the seal into place and gently tap itflush with the cylinder block with a rubber orplastic mallet.Install the torque converter drive plate or flywheel withreplacement bolts. Refer to the service manual forremoval and installation procedures.Install the transmission. Refer to the service manual forthe procedure.VIBRATION DAMPERRemoval1. Remove the drive belt(s).2. Remove the retaining bolts and separate the vibrationdamper pulley from the vibration damper.3. Remove the vibration damper retaining bolt and washer.4. Use vibration damper removal tool to remove thedamper from the crankshaft (Figure 2-2).Installation1. With the key in position, align the key slot in thevibration damper hub with the crankshaft key and tapthe damper onto the end of the crankshaft.2. Install the vibration damper retaining bolt and washer.Tighten the bolt with 108 Nom (80 ft-lbs) torque.3.Note: If the crankshaft turns before the damper bolttightening torque value is attained, the crankshaft canbe prevented from turning by placing two 5/16 x 1-112”bolts into the damper pulley holes and wedging a barbetween them. Rotate the bar until it contacts the framemember to prevent the crankshaft from turning.Install the damper pulley and retaining bolts. Tightenthe bolts with 27 Nom (20 ft-lbs) torque.4. Install the drive belt(s) and tighten to the specified tension.TIMING CASE COVERRemoval1.2.3.4.5.6.Remove the drive belt(s), engine fan and hub assembly,fan shroud, vibration damper, pulley, and key.Remove the oil pan-to-timing case cover screws andcover-to-cylinder block bolts.Remove the timing case cover, crankshaft oil seal, andgasket from the cylinder block.Cut off the oil pan side gasket end tabs flush with the frontface of the cylinder block and remove the gasket tabs.Clean the timing case cover, oil pan, and cylinder blockgasket surfaces.Pry the crankshaft oil seal from the timing case coverwith a large pry tool.Installation1. Apply sealing compound (Perfect Seal, or equivalent)to both sides of the replacement timing case covergasket and position the gasket on the cylinder block.

2.46L IN-LINE 4 (CRANKSHAFT) 1072.3.4.5.6.7.8.9.Cut the end tabs off of the replacement timing covergasket corresponding to those cut off the original gasket.Coat the front seal end tab recesses generously withRTV sealant (Mopar Gasket-in-a-Tube, or equivalent)and position the seal on the timing case cover.Apply engine oil to the seal-oil pan contact surface.Position the timing cover on the cylinder block.Place timing case cover alignment and seal installertool in the cover crankshaft opening.Install the cover-to-cylinder block bolts and the oilpan-to-cover screws.Tighten the cover-to-cylinder block bolts with 7 Nom(5 ft-lbs) torque and the oil pan-to-cover screws with13 Nom (1 1 ft-lbs) torque.Remove the cover alignment tool and position areplacement oil seal on the tool with the seal lipfacing outward.10. Apply a light film of Perfect Seal, or equivalent, on theoutside diameter of the seal.11. Lightly coat the crankshaft with engine oil.12. Position the timing case cover alignment and sealinstaller tool with seal over the end of the crankshaft(Figure 2-22). Insert draw screw tool (Figure 2-23).Install seal into timing chain cover by gently tappingwith a rubber or plastic mallet.13. Tighten the nut against the tool until the tool contactsthe cover (Figure 2-23).14. Remove the tools and apply a light film of engine oilon the vibration damper hub contact surface of the seal.15. With the key inserted in the keyway on the crankshaft,install the vibration damper, washer and bolt. Lubricateand tighten the bolt with 108 Nom (80 ft-lbs) torque.Note: If the crankshaft turns before the damper bolttightening torque value is attained, the crankshaft canbe prevented from turning by placing two 5/16 x 1-1/2"bolts into the damper pulley holes and wedging a barbetween them. Rotate the bar until it contacts the framemember to prevent the crankshaft from turning.16. Install the damper pulley. Tighten the bolts with 27Nom (20 ft-lbs) torque.17. Install the engine fan and hub assembly.18. Install the fan shroud.19. Install the drive belt(s) and tighten to the specified tension.TIMING CHAINRemovalNote: The timing chain tensioner reduces noise andprolongs timing chain life. In addition, it compensates forslack in a worn or stretched chain and helps to maintain thecorrect valve timing.1. Remove the fan and shroud.2. Remove the drive belt(s).3. Remove the crankshaft vibration damper and pulley.4.5.6.7.8.Remove the timing case cover. Refer to Timing CaseCover Removal, in this section, for the procedure.Remove the crankshaft oil slinger.Rotate the crankshaft until the zero degree (0") timingmark on the crankshaft sprocket is closest to and on thecenterline with the timing mark on the camshaft sprocket.Remove the camshaft sprocket retaining bolt.Remove the sprockets and chain as an assembly.Installation1. Turn the tensioner lever to the unlocked (down)position (Figure 2-25).2.3.4.5.6.7.8.Pull the tensioner block toward the tensioner lever andcompress the spring. Hold the block and turn thetensioner lever to the locked (up) position (Figure 2-25).Install the camshaft sprocket, crankshaft sprocket andtiming chain with the timing marks aligned (Figure 2-26).Note: To verify correct installation of timing chain,turn the crankshaft to position the camshaft sprockettiming mark at approximately the one o'clock position(Figure 2-26). This positions the crankshaft sprockettiming mark where the adjacent tooth meshes with thechain at the three o'clock position. Count the numberof chain pins between the timing marks on bothsprockets. There must be 20 pins.Tighten the camshaft sprocket bolt with 108 Nom(80 ft-lbs) torque.Release the timing chain tensioner lever.Install the crankshaft oil slinger.Install the timing case cover. Refer to Timing CaseCover Installation, in this section, for the procedure.Install the vibration damper on the crankshaft.. ..

T -7-1108 MOPAR PERFORMANCE PARTS9. Lubricate and tighten the damper bolt with 108 Nmm(80 ft-lbs) torque.Note: If the crankshaft turns before the damper bolttightening torque value is attained, the crankshaft canbe prevented from turning by placing two 5/16 x 1-1/2"bolts into the damper pulley holes and wedging a barbetween them. Rotate the bar until it contacts the framemember to prevent the crankshaft from turning.10. Install the vibration damper pulley.11. Install the dnve belt(s) on the pulleys and tighten.12. Install the fan and shroud.13. Tighten the fan and hub assembly nuts with 24 Nom(1 8 ft-lbs) torque.

PISTON AND CONNECTING ROD ASSEMBLYThe 2.461 engine’s connecting rod journal diameter is2.0934-2.0955“. Connecting rod journal width is 1.073“.For more connecting rod specifications, refer to 2.46.5 EngineSpecijications, ‘Engine Assembly’ section of this chapter.Note: The following procedure is used to service the pistonand connecting rod assemblies with the engine installed inthe vehicle and the cylinder head already removed.Removal1.2.3.4.5.6.7.8.9.Remove the cylinder head cover. Refer to CylinderHead Cover Removal, ‘Cylinder Head’ section ofthis chapter.Remove the capscrews, bridge and pivot assembliesand rocker arms.Caution: Alternately loosen the capscrews one turn ata time to avoid damaging the bridges.Remove the pushrods.Note: Retain bridge and pivot assemblies, rocker armsand pushrods in the order removed to facilitateinstallation at their original locations.Remove the spark plugs.Remove the intake manifold, gasket, exhaust manifold,cylinder head and gasket. Refer to Cylinder HeadRemoval, ‘Cylinder Head’ section of this chapter.Position the connecting rods and pistons two at a timenear the bottom of the stroke and use a ridge reamer toremove the ridge from the top end of the cylinderwalls. Use a protective cloth to collect the cuttings.Drain the engine oil.Remove the oil pan, gaskets and seals. Refer to Oil PunRemoval, ‘Oiling System’ section of this chapter.Remove the bolts, oil pump and gasket.10. Remove the connecting rod bearing caps and bearinginserts. Retain them in the same order as removed tofacilitate installation in their original locations. Referto Connecting Rod Bearings Removul, in this section,for the procedure.Note: The connecting rods and caps are stamped withthe corresponding cylinder number.Caution: Ensure that the connecting rod bolts DONOT scratch the crankshaft journals or cylinder walls.Short pieces of rubber hose slipped over the connectingrod bolts will provide protection during removal.Connecting Rods2.46L IN-LINE 4 (CONNECTING RODS) 10911. Remove the connecting rod and piston assembliesthrough the top of the cylinder bores.Installation1.2.3.4.5.6.7.8.9.10Clean the cylinder bores thoroughly. Apply a light film ofclean engine oil to the bores with a clean, lint-free cloth.Install the piston rings on the pistons, if removed.Lubricate the pistons and rings with clean engine oil.Caution: Ensure that the connecting rod bolts DONOT scratch the crankshaft journals or cylinder walls.Short pieces of rubber hose slipped over the connectingrod bolts will provide protection during installation.Use a piston ring compressor to install the connectingrod and piston assemblies from the top of the cylinderbores. Ensure that the arrow on each piston top pointsto the front of the engine (Figure 2-37).Note: Verify that the oil squirt holes in the rods facethe camshaft and that the arrows on the pistons point tothe front of the engine.Raise and support the vehicle.Install the connecting rod bearing caps and inserts attheir original locations. Refer to Connecting RodBearings Installation, in this section, for the procedure.Install the oil pump with a replacement gasket. Referto Oil Pump Installution, ‘Oiling System’ section ofthis chapter.Install the oil pan with replacement seals and gaskets.Tighten the drain plug securely. Refer to Oil PanInstallation, ‘Oiling System’ section of this chapter.Lower the vehicle.11. Install a replacement gasket and the cylinder head.Refer to Cylinder Heud Instullution, ‘Cylinder Head’section of this chapter.12. Install the exhaust manifold, a replacement gasket andthe intake manifold. Refer to the service manual forinstallation procedures.13. Tighten the mounting bolts to 31 Nom (23 ft-lbs)torque using the torque sequence outlined in theservice manual.14. Install the EGR tube assembly.15. Install the pushrods, rocker arms, bridge and pivotassemblies, and capscrews.Caution: Alternately tighten the capscrews at eachbridge, one turn at a time, to avoid damaging the bridges.l- -1-1

110 MOPAR PERFORMANCE PARTS16. Install the cylinder head cover. Refer to CylinderHead Cover Installation, ‘Cylinder Head’ section ofthis chapter.17. Install the spark plugs.18. Fill the oil pan with engine oil to the FULL MARK onthe dipstick.CONNECTING ROD BEARINGSRemoval1.2.3.4.5.Drain the engine oil.Remove the oil pan, seals and gaskets. Refer to Oil PanRemoval, ‘Oiling System’ section of this chapter.Remove the bolts, oil pump and gasket. Refer to OilPump Removal, ‘Oiling System’ section of this chapter.Rotate the crankshaft as required to position two of theconnecting rods at a time at the bottom of the stroke.Remove the connecting rod bearing caps. Remove thelower bearing inserts. Remove the upper bearing insertsby rotating/sliding them out of the connecting rods.Note: DO NOT intermix the bearing caps. Eachconnecting rod and its bearing cap are stamped withthe corresponding cylinder number on a machinedsurface adjacent to the oil squirt hole that faces thecamshaft side of the cylinder block.Installation1. Lubricate the bearing surface of each insert with cleanengine oil.2.3.4.5.Caution: Use care when rotating the crankshaft withthe bearing caps removed. Ensure that the connectingrod bolts DO NOT accidentally come into contact withthe crankshaft journals and scratch the surface. Bearingfailure would result. Short pieces of rubber hoseslipped over the connecting rod bolts will provideprotection during installation.Install the connecting rods, bearing inserts and capsaround the journals and secure them with the retainingnuts. Tighten with 45 N m (33 ft-lbs) torque.Install the oil pump with a replacement gasket. Referto Oil Pump Installation, ‘Oiling System’ section ofthis chapter.Install the oil pan with replacement gaskets and seals.Tighten the drain plug securely. Refer to Oil PanInstallation, ‘Oiling System’ section of this chapter.Fill the crankcase with engine oil to the FULL MARKon the dipstick.

Pistons and Rings2.46L IN-LINE 4 (PISTONS AND RINGS) 111Note: There is no piston or piston ring specific information for the 2.46L engine. All procedures and performance tips canbe found in the ‘Pistons and Rings’ section of Chapter 2. For piston and ring specifications, refer to 2.46L EngineSpecijcations, ‘Engine Assembly’ section of this chapter.

T --il 1112 MOPAR PERFORMANCE PARTS2.46L CYLINDER HEAD (EXPLODED VIEWS)Cylinder Head34. Oil Filler Cap35. Ventilation Valve36. Grommet37. Cylinder Head(Rocker) Cover38. Bridge39. Pivot40. Rocker Arm41. Valve Spring42. Oil Deflector43. Cylinder HeadBolt44. Cylinder HeadCore Plug45. Cylinder Head46. Plug47. Dowel Pin48. Tappet49. Snap Ring50. Cylinder Head Stud51. Push Rod52. Retainer53. Valve Locks86157A

2.46L IN-LINE 4 (CYLINDER HEAD) 11354. Intake Manifold Gasket 56. Heat Stove55. Exhaust Manifold 57. Valve@)REMOVAL AND REPLACEMENT PROCEDURESFor cylinder head specifications, refer to 2.46L EngineSpecifications, ‘Engine Assembly’ section of this chapter.Removal1.Disconnect the battery negative cable.Warning! DO NOT remove the cylinder block drain plugs orloosen the radiator draincock with the system hot andpressurized because serious burns from the coolant can occur.2.3.4.5.6.Drain the coolant and disconnect the hoses at thethermostat housing.Note: DO NOT waste reusable coolant. If the solutionis clean and being drained only to service the engine orcooling system, drain the coolant into a clean containerfor reuse.Remove the air cleaner.Remove the cylinder head cover. Refer to CylinderHead Cover Removal, in this section, for the procedure.Remove the rocker arms and bridge and pivotassemblies. Alternately loosen each capscrew one turnat a time to avoid damaging the bridges.Remove the pushrods.Note: Retain the pushrods, bridges, pivots and rockerarms in the same order as removed to facilitateinstallation in the original locations.7. Disconnect the power steering pump bracket. Set thepump and bracket aside. DO NOT disconnect the hoses.8.9.Remove the intake and exhaust manifolds from thecylinder head.Remove the intake manifold gasket. Refer to theservice manual for the procedures.10. Disconnect the ignition wire connectors and removethe spark plugs.11. Disconnect the temperature sending unit wireconnector and battery negative cable.12. Remove the cylinder head bolts, cylinder head and gasket.Cleaning and Inspection1. Thoroughly clean the machined surfaces on thecylinder head and block. Remove all gasket materialand cement.2.3.Remove any carbon deposits from the combustionchambers and from the top of the pistons.Use a straightedge and feeler gauge to check the flatnessof the cylinder head and block mating surfaces. Fortolerances, refer to 2.461, Engine Specifications,‘Engine Assembly’ section of this chapter.l- -11

114 MOPAR PERFORMANCE PARTSInstallation1. If the cylinder head is to be replaced and the originalvalves used, measure the valve stem diameter.2.3.4.Only standard size valves can be used with a servicereplacement cylinder head unless the replacement headvalve stem guide bores are reamed to accommodateoversize valve stems.Remove all carbon buildup and reface the valves.Install the valves in the cylinder head with replacementvalve stem oil deflectors.Caution: DO NOT install the temperature sending unituntil the system is filled with coolant. This permits trappedair to escape from the cylinder block and head.5.Transfer all the attached components from the originalcylinder head that are not included with thereplacement cylinder head.Caution: DO NOT apply sealing compound on thecylinder head and block gasket surfaces. DO NOT allowsealing compound to enter the cylinder bore.6.7.8.9.Apply an even coat of Perfect Seal sealing compound,or equivalent, to both sides of the replacement cylinderhead gasket and position the gasket on the cylinderblock with the word TOP facing up.Install the cylinder head. Tighten the bolts in the sequenceillustrated in Figure 3-1 with 115 Nmm (85 ft-lbs) torque.Note: Coat the threads of the stud bolt in the No. 8sequence position with Loctite 592 sealant (orequivalent) and tighten with 102 Nmm (75 ft-lbs) torque.Note: The cylinder head gasket is made of aluminumcoatedembossed steel and does not require that thecylinder head bolts be re-tightened.Connect the battery negative cable.Install the spark plugs and connect the ignition wireconnectors.10. Install the intake and exhaust manifolds. Use thecorrect tightening sequence. Refer to the servicemanual for the procedures.11. Install the alternator belt and adjust the tension.12. Install the power steering bracket and pump, ifequipped. Adjust the belt tension.13. Install the pushrods in their original locations.14. Install the rocker arms and the bridge and pivotassemblies at their original locations. Loosely installthe capscrews for each bridge and tighten alternately,one turn at a time, to avoid damaging the bridge.15. Tighten the capscrews with 26 Nom (19 ft-lbs) torque.16. Install the cylinder head cover. Refer to Cylinder HeadCover Installation, in this section, for the procedure.17. Connect the hoses to the thermostat housing and fill thecooling system to the specified level.18. Install the temperature sensor unit and connect thewire connector.19. Connect the fuel lines.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or fan. DO NOTwear loose clothing.201. Operate the engine with the radiator cap off.21. Inspect for leaks and continue operating the engineuntil the thermostat opens. Add coolant, if required.22. Install the air cleaner.I 10 R 2 3 9I83126T

2.46L IN-LINE 4 (CYLINDER HEAD) 115CYLINDER HEAD COVERCrankcase BreatherA universal high performance re-usable crankcasebreather (must have stand pipe on valve cover). Washesclean with P4529392 cleaning fluid for extra miles ofservice.P4529394Removal1.2.3.4.5.6.7.8.9.Crankcase breather.Remove the air cleaner and the PCV valve molded hose.Disconnect the PCV valve from the grommet in thecylinder head cover.Disconnect the PCV shutoff valve vacuum hose.Remove all the necessary vacuum and air hoses toprovide clearance for the cylinder head cover.Remove the cylinder head cover retaining screws.Detach the cover from the cylinder head by separatingthe RTV sealant with a putty knife or razor blade.DO NOT pry the cover upward until the seal has beencompletely broken.Pry the cover up at the pry ramps that are identified bythe words PRY HERE.Inspect the cylinder head cover for cracks.InstallationI.2.3.4.5.6.7.8.9.10. Connect the PCV valve and the PCV shutoff valve hose.11.Either a standard gasket or a room temperaturevulcanizing (RTV) silicone rubber sealant may be usedfor cylinder head cover installation.Use Mopar Gasket-in-a-Tube, or equivalent, for aformed-in-place gasket.Remove the original sealant (or gasket and adhesive) fromthe sealing surface area of the cylinder head and cover.Thoroughly clean the sealing surfaces on the cylinderhead and cover.Apply a 3 mm (l/S") bead of RTV sealant along theentire length of the cylinder head sealing surface.Before the sealant begins to cure, position the cover onthe cylinder head.DO NOT allow the sealant to come into contact withthe rocker arms or other valve assembly components.Install the cylinder head cover retaining screws andtighten the screws with 6.2 Nem (55 in-lbs) torque.Reposition and/or connect all the air and vacuum hosesthat were moved for cover removal clearance.Install the air cleaner and hoses.r -1-1

T ' 7 7116 MOPAR PERFORMANCE PARTSCAMSHAFTCamshaft and Valve GearInstallationThe 2.46L engine uses a cast iron camshaft with intake andexhaust cam lobe lifts of .254", and durations of (intake) 259",(exhaust-Nationwide) 259", and (exhaust-California) 289".Valve lengths are (for intake and exhaust) 4.7895-4.8045".For more camshaft specifications, refer to 2.461; EngineSpecifications, 'Engine Assembly' section of this chapter.RemovalWarning! The coolant in a recently operated engine is hotand pressurized. Release the pressure before removing thedraincock, cap and drain plugs.1.2.3.4.5.6.7.8.9.10. Remove the crankshaft and oil slinger.11.12. Rotate the crankshaft until the zero degree (OO) timingmark on the crankshaft sprocket is closest to and on thecenterline with the timing mark on the camshaft sprocket.13.14.Drain the cooling system.Note: DO NOT waste reusable coolant. Drain thecoolant into a clean container.Remove the radiator.Remove the drive belt(s).Remove the distributor and ignition wires.Remove the cylinder head cover. Refer to Cylinder HeadCover Removal, 'Cylinder Head' section of this chapter.Remove the capscrews, bridge and pivot assemblies,and rocker arms. Alternately loosen each capscrew oneturn at a time to avoid damaging the bridges.Remove the pushrods.Note: Position all components on a workbench in thesame order as removed to facilitate installation in theoriginal positions.Remove the tappets using hydraulic valve tappetremover. Refer to Hydraulic Valve Tappet Removal, inthis section, for the procedure.Remove the pulley (if applicable), vibration damperand timing case cover. Refer to Timing Case CoverRemoval, 'Crankshaft' section of this chapter.Remove the camshaft sprocket retaining bolt.Remove the timing chain and sprockets as an assembly.Remove the camshaft.Note: The camshaft MUST be centerlined to ensure properinstallation. Refer to the 'Camshaft and Valve Gear' sectionof Chapter 2 for complete details.1. Lubricate the camshaft with Mopar Engine OilSupplement, or equivalent.2.Install the camshaft carefully to prevent damaging thecamshaft bearings.3. Turn the tensioner lever to the unlocked (down)position (Figure 2-25).4.Pull the tensioner block toward the tensioner lever tocompress the spring. Hold the block and turn thetensioner lever to the locked (up) position (Figure 2-25).5. Install the timing chain, crankshaft sprocket andcamshaft sprocket with the timing marks aligned(Figure 2-26).6.7.8.9.Note: To verify correct installation of the timingchain, turn the crankshaft to position the camshaftsprocket timing mark at approximately the one o'clockposition (Figure 2-26). This positions the crankshaftsprocket timing mark where the adjacent tooth mesheswith the chain at the three o'clock position. Count thenumber of chain pins between the timing marks onboth sprockets. There must be 20 pins.Install the camshaft sprocket retaining bolt and tightenwith 108 N*m (80 ft-lbs) torque.Install the crankshaft oil slinger.Release the timing chain tensioner by turning thetensioner lever to the unlocked (down) position.Install the timing case cover and a replacement oil seal.Refer to Timing Case Cover Installation, 'Crankshaft'section of this chapter.101. With the key inserted in the keyway on the crankshaft,install the vibration damper, washer and bolt.11. Lubricate and tighten the damper bolt with 108 N*m(80 ft-lbs) torque.Note: If the crankshaft turns before the damper bolttightening torque value is attained, the crankshaft canbe prevented from turning by placing two 5/16 x 1 - 1/2"bolts into the damper pullet holes and wedging a barbetween them. Rotate the bar until it contacts the framemember to prevent the crankshaft from turning.12. Install the damper pulley.

2.46L IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 11713. Install the fan assembly and shroud.14. Install the drive belt(s) and tighten to the specified tension.15. Install the distributor, distributor cap and ignition wiresby rotating engine No. 1 cylinder piston until it is atTop Dead Center (TDC) in the compression stroke.16. Using a flat blade screwdriver, rotate the oil pump gearso that the gear slot on the oil pump shaft is slightlypast the three o’clock position (Figure 2-57).17. With the distributor cap removed, install the distributorwith the rotor located at the five o’clock position(Figure 2-58).18. When the distributor is fully engaged in its correctlocation, the rotor should be at the six o’clock position(Figure 2-59).Note: If the distributor is not installed correctly, or ifit is removed later, the complete installation proceduremust be repeated.19. Install the tappets using hydraulic valve tappet installer.20. Install the pushrods.21. Install the rocker arms and bridge and pivotassemblies. Tighten each of the two capscrews for eachbridge alternately one turn at a time to avoid damagingthe bridge.Note: Lubricate the hydraulic valve tappets and allvalve actuating components with Mopar Engine OilSupplement (EOS), or equivalent, during installation.The EOS must remain with the engine oil for at least1,609 km (I ,000 miles), but need not be drained untilthe next scheduled oil change.22. lnstall the cylinder head cover. Refer to CylinderHead Cover Installation, ‘Cylinder Head’ section ofthis chapter.23. Install the radiator. Connect the hoses and fill thecooling system to the specified level.24. Check the ignition timing and adjust as necessary.Measuring Cam Lobe Lift1.2.3.4.5.6.7.8.Remove the cylinder head cover. Refer to CylinderHead Cover Removul, ‘Cylinder Head’ section ofthis chapter.Remove the bridge and pivot assemblies and rockerarms. Alternately loosen each capscrew, one turn at atime, to avoid damaging the bridges. Disconnect thespark plug wire connectors and remove the spark plugs.Install a dial indicator with a piece of rubber tubingbetween the dial indicator plunger and the pushrod.Rotate the camshaft until the heel of the cam lobe(pushrod in the down position) is under the valvetappet. Set the dial indicator pointer at zero.Rotate the crankshaft until the pushrod is at itsmaximum upward position.Note the travel distance on the dial indicator. Refer to2.46L Engine Specifications, ‘Engine Assembly’section of this chapter, for the correct cam lobe lift.Repeat the procedure for each remaining cam lobe.Install the rocker arms and bridge and pivotassemblies. Alternately tighten the capscrews ateach bridge one turn at a time to avoid damagingthe bridges.9. Install the spark plugs and connect the wire connectors.IO. Install the cylinder head cover. Refer to CylinderHead Cover Installation, ‘Cylinder Head’ section ofthis chapter.

118 MOPAR PERFORMANCE PARTSVALVE SPRING AND OIL DEFLECTORNote: Each valve spring is held in place around the valvestem by a retainer and a set of conical valve locks. The lockscan be removed only by compressing the valve spring.Removal1.2.3.4.5.6.7.8.9.Remove the cylinder head cover. Refer to CylinderHead Cover Reinoval, ‘Cylinder Head’ section ofthis chapter.Remove the capscrews, bridge and pivot assembly, androcker arms for access to each valve spring to beremoved. Alternately loosen each capscrew one turn ata time to avoid damaging the bridge.Remove the pushrods.Note: Retain the pushrods, bridges, pivots and rockerarms in the same order and position as removed.Remove the spark plug(s) adjacent to the cylinder(s)below the valve springs to be removed.Install a 14 mm (1/2”) (thread size) air hose adapter into the spark plug hole.Note: An adapter can be constructed by welding an airhose connection to the body of a spark plug with theporcelain removed.Connect an air hose to the adapter and maintain at least621 kPa (90 psi) of air pressure in the cylinder to holdthe valves against their seats.Note: For vehicles equipped with an air conditioner, usea flexible air adapter when servicing the No. 1 cylinder.Use a valve spring compressor tool to compress thespring and remove the locks.Remove the valve spring and retainer.Remove the valve stem oil deflector.Installation4. Disconnect the air hose. Remove the adapter from thespark plug hole and install the spark plug.5. Repeat the procedure for each remaining valve springto be removed.6. Install the pushrods. Ensure the bottom end of eachpushrod is centered in the plunger cap seat of thehydraulic valve tappet.7. Install the rocker arms, pivots and bridge at theiroriginal location.8. Tighten the bridge capscrews alternately one turn at atime to avoid damaging the bridge.9. Install the cylinder head cover. Refer to Refer toCylinder Head Cover Installation, ‘Cylinder Head’section of this chapter.ROCKER ARM ASSEMBLYRemoval1. Remove the cylinder head cover. Refer to Cylinder HeadCover Removal, ‘Cylinder Head’ section of this chapter.2. Remove the two capscrews at each bridge and pivotassembly. Alternately loosen the capscrews one turn ata time to avoid damaging the bridges.3. Remove the bridges, pivots and corresponding pairs ofrocker arms and place them on the bench in the sameorder as removed.4. Remove the pushrods and place them on the bench inthe same order as removed.Caution: Install the deflector carefully to prevent damagefrom the sharp edges of the valve spring lock groove.1. Use an 11 mm (7/16”) deep socket and small hammerto gently tap the oil deflector onto the valve stem.2. Install the valve spring and retainer.3. Compress the valve spring with valve springcompressor tool and insert the valve locks. Release thespring tension and remove the tool.Note: Tap the spring from side-to-side to ensure thatthe spring is seated properly on the cylinder head.

2.46L IN-LINE 4 (CAMSHAFT AND VALVE GEAR) 11 9Cleaning and Inspection1. Clean all the components with cleaning solvent and usecompressed air to blow out the oil passages in therocker arms and pushrods.2.3.4.5.Inspect the pivot surface area of each rocker arm.Replace any that are scuffed, pitted or excessively worn.Inspect the valve stem tip contact surface of each rockerarm and replace any rocker arm that is deeply pitted.Inspect each pushrod end for excessive wear andreplace as required. If any pushrod is excessively wornbecause of lack of oil, replace it and inspect thecorresponding hydraulic tappet for excessive wear.A wear pattern along the length of the pushrod is notnormal. Inspect the cylinder head for obstruction if thiscondition exists.Installation1. Install the pushrods in their original locations. Ensurethat the bottom of each pushrod is centered in thetappet plunger cap seat.2.3.4.5.Install the rocker arms, pivots and bridge above eachcylinder from where they were originally removed.Loosely install the capscrews through each bridge.At each bridge, tighten the capscrews alternately oneturn at a time to avoid damaging the bridge. Tightenwith 26 Nam (19 ft-lbs) torque.Install the cylinder head cover. Refer to CylinderHead Cover Installation, ‘Cylinder Head’ section ofthis chapter.4. Remove the tappets through the pushrod openings inthe cylinder head with a hydraulic valve tappetremoval and installation tool.5.Retain the tappets in the same order as removed tofacilitate installation in the original locations.Note: It is not necessary to charge the tappet assemblieswith engine oil. They will charge themselves within avery short period of engine operation.Installation1.2.3.4.5.6.7.Coat each tappet assembly with Mopar Engine OilSupplement (EOS), or equivalent.Use a hydraulic valve tappet removal and installationtool to install each tappet in the same bore from whereit was originally removed.Install the pushrods in their original locations.Install the rocker arms and bridge and pivot assembliesat their original locations. Loosely install thecapscrews at each bridge.Tighten the capscrews alternately one turn at a time toavoid damaging the bridges.Pour the remaining EOS over the entire valveactuating assembly.Note: The EOS must remain with the engine oil for atleast 1,609 km (1,000 miles), but need not be draineduntil the next scheduled oil change.Install the cylinder head cover. Refer to CylinderHead Cover Installation, ‘Cylinder Head’ section ofthis chapter.HYDRAULIC VALVE TAPPETS (LIFTERS)Removal1. Remove the cylinder head cover. Refer to Cylinder HeadCover Removul, ‘Cylinder Head’ section of this chapter.2.Remove the bridge and pivot assemblies and rockerarms by removing the two capscrews at each bridge.Alternately loosen each capscrew one turn at a time toavoid damaging the bridge.3. Remove the pushrods.Note: Retain all the components in the same order asremoved to facilitate installation in the originalposition. Tappets must be re-installed on the same lobeor they will wear out.T

120 MOPAR PERFORMANCE PARTSOIL PANRemoval1.2. Drain the engine oil.3. Remove the starter motor.4.5.6.7.Raise and support the vehicle at the side sills.Remove the flywheel housing access cover.Remove the oil pan screws.Remove the oil pan by sliding it to the rear.OilingClean the gasket and seal surfaces. Remove all sludgeand grime from the oil pan sump.Installation1.2.3.4.5.6.7.8.9.Install a replacement oil pan front seal on the timingcase cover and apply a generous amount of RTVsealant (Mopar Gasket-in-a-Tube, or equivalent) to therecesses in the tab ends.Note: Either one of two sealing methods may be used.An RTV sealant such as Mopar Gasket-in-a-Tube, orequivalent, may be used instead of a gasket. If a gasketis used, coat both sides with a quick drying adhesivesuch as Mopar Spray-a-Gasket, or equivalent.Coat the inside curved surface of the replacement oilpan rear seal with soap. Apply a generous amount ofRTV sealant to the gasket contacting surface of the sealend tabs.Install the seal in the recess of the rear main bearingcap. Ensure it is fully seated.Cement the replacement oil pan side gaskets intoposition on the cylinder block.Apply a generous amount of RTV sealant to the endtabs of the gaskets.Apply engine oil to the oil pan contacting surface ofthe front and rear oil pan seals.Install the oil pan. Tighten the screws and the drainplug securely.Note: Tighten the 1/4-20 oil pan screws with 9 Nom(7 ft-lbs) torque and tighten the 5/16-18 oil pan screwswith 15 Nom (1 I ft-lbs) torque.Install the starter motor.Install the flywheel housing access cover.10. Raise the vehicle.11. Remove all sill supports.System12. Lower the vehicle.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put hands near the pulleys, belts or fan. DO NOTwear loose clothing.13. Fill the oil pan with engine oil to the specified level.Start the engine and inspect for leaks.011. PUMPNote: A gear-type oil pump is located at the underside ofthe cylinder block opposite the No. 3 main bearing.RemovalNote: Oil pump removal and replacement will not affectdislxibutor ignition timing because the distributor drive gearremains in mesh with the camshaft gear.1. Drain the engine oil.2. Remove the oil pan. Refer to Oil Pan Removal, in thissection, for the procedure.Caution: DO NOT disturb the position of the oil inlet tubeand strainer assembly attached to the pump body. If the tubeis moved within the pump body, a replacement tube andstrainer assembly must be installed to assure an airtight seal.3. Remove the oil pump retaining screws, oil pumpand gasket.InstallationNote: To ensure self-priming of the oil pump, fill the pumpwith petroleum jelly before installing the oil pump cover.DO NOT use grease.1. Apply a bead of Loctite 5 1.5 sealant, or equivalent, andinstall the pump cover. Tighten the cover screws with8 Nom (70 in-lbs) torque.Note: Rotate the gears to ensure that a binding conditiondoes not exist before installing the oil pump.2. lnstall the oil pump with a replacement gasket. Tightenthe short screw with 14 Nom (10 ft-lbs) torque, and thelong screw with 23 N*m (17 ft-lbs) torque.3. Install the oil pan with replacement gaskets andseals. Refer to Oil Pan Installation, in this section,for the procedure.4. Fill the oil pan with replacement engine oil to thespecified level.I.l--1n

Engine Assembly2.46L IN-LINE 4 (ENGINE ASSEMBLY) 121Note: For engine assembly information, performance modifications and tips, refer to 'Engine Assembly' section of Chapter4, 4.0L Power Tech In-Line 6.2.46L ENGINE GENERAL SPECIFICATIONSNote: The following information has been reprinted from the 1983 Jeep Service Manual.IType .............................Bore ............................Stroke ............................Dlsplacement .....................Compression Ratio. ................Compression Pressure. .............Maximum Variation BetweenCylinders .......................Firing Order.. .....................I Taxable Horsepower. ..............Fuel .............................CsmshatfFuel Pump Eccentric Diameter. ......Tappet Clearance. ...............End Play ..........................Bearing Clearance.. ...............Bearing Journal DiameterNo. 1 ..........................No. 2 ...........................No. 3.. .......................No. 4 ..........................Base Circle Runout. ..............Cam Lobe Lift ...................Valve Lift.. .....................Intake Valve limingOpens .......................Closes ......................Exhaust Valve limingOpens .........................Closes .......................Valve Overlap. .....................Intake Duration. ................Exhaust Duration. . . . . . . . . . . .Conrwctlng RodsIn Line, OHV. 4-Cylinder3.876 98.453.188 80.97150 cu. in. 2.46 liter9.2:l155-185 psi 1088-1275 kpa30 psi 206 kpa1-3-4-224.04 bhp 17.9 kwUnleaded1.615-1.625 41.02-41.28zero lash (hyd.) tappetszero (engine operation)0.001-0.003 0.0254.0762 029.2 030 51 54-51 562 019-2020 51 28.51 312 009-2010 51 03.51 051999-2000 5078.50800 001 max 0 03 max265 6 73424 to 712' BTDC258' ATDC236 ' BTDC34' ATDC46 *270270'1Total Weight (less bearings). ........657-665 gramsTotal LengIh(center.tecenter). ...... 6.1236.127 155.52-15562Piston Pin Bore Diameter. ........... 0.9288-0.9298 23.59-2362Connecting Rod Bore (less bearings). . 2,2080.2.2085 56.08.56.09Bearing Clearance. ............... 0.001.0.003 0.03-0.08(0.0015-0.002 (0.044.05Preferred) Preferred)ISide Clearance. ................... O.OlQo.019 0.250.48Maximum Twist.. .................. 0.001 per In. 0.025 PW25.4 mmMaximum Bend.. .................. 0.005 POr in. 0.0127 POf25.4 mmcnnkrhattEnd PI sy ..........................Main Bearing Journal Diameter. ......Main Bearing Journal WidthNo. 1 ...........................No. 2 ...........................NO. 3-44., ......................Main Bearing Clearance.. ...........Connecting Rod Journal Diameter. ...Connecting Rod Journal Width. ......Maximum Out-of-Round(All Journalr). ...................Maximum Taper (All Journals). .......Cyllndor @lo&0.0015.0.M)852.49962.50011.0881.0981.271-1.2731.182.1.1880.0014.0025(0.002Preferred)2.0934-2.09551.070.1.076O.OOO50.00050.0380.18583.489.63.50227.58-27.89u.2a32.3330.02.30.180.03-0.08(0.051Preferred)53.1763.2327.10-27.330.0130.013Deck Height. ...................... 9.337-9.343 237.15237.31Deck Clearance.. .................. 0.020 0.508(below deck) (below deck)Cylinder Bore Diameter (standard)., . . 3.8751-3.8775 98.42-98.48Maximum Taper. ................. 0.001 0.025Maximum Out-of43ound. .......... 0.001 0.025lappet Bore Diameter. .............. 0.9C55.0.9085 23.m23.025Cylinder Block Flatness. ............,001 It .0-.00216.0 0.031254.051152Cyllndu H..dCombustion Chamber Volume. .......Valve Arrangement. ................49.952.9 ccE-I-I.E-E-I-I-EValve Guide ID(ln1egral). ............ 0.3136.314 7.95.7.97Valve Stem4eGuide Clearance. ...... 0.0014.003 0.02-0.07Intake Valve Seat Angle.. ..........Exhaust Valve Seat Angle.. .........44.30'14-30'Valve Seat Width. ................... 0.0404.060 1.02-1.52Valve Seal Runout. ................. 0.0025 0.084Cylinder Head Flatness. .............001/1.0.002/6.00.03125~.051152

122 MOPAR PERFORMANCE PARTSLubdoalkll smmEngine Oil Capacity. ...............4 qlr.WIWOfiller changeNormal Operating Prerrure. ......... 13 pi at 600rpm 37-75 pri(max.) at100+ rpmOil Prerrure Relief.. ............... 75 pri (mx.)Gear-teBody Clearance (Radial). ..... 0.0014).00)(0.002 Prof.)Gear End Clearance, Plartigags. ..... 0.0020.006(0.002 Prof.)Gear End Clearance. Feeler Gaugs. ... 0.oocO.ooO(0.007 Ref.)PlatonWeight (1088 pin). ..................Pirton Pin Bore CanterlinstePirton3.8 litenWIWOfiller change00.6 kpa at 600rpm 256.1-517.1kp. (max.) atlwo+ rpm517.1 kp8(max.)0.0510.1020.051 Prof.)0.0510.152(0.051 Prof.)0.10160.2032(0.1778 Ref .)563.507 gramaTop.. .......................... 1.651-1.6S 41.9442.04Piston-teBore Clearance. ........... 0.0009.0.0017 0.0230.043(0.00120.0013 (0.o300.033Preferred) PreferredlPirton Ring Gap Clearance -Compmrion (both)............... 0.0100.020 0.25-0.51Piston Ring Gap Clearance -Oil Control Stwl hila.. .......... 0.0100.025 0.250.64firton Ring Side ClearanceNo. 1 Comprerrion.. ............. 0.00170.0032 0.0434.081(0.0017 Prof.) (0.043 Prof.)No. 2 Comprerrion.. ............. 0.00170.0032 0.0434.081Oil Control.. ......................(0.0017 Prof.) (0.043 Prof.)0.0010.aoB 0.034.20(0.003 Pro(.) (0.08 Pf.1.)Pirton Ring Groove HeightComprerrion (both)............... 0.07950.0805 2.0192.045Oil Control ...................... 0.1W.1895 4.784.80Platon Ring Oroovr DlvnulNo. 1 and No, 2.. ................. 3.4S3.01 87.W7.90Oil Control. ..................... 3.e3.456 87.5047.15Pirton Pin BOn 01amoI.r.. .......... 0.Q3oo.0313 23.62423.-Piaton Pin Diwtw.. .............. O.Q3oco.Q3ooPiston-tePin Clrrance. ............ 0.M.W O.m.01323.632-23.645(Laru 0,0005 (LOOlO 0.013Pref0fr.d) Pfe1.rd)Piatton Pln.to4htnrCllng CIOd.. ...... 2000 IW:f 8.9 kNPress-fit Pres.-fitaoekuAn118, hnh Rodn andTropbRockof Arm Ratio.. ................1.6:l........... 9.6409.dO 244.656-2*5.3(uPush Rod Diameter.. ............... 0.312.0.315 7.928.00Hydraulic Tappet Diemeter. ......... 0.904-0.9045 22.062-22.974Tappe14eBon c1.rence. .......... 0.m10.0025 0.034.05V.IV.8Valve bngth(Tiptc&aug. Dim. Line). .......... 4.8224.837 Int. 122.47.122.854.837-4.852 Exh. 122.85123.24Valve Stem Diameter.. ............. ,311-312 7.887.98Stem-teGuid. Clearance. ........... .001-.003 0.024.05int8ke Valw Uead Diameter. ......... 1.9051.915 40.3846Intake Valve Face Angle. ............44Exheurt Valve Uead Diameter, ....... 1.4oS1.soS 37.97-38.6Exhaurt VaIw Face Angle.. ..........44'Maximum Allowable RemW forTip Refinishing. ................. 0.010 0.25Valve Spring8Frw Length.. ..................... 1.8246.22Spring TenrionValve Cload., .................. 66-74 Ibs. 294.329at 1.825 at 41.28Valve Open. ..................... 205220 Ibr. 912-979at 1.200 at 30.40Inride Diamter.. .................. 0.9480.988 24.08-24.5

2.46L IN-LINE 4 (ENGINE ASSEMBLY) 123r - 7 - 7

~~124 MOPAR PERFORMANCE PARTS2.46L ENGINE GENERAL TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1983 Jeep Service Manual.IComponentService Set-To TorqueService Recheck TorqueAlternator Pivot Bolt or NutAlternator Adjustment Bolt38 N-m (28 ft-lbs)24 N-m (18 ft-lbs)27-47 N-m (20-35 ft-lbs)20-27 N.m (1 5-20 ft-lbs)Alternator Mounting Bracket-to-Cylinder Block Bolt38 N-m (28 ft-lbs)31-41 N.m (23-30 ft-lbs)Alternator Mounting Bracket-to-Cylinder Head BoltBlock Heater Nut45 N.m (33 ft-lbs)1.8 N-m (1 6 in-lbs)41-47 Nom (30-35 ft-lbs)1.5-2.1 N-m (14-19 in-lbs)Camshaft Sprocket Screw68 Nom (50 ft-lbs)61-75 N-m (45-55 ft-lbs)Carburetor Hold-Down NutsCoil Bracket-to-Body Screws19 Nam (14 ft-lbs)9.6 N-m (85 in-lbs)16-27 N-m (1 2-20 ft-lbs)6.7-10.1 N-m (60-90 in-lbs)Connecting Rod Bolt Nuts45 N-m (33 ft-lbs)41-47 N-m (30-35 ft-lbs)Cylinder Head CapscrewsCylinder Head Cover Nuts11 5 N.m (85 ft-lbs)6.2 N-m (70 in-lbs)108-122 Nom (80-90 ft-lbs)5-8.5 N-m (45-75 in-lbs)Crankshaft Pulley-to-Damper27 N-m (20 ft-lbs)20-34 N-m (1 5-25 ft-lbs)Clutch Housing-to-Block ScrewsClutch Housing Cover Screws75 N-m (55 ft-lbs)29 N-m (21 ft-lbs)65-84 Nom (48-62 ft-lbs)22-35 N-m (1 6-26 ft-lbs)Differential Housing-to-LeftEngine Mount BoltDipstick Tube Bracket Bolt-to-Cylinder Block54 N-m (40 ft-lbs)19 N-m (1 4 ft-lbs)47-68 N-m (35-50 ft-lbs)13-24 N.m (10-18 ft-lbs)Distributor Clamp Bracket ScrewDrive Plate-to-Converter ScrewEGR Valve Tube Nuts18 N-m (1 3 ft-lbs)30 N-m (22 ft-lbs)41 N-m (30 ft-lbs)14-27 N-m (1 0-20 ft-lbs)27-34 N-m (20-25 ft-lbs)34-47 N-m (25-35 ft-lbs)EGR Valve Bolts18 N-m (13 ft-lbs)12-24 N-m (9-18 ft-lbs)Exhaust Manifold Bolts31 N.m (23 ft-lbs)24-38 Nom (1 8-28 ft-lbs)Exhaust Pipe-to-Manifold Bolts23 N-m (1 7 ft-lbs)20-25 N.m (15-19 ft-lbs)Fan and Hub Assembly Bolts24 N-m (1 8 ft-lbs)16-34 N-m (1 2-25 ft-lbs)Flywheel-to-Crankshaft Bolts68 N-m (50 ft-lbs) Plus 60"Front Crossmember-to-Sill BoltsFront Support Bracket-to-Cylinder Block Bolts88 N-m (65 ft-lbs)60 N-m (45 ft-lbs)75 N-m (55 ft-lbs) min54-68 N.m (40-50 ft-lbs)Front Support Cushion-to-Bracket Bolts45 N-m (33 ft-lbs)36-52 N-m (27-38 ft-lbs)Front Support Cushion-to-Crossmember Bolts50 N-m (37 ft-lbs)41-61 N-m (30-45 ft-lbs)

l- -ll--l2.46L IN-LINE 4 (ENGINE ASSEMBLY) 125ComponentFuel Pump ScrewsIdler Arm Bracket-to-Sill BoltsIdler Pulley Bracket-to-FrontCover NutIdler Pulley Bearing Shaft-to-Bracket NutIntake Manifold Coolant FittingsIntake Manifold Heater ScrewsIntake Manifold ScrewsMain Bearing CapscrewsOil Filter AdapterOil Level Sensor in Oil PanOil Pan Drain PlugOil Pan Screws - 1/4 in - 20Oil Pan Screws - 5/16 in - 18Oil Pump Cover ScrewsOil Pump Attaching Screws(Short)Oil Pump Attaching Screws(Long)Oxygen SensorPower Steering Pump AdapterScrewPower Steering Pump BracketScrewPower Steering Pump MountingScrewPower Steering Pump PressureHose NutPower Steering Pump Pulley NutRear Crossmember-to-Side SillNutRear Support Bracket-to-Transmission BoltsRear Support Cushion-to-BracketBoltsService Set-To Torque22 N-m (16 ft-lbs)68 N-m (50 ft-lbs)9 Nm (7 ft-lbs)45 Nern (33 ft-lbs)27 N-m (20 ft-lbs)9 Nm (7 ft-lbs)31 N-m (23 ft-lbs)108 IV-m (80 ft-lbs)65 N.m (48 ft-lbs)33 N-m (25 ft-lbs)34 Nom (25 ft-lbs)9 Nm (7 ft-lbs)15 N-rn (1 1 ft-lbs)8 N-rn (70 in-lbs)14 Nm (10 ft-lbs)23 N-m (17 ft-lbs)48 N-m (35 ft-lbs)31 N-m (23 ft-lbs)58 N-rn (43 ft-lbs)38 N m (28 ft-lbs)52 Nl-m (38 ft-lbs)79 NIm (58 ft-lbs)41 NI-m (30 ft-lbs)45 N1.m (33 ft-lbs)41 NIm (30 ft-lbs)Service Recheck Torque18-26 N-m (1 3-1 9 ft-lbs)47-81 N.m (35-60 ft-lbs)5-12 N-m (4-9 ft-lbs)38-52 N-m (28-38 ft-lbs)20-34 N-m (1 5-25 ft-lbs)7-12 N-m (5-9 ft-lbs)24-38 N-m (1 8-28 ft-lbs)95-1 15 N-m (70-85 ft-lbs)57-75 N-m (42-55 ft-lbs)27-40 N-m (20-30 ft-lbs)27-41 N-m (20-30 ft-lbs)7-15 N-rn (5-1 1 ft-lbs)12-20 N-m (9-15 ft-lbs)7-11 N-m (60-100 in-lbs)11-18 N-m (8-13 ft-lbs)16-27 N-m (1 2-20 ft-lbs)43-52 N-m (32-38 ft-lbs)24-38 N-m (1 8-28 ft-lbs)50-64 N-rn (37-47 ft-lbs)34-47 N-m (25-35 ft-lbs)41-61 N-m (30-45 ft-lbs)54-88 N-m (40-65 ft-lbs)27-47 N-m (20-35 ft-lbs)37-52 N-m (27-38 ft-lbs)34-46 N-m (25-35 ft-lbs)

~r -in126 MOPAR PERFORMANCE PARTSComponentRear Support Cushion-to-Crossmember BoltsRocker Arm Assembly-to-Cylinder Head BoltsSpark PlugStarter Motor-to-Cylinder BlockBoltsTensioner Bracket-to-CylinderBlock BoltTiming Case Cover-to-BlockScrewsTiming Case Cover-to-BlockStudsTorque Converter Drive Plate-to-Crankshaft BoltsThermostat Housing BoltVibration Damper Bolt(Lubricated)Water Pump BoltService Set-To Torque24 N-m (18 ft-lbs)26 N-m (19 ft-lbs)37 N-m (27 ft-lbs)45 N-m (33 ft-lbs)19 N-m (14 ft-lbs)7 N-m (5 ft-lbs)22 N-m (16 ft-lbs)54 N.m (40 ft-lbs) Plus 6018 N-m (13 ft-lbs)108 N-m (80 ft-lbs)18 N-m (13 ft-lbs)Service Recheck Torque16-34 N-m (12-25 ft-lbs)22-35 N.m (16-26 ft-lbs)30-45 N-m (22-33 ft-lbs)38-51 N-m (28-38 ft-lbs)13-20 Nm (1 0-18 ft-lbs)5-12 N-m (4-9 ft-lbs)18-26 N-m (13-19 ft-lbs)14-24 N-m (10-18 ft-lbs)95-135 N-rn (70-1 00 ft-lbs)13-24 N.m (10-18 ft-lbs)

Chapter 44.0L Power Tech ln=Line 6

It8MOPAR PERFORMANCE PARTSIntroduction ............ ............... ......................................... 129................ ..................................... 130Crankshaft ........... ............ .............. ............ ........,137Connecting Rods ............................ ................ ...................... 148Pistons and Rings .......... ................ .............. ............ . . , .IS2Cylinder Head ..... ........... ................ ........... ............. 162Camshaft and Valve Gear ..... .................... ........... ............... 176.............. ........... ...............206Cooling System .......... ....................... ......... ............... 214Induction System ........ ..................... ........... ......... ,222Fuel Delivery System . ..................... .............. .................. 227.................. ............ ............ 234................... ................... 238Starting System . . .................. ................ .......... ..........247Engine Assembly ................................................. .................. ,250

4.OL POWER TECH IN-LINE 6 (INTRODUCTION) 129Note: The following procedures for the 4.0L Power Tech In-Line 6 engine are intended to be performed in-vehicle, on adynamometer or as an individual change/modification. For out-of-vehicle servicing (engine stand generally), disassembly andassembly of the engine as a whole, refer to the ‘Engine Assembly' section of this chapter. For additional 4.0L engine generalservice information, refer to the proper service manual.This chapter has been prepared as a guide for the customerwho wants added performance or reliability from his 4.0LPower Tech In-Line 6 engine. Included are tips coveringseveral different types of racing. The procedures outlinedin this chapter represent those that have been tested byDaimlerChrysler Engineering (working both at the racetrack and on the dynamometer) as part of its continuingperformance development program. This developmentprogram serves as the foundation for the MoparPerformance Parts programIntroductionThe chapter gives specific detail regarding each majorcomponent of the 4.0L engine, as well as detailingrecommended engine assembly and performancemodification procedures. It is recommended that you readthis chapter in its entirety before you begin your sixcylinder engine project. Also, much of the informationincluded in this chapter is generic to all racing engines, sothe owners of other DaimlerChrysler engines areencouraged to read this entire chapter. It is alsorecommended that you obtain the proper service manual foryour engine so that you will have complete serviceinformation on hand when you begin your project. Goodluck-and have fun!

~~ -130 MOPAR PERFORMANCE PARTSBlockINTRODUCTIONThe Jeep 4.0L Power Tech engine is a cast iron, In-Line 6cylinder design. The cylinder block is drilled forminggalleys for both oil and coolant. It has a standard bore andstroke of 98.4 x 87.4 mm (3.88 x 3.44”).The 4.0L has a liquid cooled, forced circulation coolingsystem with a capacity of 11.4L (12 quarts).The cylinders are numbered 1 through 6 from front to rear.The firing order is 1-5-3-6-2-4 (Figure 4-1).The crankshaft rotation is clockwise, when viewed from thefront of the engine. The crankshaft rotates within sevenmain bearings. The camshaft rotates within four bearings.For more information, refer to 4.0L Engine Specifications,‘Engine Assembly’ section of this chapter.~~Flywheel Attaching PackageBolts; required to attach flywheel and clutch to new engineassembly. Includes 6 flywheel bolts, 6 clutch bolts, and apilot bearing.P4529247Flywheel attaching package.Torque Converter Drive PlateThe torque converter drive plate connects the crankshaftto the torque converter and also carries the starter ringgear. For 4.0L engine only. Not SFI approved.P45’29248 Torque converter drive plate.~~Drive Plate Attaching PackageBolts required to attach torque converter drive plate to thecrankshaft and to attach the torque converter to the driveplate. Includes 6 flywheel bolts and 4 torque converter bolts.P4529249Drive plate attaching package.loo @ @ 001FIRING ORDER:1 , 5 3 6 2 4ROTATION-~~Figure 4 - 1Engine Block Hardware PackageJUW-7Includes cam bearings, various freezekore plugs andlocating pins. For use when block is tankedstress relievedand machined. For 1987-89 4.0L engines only.P4529673Engine block hardware package.Build Date CodeThe engine Build Date Code is located on the machinedsurface on the right side of the cylinder block between theNo. 2 and No. 3 cylinders (Figure 4-2).The digits of the code identify:1. 1st digit-the year (e&, 4 = 1994).2. 2nd and 3rd digits-the month (01-12).3. 4th and 5th digits-the engine type/fuelsystem/compression ratio (MX = a 4.0L 8.7:lcompression ratio engine with multi-point fuelinjection system).4.6th and 7th digits-the day of the month of enginebuild (01-31).Example: Code “401MX12” identifies a 4.0L engine witha multi-point fuel injection system, 8.7: 1 compression ratio,built on January 12, 1994.Engine Teardown Gasket SetDesigned for bearing check, bore check, or cylinder headmodificationslteardown only. Gaskets include: cylinderhead, oil pan, intakelexhaust manifold and front covergaskets. For 4.0L engine only.P4529245Engine teardown gasket set.

4.0L POWER TECH IN-LINE 6 (BLOCK) 131Block HardnessIFIRING1 5 3 6 2 4awlsROTATIONFigure 4 - 2Oversize and Undersize Component CodesJ908D-7Some engines may be built with oversize or undersizecomponents such as:Oversize cylinder boresOversize camshaft bearing boresUndersize crankshaft main bearing journalsUndersize connecting rod journalsThese engines are identified by a letter code (Figure 4-3)stamped on a boss between the ignition coil and the distributor.IWith any cast iron block, there is a relationship betweenhardness and strength. The harder it is, the stronger it is. Theassumption is that a stronger block can make more power.However, if the basic design of the block is weak, then itwill break frequently. Standard production blocks are notdesigned as strongly as “race” blocks. So if you double ortriple the power output of a standard production engine withhigh performance parts, you will have problems.We know that hard blocks don’t break and soft ones do.Racers therefore want hard blocks. If you add a strongdesign to a hard material, you will have a race block. Thismeans that the block will last longer and make more powerfor longer periods of time. Chrysler-Plymouth-Dodge-Jeephas always used a high nickel material in its cast ironblocks. This makes them harder.Rough Bored BlocksRough bored blocks have the cylinder bores roughed-in butnot finished-the surface finish on the bore is rough butmachined. That means that each cylinder must bebored-to-size and then honed. The bore-to-size operation isreferred to as the finish bore. As an engine builder, youmust leave enough material on the finish bore operation toallow for the finish hone to size the bore correctly.The advantage of rough bored blocks is you have a greaterselection of bore sizes available to you. Most race enginebuilders DO NOT want a production hone, so why payextra for it if you are going to change the bore size? Byomitting the finish bore and honing operations, the blockcan be purchased for less money.CYLINDER BLOCK PREPARATIONThe first step in preparing the block for all-out racing is tostress-relieve it (typically not required for new race blocksor many used blocks). For more details, refer to Stress-Relieving, in this section.IFigure 4 - 3IAfter the block has been stress-relieved, new camshaftbearings and core plugs should be installed. The old main capbolts should be thrown away. The block should be re-honedand the deck flatness checked. A light cut should be taken ifit is not perfectly flat. The main bearing bores will also haveto be checked and align-bored or align-honed if out ofalignment. New camshaft bearings will also be required.Block-to-Head Distortion(Refer to Head Distortion, ‘Cylinder Head’ section ofthis chapter.)

132 MOPAR PERFORMANCE PARTSStress-RelievingNote: The following is not required for thermally-cycled,used engine blocks, except for align boring and honing,which may be required on any new or used engine.The first step in obtaining straight and round bores is toselect a stress-relieved block. Only 426 Hemi engine blockswere stress-relieved in production. However, a block willstress-relieve itself with use; that is, a used block hasalready been stress-relieved (thermal cycles are the key).Heating up and cooling down is the ideal cycle - again andagain and again, which means that an engine block used inan around-town commuter vehicle is better than a blockused in a long-haul truck or police car, which isinfrequently shut off.Blocks will also stress-relieve themselves in racingapplications. A block can be built into a race engine and runseveral hundred times. It can then be rebuilt into a betterengine because the bores will be straighter and will move lesswith use. The straighter the cylinder bore, the more power theengine will make. Once you’ve got a good one, keep it.Once the engine is disassembled, the first step in preparingthe block is to remove the main bearings caps, clean alljoining faces, reassemble and torque to specifications. Thestress-relieving process consists of heating the block andmain caps to 1050°F and holding at that temperature fortwo hours. It should then be furnace cooled to 500°F at acooling rate not to exceed 200”hr. The block can then beair cooled to normal air temperature.After the block has been stress-relieved by the ‘oven’method (not by thermal cycling), new camshaft bearingsand core plugs should be installed. The old main cap boltsshould be thrown away. The block should be re-honed andthe deck flatness checked and a light cut taken if it is notflat. The main bearing bores will also have to be checkedand align-bored or honed if out of alignment. New camshaftbearings will also be required.Sonic TestingIf the block is to be used in serious racing applications, itshould be “Magna-checked” (sonic tested). With thisprocess, the thickness of the cylinder bore walls can bechecked nondestructively. This will indicate how good yourparticular block is, or it will allow you to select the bestblock of several available, if you have the option. It ishighly recommended that you have more than one blocktested so you don’t invest your time in a weak or “flexiblock.”If you only have one block, the bore-wall thickness checkreally only serves as base information and a generalperformance indicator. Write this measurement down andkeep it in your engine build-up file.However, if you have several blocks to choose from, thebest engine will be the block with the least amount of coreshift (bores with the same thickness all the way around), orthe block with the core shift in the “major thrust” direction.The major thrust direction is to the passenger side of thecylinder bore as the block is installed in the vehicle.Core ShiftIt seems as though every racer you talk to uses the term“core shift.” It’s used so frequently it seems to be the causeof every engine problem in racing! Obviously, this isn’tcorrect. Without making it too complicated, let’s look intothis subject a little closer.First of all, to discuss core shift we must have a casting. Itcan be of any material (aluminum, iron), but it has to be acasting. Second, the casting must have a “core” in it. In anover-simplified explanation, a “core” is used to cast aninternal passage in a casting. This internal passage could bea water jacket in a head or block, or an intake runner in amanifold. Not all castings use cores. Core shift is mostoften discussed relative to cylinder blocks, so we’llconcentrate on them. On any given part, there may be morethan one core. This varies from one manufacturer toanother. Cores are generally made of sand. The sand is heldtogether with a bonding agent.The cylinder block is the largest casting that we make. Themain core in the block is the water jacket. In this case, coreshift would occur if the water jacket core moved relative tothe main tooling. Since the water jacket core is set insidethe main tooling, it is possible for this core to be shifted inposition. In most cases, this shift is caused when the moltenmetal hits the core and moves or offsetsldeflects it.The core could move up or down, fore or aft, but theimportant direction is left or right. Left or right shifts movethe core in the major or minor thrust direction. This makesthe cylinder bore either thick or thin on the major thrustside. Having the core shifted so that the major thrust side issomewhat thicker is superior to being perfectly round.Consequently, having the major thrust side too thin is NOTdesired. To find out if this has occurred, the block must besonic tested.Most of the confusion relating to core shift occurs becauseracers try to find a “quick” way to determine if a block hascore shift without sonic testing! Remember that not all coreshift is bad. Looking at the front or rear of the block will nottell you if the block has core shift because you’re notlooking at the water jacket. The only way to see the waterjacket is too look down the holes in the top of the block.These holes are quite small and don’t allow you to visuallyjudge for core shift.So that brings us back at sonic testing. Sonic testingmeasures the thickness of the cylinder bore in the major andminor thrust directions. Technically speakmg, all the boresshould have the material shifted in the same direction..“

4.OL POWER TECH IN-LINE 6 (BLOCK) 133Surfacing (“Decking”)Perhaps this topic would be more properly labeled“resurfacing” because the block already has a deck surface.Sometimes this operation is called “decking” the block. Ineither case, the top surface of the block, called the deck, ismilled. This operation decreases the block’s height.Why would you “deck” (surface) the block? One possibilityis to increase the compression ratio. Another is to takeweight out of the blocMengine assembly. Most enginebuilders DO NOT feel the production machining to beacceptable in the area of flatness. The engine builder maywant to remove the production tolerance of the decks.Usually a race machine shop will machine the stock deck ofa new block ,020” to ,040”. They will take very light cuts togain the desired specifications. If it is a used engine that hasseen a lot of heat, they may have to increase these numbersto get it flat enough. In decking the block, the machine shopmust be very careful that it does not make the resulting decksurface too smooth or the cylinder head gasket will not seal.Let’s look at an example. The 4.0L engine has a blockheight of 9.45”. A race engine builder may machine 0.020”off the deck surface to gain flatness, which gives a finalblock height of 9.43”. Never make calculations based onaverage numbers like the 9.45“. Or, if you have to, leaveenough stock so that you can get exactly where you want towithout scrapping parts (.040” is preferred). What if thecrank has a stroke that is ,010’ too long, or a connecting rodthat is .OOS”” too long, or a piston that is .0OS” too tall? Itwouldn’t be the block that is wrong, but the block can fixthem all with no problem if we left our engine builder witha .040” cushion.HoningBefore the honing operation is started, the cylinder wallsshould be inspected for cracks or pits and the bores checkedfor taper and roundness. A cylinder bore is most accuratelymeasured using a dial-bore gauge. For the actual honingoperation, approximately .004” (.002” per side of material)should have been left after boring. (The size of the pistonand the piston design are other factors determining the boresize and the piston-to-wall clearance.) The hone used togain the desired surface finish is stipulated by the choice ofpiston rings, but regardless of the actual finish (perfectlysmooth or slightly rough), it should have a 45” crosshatchpattern. (Moly rings, 10-15 micro inches; chrome orstainless steel, 15-25 micro inches. A 30 micro finish isfairly rough and is close to the hone finish on a productionengine. A 5 micro finish is very smooth.) After honing, thebores should be straight (no taper) and round within +.002”.Having a STRAIGHT bore that is ROUND with NOTAPER is THE single most important step in building arace engine that produces good horsepower, high rpm.and/or high specific output.1. Honing PlatesFor a serious all-out race engine, the use of a honingplate is strongly recommended. It should be made of a1 to 1-1/2” thick steel plate. The honing plate is held onby capscrews. The screws should be torqued to thesame specifications as the standard head bolts.Thickness of the honing plate and installation torqueare very important, but of equal importance (and anitem often overlooked) is the depth of threadengagement. Bolts should be turned all the way in andthen backed off one turn for proper thread depth.2. Why u Honing Plute?At the beginning of the race season when you’rerebuilding your tried-and-true race engine or building anew engine for the upcoming season, the block shouldbe honed using a honing plate. This is the only way tomake the bores straight and round with the throttlewide open. If the bores aren’t straight and round atW.O.T. (wide open throttle), the engine won’t makeany horsepower. If you’re building several engines, orplan to do so over the next few years, it will pay to getyour own honing plate. Most people/engine buildersand machine shops don’t have honing plates forChrysler-Plymouth-Dodge-Jeep engines. Honingplates don’t wear out. Cast iron plates are lessexpensive but can break if mishandled or dropped.Billet steel plates are much stronger arid more durable.3. Honing Plate Thread EngagementThe honing plate should be held on to the block withthe same thread length as the head. This sounds easyenough, but how do you get the two to be the same?Since cylinder head distortion is what you’re trying tomatch, the first step starts with the head aftermachining. The head bolts with washers, if they are tobe used with the head on final assembly, are insertedinto the head and the length of bolt protruding out thebottom of the head is measured. We’ll assume that thismeasurement is ,900”. The bolts that are going to beused with the honing plate are inserted into the plate.

134 MOPAR PERFORMANCE PARTSThe amount that sticks out of the bottom of the platehas to be adjusted to .900". If the first pass yielded alength of 1.200", then hardened washers can beinstalled under the bolt head. Hardened washers runaround .100". So, in this example, three hardenedwashers would be used to get the correct length. (Formore information refer to Block-to-Head Distortion,'Cylinder Heads' section of this chapter.)Boring and Milling SpecificationsBecause it is a thin wall casting design, the 4.0L can onlybe over-bored ,030" (maximum), although .020"(maximum) is preferred. Regardless of the amount ofoverbore, if the engine is to be used for high output racingpurposes, the cylinder wall thickness should be checked tobe sure the block doesn't have a bad case of core shift. Thecylinder wall thickness should be the same all the wayaround or thicker on the major thrust side of the cylinderbore; that is, passenger side (as installed in the vehicle).1. When machining cylinder head and deck, be surethey're perfectly flat.2.When milling cylinder head and deck, don't makethem too smooth or you could have gasket sealingproblems. A typical production surface (100 microinches)should be your guide.The milling of the intake manifold gasket surface can bedone on the intake manifold itself instead of the head.Cylinder Bore Measurement1.2.3.4.5.6.It is mandatory to use a dial bore gauge to measureeach cylinder bore diameter (Figure 2-1 1). To correctlyselect the proper size piston, a cylinder bore gaugecapable of reading in 0.003 mm (.0001")INCREMENTS is required. If a bore gauge is notavailable, DO NOT use an inside micrometer.Measure the inside diameter of the cylinder bore atthree levels below top of bore. Start perpendicular(across or at 90 degrees) to the axis of the crankshaftand then take two additional readings.Measure the cylinder bore diameter crosswise to thecylinder block near the top of the bore. Repeat themeasurement near the middle of the bore, then repeatthe measurement near the bottom of the bore.Determine taper by subtracting the smaller diameterfrom the larger diameter.Rotate measuring device 90" and repeat steps above.Determine out-of-roundness by comparing thedifference between each measurement.7. Kf cylinder bore taper docs not exceed 0.025 mm1:0.001") and out-of-roundnesa docs not exceed 0.025mm (0.001"), the cylinder bore can bc honed. If the(cylinder bore taper or out-of-round condition exceedsthese maximum limits, the cylinder must bc bored andthen honed to accept an oversi/e piston. A slightamount of taper always exists in the cylinder bore afterthe engine has been in use for ii period 01 time.CYLINDER BLOCK ASSEMBLYHead BoltsAll cylinder head bolts should be screwed into the blockwithlout the cylinder head. Visually inspect the rows of boltsfor any that may bc bent, or lor bolts with holes drilled atany angle, or for holes that are not drilled deep enough.When the head bolts are screwed in, the dcpth of threadengagement should be checked and recorded.Note: It is recommended that iiew cylinder head bolts andmain cap bolts always be used (ifpossible) when rebuildingan engine.Bottoming TapA bottoming tap 5hould be run down all head and mainbearing bolt holes. The head bolt holes \hould bechamfered slightly to prevent the top thread from pulling upwhen the head bolt\ are torqued.Main Bearing BoresMain bearing bores must he checked for hoth specifieddiameter and alignment with each other. If either is off, analign-boring machine should be used to align-bore theblock. A crankshaft-turning tight spot indicates bores areout of alignment.."-r -17

4.0L POWER TECH IN-LINE 6 (BLOCK) 135Deck HeightOnce the main bearing bores are known to be in alignment,the deck surface of the block should be checked to make sureit is parallel with the axis of the crankshaft. The distancefrom the centerline of the crankshaft to the deck surface ofthe block should be exactly the same at the front and rear. Ifnot, the deck surface will have to be milled. At this time thedeck height can be machined to the proper dimension.Note: Deck heights that are above the block surface will beincreased by milling the block. Check the engine’sblueprint specifications before milling. The resultingmachined surface of the deck must be on the rough side toproduce a good gasket seal and prevent the head gasketfrom moving.Notching the Cylinder Bore for Connecting RodClearanceIf you are attempting to install a crankshaft from a 4.2Lengine into a 4.0L engine, you may have to notch thebottom of the cylinder bores (as required) to obtain .100“clearance (Figure 4-4).There are many variables associated with this popularmodification (too numerous to go into detail here). Formore information, call the Mopar Performance PartsTechnical Assistance Hotline at 1-248-969- 1690, or faxthem at 1-248-969-3342. They’ll be glad to help you.Rod Notch at Bottom of Cylinder BoreDowel PinsEnsure that all dowel pins used for aligning purposes arethe proper height (not too high), and that the dowel pinslocate the head properly so that combustion chambers areproperly centered over cylinder bores. Check to be sure thatthe dowel pins don’t hold the head up off the block.Note: Check without a head gasket.Rear Main Bearing Oil SealThe rear main bearing oil seal machined groove should beroughed slightly with a center punch and the rope seal mustbe seated all the way in. The rubber rear main seal shouldbe held in place with Permatex (RTV) behind the seal.Camshaft BearingsvNotchCylinder Bore Notch forBig Rods or Long Strokes-TOP of BlockWhen installing camshaft bearings, make sure that the oilholes in the bearings line up with the oil holes in the block.DO NOT replace the camshaft bearings unless they are bador the block has been tank cleaned in acid.DeburringROat -$)EYf Bottom of Cylinder BoreUse a small, fine file to remove burrs and break all sharpedges in the main bearing bores and around the cylinderbore chamfers, as well as other sharp edges on the block.Tappet BoresThe tappet bores may be shined with #400 paper to removeany rough spots or burrs. A brake cylinder hone may alsobe used with care. Tappet bore clearance is very important.If it is too tight, the lifters will stick. Use .0015” for flattappets and over ,001 5” to .003” for rollers. High clearancecan cause low oil pressure if the tappet bores are “wet.”If a big, flat-tappet camshaft that requires .100” oversizemushroom lifters is going to be used, the bottom of thelifter bore should be spot-faced to a slightly larger diameterthan the diameter of the mushroom lifter bottom. A backspot-facing tool is required to do this.CC’ing the BlockFigure 4 - 4For complete information, refer to Measuring 1/2” DownFill Volume, ‘Pistons and Rings’ section of this chapter.ADDITIONAL CYLINDER BLOCK PREPARATIONAND ASSEMBLY TIPSBuilding a high performance engine requires a lot ofmachining and assembly. Getting the bores straight, round,and with no taper is very important to making horsepower.However, there are several little items that are oftenoverlooked in engine building until it’s too late.

l- -1‘1136 MOPAR PERFORMANCE PARTSFirst, we strongly recommend that the engine builder readcompletely this chapter before any engine work is started.Before the engine is assembled, all the basic parts (block,crankshaft, head, etc.) should be cleaned, and then cleanedagain! The bearing clearances should be checked withPlastigauge (P42868 19) or micrometers (inside and outside).Before reassembling, gather all the chemical productslikely to be needed such as RTV, Loctite, etc. If any partsare to be stored after they are machined and/or cleaned,they should be sprayed with a rust preventive, wrapped innewspaper and covered with plastic bags.When the camshaft and lifters are installed, a camshaftbreak-in oil should be used on the camshaft lobes andjournals and the outside of the lifters. The camshaft breakinoil should come with the camshaft kit. If you needcamshaft break-in oil, order Lubrizol.Before totally disassembling the block, check the deckheight of the pistons. Deck height is the distance from thetop of the piston to the top of the deck surface of the block.This is an important dimension since it has a direct influenceon compression ratio. If the piston is a flat-top type, it willusually be below the deck and this is the distance that mustbe measured. A domed piston will stick up above the decksurface and the distance is measured from the deck to theflat of the piston, not the top of the dome. Mark this figuredown for future reference and completely disassemble theblock. On a new block, wait until the block is bored to sizebefore measuring the deck height.When all machine operations are complete, the blockshould be thoroughly washed out with solvent. Use bottlebrushes of suitable size to clean out all bolt holes, oilpassages, etc. Finish off with another thorough washing,using a good, common detergent and warm water. Blow orwipe dry and oil to prevent rust. Engine parts can’t be tooclean. Many early engine failures can be traced to dirt orforeign objects (metal chips, etc.) that were left in theengine when it was reassembled.MAIN CAPSHardened Washer SetsFor use with head bolts and main cap bolts.P4 120456P4 120457P4 1204S8Comprised of: (20) - 3/8” washers.Comprised of (20) - 711 6” washersComprised of: (20) - 1/2” washers.Let’s assume your main caps are O.K. and you have themall. We’ll also assume that you are building a race or highoutput engine. The problem with main caps is that they aretoo simple. If they look like the right caps and we haveenough, then we’ll probably use them even if they aren’tfrorn this particular block. We have already stepped overthe line in this last sentence. We’ll explain shortly.You1 may be asking, “If my caps aren’t broken and I haveenough, why should I change?‘’ or, “Why should I install newcaps?’ These two questions are not the same! First, rememberthat if the main caps are changed, then the block MUST bealign-bored. Always! If you are building a race engine, youalso MUST align-bore the engine. (The only exception is ifthe engine was align-bored on its last rebuild, then it shouldbe alright.) Remember our “over-the-line” sentence regardingusing caps that weren’t from our particular block? In this casewe must also align-bore the block.Remember that a weak cap doesn’t necessarily fail itself.An engine failure will more likely occur with the bearings,crankshaft, bolts, or even the bulkhead. A cap failure wouldonly occur in the most extreme cases. But it does occur.You’d like to find it when you are routinely checking thebearings, but you don’t always get that lucky!Note: It is recommended that new main cap bolts alwaysbe used (if possible) when rebuilding an engine.FREEZE PLUGSEvery block used in production uses freeze plugs. They arepressed into the sides and ends of the block. If they do theirjob correctly, you will probably never know they are there.If they fail, things can go wrong very quickly.If you are building a race engine, it is highly recommendedthat the block be thoroughly cleaned before you start. Toclean a block thoroughly, you need to remove the freezeplugs. If you have the block hot-tanked, then the freezeplugs MUST be replaced because they have lost their“press” and will fall out as soon as there is any pressure inth8e water jacket.Freeze plugs can’t be re-used, so once you take them out,you need a new set.We all know an engine must have a set of main caps tofunction. If you have a used engine block, it probably hasits own main caps, but some blocks may have broken or lostcaps. Main caps should be replaced in sets. Most usedengine blocks should have the mains align bored before theengine is assembled into a “race” engine.

~~INTRODUCTIONThe 4.0L engine uses a cast nodular iron crankshaft thatrotates within seven (7) main bearings and has a standardbore and stroke of 98.4 x 87.4 mm (3.88 x 3.44”).Crankshaft rotation is clockwise, when viewed from thefront of the engine.The crankshaft is a cross-shaped four throw design witheight counterweights for balancing purposes. Thecrankshaft is supported by seven select main bearings withNo. 3 serving as the thrust washer location. The mainjournals of the crankshaft are cross drilled to improve rodbearing lubrication. The select fit main bearing markingsare located on the crankshaft counter weights. Thecrankshaft rear oil seal is a two piece design. The front oilseal is one piece design retained in the timing chain cover.The crankshaft has a main bearing journal diameter of63.489-63.502 mm (2.4996-2.5001”), and main bearingjournal widths of (No. 1) 27.58-27.89 mm (1.086-1.098”),(No. 3) 32.28-32.33 mm (1.271-1.273”), and (Nos. 2,4, 5,6 and 7) 30.02-30.18 mm (1.182-1.188”).The crankshaft has a connecting rod journal diameter of53.17-53.23 mm (2.0934-2.0955“) and a connecting rodjournal width of 27.18-27.33 mm (1.070-1.076”).For high performance racing engines, Mopar PerformanceParts recommends a forged crankshaft. Forged crankshaftsallow you to specify to your grinder exactly what stroke youwant, and cost less to have finished than billet crankshafts.And for those of you who want an oversize bore engine, acustom ground forged crankshaft is the way to go.For more crankshaft specifications, refer to 4. OL EngineSpecz$cations, ‘Engine Assembly’ section of this chapter.~~ ~High Performance CrankshaftThis Mopar Performance Parts high performancecrankshaft has a 3.41“ stroke and has been carefullyinspected and Magna-fluxed. 4.0L engine only.P4529205High performance crankshaft.Balanced and Unbalanced CrankshaftsWhen describing crankshafts, we use words such as“balanced” and “unbalanced.” However, what is physicallydifferent about the crankshafts is not as obvious as thewords may imply.Since the unbalanced crankshaft is easier to understand,we’ll start with that one. Unbalanced crankshafts haveSOLID journals. That means there are no holes through thefirst and last crankshaft journals. Racers like this becausethey can offset grind the crankshafts if desired. Other racersC ran ks haf t4.0L POWER TECH IN-LINE 6 (CRANKSHAFT) 137who use superchargers and/or alcohol fuel like solidjournals because they see them as being stronger (becausethere are no holes in them). These are called “unbalanced’or “solid journal” crankshafts.To spin-balance a typical crankshaft that has solid journals,you have to add Mallory metal. This can be expensive.Therefore, production crankshafts have a machined holethrough the first and last journals. These are balance holes.Racers call them “balanced’ crankshafts, so we call thembalanced crankshafts. The name ONLY refers to the large1-1/16” hole (approximately) through the first and lastjournal. The crankshaft should still be balanced with itsspecific connecting rods and pistons like any other raceengine crankshaft. However, the big holes usually eliminateor cut down the use of Mallory metal.Crank BoltThe crank bolt is often used to turn the engine over by hand,but this is only a convenience item. Its real function is tohold the vibration damper on. That is why it is put on withso much torque. If the interference fit on the damper hub isnot there and the crank bolt is not torqued, the damper can’tdo its job. This will cause the crank to eventually fail.To hold the damper on properly there is a special large, hardwasher that is used. We have included this special washerin our damper attachment package (P4529677).BASIC PREPARATIONWhen preparing a crankshaft for racing applications, thefollowing steps should be performed:1. Crankshaft bearing journals should be checked forspecified diameter and clearance. If it is a hardenedcrankshaft, it shouldn’t be ground for clearance. Thesecrankshafts are hard only to a depth of .0003”. The mainbearing clearances should be 0.03-0.06 mm (0.001-0.0025I’). The best way to measure crankshaft journalsis with a micrometer. To measure main bearingclearances, the bearings can be installed, the boltstorqued to specification, and the inside diameter of thebearing measured 90 degrees to the parting line with aninside micrometer or snap-gauge. The differencebetween these two measurements is the bearingclearance. Plastigauge is accurate enough for most raceapplications (P4286819 - includes all 3 sizes).2. The bearing journals may be polished by hand, firstwith #400 and then with #600 paper. Any nicks, burrsor scratches should be polished out. Chamfer oil holesin journals and use a wet stone to break edges. Checkthe oil passages to each journal.l- -11

138 MOPAR PERFORMANCE PARTS3.4.5.6.7.8.9.Caution: With the nodular cast iron crankshafts usedit is important that the final paper or cloth polish afterany journal regrind be in the same direction as normalrotation in the engine.Crank alignment may be checked by installing theupper bearing shells in the block (at each end of thecrank only) as well as the main caps (at each end of thecrank only).Before assembly, make sure crankshaft, includinginternal oil passages, is clean. Also be sure all oilingpassages are drilled through!When assembling the crankshaft into the block, oil thebearings and journals.When installing the crankshaft, locate the main capscarefully so that the crankshaft spins freely, and torqueall caps to specifications. Then spin the crankshaft byhand through several revolutions before installing therear main seal. It should be fairly free, requiring verylittle effort. Remove the caps and check for any burrs.If present, they can be removed by gently scraping witha bearing knife. When installing the rear main seal,make sure it is properly seated; improper seating cancause the crankshaft to bind.For better race engine oiling with a high capacity oilpump, 360" main bearing oiling is desired. 360" fullygrooved main bearing sets should be used. It is NOTrecommended that the crankshaft itself be groovedbecause grooves weaken the crankshaft.A degreed damper is a must for racers since they mustset their timing by total degrees advanced at a fairlyhigh rpm (for example, 35" total at 2,500 rpm). Adegreed damper is the easiest, most accurate, and mostconvenient tool for doing this. It also aids in setting thevalve lash by giving 90" reference marks.Note: Damper degree timing tape is P4529070.There are several additional items that should bechecked during your build-up that will be helpful later:a. Measure the actual stroke of the crankshaft. Wesuggest that the extra time be invested and thattwo cylinders per crankshaft throw be measured.All measurements should be written in yourengine building notes.b.c.d.Measure the deck height using a representativeconnecting rod and piston along with the actualcrankshaft to be used. Be sure to oil the bearingsin this step.Check the crankshaft end play.Check the connecting rod side clearance on eachjournal. Refer to 'Connecting Rods' section of thischapter for instructions. Always clean all partsused before proceeding to the next step.10. Care must be exercised when tightening the bearingcaps. When the cap bolts have been torqued to 80 ft-Ibs, check to make sure that the oil pump can beinserted without binding on a main bolt hex head. If itbinds, tighten the main cap bolt just enough more (nomore than 116 turn) so the oil pump will clear the boltwith no binding.SPECIAL CRANKSHAFT PROCEDURESMeasuring Main Bearing ClearancesThere are two methods that can be used to measurecrankshaft main bearing clearances: the Plastigauge methodand the Direct Measurement method.1. Plastigauge MethodWhen using Plastigauge (P42868 19), check only onebearing clearance at a time.a. Install the grooved main bearings into the cylinderblock and the non-grooved bearings into thebearing caps.b. Install the crankshaft into the upper bearings dry.Place a strip of Plastigauge across the full width ofthe crankshaft journal to be checked.c. Install the bearing cap and tighten the bolts to 108Nom (80 ft-lbs) torque.DO NOT rotate the crankshaft. This will cause thePlastigauge to shift, resulting in an inaccuratereading. Plastigauge must not be permitted tocrumble. If it is brittle, obtain fresh stock.d. Remove the bearing cap. Determine the amount ofclearance by measuring the width of thecompressed Plastigauge with the scale on thePlastigauge envelope (Figure 2- 16). The correctclearance is 0.03 to 0.06 mm (.0010 to .0025") forall main bearing journals, with 0.05 1 mm (0.002")preferred.Plastigauge should indicate the same clearanceacross the entire width of the insert. If clearancevaries, it may indicate a tapered journal or foreignmaterial trapped behind the insert.e. If the specified clearance is indicated and there areno abnormal wear patterns, replacement of thebearing inserts is not necessary. Remove thePlastigauge from the crankshaft journal andbearing insert. Proceed to Main BearingInstallation, in this section.f. If the clearance exceeds specification, install apair of 0.025 mm (0.001") undersize bearinginserts and measure the clearance as described inthe previous steps...T -7r7

4.0L POWER TECH IN-LINE 6 (CRANKSHAFT) 139The clearance indicated with the 0.025 mm(0.001 ") undersize insert pair installed willdetermine if this insert size or some othercombination will provide the specified clearance.Example: If the clearance was 0.0762 mm (0.003")originally, a pair of 0.0254 mm (0.001") undersizeinserts would reduce the clearance by 0.0254 mm(0.001"). The clearance would then be 0.0508 mm(0.002") and within the specification. A 0.0508 mm(0.002") undersize bearing insert and a 0.0254 mm(0.001'I) undersize insert would reduce the originalclearance an additional 0.0127 mm (0.0005") and theclearance would then be 0.0381 mm (0.0015").Caution: Never use a pair of inserts that differ morethan one bearing size as a pair. For example, DO NOTuse a standard size upper insert and a 0.051 mm(0.002") undersize lower insert.If the clearance exceeds the specifications using a pairof 0.05 1 mm (0.002") undersize bearing inserts,measure the crankshaft journal diameter with amicrometer. If the journal diameter is correct, thecrankshaft bore in the cylinder block may bemisaligned, which requires cylinder block replacementor machining to true bore.If the diameters for journals 1 through 6 are less than63.45 17 mm (2.4981"), orjournal 7 is less than 63.4365mm (2.4975"), replace the crankshaft or grind it downto accept the appropriate undersize bearing inserts.Once the proper clearances have been obtained,remove the crankshaft and proceed to Main BearingInstallation, in this section.PlastigaugeWhen reassembling your engine you'll need a variety ofPlastigauge to measure bearing clearances. This popularassortment includes one blue strip for .004" - ,009"tolerances, two red strips for .002" - .006" tolerances, andtwo green strips for .001" - .003" tolerances. Each strip is12" long.P42868 19Plastigauge assortment.2. Direct Measurement MethodThe most accurate way of measuring crankshaft mainbearing clearances is directly.a.b.c.Clean the main bearing journal of oil.Determine the maximum diameter of the journalwith a micrometer. Measure at two locations 90"apart at each end of the journal.Compare the measured diameter with the journaldiameter specification listed in the Main BearingFitting Chart (Figure 4-9), and select inserts requiredto obtain the specified bearing-to-journal clearance.Top Dead Center (TDC)One of the most important basics in engine building isbeing able to find Top Dead Center (TDC). To do this, youneed a dial indicator and a bridge, which is a U-shapedbracket that will hold the dial indicator perpendicular to thepiston top. The indicator should be placed over the flat partof the piston.1. Finding TDCPlace the dial indicator (minimum 1/4" travel) ontop of the piston and rotate the piston to itsmaximum upward travel. This is TDC. On someengines this may be done without removing thehead by inserting the indicator through the sparkplug hole. Be sure the indicator is rigidly mounted.Affix a 360" protractor (or degree wheelP4452990) on the crankshaft with a pointer. Placethe pointer as close to "0" (TDC) as you can bywatching the indicator.Note: The Mopar Performance Parts 0-180-0degree wheel is easy to read because 100+ degreesread directly.Rotate the crankshaft (clockwise when facing thefront of the engine) until the dial indicator readsexactly .030" before TDC. Stop. Take readingfrom the degree wheel. Write it down. Reverserotation (counterclockwise) until the piston comesup again and the dial indicator reads .030" exactly.Stop. Take reading from the degree wheel. Thisreading should be the same number of degreesfrom "0' (TDC) as the first reading, only on theother side of "0". If it is not, move the pointer halfthe difference in degree readings in the directionof the minimum degree reading.Note 1: The .030" selected was for explanationpurposes only. Any measurement of .015" orgreater is acceptable.Note 2: The reason for reversing direction toobtain the second degree reading is to take out anyclearance in the connecting rod bearing and pin.Example: With the degree wheel, pointer, and dialindicator in position, rotate the crankshaft (clockwise)until .025" is read on the indicator. (If you go past, juststart again. DO NOT back up-go all the way around.)The degree wheel reads 8". Reverse rotation(counterclockwise) until the indicator reads .025"again. The degree wheel reads 350" (or 10" dependingon the degree wheel). Move the pointer on the degreewheel 1" to read 351". Repeat the procedure. At .025"the degree wheel should now read 9" and 351". Nowthe pointer is reading 0" at TDC exactly.

140 MOPAR PERFORMANCE PARTS~~TDC Indicator ToolThis is a handy, positive-stop tool for determining exacttop dead center (TDC) when centerlining camshafts. Thistool, made of hardened steel, is extremely accurate andcan be used on all DaimlerChrysler six cylinder engines. Ittakes the guesswork out of finding TDC.P4349737Degree WheelTDC indicator tool.Durable Mopar Performance Parts aluminum plate 0”-180”-0” degree wheel for centerlining camshafts. Featuresstep-by-step installation instructions printed on back side.P44529902. Timing MarkDegree wheel.Note: This procedure requires the timing chain casecover be bolted to the partially-assembled short block.The timing mark is composed of two lines or marks, oneon the crankshaft damper and the other on a tab on thetiming chain cover, that indicate TDC. Once you havelocated TDC with the dial indicator, this true positionshould be checked against the indicated timing mark.Any deviation from the true TDC mark should be notedand the correction made permanently on the crankshaftdamper. The new mark should be very visible. An errorin basic timing of only 2“ can be very costly in terms ofperformance and/or engine damage. A 2” error in timingcan result in a pre-ignition failure or light to heavycompression ring scuffing which results in increasedblow-by and lower horsepower output.Mallory MetalMallory metal is typically used in race engines to balancecrankshafts (refer to Figure 4-5). Many machine shops don’tlike to use it because it makes the balancing process somewhatmore complicated. However, as a racer, it’s important to knowwhat Mallory metal is and what it’s used for.Mallory metal is heavier than lead, which makes it muchheavier than steel or cast iron. It can be welded to steel. Itcan be machined similar to steel. Although lead is somewhatsoft, Mallory metal is hard. These characteristics make itmuch like very “heavy” steel. Although not chemicallycorrect, this is an adequate “simple” description.Now the question becomes, “Why do we want heavysteel?” Since we are racing, “heavy” doesn’t sound likesomething we would want to use other than for ballast. Onthe surface this is true. Looking at the general descriptionof heavy metal, we might guess that we could use it to addweight to something in the same sense that we ballast thevehicle for better weight distribution. If this was yourguess, you’d be pretty close. Mallory metal is used to addweight to the crankshaft.The next question becomes, “Why would we want to addweight to a racing crankshaft?’ First, this is related to the factthat we typically race modified production engines. Mostproduction engines since the early 1970s have used a cast ironcrankshaft. Many of these cast iron crankshafts are externallybalanced. The reason that these assemblies are externallybalanced is that cast iron is slightly lighter than steel. Sincethe piston and connecting rod stay the same in any givenengine assembly, any loss of weight from the crank’scounterweights can cause the engine to be unbalanced. To fixthis, production engineers add offset weights to the vibrationdarnper and torque converter (or flywheel), making the engineexternally balanced. In this case, “external” indicates outsideof the short block assembly.Having offset-weighted vibration dampers and torqueconverters (or flywheels) can be a problem in racing.Vibration dampers may have to be SFI approved for theclass that you run. Torque converters are a commonlychanged performance part. Flywheels can offer uniqueproblems. Balancing the engine internally solves all ofthese problems. To accomplish this, we must add weight tothe crankshaft in selected areas. Since the crankshaft ismade of cast iron, the material we add must be heavier thancast iron-Mallory metal.In NHRA and IHRA Stock and Super Stock classes,balancing is legal. It clearly states so in the rule book.NHRA technical people consider Mallory metal a 100%legal part of balancing. We (DaimlerChrysler/MoparPerformance Parts) have been doing this for many years.Adding Mallory metal to the crankshaft sounds like we aregoing to increase its weight and inertia. Actually, the totalweight stays the same. The weight that is added to thecrankshaft is removed from the torque converter. If theproblem was the damper (having to use an SFI approveddamper), then the weight added would come off thedamper. Total weight would remain basically the same.Crankshafts are balanced dynamically, or by spinning. Thismeans that a balanced crankshaft has the same inertia(assuming we kept the same pistons, connecting rods, etc.).Actually, because Mallory metal is heavier than steel or castiron and you add it near the outside diameter of the crankshaftwhere it has the maximum effect, the balanced assembly maybe slightly lighter (in weight - at the same inertia).To take this one step further, let’s look at actually lighteningthe crankshaft. One of the methods is called “knife-edging”the crankshaft. Generally, this process is NOT legal inStock or Super Stock classes. It is legal inModified/Competition classes, but read the rule book firstfor any given class. Knife-edging removes a lot of weightfrom the crankshaft; however, you can quite easily makethe crankshaft too light. Mallory metal will again balancethis knife-edged crankshaft. However, if found in a Stock orSuper Stock engine, it will be illegal. The Mallory metalisn’t illegal, the knife-edging is!

4.0L POWER TECH IN-LINE 6 (CRANKSHAFT) 141MAIN BEARINGSStreet Performance BearingsThese production style main bearings are made from AL6aluminum. Package includes complete engine set.Standard size. For 4.0L engine only.P4529207Street performance bearings.Figure 4 - 5Tuff-Triding and NitridingTufS-triding is a crankshaft surface treatment. It is apatented process that can only be done under license. It isalso an older process which is not as popular with racerstoday as it once was. The popular surface hardening processtoday is generically called nitriding. There are severalversions of it. While many people think that nitriding turnsa crankshaft black, it may actually be gray. Therefore, coloris not a good means of process identification. (Other typesof metal treatments can result in similar colors.)4.2L Engine Crankshaft InstallationIf you are attempting to install a crankshaft from a 4.2Lengine into a 4.0L engine, you may have to notch thebottom of the cylinder bores (as required) to obtain .loo"clearance (Figure 4-4).There are many variables associated with this popularmodification (too numerous to go into detail here). Formore information, call the Mopar Performance PartsTechnical Assistance Hotline at 1-248-969- 1690, or faxthem at 1-248-969-3342. They'll be glad to help you.MAIN JOURNALSCrankshaft main journals should be checked for excessivewear, taper and scoring. Limits of taper or out-of-round onany crankshaft journal should be held to 0.013 mm(0.0005"). Journal grinding should not exceed 0.305 mm(0,012") under the standard journal diameter. DO NOTgrind thrust faces of No. 3 main bearing journal. DO NOTnick crankshaft pin or bearing fillets. After grinding,remove rough edges from crankshaft oil holes and clean outall oil passages.Caution: With nodular cast iron crankshafts it is importantthat the final paper or cloth polish after any journal regrindbe in the same direction as normal rotation in the engine.Main Bearing MaterialBasically, there are three types of material used in mainbearings: Babbit, aluminum and Tri-Metal. Babbit isconsidered a soft bearing material, while Tri-Metal isconsidered hard.For all-out drag racing use, Babbit bearings arerecommended. Babbit bearings should be checked regularly.Maximum duty aluminum bearings are advisable formedium duty racing applications, and are actually preferredby some engine builders.For constant high load, high rpm use such as in oval trackracing, hard bearings made of F-77 Tri-Metal material arerecommended. If Tri-Metal bearings are used with a castcrankshaft, they should be checked frequently and replacedregularly, even though they are hard, high load hearings.High load, high rpm engines require maintenance.Pushing the bearing replacement cycle too far, or ignoringit, will usually cause an expensive failure. The costdoesn't justify the gamble.Removal1.2. Remove the spark plugs.3. Raise the vehicle.4.Disconnect the battery negative cable.Remove the oil pan and oil pump as outlined in the'Oiling System' section of this chapter.5. If equipped, remove the main bearing cap brace(Figure 4-6).6.7.8.Remove one main bearing cap and lower insert.Remove the lower insert from the bearing cap.Remove the upper insert by loosening (DO NOTremove) all of the other bearing caps and inserting asmall cotter pin tool in the crankshaft journal oil hole.Bend the cotter pin as illustrated to fabricate the tool(Figure 2-13). With the cotter pin tool in place, rotatethe crankshaft so that the upper bearing insert willrotate in the direction of its locking tab.Note: Because there is no hole in the No. 3 mainjournal, use a tongue depressor or similar soft-facedtool to remove the bearing insert. After moving the

142 MOPAR PERFORMANCE PARTS9.I1insert approximately 25 mm (l"), remove it byapplying pressure under the tab.Using the same procedure just described, remove theremaining bearing inserts (one at a time) for inspection.BLOCKMAIN BEA~NG CAP BRACFInspectionFigure 4 - 61. Wipe inserts clean and inspect for abnormal wearpatterns and for metal or other foreign materialimbedded in the lining. Normal main bearing insertwear patterns are shown in Figure 2-14.2.3.4.Note: If any of the crankshaft journals are scored,remove the engine for crankshaft repair.Inspect the back of the inserts for fractures, scrapings,or irregular wear patterns.FittingInspect the upper insert locking tabs for damage.Replace all damaged or worn bearing inserts.(Refer to the Main Bearing Fitting Chart [Figure 4-91.)The main bearing caps, numbered (front to rear) from 1through 7 have an arrow to indicate the forward position.The upper main bearing inserts are grooved to provide oilchannels while the lower inserts are smooth. Crankshaftend play is controlled by the thrust bearing which is flangedand installed at the No. 3 main bearing position.Each bearing insert pair is selectively fit to its respectivejournal to obtain the specified operating clearance. Inproduction, the select fit is obtained by using various sized,color-coded bearing insert pairs as listed in the MainBearing Fitting Chart (Figure 4-9). The bearing color codeappears on the edge of the insert. The size is not stamped onbearing inserts used for engine production.The main bearing journal size (diameter) is identified inproduction by a color-coded paint mark (Figure 4-7) on theadjacent cheek toward the flanged (rear) end of thecrankshaft, except for the rear main journal. The paint markthat identifies the rear main journal diameter is on thecrankshaft rear flange.Refer to Main Bearing Fitting Chart (Figure 4-9) to selectthe proper bearing inserts to obtain the specified bearingclearance. Refer to 4.0L Engine Specifications, 'EngineAssembly' section, for the correct main bearing clearances.When required, upper and lower bearing inserts of differentsizes may be used as a pair. A standard size insert issometimes used in combination with a 0.025 mm (0.001")undersize insert to reduce the clearance by 0.013 mm(0.0005"). Never use a pair of bearing inserts with greaterthan a 0.025 mm (0.001") difference in size (Figure 4-8).Note: When replacing inserts, install the odd size insertseither all on the top (in cylinder block) or all on the bottom(in main bearing cap).*"&%$$y7&g-Q--uJInsertUpperlowerNO.1 WNNECTlNOROD JOURNAL WEPAINT MIRKCorrectStandardFigure 4 - 70.025 mm (0.001 in.)UndersizeIncorrectStandardNo.7 MAIN JOURNUSIZEPAlNTWRK\- y wNO.6 CONNECTINGRODJOURNALSIZEPNNTWRK -n0.051 mm (0.002 in.)UndersizeI I I I191 09-179InstallationFigure 4 - 8I. Lubricate the bearing surface of each insert withengine oil.2.13..I..Loosen all the main bearing caps. Install the mainbearing upper inserts.Install the lower bearing inserts into the main bearing caps.Install the main bearing caps and lower inserts.Note: Rotate the crankshaft after tightening each mainbearing cap to ensure the crankshaft rotates freely.

~~T -'I 14.0L POWER TECH IN-LINE 6 (CRANKSHAFT) 1435.6.7.8.9.Tighten the bolts of caps 1, 2, 4, 5, 6, and 7 to 54 Nom(40 ft-lbs) torque, then tighten to 95 Nom (70 ft-lbs)torque. Finally, tighten the bolts to 108 N*m (80 ft-lbs)torque.Push the crankshaft forward and backward. Load thecrankshaft front or rear and tighten No. 3 cap bolts to54 Nom (40 ft-lbs) torque, then tighten to 95 Nom (70ft-lbs) torque. Finally, tighten the bolts to 108 Nom (80ft-lbs) torque.Check the crankshaft end play. Refer to CrunkshuftEnd Pluy, later in this section.If the crankshaft was removed, install the crankshaftinto the cylinder block.If equipped, install the main bearing cap brace andtighten the nuts to 47 Nom (36 ft-lbs) torque.10.11.12.Install the oil pump assembly and tighten the attachingbolts to 23 Nom (17 ft-lbs) torque.Install the oil pan with replacement gaskets and seals.Refer to the proper service manual for the procedure.Tighten the drain plug securely.13. Lower the vehicle.14. Install the spark plugs. Tighten the plugs to 37 Nom(27 ft-lbs) torque.1s. Fill the oil pan with engine oil to the full mark on thedipstick level.16. Connect the battery negative cable.

~~144 MOPAR PERFORMANCE PARTSMain Bearing Fitting Chart-Crankshaft Journals #l- #6Corresponding Crankshaft Bearing InsertColor CodeDiameterUpper Insert Sizelower lnsert SizeYellow63.5025-63.4898 mm(2.5001-2.4996 in )Yellow - StandardYellow - StandardOrange63.4898-63.6771 mm(2.4996-2.4991 in.)0.0127 mm (0.0005 in.)UndersizeBlue - Undersize0.025 mm (0.001 in.)Yellow - StandardBlue63.4771-63.4644 mm(2.4991-2.4986 in.)0.0254 mm (0.001 in.)UndersizeBlue - Undersize0.025 mm (0.001 in.)Blue - Undersize0.025 mm (0.001 in.)IIGreen63.4644-43.45 17 mm(2.4986-2.498 1 in.)0.0381 mm (0.0015 in.)UndersizeBlue - Undersize0.025 mm (0.001 in.)Green - Undersize0.051 mm (0.002 in.)Red63.2485-63.2358 mm(2.4901 -2.4896 in.)0.254 mm (0.010 in.)UndersizeRed - Undersize0.254 mm (0.010 in.]Red - Undersize0.254 mm (0.010 in.]Color CodeDiameterUpper Insert Sizelower Insert SizeYellow63.4873-63.4746 mm(2.4995-2.4990 in .)Yellow - StandardYellow - StandardOrange63.4706-63.4619 mm(2.6990-2.4985 in.)0.0127 mm (0.0005 in.)UndersizeBlue - Undersize0.025 mm (0.001 in.)Yellow - Standord11 II1I63.4619-63.4492 mm(2.4985-2.4980 in .)0.0254 mm (0.001 in.)UndersizeLBlue - Undersize0.025 mm (0.001 in.)IBlue - Undersize0.025 mm (0.001 in.)Green63.4492-63.4365 mm(2.4980-2.4975 in.)0.0381 mm (0.0015 in.)UndersizeBlue - Undersize0.025 mm (0.001 in.)Green - Undersize0.051 mm (0.002 in.)63.2333-63.2206 mm(2.4895-2.4890 in.)0.254 mm (0.010 in.)UndersizeRed - Undersize0.254 mm (0.010 in.)Red - Undersize0.254 mm (0.010 in.)J9409-29Figure 4 - 9

4.0L POWER TECH IN-LINE 6 (CRANKSHAFT) 145Crankshaft End PlayRefer to Figure 2- 18.1. Attach a magnetic base dial indicator to the cylinderblock at either the front or rear of the engine.2. Position the dial indicator rod so that it is parallel to thecenterline of the crankshaft.3. Pry the crankshaft forward; position the dial indicatorto zero.4. Pry the crankshaft forward and backward. Note the dialindicator readings. End play is the difference betweenthe high and low measurements. Correct end play is0.038-0.16.5 mm (0.0015-0.0065”). The desiredspecifications are 0.05 1-0.064 mm (0.002-0.0025”).5. If end play is not within specification, inspect crankshaftthrust faces for wear. If no wear is apparent, replace thethrust bearing and measure end play. If end play is stillnot within specification, replace the Crankshaft.REAR MAIN OIL SEALThe crankshaft rear main bearing oil seal consists of twohalf pieces of neoprene with a single lip that effectively sealsthe rear of the crankshaft (Figure 4-10). Replace the upperand lower seal halves as a unit to ensure leak-free operation.7. Coat the outer curved surface of the lower seal withsoap and the lip of the seal with engine oil.8.9.Position the lower seal into the bearing cap recess andseat it firmly.Coat both chamfered edges of the rear main bearingcap with Mopar Gasket-in-a-Tube, or equivalent.Caution: DO NOT apply sealant to the cylinder blockmating surfaces of the rear main bearing cap becausethe bearing-to-journal clearance would be altered.10. Install the rear main bearing cap.11. Torque all main bearing bolts to 108 Nom (80 ft-lbs).IREAR MAIN BEARING SEALv 7’BEARINGRemovalTo replace the rear main oil seal, the transmission must beremoved. Refer to the service manual for the procedure.1. Remove the flywheel or torque converter drive plate.2. Remove the oil pan. Refer to the proper service manualfor the procedure.3. Remove the rear main bearing cap (No. 7).4. Push the upper seal out of the groove. Ensure that thecrankshaft is not damaged.5. Remove the lower half of the seal from the bearing cap.InstallationI.2.3.4.5.6.Wipe the seal surface area of the crankshaft until clean.Apply a thin coat of engine oil.Coat the lip of the seal with engine oil.Position the upper seal into the groove in the cylinderblock. The lip of the seal faces toward the front of theengine.Place the lower half of the seal into the bearing cap(Figure 4- 10).Coat both sides of the lower seal end tabs with MoparGasket-in-a-Tube, or equivalent. DO NOT applysealant to the lip of the seal.VIBRATION DAMPERFigure 4 - 10The reason for a vibration damper on an engine is todampen the frequencies and/or harmonics that are createdwhen the engine runs (rotates). In simplified terms, to“dampen” means to soften or decrease the effect. This keepsthe crankshaft from breaking, helps it last longer, and helpsbearing durability. In some engines you could even failblocks because of excessive vibration. That’s why a solidhub damper (or no damper at all) breaks the crankshaftquicker. This durability effect is greater in an oval trackracing vehicle than a drag racing vehicle, and greater in abracket racer than a Super Stocker (for example).In the past, we’ve discussed the weight factor in rubberdampers. To summarize, the heavier the damper ring, themore effective the damper is. Therefore, on oval trackvehicles, Chrysler-Plymouth-Dodge used a much largerdamper to maintain durability.

146 MOPAR PERFORMANCE PARTSCurrently, the NHRA requires an SFI approved vibrationdamper as mandatory equipment in Comp Eliminator,Super Stock, Super Comp, Super Gas, and Super Street.They are also permitted in Stock Eliminators. Since January1991, these SFI dampers have been mandatory on all E.T.bracket vehicles that run 10.99 and quicker. If you run a fastvehicle, you should be aware of these special dampers.There are basically three vibration damper approaches thatcan be used. You can use a solid hub damper, afluidviscous damper, or a rubber-style damper. DO NOTUSE A SOLID HUB DAMPER. It breaks crankshafts. Thisleaves the comparison between rubber and viscousdampers. Realize that production (stock) dampers work finein stock condition, but they are not legal in fast vehicles;i.e., they are not SFI approved. Now the question becomeswhich one to use?The first consideration is cost. Rubber dampers tend to beless expensive. However, this is like selecting a cast ironintake manifold over an aluminum one because the cast ironmanifold costs less. There’s more to it than that.The second consideration is inertia. This translates into adamper’s rotational weight. Without getting into fancyterms with a rubber damper, everything has to rotate withthe crankshaft and at the same speed (rpm) as thecrankshaft. This isn’t true of a fluidhiscous damper. Alarge part of the viscous damper’s weight doesn’t follow theengine’s rpm exactly. It works something like a viscous fan.This can be a big advantage in a drag engine or short trackengine where engine speeds change quickly and by largeamounts.One of the characteristics of a rubber damper is that it hasto be tuned to a selected rpm band of operation. This meansthat, for any given engine package, the damper is tuned toa specific rpm. The viscous damper does a better job at awide range of frequencies (rpms). This again is a bigadvantage for the racer who races under many differentconditions, rpms, track lengths, etc.The only real “problem” with rubber dampers is that therubber can deteriorate. This can manifest itself in the outerring slipping. This causes the timing mark to move. At thispoint the damper should be replaced.In summary, we recommend that a steel ring (SFIapproved) vibration damper be used for general highperformance (dual purpose) vehicles, and a viscous/fluidvibration damper be used for race-only drag, oval track, orendurance vehicles.Damper Attachment PackageAttaching bolt package necessary to attach damper tocrankshaft.P4529677 Damper attachment package.Vibration Damper FailureBasically, vibration dampers keep the crankshaft frombreaking. Longer stroke crankshafts work the vibrationdamper harder. So do higher rpm and more output to alesser degree. Lighter dampers don’t do as good a job asheavy dampers. Racing engines today are getting largerwith longer strokes. We need the best damper we can get tokeep the crankshaft from breaking. Without extensivetesting, the best rule is the heavier the better. Theproduction weight damper is another good guideline sincethere has been more testing on it than any other.Most crankshaft failures are the result, not the cause. Thedamper causes the crankshaft to fail, not the other wayaround. If a crankshaft fails, always look to oiling first, thenthe damper. You can’t blame an oiling failure on thedamper. But you also have to select the damper that allowsthe crankshaft to work. If you take weight out of the damperand the crankshaft fails, you know you went too far!Vibration Damper Performance TipsWe have covered the advantages of a good race vibrationdamper. Like any race piece, there are always littleproblems that crop up as you get into actual racing, such asnotching pistons for a big camshaft and matching ports onthe intake manifold. Vibration dampers are no exception.First of all, always double check the timing mark. Doublecheck it against actual top dead center (TDC). This tipreally has nothing to do with the damper itself. We(DaimlerChrysler) have told racers over and over again tocheck the timing marks on their dampers. Check, check,and recheck! You should never switch dampers withoutchecking the timing mark. Remark your damper asrequired. (Refer to Top Dead Center (TDC), in this section,for complete information.)Another tip concerns pulley spacing. Proper spacing hasbeen a problem on every high rpm engine built. Aluminumpul!eys add to the complexity of the problem. There is noeasy solution. Aligning the various pulleys so that all thebelts run true takes a little bit of patience and somemeasuring, but it must be done.Removal1, Remove the drive belt(s).2. Remove the retaining bolts and separate the vibrationdamper pulley (V-belt ONLY) from the vibration damper.3.4.Remove the vibration damper retaining bolt and washer.Use a vibration damper removal tool to remove thedamper from the crankshaft (Figure 2-2).

4.0L POWER TECH IN-LINE 6 (CRANKSHAFT) 147Installation1.2.3.4.With the key in position, align the key slot of thevibration damper hub with the crankshaft key and tapthe damper onto the crankshaft.Install the vibration damper retaining bolt and washer.Tighten the bolt to 108 Nmm (80 ft-lbs) torque. If thecrankshaft turns before the damper bolt torque value isattained, the crankshaft can be prevented from turningby placing two 5/16'' x 1-1/2" bolts into the damperfront pulley holes and wedging a bar between them.Rotate the bar until it contacts the frame member toprevent the crankshaft from turning.Install the damper pulley (V-belt only) and retainingbolts. Tighten the bolts to 27 Nmm (20 ft-lbs) torque.Install the drive belts(s) and tighten to the specifiedtension. Refer to the service manual for the properspecifications and procedures.TIMING CHAIN AND SPROCKETSInstallation of the timing chain with the timing marks on thecrankshaft and camshaft sprockets properly aligned ensurescorrect valve timing. A worn or stretched timing chain willadversely affect valve timing. If the timing chain deflectsmore than 12.7 mm (1/2"), replace it. The correct timingchain has 48 pins. A chain with more than 48 pins willcause excessive slack. For removal and replacementprocedures, refer to the proper service manual.Jeep Gear DrivesReplace conventional Jeep timing chain and gear sets andeliminate chain induced cam timing fluctuations with thisMopar Performance Parts dual idler gear drive camshaftcenterlining drive system. Rugged and durable for off-roadapplications. Fits all 4.0L, 4.2L, and 2.5L Jeep engines.P5249009Jeep gear drives.All-out Race Chain and SprocketsCloyes matched sprockets and double roller chain for alloutrace applications. Has three matched keyways toadjust cam timing. Kit includes Magna-fluxed sprocketsand roller timing chain. For 2.5L and 4.0L engines only.PS2495 19Installation TipsAll-out race chain and sprockets.1. Be extremely careful to apply full torque to thecamshaft sprocket attaching bolts. It is also advisableto apply Loctite. If these precautions aren't taken,engine torsional vibration may cause the camshaftbolts to loosen and the camshaft will turn. If the boltsloosen, the locating dowel will shear off because it isnot intended as a load carrying member. As an extraadded measure, use at least Grade 8 bolts.2. The bushings in the timing chain rollers willdeteriorate with hard usage. Change the timing chainwhen it becomes stiff and the links DO NOT movefreely, as this indicates bushing breakage.Also, replace camshaft andor crankshaft sprockets ifthere is any evidence of teeth being bent throughdropping or other mishandling. Bent teeth may breakoff causing the chain to break.Note: When installing a new camshaft or reassemblingthe engine after an overhaul, coat the camshaft lobesand tappets liberally with Mopar Engine OilSupplement (or equivalent). This aids camshaft andtappet break-in and helps prevent scuffing.

148 MOPAR PERFORMANCE PARTSINTRODUCTIONThe 4.0L engine's connecting rods are made of castmalleable iron with a total weight (less bearings) of 657-665 grams (23.2-23.5 oz.), and a total length (center-tocenter)of 155.52-155.62 mm (6.123-6.127").Connecting rod bore diameter (less bearings) is 56.09-56.08 mm (2.2085-2.2080").For more connecting rod specifications, refer to 4.0L EngineSpecifications, 'Engine Assembly' section of this chapter.Connecting RodThese heavy duty forgings are shot-peened and Magnafluxed.Includes high strength bolts. Can be used as heavyduty stock replacement. For 2.SL and 4.0L engines only.(Sold individually.)P4529209Connecting rod.Connecting Rod BearingsThese connecting rod bearings are made of productionstylematerial, Available in standard and two undersizes.For Jeep 2.5L and 4.0L engines only. (Sold individually.)P4529208P4529236P4529238Connecting RodsConnecting rod bearings, standard size.Connecting rod bearings ,.001" undersize.Connecting rod bearings, ,010" undersize.BASIC CONNECTING ROD PREPARATION ANDINSTALLATION TIPSNote: The following information is for the preparation ofsteel connecting rods only.1. Connecting rods should be checked for alignment; boresshould be parallel. Check big and small ends for size.2.3.Using a small file, deburr the connecting rods, payingparticular attention to the mating surfaces and tabgroove. You need the clamping effect of a 60 microbore. The sides should be polished by hand on a flatplate using #600 paper. Proper side clearance should be0.250.48 mm (0.010-0.019"). DO NOT increase sideclearance past .0 19" as this increases the oil demand ofthe engine. It will also allow too much oil on thecylinder walls which will overload the rings and allowexcess oil in the combustion chambers.In an engine that is to be used in a high rpm situation,the connecting rods and connecting rod bolts should beMagna-Glo checked for cracks or forging flaws.4. A race engine should always use heavy dutyconnecting rod bolts and nuts.5. The connecting rod bearing clearance is 0.25-0.76 mm(0.00 1-0.003"). Preferred bearing clearance is 0.044-0.050 mm (0.0015-0.0020").6.7.8.9.The connecting rod bolt head should be seated againstthe flat, machined surface in the connecting rod.For a race engine, the big end of the connecting rodshould be sized to the minimum diameter to get themaximum crush from the bearing.Shot-peening the rods is recommended if they haven'tbeen already.Some race engines use floating piston pins. On theseengines, the pin-to-connecting rod clearance should bechecked. On standard production engines that use apressed pin, the amount of interference should bechecked. (Refer to 4.0L Engine Spec$cations, 'EngineAssembly' section of this chapter.)10. Connecting rods with full floating pins to be used inracing applications should have the small end of theconnecting rod drilled with a small hole(approximately 3/32") for increased piston pin oiling.The best location for this oiling hole is the top of theconnecting rod above the pin (Figure 4-11). Pin oilingholes in the sides (5 o'clock or 7 o'clock, for example)weaken the connecting rod itself and therefore areNOT recommended. One hole in the top does the bestjob of oiling the pin and maintaining the connectingrod'5 strength.rPiston Pin Oiling Hole1Centerline Piston Pin 7;4, , I1 ;f .i/;Pn-OlamelFigure 4 - 11Piston PinCenterline

4.0L POWER TECH IN-LINE 6 (CONNECTING RODS) 149SPECIAL CONNECTING ROD INSTALLATIONPROCEDURESRod RatioFor all-out modified race engines, it is recommended that arod ratio (length of the rod divided by the stroke) of 1.75 to1.85 be maintained if possible for best performance. (Thestock 4.0L engine has a rod ratio of 1.78 - this is consideredthe best overall choice.) Side clearance should be 0.25-0.48mm (0.010-0.019”).Measuring Side ClearanceSlide snug-fitting feeler gauge between the connecting rodand crankshaft journal flange. The correct clearance is0.25-0.48 mm (0.010-0.019”). DO NOT increaseconnecting rod side clearance (two rods) beyondspecifications. Replace the connecting rod if the sideclearance is not within specification.Note: Excessive side clearance increases the oil demand ofthe engine as a result of excessive oil leakage past theconnecting rods. Increasing oil demand reduces the oilavailable for lubrication and cooling at high engine speeds.Excessive side clearance also increases the amount of oilsprayed on the cylinder walls overloading the oil rings.The excessive oil then ends up in the combustionchamber and can cause pre-ignition. (By definition, oil isa very low octane fuel!)Cap AlignmentSometimes the simplest questions can be the hardest toanswer. In some cases you assume that everyone knows theanswer already. For example, someone asks the question,“Can you reverse the cap on a connecting rod?” The answeris, “No!” Although this is correct, the follow-up question(“why?”) is not so easy to answer. During engine assemblywe line up the numbers on the sides of the connecting rods.Therefore, if we reversed the caps, the numbers would notline up. Sounds good, but is it the complete answer?Since we (Mopar Performance Parts) are in the partsbusiness, we should have an answer to this question. Afterall, there are no numbers stamped on the side of serviceconnecting rods or Mopar Performance Parts connectingrods (or any aftermarket connecting rod for that matter).Therefore, the numbers can’t be used to tell us why. Doesthis mean that the caps can be reversed‘? How about on aservice connecting rod? The answer is still “No!” We’llhave to look deeper to find out why.Connecting rod cap tab slots are a feature that you maythink will lead to the “why?’ answer. There is a slot in thecap and one in the connecting rod that align the bearingshells. These two tabs (or slots) have to be together. Thiswould mean that the two slots would be next to the samebolt. Although this is true, it is NOT the complete answer.(It is only coincidence!)If you take the cap off the connecting rod assembly, youwill notice that there is a V-groove across the parting faceof the cap. You will note that the V-groove is on theopposite side from the bearing tab slot. There is also a smallV-notch in the bearing shell which should be installed toline up with the V-groove in the cap. This groove provideslubrication of the cylinder wall on the opposite bank. We’regetting warmer!In racing and other very high performance engines, theconnecting rod caps may not have a V-groove. Extremelyhigh rpm applications don’t need any more oil on thecylinder walls, so the V-groove may be omitted. Eventhough the V-groove isn’t always there, the fact that it isdesigned to oil the opposite wall leads us to the correctanswer. The groove-to-wall relationship means that how theconnecting rod fits into the crankcase is important.The key to all of this is to notice that the chamfer on the bigend of the connecting rod is not the same on both sides.There is a big chamfer on one side and a small chamfer onthe other. The big chamfer goes toward the crankshaft whilethe small chamfer goes toward the other connecting rod. Ifthe cap gets reversed, then there would be a small chamferon the connecting rod and a large chamfer on the cap. Thisis how you can tell that a cap had been reversed. DO NOTassume that a used engine did not have some of its capsreversed. The proper way to install the connecting rod intothe engine is that the right cylinder bank (#2, 4, 6) shouldhave the large chamfer toward the rear of the engine. Theconnecting rods on the left bank (#l, 3, 5) should have thelarge chamfer toward the front of the engine. The servicemanual ties the direction of the chamfer to the “notch” inthe top of the piston. In racing we may reverse the pistonsor have no offset and therefore no notch or arrow. Thereforeit is best to install connecting rods by chamfer and cylinderlocation. The service manual also says that you should fitall connecting rod and piston assemblies on one bank untilcomplete. This is important. DO NOT alternate from onebank to another.

150 MOPAR PERFORMANCE PARTSWe began this discussion trying to find out how to tell if acap had been reversed. We now know how to locate the capand how to install the connecting rod assembly in theengine. These two items are closely related because themethod of determining main cap orientation and the key toinstalling connecting rods are the same. It is important toknow both because once the connecting rod and piston areassembled, the cap still has to be removed one more time toget the connecting rod on to the crankshaft. One morechance to reverse the cap or the connecting rod. Our maincheck on the assembly at this point is usually the valvenotch on the top of the piston. However, it is also a goodidea to double check the chamfer-crankshaft relationshipafter the connecting rod/piston installation to verify that acap didn’t get reversed in the last step.Connecting Rod Bolt ProtectorsIn every engine assembly or build-up, the piston andconnecting rod assembly must be installed into the blockand on to the crankshaft. During this phase of engine buildup,the connecting rod bolts have to be protected. This isbecause when the connecting rod cap is removed to allowfor the installation of the connecting rod and pistonassembly and the bearing shells, the connecting rod boltspressed into the connecting rod are left sticking outunprotected. Aluminum connecting rods have theconnecting rod bolts threaded into the connecting rod beamand are, therefore, one of the few exceptions to thiscondition. In any case, the bolts that stick out must beprotected during installation.To protect the bolts, cover the connecting rod bolt threads.There are several choices for protectors. The “Pros” tend touse threaded brass rods. Another option is simply a piece ofrubber fuel line. Our favorite is neoprene (clear plastic)line. Lengths are somewhat optional, but should be at least9” - 12” long for the top bolt. The second piece, for thebottom bolt, could be as short as 3“ - 4” long, but 9” - 12”long is recommended,The main reason the threads need to be covered is to protectthe crankshaft journal during piston-connecting rodinstallation. If you don’t use protectors, it’s very easy toscratch the connecting rod journal with the end or threadsof the connecting rod bolt. Crankshafts are much moreexpensive to repair or replace than connecting rod bolts.A secondary function of connecting rod bolt protectors is toguide the connecting rod over the crankshaft journal duringinstallation. This is only true if you use at least one longprotector. If you use short ones (or none at all), then theconnecting rod can easily end up on the wrong side of thejournal, which can result in other damage.The proper procedure for installing the connecting rod andpiston assembly begins with the crankshaft’s rod throw atthe bottom of its travel, or BDC (Bottom Dead Center).Generally, the cylinder that you are working on should betipped on its side. This makes slipping the connecting rod,piston and ring assembly into the block easier. In thisconfiguration, the long protector should go over the top ofthe connecting rod journal. Before you make an error,remember that the piston MUST be installed into the blockin its proper orientation for pin offset, valve notches, etc. Sothe first task is to determine this orientation BEFORE youinstall the connecting rod bolt protectors. Now put the longprotector on the top bolt as installed. Somewhat confused?Now you can see why using two long protectors might beeasier to work with and is the recommended choice.As soon as the piston and connecting rod assembly is seatedagainst the crankshaft journal, the connecting rod boltprotectors are removed.ALUMINUM CONNECTING RODSNote: Aluminum connecting rods should be used ONLY inconjunction with lightweight pistons.Aluminum connecting rods are a race-only piece. Althoughmost standard production connecting rods are designed forpressed-pins, most race pistons are designed for fullfloating pins. When building a race engine, the pistonswould generally be replaced before the connecting rods.For an all-out race engine there are advantages to the fullfloating pin. (Be sure to check pin clearance in theconnecting rod upon assembly.)If y~ou broke a steel connecting rod, you’d probably buy anew one, rebuild it and put everything back together.Aluminum connecting rods aren’t quite that easy. (By“breaking” we mean a partial failure like a scuffed big end,overheated, bent or nicked from handling. If the connectingrod breaks in two, there won’t be much left to “put backtogether.”) With aluminum connecting rods, if you drop oneand nick it, you can replace it with a new one. However, ifafter several runs you scuff it, overheat it, bend it, etc., youdon’t want to just replace it. Your best bet is either toreplace all six connecting rods or to send the five goodpiecl-s back to the manufacturer and have them “rebuilt”and matched to the sixth. We strongly recommend keepingany instruction sheet or other manufacturer information thatmight come with your specific set of connecting rods tohelp you contact the manufacturer at a future date.The main advantage of aluminum connecting rods is theirlighter weight. However, they do require some specialconsiderations. These special considerations are primarilyclearances, which may be slightly different from steelconnecting rod numbers. These differences can beimportant. Be sure to check with the manufacturer forcorrect specifications.l- - T ’ l

T - T i l4.0L POWER TECH IN-LINE 6 (CONNECTING RODS) 151CONNECTING ROD BEARINGSFor racing purposes there are two special connecting rodbearings materials used: Babbit and Tri-Metal. In general,Tri-Metal is preferred for oval track racing, Babbit for dragracing.InstallationFit all connecting rods on one cylinder bank untilcompleted. DO NOT alternate from one bank to another,because when the rods are assembled to the pistonscorrectly, they are not interchangeable from one bank toanother.The bearing caps are not interchangeable and should bemarked at removal to ensure correct assembly.Each bearing cap has a small V-groove across the partingface. When installing the lower bearing shell, make certainthat the V-groove in the shell is in line with the V-groovein the cap. This provides lubrication of the cylinder wall inthe opposite bank.The bearing shells must be installed so that the tangs are inthe machined grooves in the rods and caps.Limits of taper or out-of-round on any crankshaft journalsshould be held to 0.0254 mm (0.001"). Bearings areavailable in 0.025 mm (0.001"), 0.051 mm (0.002"), 0.076mm (0.003"), 0.254 mm (0.010") and 0.305 mm (0.012")undersize. (Contact your local Chrysler-Plymouth-Dodge-Jeep dealer for ordering information.)Note: Install connecting rod bearings in matched pairs. DONOT use a new bearing half with an old bearing half. DONOT file the rods or bearing caps.Measuring Connecting Rod Bearing Clearance1.2.3.4.5.Wipe the journal clean of oil.Use short rubber hose sections over rod bolts duringinstallation.Lubricate the upper bearing insert and install inconnecting rod.Use a piston ring compressor to install the rod and pistonassemblies with the oil squirt holes in the rods facing thecamshaft and the arrow on the piston crown pointing tothe front of the engine (Figure 2-37). Verify that the oilsquirt holes in the rods face the camshaft and that thearrows on the pistons face the front of the engine.Install the lower bearing insert in the bearing cap. Thelower insert must be dry. Place a strip of Plastigaugeacross the full width of the lower insert at the center ofbearing cap. Plastigauge must not crumble in use. Ifbrittle. obtain fresh stock.6. Install bearing cap and connecting rod on the journaland tighten nuts to 45 Nom (33 ft-lbs) torque. DO NOTrotate crankshaft. Plastigauge will smear, resulting ininaccurate indication.7.8.Remove the bearing cap and determine the amount ofbearing-to-journal clearance by measuring the width ofcompressed Plastigauge by using the scale on thePlastigauge envelope (Figure 2-16). The correctclearance is 0.025 to 0.076 mm (0,001 to 0.003").Plastigauge should indicate the same clearance acrossthe entire width of the insert. If the clearance varies, itmay be caused by either a tapered journal, bentconnecting rod, or foreign material trapped betweenthe insert and cap or rod.If the correct clearance is indicated, replacement of thebearing inserts is not necessary. Remove thePlastigauge from crankshaft journal and bearing insert.Proceed with installation.9. If bearing-to-journal clearance exceeds thespecification, install a pair of 0.0254 mm (0.001")undersize bearing inserts. All the odd size inserts mustbe on the bottom. Service replacement bearing insertsizes are stamped on the backs of the inserts. Measurethe clearance as described in the previous steps.10. The clearance measured with a pair of 0.0254 mm(0.00 1 ") undersize bearing inserts installed willdetermine if two 0.0254 mm (0.001") undersize insertsor another combination is needed to provide the correctclearance. (Refer to Connecting Rod Bearing FittingChart [Figure 4- 151 .)Example: If the initial clearance was 0.0762 mm(0.003"), 0.025 mm (0.001") undersize inserts wouldreduce the clearance by 0.025 mm (0.OOlll). Theclearance would be 0.002" and within specification. A0.051 mm (0.002") undersize insert would reduce theinitial clearance an additional 0.013 mm (0.0005").The clearance would then be 0.038 mm (0.0015").11. Repeat the Plastigauge measurement to verify yourbearing selection prior to final assembly.12. Once you have selected the proper insert, install theinsert and cap. Tighten the connecting rod bolts to 45N*m (33 ft-lbs) torque.

152 MOPAR PERFORMANCE PARTSPistons and RingsIPart NumberCast Pistons and Rings for Jeep 4.0L EnginesBore StrokeIP48769623.905" 3.41" 6.125" 9.2: 1PISTONSThe 4.0L engine uses high strength aluminum alloy pistonswith an anodized top ring groove and crown. Piston skirtsare coated with a solid lubricant (Molykote) to reducefriction and provide scuff resistance. A pressed fit piston pinis used to attach the piston and connecting rod. The pistoncombustion cavity is a single quench design. For morepiston (and piston ring) specifications, refer to 4.0L EngineSpecifications, 'Engine Assembly' section of this chapter.In summary, the secret with pistons is that they belightweight and have smooth, round tops if they are domed.The secret with piston rings is to get them to seal to thepiston and the bore at W.O.T. (wide open throttle).Piston Compression Ratio RatingsPistons are usually described by their bore or overbore sizeand their rated compression ratio. This compression ratiorating seems to get people confused. Generally there are8.0:1, 9.0:1, 10.5:1, ll.S:l, and even 12.S:l pistons. Thereare dished and domed pistons. Generally domed pistonshave a high compression ratio rating and dished pistonshave a low compression ratio rating. However, the pistondoesn't have a compression ratio by itself. It has to beinstalled into an engine.In an effort to help clarify this situation and help racersknow what they are basically getting, most pistonmainufacturers rate their pistons by compression ratio. Todo this, they assume that the engine is at blueprint ornontinal specifications. For example, Mopar PerformanceParts has a line of 9.2:1 pistons. If your engine had anominal compression ratio of 8.2:l from the factory andyou installed these pistons, then you would have a 9.2:lcompression ratio.The, confusion comes in because most engines don't havethe actual nominal compression ratio. It might be 8.2:l. Itmig,ht be 8.0: 1, or possibly 7.8: 1. If your engine really hasa 7.8:l compression ratio and you install 9.2:1 pistons,you'll actually have an 8.8: 1 compression ratio. The pistonis only one of many factors that contribute to the exactcompression ratio. There is cylinder head volume (cc) andgasket thickness. There is also the deck height which takesinto account connecting rod length changes, strokevariations, and block height machining tolerances. (Valvenotches, chamfers, disWdome volumes, and pin height areassumed to be part of the piston.)So when you change the piston design and move the pindown to increase the compression ratio (or add a dome),you are only changing the piston. Let's assume that thedeck tolerances are ,020" to .030" below the cylinder head,and the cc range is from 68 to 72. The piston itself can'tchange variations in these other parts. On any given engine,the difference is between the rated compression ratio for thepistons and the engine's actual nominal compression ratio.For example, if the engine's actual nominal compressionratio is 8.2:1, then 9.2:l pistons increase the compressionratio one point (9.2 - 8.2 = 1). Therefore, if the engine'sactual nominal compression ratio is 7.8: 1, then the resultingcompression ratio after installing 9.2:1 pistons is 8.8:l. Theonly way to determine if your engine has an 8.2: 1 or 7.8: 1compression ratio is to measure it. This requires you to cc theheadls, measure the deck heights with a micrometer or similardevi'ce, and check the compressed thickness of the gaskets.All pistons share this problem. If you don't make the requiredmeasurements, you won't ever know you're exact compressionratio. And there are still other variations. The only way toremove all these variations is to blueprint the engine.

4.0L POWER TECH IN-LINE 6 (PISTONS AND RINGS) 153Piston ShapeNot all pistons are the same “shape.” Each engine has apiston shape and resulting combustion chamber shape thatwill provide the best engine output at a given compressionratio. The simplest way to solve this problem in wedgeengines is to use a flat piston. Typically, an engine with11 .O: 1 compression ratio will make more power with a flatpiston than it will with a domed piston.For higher compression ratios, a domed piston must be usedand, therefore, the shape becomes important. The sparkplug relief needs to be enlarged, the top of the dome shouldbe “radiused” with as large a radius as possible, and allsharp edges usually located around the valve notchesshould be removed and smoothed as much as possible,especially in the piston notch and spark plug relief areas.Also, don’t use any more dome height than is required.Stated another way-keep the dome as low as possible. Insummary, a low, round and smooth shape is best formaximum power.The vast majority of production engines use flat pistons.Many high performance racing engines use a domed piston.The problem is that the domed piston isn’t always best forperformance. The flat piston engine typically makes asmuch power as the domed piston engine, if not more. Why?First, a typical domed piston is heavier than a typical flatpiston. The higher compression ratio of the domed pistonengine means that you have to use racing gasoline ratherthan “pump” gas or “blends.” Without racing gas, thehigher compression ratio is wasted and actually results inlower output. Domed pistons can be made to work, but theactual shape of the dome is very important. Each enginefamily uses a different shape. If reshaping is not done, thenthe flat piston will provide more power.In summary, for most racers and most racing engines, flatpistons are the best performance choice. However, if goodracing gas is used and the dome is properly shaped, thendomed pistons can be beneficial.Piston-to-Head ClearanceWhen putting an engine back together, the most oftenoverlooked clearance is the distance between the piston andthe cylinder head at top dead center. The minimum pistonto-headclearance should be .040” (low) and .060“ (high).Piston-to-head clearance becomes very important in highcompression ratio engines, especially with domed pistons.This isn’t a good place to gamble. If the piston hits thecylinder head, it can cause the piston skirts to fail and thepin locks to beat-out or fail. In some cases, it can cause thehead gasket to blow. Blowing the head gasket or failing apin lock isn’t a big failure by itself, but what happens nextcan be!The easiest and most reliable way to check piston-to-headclearance is to put the piston at TDC with the head installedand then remove or loosen the connecting rod cap. With adial indicator installed parallel to the connecting rodcenterline, the connecting rod and piston assembly can nowbe pushed up until the piston touches the cylinder head. Theindicator will read precisely the amount of clearance. If theclearance is measured without a head gasket, then add inthe gasket thickness for the total installed clearance. Flatpistons are easier to measure than domed pistons. Modelingclay can also be used to measure the clearance, but youshould leave an extra .025” clearance (i.e., .080” total) justto be safe, especially if you like to cut it close.Valve-to-Piston ClearanceValve-to-piston clearance is equally important. Engines thatmust race in conjunction with 4 or 5-speed manualtransmissions should have the following valve-to-pistonclearances: Intake 0.100” minimum; Exhaust 0.100”minimum. The valve-to-piston clearance is usuallymeasured by placing modeling clay on the piston, manuallyturning the engine over with the head bolted on, the cam,lifters, pushrods, etc., adjusted to zero lash, and the camproperly centerlined. The thickness of the clay left on thepiston is then measured by sticking a steel scale in at thethin spots. A dial indicator can also be used by using a light,‘checking’ spring and measuring the actual clearance ateach point in one degree increments from 10 degrees beforeTDC to 10 degrees after. This second method is moreaccurate but takes a little longer. Also keep in mind that ifyou change the camshaft centerline, you’ll change valve-topistonclearance. Generally, if the centerline is advancedtoward TDC (actual centerline moved from 110” to 106”,for example), you’ll end up with less clearance. Thisclearance should always be measured with a new camshaftat the proper centerline.Piston Race PreparationThe performance secrets for pistons are that they be light inweight and also have a smooth, round top (if it’s a domedpiston). The secret to performance in rings is to get them toseal to the piston and to the cylinder bore at W.O.T. (WideOpen Throttle).For obvious reasons, pistons are not interchangeablebetween various engines. Factory pistons have the pinoffset to reduce piston slap. By reversing the offset(reversing the piston), you can reduce engine friction.High compression pistons have a large dome that sticks intothe combustion chamber. In some cases this dome willstrike the spark plug and close it up. Therefore, the end ofthe plug should be given 1/4” clearance in the shape of aspherical cup. This will also aid in flame propagationbecause the plug will be less shrouded.

- -1154 MOPAR PERFORMANCE PARTSBecause of gasoline limitations, compression ratios shouldnot exceed 12.5: 1 for competition; 10.5-1 1.0:1 for generaloff-road use, unless you have access to high qualitypremium fuel (103 octane).The most important consideration about pistons is weight.Forged pistons are stronger than stock cast pistons and tendto be equal to or heavier than stock pistons. For racingpurposes, lighter weight is where the performance is.Forged racing pistons at less than 500 grams can beobtained. However, they have to be custom made and aremore expensive. Once the piston is lighter, the pin can belighter, the rod lighter and the balanced crankshaft lighter.A word of caution, however! You can go too far andweaken the piston in a vital area, causing it to fail. This typeof failure tends to make an expensive mess.There are many clearances related to a racing piston. Wehave outlined most of these clearances, such as piston-towall,valve-to-piston, etc. However, many engine buildersforget about the piston-to-head clearance. We suggest .040"(low minimum) and .060" (high minimum). The problem isthat if the engine builder cuts it too close, say .030", thepiston will hit the cylinder head. This can result in a blownhead gasket, broken pistons, broken pins or pin locks. Theclearance becomes very important in high compressionratio engines, especially with domed pistons.Reversing Pistons With Offset Pins(Refer to Offset Pins later in this section.)CC'ing the BlockWith an ordinary flat-top piston, the block is not cc'd. Theneed for cc'ing the block arises only if the piston is domedor if the valve clearance notches or reliefs are quite large.COMPRESSION RATIOAlmost everyone talks about compression ratio, but veryfew non-professionals really know what it is. The followingprocedures show you how to make compression ratiomeasurements, plus how to calculate your actualcompression ratio.The formula for determining compression ratio is as follows:VBDCCompression Ratio = VTDCThe first step is to look at the cylinder volumes. (See Chart 1 .)This is the volume of one cylinder in cc's.Chart 1- En- Bore x StrokeCvl. Head Vol. (cc)2.51,4 cyl. 3.876 x 3.188 6 16.454.01, 6 cyl. 3.88 x 3.44 666.524.21,6 cyl. 3.75 x 3.895 704.955.91, (360 CID) V-8 4.08 x 3.44 737.00The volume above the piston at BDC (Bottom DeadCentler) is equal to the piston displacement plus thechamber volume. (Chamber volume is the volume abovethe piston at TDC [Top Dead Center].)Next, break down the volume above the piston at TDC intoits separate parts. This volume is the total combustionchamber volume. It consists of four basic parts: cylinderhead volume, gasket volume, piston deck clearance andpiston dish or dome. The head volume is typically measuredseparately with the head off the engine. The gasket volumeis a function of its thickness, and that is measured using amicrometer. Head gasket volumes run in the 10-15 cc range.(We'll discuss that in more detail shortly.) The deckclearance and dish or dome measurements are best lumpedtogetlher and measured under the 1/2" down fill volume. Inshort., as long as you have a completelypat piston (no dish,dome or notches), you can measure deck clearance with adial indicator and treat it as another (or thicker) gasket. It'sa quick and easy method, but it only works with aPat piston.The 1/2" down fill volume method for measuring the pistondish or dome is based on a calculated volume. Refer to Chart 2.Chart 2Enaine 1/2" Fill Down Volume Tvpical Head cc's2.5L 96.68 49.94.0L 98.85 64.54.2L 90.50 64.55.9L 107.12 58.6(360 CID)With the 1/2" down fill volume method, the piston isbrought to TDC using a dial indicator placed in the middle(flat spot) of the piston. The piston is then lowered in thecylinder bore SOO" (1/2").Example: If the original deck clearance was ,022" at TDC,then the piston is lowered to S22" below the deck surface.Now the piston is sealed and the cc's are measured similarto the cylinder head. Once you have the actual, measured1/2"down fill volume, you can compare it to the one listedin Chart 2.

4.0L POWER TECH IN-LINE 6 (PISTONS AND RINGS) 155The best way to show the aspects of this number is byexample. Let's assume that you have a 4.0L In-Line 6cylinder engine which shows a 98.85 cc volume for its 1/2"down number. If you have a flat piston at zero deck, youwould measure 98.85 cc for your 1/2" down fill volume. Ifyou have a 15 cc dish in the piston, you would measure11 3.85 cc. On the 4.0L, the typical (stock) deck clearance is.022" below, which calculates to 4.35 cc. Therefore, if yourdished piston was actually .022" down, then the measuredvolume would be I 18.2 cc.If you have valve notches in addition to these other featuresthat are large enough to hold 3 cc for the intake and 2 cc forthe exhaust, then the total volume would be 123.2 cc. If youswitch pistons to a IO cc dome design and keep your 3 and2 cc valve notches and the ,022" below deck (deckclearance is measured to the tlat of the piston, not the top ofthe dome), what is your resulting volume'? First, the 98.85stays the same. The IS cc dish disappears and is replaced bya negative IO cc (-10) resulting in 88.85. The deck is thesame so that adds 4.35, and the notches are the same at 5 cctotal. Therefore, the end result would be 98.2 cc.Now run through a compression ratio calculation. (Use the4.0L engine and the IS cc dished piston example justdiscussed.) You measured 123.2 cc for your 1/2" down fillvolume (ordinarily you don't know how big the dish is orhow large the notches are. so the total volume is all youknow). List your measurements (known data): Head -64.5cc, Cylinder volumc - 666.52 cc, Gasket thickness - .065",1/2" down fill volume- 123.2 cc.First you need to convert the gasket thickness into a ccvolume. This is easily done by multiplying the gasketthickness by the 1/2" down fill volume, and then multiplythat answer by 2. (In this example, .065 x 98.85 x 2 = 4.35cc.) The piston volume is found by subtracting the two 1/2"down fill volumes (123.2 - 98.85 = 24.35). This is a'positive' volume since it is larger than the calculatedvolume from Chart 2. The total combustion chambervolume is 64.5 + 4.35 + 24.35 = 93.20 cc. This is thevolume above the piston at TDC. The volume above thepiston at BDC is equal to 666.52 + 93.20 = 759.72 cc.Therefore, the actual compression ratio for this example is759.72 + 93.20 = 8.15.Measuring 1/2" Down Fill VolumeWith an ordinary flat top piston, the block is not cc'd. Theneed for cc'ing arises only if the piston is domed or if valveclearance notches or reliefs on the piston top are quite large.The same basic technique is followed in either case.Assuming that part of the piston protrudes above the block,choose some common measurement, say 1/2" (SOO"), androtate the crankshaft until the piston (with piston ringsinstalled) has lowered itself from top dead center (TDC) bythis amount. (If not 1/2", a measurement must be chosenthat will ensure that the entire piston is below the block'sdeck.) This amount should be measured very accurately bya dial indicator. The piston should now be sealed to thecylinder wall with a thin film of light grease, being carefulnot to have any grease extend past the top of the piston. Aflat piece of Plexiglas with a hole drilled through it shouldnow be placed over the cylinder bore and also sealed witha thin film of light grease. With a burette (graduated in cc's)containing colored fluid, fill the cylinder. By knowing thecc's that were added to the cylinder, and by knowing theamount that the piston was lowered from TDC, the volumeof piston's dome (or "dish") can be calculated.PISTON RINGSNote: For piston ring availability and recommended usage,refer to the Cust Pistons und Rings chart earlier in this section.The subject of piston rings seems to come and go as a hotspot for performance activity. Piston rings obviously haveto do their job if the engine is going to do its job-makepower. By the same token, piston rings cause very fewproblems by themselves. If there's a problem with a ring,it's usually caused by something else such as the enginebuilder. We've all broken rings trying to get them on to thepiston or when putting the whole assembly into the engine.We'll be more careful next time, but we still broke the ring.This isn't the ring's fault. With the ring causing so fewproblems once installed, why try to fix it? New inventionsburst upon the scene and everyone tries them. They thenfall back into their position and everything quiets downagain. Rings today are in this position.Basically there are three styles of "trick" race rings: Dykes,Headland and gas ports. A Dykes ring is an L-shaped ringthat we've used in Hemi engines since the 1960s. TheHeadland is a bigger section Dykes that's located right at thetop of the piston. They're usually used with flat-top pistons.Both require custom cut ring grooves, so they typicallyrequire special pistons. Gas ports are typically used withvery thin rings -043" or .03 1 ". Gas ports do work, but theyload the cylinder walls very heavily and tend to wear outquickly. The Headland ring works best at lower speeds. TheDykes ring works best at high speeds. The moly-coatingworks best on any of the rings, but you cannot butt the ringends under load or the ring seal will be gone. You can't takechances with too tight a ring gap with a moly-coated ring. Inspite of this, moly-coated rings are still preferred.The main action today in piston rings by volume is in the5/64" and 1/16" designs. They are NOT interchangeable. The5/64" is the production ring and fits on the production piston.The 1/16" ring is a race/performance ring and only fits onaftermarket race/performance pistons that are cut for thatstyle ring. Typically, all domed pistons use this ring style.One of the characteristics of the ring that is often overlookedis the clearance of the ring in the piston's ring groove. It isimportant to keep this to a minimum. Also, check the sideview of the groove to be sure that it hasn't been worn into aV-shape where the clearance is at a minimum.

156 MOPAR PERFORMANCE PARTSIn summary, the secret with piston rings is to get them to sealto the piston and the bore at W.O.T. (wide open throttle).PISTON PINThe piston pin rotates in the piston only, and is retained by thepres interference fit of the piston pin in the connecting rod.RemovalPiston pins are press fit into the connecting rods and requireno locking device.1. Position the piston and connecting rod assembly on anarbor press.2.Apply force to a piloted driver and press the pincompletely out of the connecting rod and pistonassembly (Figure 2-49). Note position of the pinthrough the gauge window of removal support tool.InspectionBasic Piston Ring PreparationThe basic preparation of the piston rings should consist ofthe following steps.1.2.3.4.5.Check ring grooves for burrs, then for proper sideclearance. Side clearance of the ring in the pistongroove is very important and can be checked with afeeler gauge. Be sure that a used piston’s groove isn’tworn in the shape of a wedge. It doesn’t do any goodto seal the ring to the cylinder wall if it isn’t sealed tothe piston groove.Check ring end gap against specification. DO NOT inany case exceed specifications as this will allow toomuch blow-by, causing power loss andlor allowing toomuch oil to reach the combustion chamber which cancause detonation. The ring gap ends must be squareand parallel.Use a fine stone to deburr rings and to just barely breakedges on end gaps. Break the edges using #600 paper,but DO NOT chamfer.DO NOT install rings that were made for a larger bore.A special .005” oversize ring is best for lowering thering end gap. In stock-type rings, low tension isimportant to lowering engine friction and increasingthe engine’s output. When you are gapping the rings inthe bore, light-check them for being oval. Oval rings ina round bore will only seal in a couple of places, andtherefore the engine won’t make any power. Oval ringsare the result of installing rings that are .020” (or more)larger than the bore.Clean all parts before proceeding.1. Inspect the piston pin and pin bore in the connectingrod for nicks and burrs. Remove as necessary. Neverireuse a piston pin after it has been installed in and theniremoved from a connecting rod.2.3.4.With the pin removed from the piston and connectingrod, clean and dry the piston pin bore and thereplacement piston pin.Position the piston so that the pin bore is in a verticalposition. Insert the pin in the bore. At roomtemperature, the replacement pin should slidecompletely through the pin bore in the piston by forceof gravity.Replace piston if pin jams in the pin bore.Installation1.2.3.4.5.6.Insert the piston pin pilot through the piston andconnecting rod pin bores. Ensure that the arrow on thepiston crown is pointing up (Figure 2-SO).Position the pin pilot, piston and connecting rod on asupport with the squirt hole of the connecting rod to theleft-hand side (Figure 2-50).Insert the piston pin through the upper piston pin boreand into the connecting rod pin bore (Figure 2-49).F’osition the piloted driver inside the piston pin(Figure 2-49).[Jsing an arbor press, press the piston pin through theconnecting rod and piston bores until pin pilot indexeswith the mark on the support. The piston pin requiresan 8900 N (2,000 pounds) press-fit. If little effort isrequired to install the piston pin in the connecting rod,or if the rod moves laterally on the pin, the connectingrod must be replaced.Remove the piston and connecting rod assembly fromthe press. The pin should be centered in the connectingrod (* 0.792 mm or * 0.0312”).

4.0L POWER TECH IN-LINE 6 (PISTONS AND RINGS) 157Offset PinsIt’s commonly known that you can turn pistons around. Thepiston, when originally made, had an offset pin. This offsetpin makes the engine run quieter. By reversing the piston (thearrow on the top of the piston now points to the rear of theengine instead of the front [stock] installation position), youreverse the centerline placement of the pin. This makes theengine noisier, but it will also produce a little more torque.This is a gray area for most types of racing because therules usually state only that stock pistons must be used, notwhether or not their installed positions can be changed.Being a political situation, it’s up to the racer to decide if hewants to chance it.Pin CoatingsSpecial coatings on engine parts are becoming more andmore popular. On low stressed or non-moving parts thesecoatings don’t seem to cause any problems. However, theiractual value can be debated.The top of the piston has been a popular area to applycoatings to, as have headers. For the most part, these twodon’t cause problems. Problems seem to come in relative tohighly stressed, moving parts such as piston pins andconnecting rods. There are some areas such as valve tips,rocker arms, and rocker shafts that could benefit fromcoatings, but we know of no specific one for the job that’sproven successful at this time. There are so many, it’s hardto evaluate them all.One problem area, however, can be the piston pin. Mostpeople wouldn’t coat their connecting rods with anythingother than engine oil and would be wary of any connectingrod that they found to be coated if it looked or felt different.This same sharpness and attention doesn’t seem to apply tothe pin. The pin may not move as much as the connectingrod, but it sure is highly stressed! We all know whathappens if the pin fails. To us this sounds like a bad area togamble in. In general, piston pin failures are pretty rare, andMopar Performance Parts has never recommended“coating” the pin. We still don’t, but let’s analyze what thecoatings will do to the pin. We’ll keep it general because ofthe number of possible coatings.Since the pin is made of steel or tool steel and the piston isaluminum, the ends of the pin that ride in the piston aren’tlikely to be affected from a lubrication standpoint. Acoating could affect the metallurgy of the pin and weakenit, but this is hard to cover in a general discussion. With afloating pin, there’s a bushing in the small end of theconnecting rod. Given proper clearance with the connectingrod and the characteristics of the bushing material, coatingsshouldn’t cause any problems with a floating pin.However, with a pressed pin, an interference fit between thesteel connecting rod and the steel pin is what holds the pinin place. Engine coatings are usually designed for frictionreduction. Heat barrier coatings are used on pistons, butshouldn’t be considered for piston pins (we hope)!Applying a coating to a pressed pin weakens theinterference fit and allows the pin to slide out with theobvious disastrous results. More interference might help,but now the small end of the connecting rod may becomeoverstressed due to the excessive press. You may evenbreak the parts (pin and/or connecting rod) on assembly.Probably the easiest way to visualize this is the old “STPtest.” Anyone can pick up a blade-type screwdriver betweentheir fingertips. Apply STP and it slides out. Apply a coatingto the pin and the pin slides out also. Solution -don’t applycoatings to piston pins. Engine oil (or STP, etc.) is not acoating. Moral of the story-if you use trick coatings andhave an engine failure, don’t blame the engine parts!Pin OilingThere are many ways to oil a piston pin. There are also twotypes of piston pins: pressed and full floating. The pistonmay oil the pin with a vertical hole in the pin tower, a slotin the pin bore, or a hole from behind the O-ring groove,along with several other designs. Each piston manufacturerhas its favorite. There is no right or wrong way to do it. Butthere has to be some pin oiling. If you don’t have enough,the pin will scuff. This may mean that the hole isn’t bigenough, not that the hole or slot is in the wrong place. Overthe last 20 years we have rarely seen pin scuffing if good oilis used and the engine is properly maintained. Full floatingpins seem to be less likely to scuff in the piston. They willscuff if the pin clearance is too small. They will also scuffif a poorhad oil is used or run for long periods of time.The most likely area for problems related to pin oiling is onsupercharged engines, turbocharged engines and perhapsengines with big loads of nitrous oxide. Talk to the actualpiston manufacturers (TRW, Venolia, Ross, etc.) for moredetails on why the company chose its particular style.

158 MOPAR PERFORMANCE PARTSPISTON AND CONNECTING ROD ASSEMBLYRemoval1.2.3.4.5.6.7.8.9.Remove the cylinder head cover. Refer to CylinderHead Cover Removal, ‘Cylinder Head’ section of thischapter for the procedure.Remove the capscrews, bridge and pivot assembliesand rocker arms. Alternately loosen the capscrews, oneturn at a time, to avoid damaging the bridge. Retainthem in the same order and position as removed tofacilitate installation in their original locations.Remove the pushrods. Retain them in the same orderand position as removed to facilitate installation intheir original locations.Remove the cylinder head and gasket. Refer toCylinder Head Removal, ‘Cylinder Head’ section ofthis chapter for the procedure.Position the pistons one at a time near the bottom of thestroke and use a ridge reamer to remove the ridge fromthe top end of the cylinder walls. Use a protective clothto collect the cuttings.Drain the engine oil.Remove the oil pan, gasket and seals. Refer to theproper service manual for the procedure.If equipped, remove the main bearing cap brace(Figure 4-6).Remove the connecting rod bearing caps and inserts.Retain them in the same order as removed to facilitateinstallation in their original location. The connectingrods and caps are stamped with a correspondingnumber or letter combination.Caution: Ensure that the connecting rod bolts DONOT scratch the crankshaft journals or cylinder walls.Short pieces of rubber hose, slipped over the connectingrod bolts, will provide protection during removal.10. Remove the connecting rod and piston assembliesthrough the top of the cylinder bores (Figure 4-12).Figure 4 - 12J8909-166

l- ' T r l4.0L POWER TECH IN-LINE 6 (PISTONS AND RINGS) 159Inspection1. Connecting Rod BearingsInspect the connecting rod bearings for scoring andbent alignment tabs. Check bearings for normal wearpatterns, scoring, grooving, fatigue and pitting.Replace any bearing that shows abnormal wear.Inspect the connecting rod journals for signs ofscoring, nicks and burrs.2. Connecting RodsMisaligned or bent connecting rods can causeabnormal wear on pistons, piston rings, cylinder walls,connecting rod bearings and crankshaft connecting rodjournals. If wear patterns or damage to any of thesecomponents indicate the probability of a misalignedconnecting rod, inspect it for correct rod alignment.Replace misaligned, bent or twisted connecting rods.Cylinder Bore MeasurementRefer to 'Block' section of this chapter for the procedure.Fitting Pistons- Bore Gauge MethodTo correctly select the proper size piston, a cylinder boregauge capable of reading in 0.003 mm (.OOOl")INCREMENTS is required. If a bore gauge is not available,DO NOT use an inside micrometer.1. Measure the inside diameter of the cylinder bore at apoint 49.5 mm (1-15/16") below top of bore. Startperpendicular (across or at 90 degrees) to the axis of thecrankshaft at point A and then take an additional borereading 90 degrees to that at point B (Figure 2-34).2.3.4.Coated pistons, piston pins and connecting rods arepre-assembled. The coated piston and connecting rodassembly can be used to service previously builtengines; however, they MUST be replaced as completesets. Tin coated pistons should not be used asreplacements for coated pistons.The coating material is applied to the piston after thefinal piston machining process. Measuring the outsidediameter of a coated piston will not provide accurateresults. Therefore measuring the inside diameter of thecylinder bore with a dial bore gauge is MANDATORY.To correctly select the proper size piston, a cylinderbore gauge capable of reading in 0.003 mm (.0001")increments is required.Piston installation into the cylinder bore requiresslightly more pressure than that required for noncoatedpistons. The bonded coating on the piston willgive the appearance of a line-to-line fit with thecylinder bore.Piston Size ChartCylinder BoreSizePiston LetterSize98.438 to 98.448 mm A(3.8755 to 3.8759")98.448 to 98.458 mm B(3.8759 to 3.8763")98.458 to 98.468 mm C(3.8763 to 3.8767")98.468 to 98.478 mm D(3.8767 to 3.8771")98.478 to 98.488 mm E(3.8771 to 3.8775")98.488 to 98.498 mm F(3.8775 to 3.8779")Fitting Rings1. Carefully clean the carbon from all ring grooves. Oildrain openings in the oil ring grooves and pin bossmust be clear. DO NOT remove metal from thegrooves or lands. Doing so will change ring-to-grooveclearance and will damage the ring-to-land seating.2.3.Measure the ring side clearance with a feeler gauge fitsnugly between the ring land and ring (Figure 4- 13 andFigure 4-14). Rotate the ring in the groove. It mustmove freely around the circumference of the groove.RinP Side Clearance MeasurementTop Compression RingSecond Compression RingOil Control RingPlace ring in the cylinder bore and push down with aninverted piston to position near lower end of the ringtravel. Measure ring gap with a feeler gauge fit snuglybetween ring ends (Figure 2-39).Ring GaD MeasurementTop Compression RingSecond Compression RingOil Control Ring0.042 to 0.084 mm(0.0017 to 0.0033")0.042 to 0.084 mm(0.0017 to 0.0033")0.06 to 0.21 mm0.0024 to 0.0083")0.229 to 0.610 mm(0.0090 to 0.0240")0.483 to 0.965 mm(0.0190 to 0.0380")0.254 to 1.500 mm(0.010 to 0.060")

160 MOPAR PERFORMANCE PARTS4.5.6.7.8.9.Refer to Figure 2-48 for position of the ring gaps wheninstalling piston rings.The oil control rings are symmetrical, and can beinstalled with either side up. It is not necessary to usea tool to install the upper and lower rails. Insert oil railspacer first, then side rails.The two compression rings are different and cannot beinterchanged. The top compression ring can be identifiedby the shiny coating on the outer sealing surface and canbe installed with either side up. (Figure 2-45).The second compression ring has a slight chamfer onthe bottom of the inside edge and a dot on the top forcorrect installation (Figure 2-46).Using a ring installer, install the second compressionring with the dot facing up (Figure 2-47).Using a ring installer, install the top compression ring(either side up).10. Position the gaps on the piston as shown in Figure 2-48.Ring GaD OrientationOil spacer-Gap on centerline of piston skirt.Oil rails-gap 180" apart on centerline of pistonpin bore.No. 2 Compression ring-Gap 180" from top oilrail gap.No. 1 Compression ring-Gap 180" from No. 2compression ring gap.GROOVE HEIGHTA 1 .SO-1.555 mm (0.0602-0.061 2 in)B 4.035-4.060 mm (0.1589-0.1598 in)InstallationFigure 4 - 14Each bearing insert is selectively fitted to its respectivejournal to obtain the specified operating clearance betweenthe bearing and the journal. In production, the select fit isobtained by using various-sized, color-coded bearinginserts as listed in the Connecting Rod Bearing FittingChart (Figure 4-15). The color code appears on the edge ofthe bearing insert. The size is not stamped on inserts usedfor production of engines.The rod journal is identified during the engine productionby a color-coded paint mark on the adjacent cheek orcounterweight toward the flanged (rear) end of thecrankshaft. The color codes used to indicate journal sizesare listed in the Connecting Rod Bearing Fitting Chart(Figure 4-15).When required, upper and lower bearing inserts of differentsizes may be used as a pair. (Refer to Connecting RodBearing Fitting Chart [Figure 4-15].) A standard size insertis sometimes used in combination with a 0.025 mm (0.001")undersize insert to reduce clearance 0.013 mm (0.0005").Caution: DO NOT intermix bearing caps. Eachconnecting rod and its bearing cap are stamped with eitheran associated cylinder number or letter combination on amachined surface adjacent to the oil squirt hole that facesthe camshaft side of the cylinder block.Figure 4 - 13

4.0L POWER TECH IN-LINE 6 (PISTONS AND RINGS) 1611.2.3.4.5.Clean the cylinder bores thoroughly. Apply a light film ofclean engine oil to the bores with a clean, lint-free cloth.Install the piston rings on the pistons if removed. Referto Piston Ring Installation, in this section for theproper procedure.Lubricate the piston and rings with clean engine oil.Caution: Ensure that connecting rod bolts DO NOTscratch the crankshaft journals or cylinder walls. Shortpieces of rubber hose slipped over the connecting rodbolts will provide protection during installation.Use a piston ring compressor to install the connectingrod and piston assemblies through the top of thecylinder bores.Ensure the arrow on the piston top points to the frontof the engine.Note: For racing applications, refer to ReversingPistons with Offset Pins, in this section.6. Raise the vehicle.7. Install the connecting rod bearing caps and inserts inthe same positions as removed.Caution: Verify that the oil squirt holes in the rodsface the camshaft and that the arrows on the pistonsface the front of the engine.8. If equipped, install the main bearing cap brace (Figure4-6). Torque nuts to 47 Nom (35 ft-lbs).9. Install the oil pan and gaskets. Refer to the properservice manual for procedure.10. Lower the vehicle.11. Install the cylinder head, pushrods, rocker arms,bridges, pivots and cylinder head cover. Refer to‘Cylinder Head’ and ‘Camshaft and Valve Gear’sections of this chapter for procedures.12. Fill the crankcase with engine oil.CONNECTING ROD BEARING FITTING CHARTCORRESPONDING CONNECTING ROD BEARING INSERTColor CodeDiameterUpper Insert SizeLower insert SizeYellow53.2257-53.2079 mmYellow - StandardYellow - Standard(2.0955-2.0948 in.)Orange53.2079 - 53.1901 mmYellow - StandardBlue - Undersize(2.0948 - 2.0941 in.)0.0178 mm (0.0014 in.)0.025 mrn (0.001 in.)Undersize53.1901 - 53.1724 mmBlue - UndersizeBlue - Undersize(2.0941 - 2.0934 in.)0.025 mrn (0.001 in.)0.025 mm (0.001 in.)0.0356 mm (0.0014 in.)Undersize52.9717 - 52.9539 mm(2.0855 - 2.0848 in.)Red - Undersize0.254 mm (0.010 in.)Red - Undersize0.254 mrn (0.010 in.)0.254 mm (0.010 in.)Figure 4 - 15.-T

162 MOPAR PERFORMANCE PARTSINTRODUCTIONOne of the most important parts of any engine assembly isthe cylinder head. It holds the key to making power. It alsooffers the opportunity to make more horsepower.Camshafts, headers, and carburetion can only go so farmaking horsepower without the cylinder head. Cylinderheads can be expensive; however, this may be one place inthe engine where spending the extra money is worth it.The 4.0L engine uses a cast iron cylinder head with acombustion chamber volume of 64.45-67.45 cc. It containstwelve valves made of chrome plated heat resistant steel,valve stem seals, springs, retainers and keepers. Thecylinder head, valve seats and guides can be resurfaced forservice purposes.The cylinder head has a quench-type combustion chamberthat creates turbulence and faster burning of the aidfuelmixture, resulting in good fuel economy. Valve lengths are(for intake) 122.4-122.8 mm (4.822-4.83”), and (forexhaust) 122.8-123.2 mm (4.837-4.852”).For more cylinder head specifications, refer to 4.0L EngineSpecifications, ‘Engine Assembly’ section of this chapter.SELECTIONFifteen years ago, cylinder head selection was very limited,so the picking process was pretty easy. Today, this situationhas reversed. Aftermarket suppliers today offer many typesof cylinder heads with different materials, different valves,bigger ports, different valve gear, unique combustionchambers, revised valve angles and locations, etc. The goodnews is the engine builder or racer has more to choosefrom, but the bad news is he must make a choice!With so many heads to choose from, we have to find amethod of choosing the head that we want. Descriptionssuch as “Race,” “Street,” or “Stock” are no longeradequate. There are many comparisons that can get acustomer to choose the wrong head, or spend money that hedidn’t have to. We can’t solve all these problems, but wecan help clarify the situation.One of the biggest mistakes that a racer can make is tomix-and-match features. This approach can be veryexpensive and is best left to the professional engine builder.So for this discussion, we will assume that we can do valvework or even porting, but we don’t want to re-machine ourcylinder heads.Cylinder HeadThe key to making any major selection for a race engine(such as a cylinder head) is to list your priorities. To keep itsimple, answer the question, “Why do you want new headsand what do you think they are going to do for you?’ Theanswer should be your top priority. The second thing toconsider is sequence. If you have five questions or concerns(1 through 5) and you ask them in sequence (1 through 5),you may end up with an answer. However, if you reversethe process and ask the same questions in the reverse order(5 through l), you may end up with more questions! MoparPerformance Parts wants to help you pick the best head foryour application. Other sources/articles want to sell you thehead that they happen to have or are discussing. That is thetrap that you tend to fall into when you look at the specificson any given head. But now that there are so many, youneed to look at the overall picture.Regarding cylinder heads, the FIRST decision that youshould make is material: cast iron or aluminum? There areso many of both kinds with so many different features thatyou need to make this choice up-front. Aluminum heads arelighter, more expensive, and offer repairability. Cast ironheads are less expensive, more durable, heavier, and put upwith more abuse. In general, aluminum heads take heat outof the combustion chamber, so an engine will act like it haslost 1.5 to 2 points of compression ratio. Therefore, if youhad an 8.0: 1 compression ratio cast iron head engine, youwould have to run an aluminum head at 10.0: 1 (estimated).The second decision is combustion chamber shape. Mostcast iron heads have the same chamber shape as production,but there are exceptions. Almost all aluminum heads aredifferent. The trick here is the piston. If the piston has adome on it or if it sticks above the deck surface, then youMUST have a head that will work with your dome. Mostdomed pistons are designed for a production cast ironcombustion chamber. If you have a flat piston, then you areOK. ’Yes, you can replace the pistons, but this is an addedexpense and could cost up to $1,000 or more. If in doubt,go back to your priorities list and write down the cost.The third decision is valves. There are several aspects ofvalves, but the most obvious is diameter. Bigger is better,right? Well, almost! Bigger also means bigger valvenotches in the piston. This is a machining operation that canbe added to the piston, but cost must be considered. Add thecost tmo your list. Bigger diameters can also hit the bore wall.Bore walls can be notched, but this is not your first choice.You also get more shrouding if you use big valves on smallbore sizes. Valve location and valve angle must also beconsidered. Not only is the dome related to these valveaspects, but also the valve notches. They must be fixed togive the proper clearance. Even a flat piston can be aproblem if there is no material under the piston top whereyou want to put the new notches.

4.0L POWER TECH IN-LINE 6 (CYLINDER HEAD) 163The most popular performance aspect of cylinder heads isair flow or cfm. Although you should consider both intakeand exhaust flow when evaluating a head, only the intaketends to be considered by most racers. Additionally, midliftflow and “area under the curve” numbers are moreimportant than the peak flow number, although peak flow isthe “popular” number. (Refer to Evaluating Cylinder HeadAir Flow, later in this section, for more information.)Valve gear is a very complicated area. You must havesomething that works. Since it must work with the head andthe block that you are using, you must consider it. Headscan be very expensive. If you are building a new engine,you can get any system you want, it just costs money. Butif you have a valve gear system already that you want touse, or you have an existing engine that you want to installthe head on to, then you should consider the valve gear.New valve gear could cost as little as a few hundred dollarsor as high as $2,500 (or more). Although the valve gear forcast iron heads tends to be the most readily available andthe least expensive, there may be aluminum heads alsoavailable that can use all or some of the same hardware.Intake manifolds can also be very expensive. Big intakestake big intake manifolds. Exhaust port flanges may change.Standard production intake/exhaust gaskets (P4529243) arereadily available from Mopar, or easily modified fromexisting parts. If a special gasket is required and it is onlyavailable from one, non-Mopar source, be careful.Although the valve cover is not changed very often(because of the added expense and complexity), there arecases where the valve cover shape was changed and the oldcover will NOT fit on a new head. Be sure to check this outbefore you buy!Cylinder head attaching hardware is rarely changed. However,in some cases the head bolts may have been changed. Find outbefore you buy-this can be a hidden expense.The cylinder head must get oil under pressure. Some casesrequire external oiling. Oil returns are never talked aboutbut are necessary. Drag racers don’t usually consider oilreturns, but they should.An aluminum head is about 20 pounds lighter than a typicalcast iron head. Most cast iron heads for a given engineweigh the same. A heavier cast iron head would certainlynot be desired. Some aluminum heads may only be five toten pounds lighter than a production cast iron head, but thisis usually caused by added “features.”Finally, we have the camshaft. You might ask what thecamshaft has to do with the cylinder head. The camshaftdetermines how much lift you are going to use. If you use.600” or less, then you don’t want big port windows andextra big valves. If the vehicle is heavy, you also DO NOTwant big ports and big valves. If you have largedisplacements, then you almost have to have large ports andbig valves. There are solutions to some of these problems,but they cost more money.What does all this mean? If you make the material choicefirst (aluminum or cast iron) then consider pistons andcamshaft lift, the decision is made by adding up the costs.Refer the total cost back to your priorities list and youshould have the best answer for you and your race vehicle.There are so many ways to get high flow today that youcannot consider air flow only and expect to choose the righthead. As more heads come on to the market and more featuresare added to each version, this process will becomeeven more important.CYLINDER HEAD REMOVAL AND INSTALLATIONPROCEDURESRemovalThe following procedure can be performed with the enginein or out of the vehicle.Warning! DO NOT remove the cylinder block drain plugsor loosen the radiator draincock with the system hot andpressurized because serious burns from the coolant canoccur.1. Drain the coolant and disconnect the hoses at thethermostat housing. DO NOT waste reusable coolant.If the solution is clean and is being drained only toservice the engine or cooling system, drain the coolantinto a clean container for reuse.2. Remove the air cleaner.3. Remove the fuel pipe and vacuum advance hose.4. Remove the cylinder head cover. Refer to CylinderHead Cover Removal, in this section for the procedure.5. Remove the capscrews, bridge and pivot assembliesand rocker arms. Alternately loosen each capscrew oneturn at a time to avoid damaging the bridge.6. Remove the pushrods. Retain the pushrods, bridges,pivots and rocker arms in the same order as removed tofacilitate installation in their original locations.7. Loosen the alternator drive belt and remove thealternator bracket-to-cylinder head mounting bolt. Theserpentine drive belt tension is released by looseningthe alternator.8. Disconnect the power steering pump bracket. Set thepump and bracket aside. DO NOT disconnect the hoses.

7- -Tim164 MOPAR PERFORMANCE PARTS9. Remove the intake and exhaust manifolds from thecylinder head. Refer to the service manual for theproper procedures.10. If equipped with air conditioning, perform the following:a.Remove the air conditioner compressor bracketbolts from the cylinder head.b. Remove the bolts from the A/C compressormounting bracket and set the compressor aside.c.Loosen the through bolt at the bottom of the bracket.11. Disconnect the ignition wires and remove the spark plugs.12. Disconnect the temperature sending unit wireconnector and battery negative cable.13. Remove the ignition coil and bracket assembly.14. Remove the cylinder head bolts. Bolt No. 14 cannot beremoved until the head is moved forward (Figure 4-16). Pull bolt No. 14 out as far as it will go; thensuspend the bolt in this position (tape around the bolt).15. If this was the first time the bolts were removed, put apaint dab on the top of each bolt. If the bolts alreadyhave a paint dab on the top or you don’t know if theywere used before, discard the bolts.16. Remove the cylinder head and gasket (Figure 4-16).CYLINDERHEADCY Ll NDER/ MEAD BOLTS \J9009-55Heavy Duty Cylinder Head GasketThe single, heavy duty head gasket is designed for the4.01- engine (only). Can be used as replacement.P45 29242 Heavy duty cylinder head gasket.PreparationThe basic cylinder head preparation should be checked outand reworked in accordance with the following procedures.1. The cylinder head should be “cc’d” and the volumecompared to specifications. Any milling that is requiredshould be done, and the chamber volume rechecked.2. The head should be checked for squareness and for anycracks or flaws. The valve guides should also bechecked for wear and replaced if necessary.3. Heads with a seat runout of less than .001” should havea valve job done. Refer to ‘Camshaft and Valve Gear’section of this chapter for more information.4.5.6.7.The head should be installed on the block without thehead gasket to check dowel pin height. Dowel pinsshould NOT hold the head up off the block surface; theyshould only locate the head over the cylinder bores.When high lift camshafts are installed in productionbasedengines, the keepers may hit the valve guide. Thisshould be checked at the cam’s maximum lift. The guideshould be shortened to give .loo” clearance between thetop of the guide and the bottom of the keepers.When dual valve springs are used, the inner spring seatmay have to be cut down flush with the outer spring seat.Check the cylinder head oiling hole. Be sure that it isopen and that the drill didn’t break off and remain inthe hole. Check the block for a similar hole, both sides.The camshaft bearing holes should line up with thecylinder head oiling holes and not restrict them. It isNOT recommended that oil to cylinder heads and valvegear be restricted.Cleaning and InspectionFigure 4 - 16Thoroughly clean the machined surfaces of the cylinderhead and block. Remove all gasket material and cement.Remove any carbon deposits from the combustionchambers and top of the pistons.Use a straightedge and feeler gauge to check the flatness ofthe cylinder head and block mating surfaces. Refer to 4.0LEngine Specifications, ‘Engine Assembly’ section of thischapter, for more information.

4.0L POWER TECH IN-LINE 6 (CYLINDER HEAD) 1658. To ensure engine gasket sealing, proper surfacepreparation must be performed, especially with the useof aluminum engine components and multi-layer steelcylinder head gaskets.9.NEVER use the following to clean gasket surfaces:A metal scraperAn abrasive pad or paper8 A high speed power tool or wire brushNote: Multi-Layer Steel (MLS) head gaskets require ascratch-free sealing surface.ONLY use the following for cleaning gasket surfaces:Mopar Brake and Parts Cleaner (or equivalent)8The latest tech trend in Stock and Super Stock racing isto “cc” the ports - both intake and exhaust. This isn’t atechnique to increase performance; rather, it’s ameasurement technique used by the NHRA and IHRAat the tech barn. They have a cc number for the portvolume and your cylinder heads will be checkedagainst that number.InstallationA plastic or wood scraperIf the cylinder head is to be replaced and the original valvesused, measure the valve stem diameter. Only standard sizevalves can be used with a service replacement cylinder headunless the replacement head valve stem guide bores arereamed to accommodate oversize valve stems. Remove allcarbon buildup and reface the valves. Refer to Valve Refacing,‘Camshaft and Valve Gear’ section for the proper procedure.Install the valves in the cylinder head using replacementvalve stem oil seals (Figure 4-17). There are markingson the top of the seals indicating intake valve (INT) orexhaust valve (EXH). Refer to Valve and Valve SpringRemoval and Installation, ‘Camshaft and Valve Gear’section of this chapter for the proper procedures.Transfer all attached components from the originalcylinder head that are not included with thereplacement head. DO NOT install the temperaturesending unit until coolant is installed. This permitstrapped air to escape from the cylinder block and head.Refer to the service manual for the proper procedure.Caution: DO NOT apply sealing compound on thecylinder head and block gasket surfaces. DO NOTallow sealing compound to enter the cylinder bore.Coat the cylinder bores with clean engine oil.4. Install the cylinder head. Tighten the bolts in sequence(Figure 4- 18) as follows:5.6.7.POSITION1,4,5,12,138,9Caution: Cylinder head bolts should be reused onlyonce. Replace head bolts if they have either a paint dabon the top of the bolt, or it is unknown if they werepreviously used.a. Coat the threads of the stud bolt in the No. 11position with Loctite 592 sealant, or equivalent,before installation.b. Tighten all cylinder head bolts to 29 Nom (22 ft-lbs)torque using the tightening sequence.c.d.e.Tighten all cylinder head bolts to 61 Nom (45 ft-lbs)torque using the tightening sequence.Recheck all cylinder head bolts at 61 Nom (45 ft-lbs)torque using the tightening sequence.Tighten all cylinder head bolts (except No. 11) to149 Nom (1 10 ft-lbs) torque, and tighten bolt No.11 to 135 Nom (100 ft-lbs) torque using thetightening sequence.Note: Clean and mark each bolt with a dab of paintafter tightening. Should you encounter a set of boltswhich were painted during an earlier servicingoperation, replace them!2,3,6,7,10,11,14Cylinder Head BoltsDESCRIPTION1/2 in.-13 BOLT1/2 in.-13 BOLT WITH DOWELPOINT1/2 in.-13 WITH 7/16 in.-14 STUDENDConnect the battery negative cable.Install the ignition coil and bracket assembly.Install the spark plugs and connect the ignition wires.Tighten the spark plugs to 37 Nom (27 ft-lbs) torque.8. Attach the air conditioner compressor mountingbracket to the cylinder head, if removed.9. Install the intake and exhaust manifolds. Use thecorrect tightening sequence. Refer to the servicemanual for the proper procedures.IO. Install the alternator bracket bolt on the head. Installthe alternator belt and adjust the tension.11. Install the power steering bracket and pump. Adjust thebelt tension. Refer to the service manual for drive belt(including serpentine) adjustment procedures.12. Install the pushrods in the order removed.

166 MOPAR PERFORMANCE PARTS13. Install the rocker arms and the bridge and pivotassemblies in the order removed. Loosely install thecapscrews for each bridge and tighten alternately oneturn at a time to avoid damaging the bridge. Tightenthe capscrews to 28.5 Nom (21 ft-lbs) torque.14. Install the cylinder head cover.15. Connect the hoses to the thermostat housing and fill thecooling system to the specified level. Refer to theservice manual for the proper procedure.16. The automatic transmission throttle linkage andcable must be adjusted after completing the cylinderhead installation. Refer to the service manual for theproper procedure.17. Install the temperature sending unit and connect thewire connector.18. Connect the fuel pipe and vacuum advance hose.Warning! Use extreme caution when the engine isoperating. DO NOT stand in direct line with the fan.DO NOT put hands near the pulleys, belts or fan. DONOT wear loose clothing.19. Operate the engine with the radiator cap off. Inspect forleaks and continue operating the engine until thethermostat opens. Add coolant, if required.20. Install the air cleaner.-FRONT___--- +--------*--- -/Figure 4 - 18--CYLINDER HEAD PERFORMANCE ANDASSEMBLY TIPSAlignment14J92W-38With the crankshaft and piston removed, check the alignmentof the combustion chamber over the cylinder bore. If it needsto be corrected, use offset dowel pins in the block.Piston-to-Head Clearance(Refer to Piston-to-Head Clearance, ‘Pistons and Rings’section of this chapter.)Oil RestrictionWe DO NOT recommend restricting oil to the cylinderheads. Leave all the passages stock size and be sure thatthey are unobstructed.Valve-to-Valve ClearanceValve-to-valve clearance is measured with both valves “onthe seat.” Being a wedge head design and having the valvesparallel allows this clearance to be minimum- around .020”to .030“. Check with your valve grinder to be sure. Formore information, refer to Valve Clearances, ‘Camshaftand Valve Gear’ section of this chapter.Measuring Cylinder Head Combustion ChamberVolumeCylinder head milling and cc’s are closely related and arevery important when blueprinting. Cylinder head cc’ing isthe volume of the combustion chamber in cubiccentimeters. Milling the head is to remove metal from thehead gasket surface to decrease the combustion chambervolume. This operation should only be done by anexperienced machine shop.EXHAUSTVALVEFigure 4 - 17. .,

T --nn4.0L POWER TECH IN-LINE 6 (CYLINDER HEAD) 167After grinding valve seats, it is recommended that theactual volume of the combustion chambers be measured.The seats need to be ground to get them to the final heightand to be sure that they’ll seal. Measuring the volume canbe done by placing the head, chambers up, on a levelsurface. Valves should be in place and spark plugs shouldbe threaded all the way in. Coat the area around thechamber being measured with light grease to provide a seal,then place a piece of Plexiglas over the chamber.The Plexiglas should have a hole in it large enough topermit the entry of the checking fluid and the exit of air. Aburette, graduated in cubic centimeters with a capacity of atleast 100 cc, makes an excellent checking vessel. Plainwater, colored with a touch of Mercurochrome (to make iteasier to read) may be used as a checking fluid.Fill the chamber with fluid; make sure all air is out of thechamber and that the chamber is completely full; then readthe volume on the burette. If the volume is too large, thecompression ratio will be less than specified and thevolume will have to be reduced. This can be done byreferring to the individual engine specification to determinehow much will have to be milled from the head surface toreduce it to the desired number of cubic centimeters. DONOT reduce below the specified minimum and DO NOT,under any circumstances, sink the valves in an attempt toequalize chamber volumes. Sinking the valves disturbs theair flow characteristics of the valve port and seat with asubsequent horsepower loss. Sharp edges and burrs shouldbe removed from any area in the combustion chamber toprevent hot spots that could cause detonation or preignition.Be sure to write all your measurements down.Block-to-Head DistortionBlock-to-head distortion is a concern anytime the head hasbeen removed. Even just taking it off to put a new headgasket on will allow it to distort. Also, the length of themotor in conjunction with a cast iron cylinder head actuallydistorts the block. Because of this, the re-application of thehead is very critical. If it’s not done using a specifictechnique, the distortion between the block and head will bedifferent from when it was manufactured.There are many reasons why distortion occurs. When theengine is new it has bolts and holes that have never beenused. When the engine is being re-assembled, the head hasalready taken a heat set from being used. Even if you usenew bolts, you’re still threading them into used holes.There’s no way you can have the same torque value on areinstalled head as you do on a brand new build-up.Also, you have four bolt holes around each cylinder, whichis a fairly wide spread of bolts. Many V-8 engines have 5around each cylinder, but most 4 and 6 cylinder engineshave only four. So, because of the length of the engine,when you take a cast iron cylinder head and bolt it to the topof the block, it actually creates distortion on each of thehead bolts. And of course these bolts are connected to theblock and they go through to the main web, so they coulddistort the main web also.Because of this, any operation done to the block should useeither a honing plate (preferred) or an actual cylinder headmounted on to the block (not a simulated cylinder head, buta specially modified one to accept clearance of the boring barand the hone so you or your machinelrace shop can bore andhone through the bottom of the block with the cylinder headactually mounted on it). Also, any work that is done to themain web and bores should be done with either a honingplate or specially modified cylinder head bolted on the block.This technique was originally used on In-Line 6 cylinderengines (because of their length), but is now recommendedfor all engines. This technique is so reliable and there havebeen so few problems with distortion that almost all raceteams use it on every engine they build. The only procedureyou wouldn’t have the head bolted on for is to cut the deckof the block.It’s attention to details such as this that makes theperformance difference!

168 MOPAR PERFORMANCE PARTSSpring Seats and Valve GuidesWe typically discuss big camshafts in simple terms. We talkabout valve springs, retainers, pushrods, and tappets.Hidden in all this is the assumption that you can physicallylift the valve as high as the camshaft selected dictates. Thevalve spring is specially selected, based on the lift of thecamshaft and the manufacturer’s recommendations. Onceyou’ve made that choice, what else could there be? Thereare two basic problems - spring seats and valve guides.With hydraulic camshafts the valve guide is the mainproblem. With stock heads, if the camshaft has more thanSOO” lift, the valve guide will have to be shortened. This iscaused by inadequate keeper-to-guide clearance atmaximum camshaft lift. As a general rule, it’s always agood idea to check this clearance anytime a higher liftcamshaft is installed.With high lift mechanical camshafts, the racer usuallyinstalls dual springs. Dual springs typically require theinner spring seat to be “cutdown” even with the outerspring seat. Dual springs can also cause a related problemwith the guide. The inner spring in a dual spring has asubstantially smaller inside diameter than that of a stockspring. This may require the outside diameter of the guideto be reduced.To increase installed height, the spring seat may be milleddown a maximum of .050”; however, this should NOT bedone unless all other methods of increasing the installedheight have already been used.Diagnosing Valve Seat Insert FailuresCast iron heads have the valve seats machined directly intothe cast iron. Although you can use a valve seat insert in acast iron head, it is usually done only as a repair. Valve seatinsert failures in cast iron heads are not very common. In aregular cast iron head, the valve seat doesn’t tend to “fail,”but it can wear out.Valve seat inserts are used in almost all aluminum heads. Itis common to use a different material for intake and exhaustseat inserts.Seat inserts take a lot of abuse. Certainly, seat inserts arenot very exciting and probably are not noticed in a casuallook at a head. In a cast iron head, it can be almostimpossible to tell if it has inserts or not; it is much easier totell in aluminum because of the slight difference in color ofthe two materials. Inserts tend to be made out of a specialcast iron, or in some cases, beryllium-copper. They are verystrong and are designed to work in high temperatures.These valve seat inserts are “pressed” into the aluminumhead. There are different techniques that use liquid nitrogen“cooling” of the seat with a mild heating of the aluminumhead. It is all calculated to give a specific “press” into thehead. Once installed, it isn’t going to come out unlesssomething changes -a failure.A common mistake made during an aluminum cylinderhead failure analysis is to notice a valve seat insert missingand assume that the insert failed. Usually, this is the wrongassumption !Under normal operation, it is pretty hard to fail a seat insert.This is not to say that you can’t break a seat insert. Toanalyze a seat failure, it is best to start with as many factsas possible. One of the problems is that there is probablyvery little left of the seat insert itself. There may be six orsix hundred pieces. In an aluminum head, if you fail oneseat, you will probably fail two in the same cylinder- intakeand exhaust. In an oval track head, it is very common to seeboth seats “fail” at once.If you see that both seats are gone, what do you thinkfailed? Both inserts fell out at the same time? Not toolikely! Whether you see one or two inserts missing, the bestbet is that the seat insert did not fail first. However, becauseit is gone, the most popular guess is that it failed. But if itdidnl’t fail, what happened?Although not common anymore, a seat insert can fall out.For it to fall out, it must not have had enough press on it atinstallation. If this is true, then it will fall out almostimmediately. However, an improper installation is morelikely than not to be caught by the head assembler when theheads are being put together.Once it gets past the first thermal cycle or two, the onlyknown cause of seat insert failure is heat. If the engine getstoo hot, the seat takes a real beating.If we get past the mistakes category and can rule out toomuch heat, the best bet is that the valve is hitting the seatinsert at an angle. You could call this a “bent valve,” but itmay not be bent very much or it may not be as bent like youwould think. It may also be caused by foreign materialgetting between the valve and the seat insert. Once thevalve and piston strike the seat insert like a ball-peenhammer, it will crack. From there it is only a very short timebefore a second crack appears, a third, etc. Once crackedthrough, the insert loses its press and a small piece cancome out. As soon as the first small piece is out, then theyare all going to come out and crack into more pieces,leaving you with one seat insert hole and lots of littlepieces. As soon as the first insert is gone, its mate willquickly follow because it now takes all the abuse eventhough it was not part of the first failure. Both seat insertsgone. The cylinder head will also be a mess. Summary?Head failure - not very likely. Insert failure - not too likely.Valve failure - very likely. Bent valve - most likely. Foreignmaterial -maybe. Valve gear-possible (more facts orobservations required to rule this out).

4.0L POWER TECH IN-LINE 6 (CYLINDER HEAD) 169Aluminum Head ThreadsRacers are familiar with cast iron cylinder heads and intakemanifolds. These cast iron parts may be heavy, but they arestrong and durable. For performance purposes we typicallyreplace the cast iron intake manifold with an aluminum one.You probably don’t take any special precautions with thesemanifolds. This could start causing problems because youshould be more careful with aluminum threads than you arewith cast iron threads. You may have developed some badhabits with cast iron parts that are going to cause you tocross-thread, strip, or pull threads out of aluminum heads.For example, if the intake manifold doesn’t fit, you can’tjust use the intake manifold bolts to “pull” it into place. Youmust be careful with any screw or bolt that is threaded intoaluminum. You should also use hardened washers betweenthe head of the bolt and the aluminum part. This isespecially true of head bolts. Although not mandatory, itwill make the heads last longer. It also helps the boltkrewretain its torque. Torque sequences and specificationsshould always be followed exactly.Hardened Washer SetsFor use with head bolts and main cap bolts.P4 120456P4 120457P4 120458WeepingComprised of (20) - 3/8” washers.Comprised of (20) - 7/16“ washers.Comprised of (20) - 1/2” washers.This is one of those titles that is very misleading. On thesurface you might think that we are going to talk aboutbroken engines or other “sad” times. Actually, weepingrefers to slow gasket leaks.All engines have weeping problems. How much depends ontheir use and how much strain they are under. Mostprofessional engine builders have found solutions toweeping they apply to every engine they build. Before weget into the fixes, let’s define the problem a little betterbefore we assume that it’s something that it isn’t and jumpin the wrong direction!A gasket is designed to seal two surfaces or parts together.For example, a head gasket is designed to seal the cylinderhead to the block. The intake manifold gasket is designed toseal the intake manifold to the cylinder head. In either case,there are at least two aspects to this “sealing” problem. Forexample, the head gasket must seal the compression that isbuilt up in the cylinder. It must also seal the water betweenthe head and the block. Although you might think the toughproblem is sealing the compression and that sealing thewater is easy, the reverse is probably more common. Today,this water sealing problem is most commonly seen asweeping. Many years ago (back in the 1950s and 1960s),this situation was probably reversed and sealing thecompression was the more difficult problem. Gaskettechnology has come a long way. However, when buildingor rebuilding engines, there are several gasket installationtips you should follow. Some are common to all engines,and some are unique to the type of engine being built.Some high performance race engines use an O-ring and acopper gasket. It is common to use copper gaskets onaluminum heads. Copper gaskets like to weep, so you mustfollow the gasket manufacturer’s instructions “to-theletter.”If not, the engine will leak water!One tip common to all engines is to put the gasket that isgoing to be used on the engine block to be sure thateverything “lines up.” Be sure that this check is done with thegasket in the “top” position. In many cases you will noticethat this check will show certain holes in the block that arenot in the gasket. This has to do with water flow and “steam”holes. Each gasket design may be different in this aspect.The next thing to check with the gasket on the block is thewater sealing around the water holes that go through thedeck surface. Each hole in the deck should be ringed with asealing lip or bead. Larger water holes are especiallyimportant. In some engines, the water holes are very largeand the gasket may overhang the holes. The gasketoverhang itself is not a problem, but if the bead gets closeto the edge of the water hole then it will probably weep. Thesolution, if observed, is to ring the hole with a small beadof RTV on the top and bottom sides of the gasket. Big waterholes that are cast into the block’s deck surface are hard tocontrol because they are not generally machined surfaces. Ifin doubt. add RTV.

, .170 MOPAR PERFORMANCE PARTSPORTED CYLINDER HEADUsing ported cylinder heads is a very popular way ofincreasing an engine’s performance. However, ported headsaren’t cheap. At this point, think how much you’d pay forported heads for your race engine. Write it down nowbefore reading the rest of this section.Ported heads could be worth 20 to 50 hp more than standardheads. But, unlike camshafts and valves, you can’t put aspecification on a ported head to tell how good it is. Acamshaft has lift and a valve has diameter, both of whichyou can use as guides. Ported heads are more related to“who did them.” Visual inspections don’t seem to help.“Pretty ones” may not make any power at all, or they maybe great. Even cost isn’t a good guide. You can take yourheads to a porting service and be charged $500 to $5,000,or even more depending upon how much work is done. Justspending a lot of money on heads doesn’t mean that theywill go fast. You can say that if you want better headsthey’ll cost you more, but the total dollars spent in relationto value isn’t totally reliable.There are some pretty straightforward reasons for this.First, ported heads are all hand labor. The fancier you get,the longer it takes. Extra time costs extra money. You alsohave to factor in flow bench time and the knowledge of“where-the-thin-spots-are.” If you port your own heads(cast iron), it’s a good bet that you’ll ruin at least one headby breaking through into the waterjacket. A porting servicewill usually take one head and cut it up to find where thethin spots are before porting the actual set. All of this has tobe factored into the price.The performance that ported heads offer varies a lot. If youdo your own you might be looking at 5-15 hp. An econoporting service could give 15 to 25 hp. New ported headscould yield between 35 and 55 hp. The performance gainslook good, but let’s look at price.Ported head assemblies can cost as much as $900 to $1,200each. On the surface this sounds like a lot. Looking at thepower numbers, getting a higher output, higher quality piecemay be worth the extra money. In truth, it’s a much betterdeai than that. With a porting service, you provide the headcasting (probably used), valves, etc. With a new ported headassembly, you receive it fully assembled - valves, springs,retainers, and new castings. A new casting costs as much as$350. This again sounds high, but there are a couple tricks.First, this is a new head casting-not used or rebuilt! Second,you can get a used casting for half this price, but you’ll haveto install bronzewall guides and regrind the seats before youget a good head. The problem is that horsepower potential isdirectly proportional to the number of valve jobs done on thehead. In other words, the more valve jobs done, the lesspower the engine makes. A new casting has the absoluteminimum number of valve jobs-one.Now, if you add $300 (on the average) for new valves, springs,retainers, seals and locks, add the cost of the new casting(about $350) and the porting costs (on average, $1 50 - $200 forone head), you could wind up spending $1,000 - $1,250 for arace prepared head. However, a new ported head assemblytypically costs between $900 - $1,200, and comes fullyassembled with hrund new parts. Often times, a new portedhead assembly is the best deal. Cost vs. perjhnance is the key.Do your homework first and then decide where best to spendyour money.Swirl PortsThe term “swirl port” was introduced in 1986-87 and waspopularized by the press and racers. We use it in our MopurPerformance Parts Catalog relative to many of ourcylinder head castings. Many standard production cylinderheads have swirl ports and they have a swirl port intakeshape. Their ports were designed using swirl porttechmology. All these statements are true. The confusionseems to come in relative to the combustion chamber shape.There are many wedge-shaped combustion chambers andit’s (difficult to put them into specific categories. One of thelatest is the heart-shaped chamber. The term was first usedby us in reference to our small block 3 I8 V-8 ‘A’ engineswirl-port head (approximately 1986-87 production). Thisseerns to be where the tie-in comes. Since the 3 18 had bothswirl ports and a heart-shaped chamber, some peopleassumed that the chamber was the “swirl.” It wasn’t!The press (primarily performance magazines) hasn’t helpedthe situation. They tend to misuse the term “swirl” inarticles on horsepower development, cylinder heads andairflow. This isn’t totally the fault of the press. Racers alsotendl to misuse the term. Since it (swirl) is the latest “trick,”every racer has swirl heads. This all leads to confusion. Totry and clarify this situation, we’ll need to back up and givean explanation based on technology rather than “hype.”..T - -Tri

-1174.0L POWER TECH IN-LINE 6 (CYLINDER HEAD) 171First, let’s define “swirl.” In its simplest sense, swirl is howthe air flow enters the combustion chamber. In a moretechnical sense, swirl is the flow around the center of thecylinder (as viewed from the top). A problem arises fromtrying to attach the definition of swirl to a shape. Forexample, the 318 ‘A’ engine swirl port (intake) is tall andslunny. However, there are tall, skinny ports that don’tswirl. There are also square and round ports that do.In practice, the press and racers seem to use a differentdefinition for swirl. They don’t write it down or explain itthis way, but their usage would imply that swirl means highflow! This isn’t technically correct, so Mopar PerformanceParts will stay away from it. Just realize that in pressarticles if you see “swirl” written, just substitute the termhigh flow and you should have a better understanding ofwhat is being reported.Remember, today’s engines are compromises. Theproduction compromise relative to heads is higher flow,improved output, better emissions, more fuel economy, and(the latest) less noise. Swirl became an important designfactor in cylinder heads because auto manufacturers werelooking to improve emissions. The emissions-improvingswirl port led to higher flow which led to better output andmore fuel economy. However, many swirl port designs canlead to less output, so it’s up to the racerlengineer to pickthe best one for his application.PortingThe most important part of the port is the bowl areabetween the valve seat and the radius on the floor, Blendingthe machined bottom cut into the cast surface gives a largeincrease in port flow. If you use porting templates, DONOT remove more metal than is required to fit thetemplates. Excess metal remova 1, especially on the floor,can cause very poor flow.For all-out modified racing, a professional porting serviceshould be contracted.Flow BenchStated simply, a flow bench is an air pump that allows you tomeasure the amount of air that passes through a given orifice.Flowing cylinder heads is what most flow benches are usedfor, and to this end they can provide very useful data. To aporting service professional a flow bench can be invaluable.It’s unrealistic for one racer to own a flow bench to flowone cylinder head. Flow bench services are offered bymany speed shops. The problem comes in relative to theaverage racer. He may want his head “flowed” because thepros do it. Unfortunately, the engine isn’t going to go anyfaster with a “flowed’ head unless some modification isdone. Having the flow chart is interesting, but in high gearit’s no match for oversize valves or a bracket valve job.

172 MOPAR PERFORMANCE PARTSWhere flow benches become very useful is in makingmodifications to cylinder heads. How big a valve to install?What shape to make the port? Valve seat angles? All portsflowing equally? Obviously, these are questions theprofessional cylinder head service needs answered. Once heknows the answers, the racer is paying for modifications tothe head, not the flow chart. As a racer, don’t end up racingflow benches!As a general rule, don’t flow your cylinder head unless theshop is making a change or modification to the head andyou want to see the resulting gain. Also, don’t get intoabsolute number comparisons. A flow bench is only a tool.As a tool it’s helpful in making modifications, but it’s hardto turn a flow bench into a race vehicle!Evaluating Cylinder Head Air FlowCylinder head air flow is a popular topic because it isgenerally believed that more air flow leads to more power.Although this is true in some cases, there are manyexceptions. The purpose of this discussion is to give yousome tips that will help you evaluate cylinder head air flow.First, let’s look at the current situation. All racers want toknow how much air their heads flow, and then they will tellyou their heads flow “X” cfm. That’s it! All racers seem touse this “one number system” to discuss their heads.Although this seems quite simple, it can lead to muchconfusion. So let’s clarify a few things before we move on.The one number system assumes that the number is the“peak number” for the intake port of the head. Although nopressure drop is typically mentioned, you can probablyassume that it is 28 inches. (Although many people actuallyflow at pressure drops of 3, 10, or 25 inches, 28 gives youthe biggest number, so that has become the “standard.”)There is a chart that allows you to use a correction factor tocorrect flow data from one pressure drop to another. Sincedifferent flow benches DO NOT give the same flownumbers for the same head, we recommend you not get toohung-up on absolute numbers and try to do all your flowtesting on the same flow bench. This tip really relates to theflow bench itself. For now we will assume that you have aflow curve comparison and want to figure out which curveis best. Let’s look at some typical flow curves.In Figure 4- 19 you see the typical flow curve of an intake port.In 1 his curve, we are comparing cylinder head “A” to cylinderhead “B.” This is somewhat typical of a standard productionhead being compared to a race head. Head “A” is obviouslybetter. It has more “area under the curve.” It outflows head“B” at both high lift and low lift. This one is too easy!Figure 4-20 is perhaps more common. In this example, head“B” flows 290 cfm (peak) and head “A” flows 285 cfm(peak). In this case, head “B” has the higher number or betterpeak flow. However, head “A” has more area under thecurve. Area under the curve is the area formed by the X-axis(or valve lift line) and the flow curve line for the head. In thiscase, head “B” only exceeds head “A” at one point (.700“lift), while head “A’ wins at .300”, .400”, and S00” lifts.To evaluate area under the curve properly, you have to dosome calculating. However, the performance press hasn’tyet come up with a common, acceptable-to-all formula forcalculating area under the curve, and there are no readilyavailable numbers for what this “area” is supposed to be.No one gives “area” numbers. However, area under thecurve is what you really what to know! In our example,head “A” will win. It will make the vehicle quicker at thedrag strip and it will make more power on the dyno.Now let’s back up. Let’s assume you have been using head“A” on your current race engine and you bought head “B”because it flowed more air. Figure 4-20 shows “B” with 290cfm at peak, so it does flow more air. You install this newhead and your vehicle goes slower. Now you are probablyupset! Statements like “high flow heads don’t work,” “bigports go slow,” etc., are made. But high flow heads dowork - if they are done like head “A”.

4.0L POWER TECH IN-LINE 6 (CYLINDER HEAD) 173Heads must have more area under the curve if they aregoing to work in a drag or oval track vehicle; that is, nreounder the curve is more important than peakjow. Otheritems such as big intake ports are harder to tie to specificflow characteristics. If head “A” has bigger ports, then theywork. Bigger valves and bigger ports generally help thehigh lift part of the curve. However, some big ports helpboth ends of the curve.In Figure 4-21, we have another common flow curve. Thisis typical of a head that has been ported, or one that had bigvalves installed. Head “A” is assumed to be a big valve,ported version of head “B”. Head “A” has more area underthe curve and has more peak flow. Now let’s assume thatyou are building (choosing) this head for a dual purposeapplication and you are only using a .425“ lift hydrauliccamshaft. Remember that .425” is a design number and ouractual rocker ratio may be 1.46, rather than 1.50 (forexample). Plus we have deflections and geometry toconsider. So the at-the-valve lift may be closer to ,410“. Atthe .410” lift point on the flow curve it looks like a tie. Ifthat were true, then head “B” should be the “winner”because it is less expensive for the same performance.Now let’s go back to Figure 4-19. If you again restrict thevalve lift to .410”, head “A” still wins. It still has more areaunder the curve than head “B” and has more peak flow. It isimportant to note that just because you restrict the valve liftthat is being used, you DO NOT always change which headis the better choice.If you installed head “A” from Figure 4-19 on your raceengine, it would make more power than head “B” whetheryou used a .700” or a .600” lift camshaft. Actually, the powercurves would look very similar to the flow curves. Thismeans that a dyno power curve would show head “A”making more power at each rpm greater than the torque peak.Now, assuming that you have a race engine and have usedtypical race engine parts (4-Bbl. carburetor, non-restrictiveexhaust system, etc.), we’ll assume that the head “A” powerpeak is 700 hp at 7,500 rpm. If you restrict the rpm to 5,000,head “A” still makes more power. Because head “A” flowsso much more air, you could say it is a high rpm head. Thatis true, but it also makes more power at lower rpm. Now ifyou switched to the heads in Figure 4-20, the more yourestricted head “A’, the greater the winning margin. Thisgets us back to the area under the curve.A cylinder head selected by the area under the curvemethod will generally win. Since this is so important inmaking the right selection for a race vehicle (and findingthe area is not easy), we have a short-cut method. Comparethe flow rates at a point that is half your actual peak valvelift. For example, if you are going to use a camshaft that hasan actual valve lift of .700”, then look at the flow rates at.350’ lift. If you are going to use a .600” lift camshaft, thencompare them at .300” lift. Remember this half lift numberis more important than the peak lift number in making yourselection. This number is considered your mid-lift flow andis the most important number on the flow chart! If you hurtthis number, you will probably slow the vehicle down.So far we have only discussed the intake side. This will alsoget us into trouble. Having a good intake side with a badexhaust side will also make the vehicle go slower.However, because the exhaust side always has a smallerpeak number, everyone only talks about the intake side. Theexhaust side is certainly just as important. You would liketo have the exhaust side flow about 80 percent of the intake,although this tends to be an ideal since few exhaust portsare actually this good. (Production heads tend to run about65 percent.) If you have a good exhaust port, then you cantrade some of its performance for more on the intake side.At this point you could have good intake ports but badexhaust ports, so now which head would you pick? This isa much more complicated question! There is no singleanswer. Remember Figure 4-20. The best choice was theone that had the best area under the curve. A complete headcomparison gives you two port areas to consider, thereforeyou also have two mid-lift flow points to consider.

--r n174 MOPAR PERFORMANCE PARTSIf they all point in the same direction, you have a winner! Ifthey don’t (which is more likely), you have to makechoices. Pick the best intake based on area and the bestexhaust based on area or mid-lift flow. Multiply the intake’speak flow by .80 and compare to that head’s exhaust flow.For example, in Figure 4-20, head “A” was selected as thebetter head and it had a peak flow of 285. The 80 percentnumber would be 228 for the exhaust side on this head. The70 percent number would be 200 cfm. You would want theactual exhaust flow to be between 200-228 cfm.I Air Flow - cimTYPICAL AIR FLOWIntake PovtIf you had two heads that both flowed 285 cfm on the intakeside, then the head that flows better up to the 80 percentnumber on the exhaust side is the best choice. This soundslike it’s easy to get to 80 percent on the exhaust side.Nothing could be further from the truth. Remember, theexhaust side gets the smaller valve. The typical productionvalve area comparison between intake and exhaust valvediameters gives the exhaust valve 65-70 percent of the areaof the intake. To get 80 percent flow out of a valve area thatis 30-35 percent smaller means the exhaust port has toactually be a better flowing port than the intake.Putting in bigger exhaust valves will limit the size of valvewe can put on the intake side. That is why the exhaust sideis so important. You want to get the flow out of the portitself, not out of a bigger valve.L50’Air Flow - cfrnI I I I I1W 200 300 400 500 600 700Valve LiftFigure 4 - 20TYPICAL AIR FLOWIntake PortLir Flow - cfmTYPICAL AIR FLOWIntake Port50 -’I I I I I I100 200 300 400 500 600 700Valve LiftI I I I 1 I I100 200 300 400 500 600 701Valve LiftFigure 4 - 19Figure 4 - 21Oversize Valve Seats and GuidesIn some cases, cylinder head porting has to be done tochange some design characteristic of the head. In othercases, it must be done because heads are worn-out or havebecome damaged due to a bent valve, etc. In a cast ironhead, the seats and guides are machined directly into thecast iron. There is no seat or guide insert. (There areinstances where inserts are used in cast iron heads, but thistends to be the exception.)

4.0L POWER TECH IN-LINE 6 (CYLINDER HEAD) 175In aluminum heads, the seats and guides are always inserts.The insert (seat or guide) must be “pressed” into thematerial of the cylinder head. The amount of “press” iscalled the interference fit because the insert itself is actuallylarger than the machined hole into which it goes. Theamount of press is measured in thousandths of an inch(.001”). On a given part it may be ,002’’ or .003”. The trickcomes when you remove a seat or guide. You cannot put inthe same size that you just took out. You must use anoversize seat or guide. The inside diameter can be the samesize if desired, but the outside diameter has to be larger.When you remove a seat or guide, the hole left is slightlylarger than before and it may not be perfectly roundanymore. The same size seat or guide installed in this largerhole will have less press than before, or perhaps no press atall. This means the seat or guide can “fall out” or break (asit falls out). It would be bad for the head in either case!This situation is somewhat like honing the block. When were-hone it, the bores will actually become larger(oversized). Therefore, once you remove a seat or guide,you MUST install an oversize part as the replacement. Ifthe head has been repaired or modified already, then youmust move up to the next size oversize. Each oversize partrequires that the head be machined (sized) properly prior toinstallation. At this point, the head is only as good as themachine shop that did the work.Cleaning and InspectionReplace the cover if it is cracked or damaged in any way. Ifthe pre-cured RTV seal is damaged, replace the cover.If a replacement cover is installed, transfer the PCV valvegrommet and oil filler cap from the original cover to thereplacement cover.Remove any original sealer from the cover sealing surfaceof the cylinder head and clean the surface using a fabriccleaner. Remove all residue from the sealing surface usinga clean, dry cloth.Installation1. Clean the cover and cylinder head sealing surfaceusing a clean dry cloth.2. Install the cover and retaining bolts. Tighten theretaining bolts to specification.3.4.Install the cruise control servo (if removed).Install the PCV molded hoses to the cylinder head cover.CRUISECONTROL.SERVOCYLINDER HEAD COVERCrankcase BreatherA universal high performance re-usable crankcase breather(must have stand pipe on valve cover). Washes clean withP4.529392 cleaning fluid for extra miles of service.P4529394Crankcase breather.CYLINDERHEADCOVERRemoval1. Remove PCV molded hoses from the cover (Figure 4-22).2. Remove the cruise control servo, if equipped(Figure 4-22).3.Remove cylinder head cover retaining bolts.14.Lift and remove the cover. The cylinder head coverutilizes a pre-cured RTV sealer that is attached to thecover. Inspect the sealer for cracks and/or damage thatmay have occurred during removal.HOSE-1805. Small cracks in the sealer are allowed and can berepaired by applying RTV sealer to the cracked areabefore cylinder head cover installation.Figure 4 - 22

8. .~~176 MOPAR PERFORMANCE PARTSCAMSHAFTCamshaft and Valve GearThe 4.0L engine camshaft is made of cast iron with twelvemachined lobes and four bearing journals. The camshafthas intake and exhaust valve lifts of 10.29 mm (0.405"),intake and exhaust cam lobe lifts of 6.43 mm (0.253"), andintake and exhaust durations of 270".For racers, choosing the correct camshaft to match thecompression and carburetion of the engine is the most criticalperformance area to consider. The "3 C's" of engine building(compression, carburetion, and camshaft) must always bedecided upon before the engine is built or, more importantly,money is spent. In fact, one of the most common errorsamong racers is to choose a "hot" camshaft withoutconsidering the compression ratio and carburetion set-up tobe used, all of which must work in complete harmony for theengine to perform at its peak level at all times.The racer's camshaft choice will also dictate the rest of thevalve gear. The important areas in camshaft and valve gearare profile selected by application, installation centerline,clearances (especially valve-to-piston and clearance at coilbind), and valve spring loads. We'll cover these items inlater sections.IJeep Gear DrivesReplace conventional Jeep timing chain and gear sets andelinlinate chain induced cam timing fluctuations with thisMopar Performance Parts dual idler gear drive camshaftcenterlining drive system. Rugged and durable for off-roadapplications. Fits all 4.0L, 4.2L, and 2.5L Jeep engines.P5249009Camshaft Bearing SetJeep gear drives.Made of production material. Complete engine set forJeep 2.5L and 4.0L engines.P4529226Camshaft bearing set.Jeep 4.0L Hydraulic Camshaft Specifications ChartI I I I I I I IIMild Comp.P4.529229 2481248" 108" Mild Comp.P4.529230 2561256" 40" 108" Mild Comn.Jeep 4.0L Hydraulic Camshaft Application IChartPerformance Best Choice Street RodPhase I P4.529228Phase I1P4.529229 P4529229Phase I11P4529230P4529229

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 177CAMSHAFT SELECTIONThere are literally thousands of camshaft designs to choosefrom. Picking the correct one for you and your enginewithout spending too much money is a very tough job.Selecting the type of camshaft (hydraulic, mechanical,roller) is usually the hardest job.Keep in mind that these basic decisions should be made beforeyou go to the track, while you're building the engine. Oncebuilt, the engine will dictate many of the cam's characteristics.Thls choice does affect the valve-to-piston clearance.The easiest way to identify the type of camshaft is bylift-each category has a lift range in which it works best.LlFT TYPE COMMENTS0-,520'' Hydraulic Low maintenance,inexpensive,simplest installation and setup..490-.620" Mechanical Higher rpm, simple..620-.700" Mechanical- High output without roller'sMushroom expense..600-.750" Roller Ultimate power, mostexpensive, most complicated,highest maintenance.The preceding chart can be used to generalize your camshaftselection, although there is some overlap as well as somespecial considerations. It is very general. Your choice maybe already made for you by your local race sanctioning body(check the rule book). Roller and mushroom camshafts arecommonly ruled "out," and sometimes camshafts are limitedto any hydraulic or any flat-tappet.Racing Camshaft SelectionIn mid-race season, many racers are looking to upgradetheir engine's performance. The camshaft is one part that isoften changed. The question is, what direction to go? Toanswer this, we have to back up to how we made ouroriginal or existing choice. To this end, let's review somegeneral selections.A camshaft can be selected by knowing the performancelevel desired for the vehicle and track-type. This is the bestway to select a camshaft, but we have to know how fast thevehicle is going to go. As we're building the engine andselecting our initial camshaft, this performance estimate issomewhat of a guess. Once we've run the engine at thetrack, we can improve upon this guess.Camshafts can be selected based on many different aspects.The best sources of information for selecting camshafts areas follows, listed in order of importance:Dyno curve-in vehicle testThis book0 Camshaft liftOverlapAdvertised durationDuration at fiftyWe hope you will read this entire book to gain as muchknowledge as you can. But say you need more informationto narrow your choice. Now what do you do? Camshaftspecifications can be used to indicate some engineperformance characteristics and potential. Although not asgood or reliable as actual tests, camshaft specifications canindicate trends in an engine's performance. Let's look at thevarious specifications in order of importance.1. LiftHas a direct effect on power, especially under .600".More lift, more power (less torque).2. OverlapAffects idle quality and driveability.3. DurationNot too useful in general. For lifts under .600", theadvertised duration can be useful as long as all thecamshafts being considered are from the samemanufacturer. If more than one manufacturer isinvolved, go back to lift. Duration at fifty (.OSO") isuseful in hard core, all-out race camshafts andcamshafts with lifts over .600".Studying this list closely you'll notice that, of all the camshaftspecifications available, lift is the one to use if test results orMopar Performance Parts recommendations are not available.

178 MOPAR PERFORMANCE PARTSCAMSHAFT REMOVAL AND INSTALLATIONPROCEDURESRemovalWarning! The coolant in a recently operated engine is hotand pressurized. Release the pressure before removing thedraincock, cap, and drain plugs.1.2.Disconnect the battery negative cable.Drain the cooling system. DO NOT waste reusablecoolant. If the solution is clean, drain it into a cleancontainer for reuse.3. Remove the radiator. Refer to the service manual forthe proper procedure.4. Remove the air conditioner condenser andreceiveddrier assembly as a charged unit, if equipped.Refer to the service manual for additional informationpertaining to the A/C system.5. Remove the distributor cap and mark the position ofthe rotor.6. Remove the distributor and ignition wires.7. Remove the front fasciahumper andor grille, as required.8. Disconnect camshaft position sensor electricalconnector and remove camshaft position sensor (ifequipped).9. Remove the cylinder head cover. Refer to CylinderHead Cover Removal, ‘Cylinder Head’ section of thischapter, for the procedure.10. Remove the capscrews, bridge and pivot assembliesand rocker arms. Alternately loosen each capscrew oneturn at a time to avoid damaging the bridges.11. Remove the pushrods. Position all components on aworkbench in the same order as removed to facilitateinstallation at the original locations.12. Remove the cylinder head and gasket. Refer toCylinder Head Removal, ‘Cylinder Head’ section ofthis chapter, for the procedure.13. Remove the hydraulic valve tappets.14. Remove the vibration damper. Refer to VibrationDamper Removal, ‘Crankshaft’ section of this chapter,for the procedure.15. Remove the timing case cover. Refer to the properservice manual for the procedure.16. Remove the timing chain and sprockets. Refer to theproper service manual for the procedure.17. Remove the two thrust plate retaining screws andthrust plate (if equipped).18. Remove the camshaft.InspectionI.2.3.4.5.Inspect the cam lobes for wear.Inspect the bearing journals for uneven wear patternor finish.Inspect the bearings for wear.Inspect the distributor drive gear for wear.If the camshaft appears to have been rubbing againstthe timing case cover or the camshaft thrust surfaceappears to have excessive wear, examine the oilpressure relief holes in the rear cam journal to ensurethat they are free of debris.Installation1.2.3.4.5.6.7.8. Install the vibration damper.9. Install the damper pulley, if removed.10. Install the fan assembly and shroud.11. Install the dnve belt(s) and tighten to the specified tension.Refer to the proper service manual for the procedure.12.13.Lubricate the camshaft with Mopar Engine OilSupplement, or equivalent.Carefully install the camshaft to prevent damage to thecamshaft bearings.If equipped, position camshaft thrust plate and installretaining screws. Tighten screws to 24 Nmm (18 ft-lbs).Install the timing chain, crankshaft sprocket andcamshaft sprocket with the timing marks aligned.Refer to the proper service manual for the procedure.Install the camshaft sprocket retaining bolt and tightento specified torque (varies by year-refer to properservice manual for correct torque specification).Install the crankshaft oil slinger.Install the timing case cover with a replacement oil seal.Refer to the proper service manual for the procedure.Rotate the crankshaft until the No. 1 piston is at theTDC position on the compression stroke.Install the distributor, cap and ignition wires. Install thedistributor so that the rotor is aligned with the mark madeduring removal. The rotor should be aligned with the No.1 cylinder spark plug terminal on the cap when thedistributor housing is fully seated on the cylinder block.14. Install the hydraulic valve tappets.Note: Lubricate the hydraulic valve tappets and allvalve actuating components with Mopar Engine OilSupplement, or equivalent, during installation. MoparEngine Oil Supplement must remain with the engine oilfor at least 1,609 km (1,000 miles); However, it does nothave to be drained until the next scheduled oil change.

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 17915. Install the cylinder head. Refer to Cylinder HeadInstallation, ‘Cylinder Head’ section of this chapter forthe procedure.16. Install the pushrods.17. Install the rocker arms and pivot and bridgeassemblies. Tighten each of the two capscrews for eachbridge alternately one turn at a time to avoid damagingthe bridge.18. Install the cylinder head cover. Refer to Cylinder HeadCover Installation, ‘Cylinder Head’ section of thischapter for the procedure.19. Install the A/C condenser and receiveddrier assembly,if equipped. Refer to the service manual for additionalinformation pertaining to the A/C system.Caution: Both service valves must be opened beforethe air conditioning system is operated.20. Install the radiator, connect the hoses and fill thecooling system to the specified level. Refer to theservice manual for the proper procedure.21. Check the ignition timing and adjust as necessary.22, Install the grille and bumper, if removed.23. Connect the battery negative cable.CAMSHAFT INSTALLATION TIPS1.2.3.4.5.When installing the camshaft sprocket, use at leastGrade 8 bolts with Loctite and safety wire. It ispossible for high speed engine harmonics to causethese bolts to loosen if precautions aren’t taken. (Notrequired while centerlining the camshaft.)Because of the production tolerances mentionedearlier, it is possible for the crankshaft-to-camshaftrelation to be several degrees off, either advanced orretarded. It is important that this timing be correct toproduce maximum performance.While the engine is still without heads, the timing markson the crankshaft damper and the timing chain covershould be checked for accuracy of the “0” TDC mark.Advancing or retarding a camshaft should only be doneto install the camshaft at its designed centerline. It isvery important to have the centerline correct. Mostcamshafts will have the design centerline stated as partof the specifications along with duration and lift. If itisn’t given, it can be calculated. Advancing orretarding a camshaft from its designed centerline is notrecommended because it will cut down on the overallefficiency of the engine (although there are exceptionsto this general rule).Before installation, the camshaft and tappets should beliberally coated with Mopar Engine Oil Supplement.This lubricant will stick to the surface without drainingoff and will prevent scuffing when the engine is firedup for the first time. It has been determined that this iswhen most camshaft damage takes place.7 7 TT-

180 MOPAR PERFORMANCE PARTSCAMSHAFT INSTALLATION TROUBLESHOOTINGFor a performance enthusiast and an engine builder,installing a camshaft is one of the most common operations.Camshafts are changed frequently and for many reasons.It’s just about the most popular thing to do to an engine.We have discussed how to centerline your camshaft formany years. We put the instructions on the back of ourdegree wheel (P4452990). We put the instructions on theback of every camshaft card that goes into every camshaftpackage we sell. We recommend that you use the camshaftcenterline method when installing the camshaft. We explainwhat this method is and how to do it. (You need two tools:and degree wheel and a dial indicator.) Getting the camshaftinto the block is NOT the problem. The problem comeswhen we attach it to the crankshaft. This is why we talkabout “centerline” (the relationship between the crankshaftand the camshaft).In the past few years we have learned that there are noproblems with the camshaft. There are no problems withthe instructions. Problems typically occur because theinstructions “were lost.” Another problem is using the “notools” approach (no degree wheel or dial indicator). Badplan! A degree wheel is very inexpensive and very easy toobtain. Dial indicators can be borrowed or rented.Here are some simple guidelines you should always followwhenever possible:1. Always centerline the camshaft.2. If you are not going to use a degree wheel and dialindicator, DO NOT use multi-keyed sprockets orsprockets with offset bushings. If you already have amulti-keyed sprocket or offset bushing camshaftsprocket, then get a new sprocket set.3.With a stock, single key sprocket, line up the dots asbest you can.4. If the engine runs poorly, DO NOT blame thecamshaft. Obtain a degree wheel and a dial indicatorand find the actual TDC and camshaft centerline. Formore information, refer to Cumshufi Centerline, laterin this section.SPECIAL CAMSHAFT THEORIESCamshaft DurationWe have all discussed camshaft duration at one time oranother. Duration is commonly used to describe any givencamshaft. “It’s a 280 degree camshaft,” is a typicalstatement. In the past, we have discussed duration relativeto using it as the method by which to choose a camshaft.The conclusion was that duration is the poorestspecification to use for selection purposes. Lift is the mostvaluable camshaft specification.Then we have “duration at 50.” This is commonly used inreference to race and other aftermarket camshafts.Production camshafts use an “advertised duration” to referto their camshafts. Advertised duration is also used by allthe aftermarket camshaft grinders for virtually allcamshafts with less than .600” to .650” lift (at the valve).This is beginning to get confusing! We have more durationsthan we know what to do with. So to this end, let’s see whatwe really know about duration. First, duration is measuredin degrees. Second, camshaft duration is generally anumber that’s greater than zero but less than 360. Third,there are two crank degrees for each camshaft degree. (Tosimplify, we’ll consider everything in crank degrees.)This duration topic isn’t as easy as you probably thought!With our camshaft selection hanging in the balance, let’sexamine a typical camshaft card and see if we can gathersome more data. An aftermarket camshaft card will listinformation similar to the following: lift, advertisedduration, duration at 50 (.050”), overlap, centerline, intakeopening, intake closing, exhaust opening, exhaust closing,and valve spring requirements.Intake and exhaust opening and closing points are givenin degrees. These four numbers are generally consideredthe events.Ovevlup is the relation between the intake and exhaustlobes, and centerline is the relation of the intake lobes toTDC (top dead center) or to the exhaust lobe. In either case,although they are both measured in degrees, neither overlapnor centerline is specifically “duration.”To help define duration, let’s focus on the intake lobe (wecould have selected the exhaust lobe). Looking only at theintake lobe, one of the unique features of duration becomesobvious; that is, the sum of the intake opening, the intakeclosing, plus 180, equals the duration. Therefore, if theintake opens at 30 degrees BTDC (before top dead center)and closes at 50 degrees ATDC (after top dead center), thenthe duration is 260 degrees (30 + 50 + 180 = 260).[IITIntake Duration = 1.0. + I.C. + 180The same basic equation also works for the exhaust side:Exhaust Duration = E.O. + E.C. + 180What’s different about the exhaust lobe is when the eventoccurs; for example, the exhaust opens BBDC (beforebottom dead center) and the exhaust closes ATDC. (Referto Figure 4-23.)r --Tn

- n ri4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 181Looking at Figure 4-23, we can see the layout (plot) of atypical camshaft with the intake and exhaust lobes shown.You can tell it's a fairly mild camshaft because it has justunder ,300" lift (.450" at the valve). This plot shows theoverlap and centerline relationships to TDC, but we'reconcerned with duration.In simple form, duration is the width of the "hump" of thebell-shaped curve at a given lift point. The further up(height) you go from the "zero" lift line, the narrower thecurve gets. To explain, draw a straight line from the .100"lift mark on the left. Where this line intersects the curvegives us the timing events. (Refer to Figure 4-24.)On the exhaust lobe, these points are E.O. = 30 BBDC andE.C. = 30 BTDC. Applying a little math we find that thislobe's duration at .100" is 180 degrees. Drawing a similarline from the .0S0" lift mark yields these events: E.O. = 40BBDC and E.C. = 20 BTDC. Therefore, duration at 50(.OSOll) = 200.This comparison shows the many aspects of duration. It canbe measured at any lift that you'd like. It could be .020",.050", . 100", or any other number. The duration at .020" islarger than the duration at ,050". The duration at .050" islarger than the duration at .100".Advertised duration is a little more complicated. It isgenerally measured between zero lift and .025" lift.However, it is not a constant. Different manufacturers usedifferent numbers. Generally, this number is determined bythe computer software that generates the curve (i.e., lifttable). Since most aftermarket and OE manufacturers usesomewhat different computer software programs, theadvertised duration number comes out different even if theactual profiles are the same. Generally, the advertisedduration is larger than the duration at .050".Going back to our earlier discussion, intake and exhaustopening and closing event numbers aren't the samebetween advertised and .050" duration numbers. However,most aftermarket manufacturers are consistent with theirnumbers; for example, 1.0. at 30 degrees and .050". Ifyou're not sure, simply add the numbers for the events andcompare to the two duration numbers.We hope this helps you to understand duration and whythere are so many duration numbers. However, always keepin mind that duration is not as good as lift for comparing orselecting camshafts.I1EXHAUSTFigure 4 - 23EXHAUSTCamshaft CenterlineFigure 4 - 24INTAKEINTAKEThere are three ways of checking a camshaft for correctinstallation. A common method is to "line-up-the-dots.''This is acceptable for standard vehicles, but is notrecommended for performance camshafts. A secondmethod, recommended by many shops and some camshaftgrinders, is to check the intake and exhaust valve openingand closing events against TDC (top dead center). This isbetter than the "dots" system, but we don't feel it's asaccurate as the "centerline" method. The centerline methodis also much easier to understand.

*I182 MOPAR PERFORMANCE PARTSIf you're going to swap camshafts, you've spent goodmoney for a new camshaft and you want to improve on thestock one or whatever is currently in the engine. If you DONOT centerline, then you DO NOT get the full value ofyour investment and you probably won't achieve thedesired improvement. Once the engine is disassembled tothe point of installing the camshaft, centerlining thecamshaft costs very little and only takes a few minutes todo. If you have a problem with the engine's performanceafter assembly, you will ultimately need to centerline thecamshaft. Centerlining may be a minor problem of a fewdegrees or a major problem of a tooth or two on thecamshaft sprocket. Usually the problem isn't with thecamshaft itself, except relating to installation; i.e.,centerline. By centerlining the camshaft at installation, youcan concentrate on carburetors, ignition, and assemblyproblems (such as gasket leaks) to identify any problem.But if you didn't centerline the camshaft, you can't say forsure that it is the carburetor, ignition, etc. To centerline thecamshaft with the engine together requires partialdisassembly. This is a lot of extra work. One added benefitof centerlining relates to advancing or retarding thecamshaft for improved performance. You don't knowwhich direction or the number of degrees to change if youdon't know the original centerline first.Note: When checking camshaft centerline, ALWAYSrotate the engine clockwise from the front. This is thenormal direction of engine rotation. By rotating the enginein this manner, the clearances in the camshaft drive system(chain, sprockets, keys, etc.) will be taken up just as theyare when the engine is firing, and your measured camshaftcenterline will be what the engine sees when it is firing.The procedure is as follows:With the camshaft in place, insert the intake valvetappet for the No. 1 cylinder.Place a dial indicator on the tappet parallel to the tappetcenterline or on the retainer parallel to the valve centerline.Install a degree wheel (P4452990) so its pointerindicates TDC when the No. 1 piston is at TDC.Turn the engine over (clockwise from the front) untilthe dial indicator is at maximum camshaft lift. Zero theindicator at this point.Turn the engine over (clockwise from the front) untilthe indicator reads .025" before reaching maximumlift. Stop. Read the degree wheel and write down thenumber of degrees. Continue rotating the engine in thesame direction (clockwise) past maximum lift (zeroindicator reading) until .025" is read again on theindicator. Stop. Read the degree wheel. Write it down.Add the two degree wheel readings and divide by two.The answer is the camshaft centerline.Note: The .025" was used for illustration. Anymeasurement above .020" is acceptable.Example: Let's assume that you are going to use acamshaft with a centerline of 110". Now let's go throughthe installation procedure with this camshaft. We'll installthis 110" camshaft at 108" centerline.The camshaft and timing chain or gear drive are installed.The lifter is installed on the No. 1 intake lobe. The degreewheel is bolted to the crankshaft and set to read TDCcorrectly with a pointer. The dial indicator is zeroed at themaximum lift of the camshaft. Now, rotate the engineclockwise and approach the indicator reading of .020"carefully, since you must not reverse the direction ofrotation. At .020" the degree wheel reads 90". Record thereading and continue to rotate the engine clockwise throughzero until the indicator reads .020". The degree wheel nowreads 134". Add 90" plus 134" and divide by two. Answer:112". Thus, you must advance the camshaft 4" in order tohave the centerline at 108". Offset bushings (P3690936) areused for this purpose. (360 AMC V-8 engines use offsetkeys.) Use the proper offset bushing (or key) so that thecenterline of the camshaft is moved forward (advanced) inthe direction of its rotation.Now repeat the steps with the advanced camshaft position.You should read 86" at .020" before maximum lift on theindicator and 130" at ,020" after maximum on the indicator.Add 86" to 130". Answer 2 16". Divide this by two. Answer108". The camshaft is now installed correctly. If ,040" wasselected instead of .020" for the indicator reading, the laststep would be as follows. You would read 70" at .040"befoire maximum lift and 146" at ,040" after maximum lift.The two numbers added together yield 216" and thisdivided by two gives 108".Note: Changing the camshaft centerline 1in engine performance.will not be seenIf you DO NOT have a degreed damper, damper degreetiming tape (P4.529070) is recommended.Damper Degree Timing TapeImprove timing accuracy of your engine with this timing tapepackage. Marked in 90" increments. Self-adhesive stripadheres to crankshaft vibration damper for clear identificationof marks. Permits initial total spark advance up to 60" insteadof only 10"-15" as on chain case timing tab. Works on all 7-1 /4" diameter non-grooved vibration dampers.P4.529070 Damper degree timing tape.TDC Indicator ToolThis is a handy, positive-stop tool for determining exactTop Dead Center (TDC) when centerlining camshafts.This tool, of hardened steel, is extremely accurate and canbe used on all DaimlerChrysler engines. It takes theguesswork out of finding TDC.P434'3737TDC indicator tool.

-1n4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 183I. Degree WheelsBuilding a new engine (or rebuilding an old one)typically means installing a camshaft or checkingthings such as TDC and camshaft centerline. Theseoperations will require a degree wheel to do accurately.The most popular use of degree wheels is forcenterlining camshafts. Secondary uses related to TDCand setting valve lash are very straightforward and tendto use the "0' position, or TDC, and the point 180degrees from zero; that is, there are no calculations.However, calculations are required to find the camshaftcenterline. This brought about a unique feature of theMopar Performance Parts degree wheel (P4452990).Most degree wheels on the market are numbered 0-90-0-90-0. The Mopar Performance Parts degree wheel is0-90-180-90-0. The reason for this is camshaftcenterlining. A typical camshaft centerline is 108degrees. On the ordinary degree wheel, the actualposition is 18 degrees past the 90 degree point, or anactual degree wheel reading of 72 degrees. Confused?Confusion on this is very common and is another placefor errors, which you don't want when you're installingthe camshaft. The Mopar Performance Parts degreewheel will read 108 degrees directly. Also, using .035"below maximum lift as the measuring point, the typicalcenterline measurements of 70 degrees and 146degrees (that is, 70 + 146 = 216 +- 2 = 108) will readdirectly. This feature should make camshaftcenterlining easier to understand and execute correctly.The Mopar Performance Parts degree wheel also hasinstructions printed on the back side.That doesn't look too tough-right? For fun, let's runthrough the same measurements using a non-MoparPerformance Parts degree wheel. The first measurementwill stay the same at 70. But the second measurementwill now be 34 degrees on the 0-90-0-90-0 style wheel.Now what do you do? Add the two readings and divideby two. That gives 104 divided by two, which is 52. Butwe know that the correct centerline is 108 degrees.Confusing, isn't it? Now you can see some of theadvantages of the 0-90- 180-90-0 Mopar PerformanceParts degree wheel.Degree WheelDurable Mopar Performance Parts aluminum plate, 0"-90-180"-90-0" degree wheel for centerlining camshafts.Features step-by-step installation instructions printed onback side.P4452990Degree wheel.

184 MOPAR PERFORMANCE PARTS2. OKwt Curnshufi BushingsWe have our engine built and we’re off racing. We nowfind some little problems. The vehicle doesn’t launchas hard as we though it would! Maybe the camshaft istoo big or at least seems to be! Now what do we do?The usual solution to these problems is to change thecamshaft centerline. This is physically accomplishedby using an offset camshaft device.Once the camshaft manufacturer machines the driveend of the camshaft, the “straight-up” position can’t beeasily changed. You can always have the problem ofbeing a “tooth off,” but that’s an installation mistake.We’ll assume that we centerlined the camshaftproperly and everything is where the manufacturerrecommends it. As mentioned, after we run the vehiclewe may find that we want to change the centerline(advance or retard) to improve the performance of ourspecific package. There are two basic methods: offsetkeys and offset bushings.Jeep 4.0L and 2.SL engines use offset bushings. (The360 AMC V-8 uses offset keys.) The relationship ofthe camshaft drive to the camshaft is controlled by adowel pin in the end of the camshaft. This dowel pinfits into a hole in the camshaft sprocket and properlylocates the camshaft. If you want to change thisrelationship you use an offset bushing. To do this youdrill out the sprocket hole to the outside diameter of thebushing and insert the bushing into this hole. Theinside diameter of the bushing fits over the dowel pin.With this system you do need a zero offset bushing toget back to standard. These offset bushings come inpackage P3690936.Camshaft Offset Bushing SetFor centerlining camshafts, all engines. Includes fivebushings: 2, 4, 6, and 8 degree offset, plus one on-centerbushing. Installs in camshaft sprocket. For all Jeep 4.0Land 2.SL engines.P3690936Camshaft offset bushing set.Calculating Duration at FiftyMany engine wizards and scientists discuss camshafts interms of “duration at fifty” (actually .OSO” or fiftythousandths). This is acceptable for roller/race camshaftswith lifts over .620” andor advertised durations over 320degrees. For hydraulic and small mechanical camshafts ithas little value and, if used, will almost surely lead toselecting the wrong camshaft. As a camshaft selectionspecification, it rates last! It can be very valuable for racecamshafts, but small camshafts are better off using lift andadvertised duration, or even overlap.All this aside, some racers still want to know what theduration at fifty is. We haven’t published it because it has novalue and will lead the racer to select the wrong camshaft.However, in an effort to satisfy the “scientist” in all racers,we’rl- going to give you an equation that you can use tocalculate the duration at fifty for our various small camshafts.(It does not apply to camshafts with over ,620” lift.)To calculate the duration at fifty number for a productioncamshaft, you multiply the advertised duration by .777. For aMopar Performance Parts camshaft you multiply theadvertised duration by .8SO. For example, a productioncamshaft with an advertised duration of 260 degrees has acalculated duration at fifty of 202 degrees. Keep in mind thatif you use this information to select a camshaft for your engineyou are almost guaranteed to get the wrong one! Thisinformation is “for reference only,” as they say in engineering!Base CircleThe term “base circle” describes one of the characteristicsof camshafts. Because the base circle does not directlycontribute to the horsepower potential of thecamshafvengine combination, it is a term that isn’t wellknownor understood. Duration, lift, and overlap are the“popular” terms.In reality, the tappet (cam follower) spends more time on thecam’s base circle than it does lifting the valve. Also,whenever you discuss camshaft lift or lobe lift, you areindirectly discussing the base circle. The nose height ormaximum lift of the camshaft lobe/profile is generallyunderstood and can be pointed out on an actual camshaft to abeginning “student” by most of us “knowledgeable racers.”The base circle is located 180” (or the opposite side) fromthe nose of the camshaft. The lobe lift or camshaft lift isdefined as the difference between the nose height and thebase circle.Let’s look at several examples of how to use the cam’sbase circle.First let’s look at a 300 degree duration camshaft(advertised, not at .OSOl’). We know that the camshaftrotates at 1/2 the crankshaft speed, or that the crankshaftrotates twice for one revolution of the camshaft. Camshaftduration numbers are given in crankshaft degrees. Thismeans that our 300 crankshaft degree camshaft really has alobe that extends around the camshaft for 150 degrees (300divided by 2). Since a full circle has 360 degrees, the basecircle on our 300 degree camshaft extends for 210 degrees(360- 150). Miscellaneous trivia: the 210 degree base circleis larger than the 150 degree camshaft lobe profile that liftsor opens the valve.*.r --n TT

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 185Second, the base circle is measured as a "height" ordistance from the center of camshaft. On a typical V-8camshaft (for example) this height might be ,750". If thiscamshaft had a lobe lift of .333" (valve lift of SOO"), thenthe nose height would be 1.083'' (.750 + 333). This heightwould also be measured from the center of the camshaft.The important thing to remember is that the nose heightbasically doesn't change for any given engine. The basecircle has to change from one lift profile to another.This oddity of the nose height staying constant and the basecircle changing is caused by a special physical condition inoverhead valve engines. The nose of the camshaft must fit inthrough the camshaft bearings in which the camshaft journalsride. This essentially defines the maximum height of the noseof the camshaft. If the nose height were any higher, itcouldn't be installed through the camshaft bearings. (This isnot a problem on overhead camshaft engines.)Question: If the nose of the camshaft can't be increased,then how are higher lift profiles made? Answer: Bygrinding down the base circle. There really isn't any otherchoice. This may sound bad for high lift camshafts, buteven a ,750" lift, all-out race hydraulic camshaft onlyrequires the base circle to be actually "cut-down" .160"from a SOO" lift.There is one small error in this discussion that can lead toconfusion. We converted our 300 degree camshaft(advertised) to 150 camshaft degrees and compared it to the210 degree base circle. A 300 degree camshaft is typical ofhigh performance hydraulic or a mild mechanical camshaft.However, we left something out to simplify the discussion.We left off the ramps!Although not the same, hydraulic and mechanicalcamshafts both have ramps. Ramps are defined anddesigned differently by different manufacturers and fordifferent applications. They could run 20 to 30 degrees perside which adds to the cam's physical duration andincreases it to 170-180 degrees. This makes the base circleand the "lift" profile itself almost equal in duration. Thissounds like a small detail, but it should not be passed overtoo quickly. Remember, our example is basically a mild,high performance hydraulic design, perhaps 235-240"duration at .050".Many people in the field like to check the cam's lift outsideof the engine by using a dial vernier (or micrometer) andmeasuring across the nose and across the flanks (sides).Actually, they measure from the base circle to the nose ofthe camshaft. In our example, this measurement would be1.833" (1.083 + .750). In theory, the steps of measuringacross the sides would measure from base circle to basecircle. In our example, this would yield 1.500" (.750 +.750). If we subtracted these two numbers, we'd get thecam's lobe lift (1.833 - 1.500 = ,333"). Numbers cun bemagic! Nice theory, and it actually works well on stockcamshafts. However, in high performance designs, we havea small "built-in" error.In the second measurement (across-the-sides), we actuallymeasure from ramp to ramp. By nature, the ramp moves orlifts slowly so we may only be picking up .010" per side forthe ramp lift. In more radical camshafts, this number getsmuch higher. In our mild example, the .010" ramp errorwould mean that we measured from .760" (.750 + .010) to,760 or a total measurement of 1.520". Now this doesn'tseem like much of an error, so why the big fuss?The problem comes about relative to the camshaft liftcalculation. In our example, we'd now incorrectly calculatethat the cam's lift is ,313" (1.833" - 1.520"). Still not surewhy so small an error is important? The whole reason formaking these measurements is to identify the camshaft. Inmany cases, we don't know what the actual lift is. We aretrying to use the actual, measured lift to identify thecamshaft. Therefore, we'd multiply the measured camshaftlift by 1.5, and find that the camshaft has .470" (.313 x 1.5)of valve lift. Comparing this to a camshaft lift table, we'dpickhdentify the wrong camshaft.Note: Always measure a performance or race camshaftwith a micrometer to ensure accuracy.VALVE GEARThis section is designed to tie all the valve gear informationfor the 4.0L Power Tech engine together in one place. Thevalve gear - especially camshaft and valve spring selectionand their effect upon the remaining components -is one ofthe most important areas in the performance of your enginenext to the induction system. The valve train area has beenexpanding rapidly in recent years which has led to a lot ofconfusion. Deciding what piece to use, where and withwhat other parts has become very complicated. Add to thisthe similar parts available from Mopar Performance Parts,Crane, Competition Cams, Isky, etc., and it becomes almosthopeless to sort it all out.In this chapter we will concentrate on the 4.0L Power Techengine which is a wedge. We will stay strictly in the valvetrain area. Related subjects and areas such as engineblueprinting and individual engine part numbers andspecifics are covered in separate sections.Some of the information that will be covered has beenstated in other sections of this book. Valves, cylinder heads,and camshafts are closely related areas, and much of theinformation overlaps. We will put all this currentlypublished information together in this section. We'll alsoadd some new parts, part numbers and information thathave become available, but things are changing quickly.Please keep in mind that the information gathered in thissection contains the latest recommendations and that other(older) sources may differ.T-1 n

186 MOPAR PERFORMANCE PARTSGeneral Valve GearWe will begin by familiarizing ourselves with the generalvalve gear or valve train system. Valve gear is generallydivided into two separate groups: hydraulic and mechanical.Hydraulic Valve GeurThe hydraulic valve gear is usually production orstandard on any particular engine (such as the 4.0L).The parts that are unique to the hydraulic valve gearare the stamped steel rocker arm, the double-malepushrod and the hydraulic lifter.Jeeps have a unique hydraulic valve gear arrangementthat could be considered a ball stud valve geararrangement. Though not to a great extent, this ballstud valve gear allows Jeeps to have some adjustmentin the valve gear via the unique twin rockerlpushrodarrangement.Mechanical Valve GearThe second group of valve gear is generally lumpedtogether under the “mechanical” heading. It could alsobe called adjustable valve gear because the majorvisual difference of this group is the adjustable rockerarm. This would be descriptive but somewhat of amisnomer since adjustable rocker arms can be usedwith a hydraulic camshaft. However, it is mandatorythat mechanical camshafts use adjustable rocker arms.Mechanical valve gear is also used with rollercamshafts.Valve Gear SelectionOnce the camshaft and valve spring are selected, the rest ofthe valve gear can be selected. The camshaft, whetherhydraulic or mechanical, will select the lifter, pushrod androcker arm. The valve spring will dictate the valve seal. Theonly independent left is the valve. This is also selected byapplication. (Refer to Vulves, later in this section, forcomplete information.)Note: The full valve gear must be considered if thecamshaft is to be changed. Whether the camshaft is to bechanged or not is left up to the individual to decide.VALVE GEAR PERFORMANCE AND ASSEMBLYTIPS1. If mushroom lifters are to be used, install them andcheck to see that they all hit the surface which youground evenly on the bottom of the lifter bore. Thereshould be no high spots. Also, check for clearance tothe camshaft bearing shell. Grind clearance notch inthe camshaft bearing where required.2.3.4.5.6.If roller lifters are to be used, the bar (or other locatingdevice) should be checked for block clearance afterinstallation. Some roller lifter setups require blockgrinding to allow the two lifters and bar locator to goup and down freely.’Valves should be measured to be sure they are theproper size and should be inspected for flaws or otherdamage. Measure the actual outside diameter of thevalves to be used and record the information.Valve springs should be load checked. Weak ones willhave to be replaced. Record loads and height checked at.Note: Not all spring testers are the same. Many are notmaintained and calibrated on a frequent basis. Thismakes the absolute value oT spring loads quiteunreliable. However it is a very good comparative tool;i.e., measuring all springs on the same tester ormeasuring the same spring new and used. The biggeradvantage of load checking is to see if the springs have“gone away” or to see if a second set of the same springis as “strong” as the first set which worked well.With the valves, keepers and retainers installed, checkthe valve spring height. This should be compared to thespring load information and the correct thickness shimchosen to get the same installed spring load on eachvalve. Spring installed height must be carefullycontrolled to avoid “coil bind” by providing at least.loo“ more height at maximum valve lift than the solidheight of the spring.With the same spring height setup as #S, measure theouter valve spring height, the inner valve spring height,and the keeper-to-valve guide clearance. The camshaftlift (lift of the camshaft measured at the lobe or lifter)cnultiplied by the rocker arm ratio plus .OSO” should beless than the keeper-to-guide clearance in the valveclosed position or the guide will have to be shortened.h4easure the “solid height” of both the inner and outersprings. This solid height plus .loo” plus the valve lift(‘camshaft lift multiplied by the rocker arm ratio)should be equal to or less than the installed height foreach spring.

4.OL POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 18713. The proper adjustment (ideal) for a mechanical rockeradjusting screw is to have only one thread showingbelow the rocker arm with the valve lash set properly(two may be OK, three shaky, etc., but high rpm makesonly one thread showing more desirable). Thisobviously requires custom length pushrods for everyengine. If you’ve “smoked” your pushrods and you hadall the threads showing below the rocker (i.e., pushrodis too short), more oil to the valve gear won’t cure theproblem. Only longer pushrods will do the job.14. Write down all rneasureinents made.SPECIAL VALVE GEAR THEORIES7. Check rocker arm-to-valve tip relationship foralignment. Improper alignment can place undue sideloads on valves, causing rapid valve guide wear.8.9.Check valve tip for scuffing or high wear.Check the pushrods for straightness and for length. Ifthey are too short, they can’t be adjusted to workproperly. If they are too long, they will over-angle therocker arm and, with high lift camshafts, hit the bottomof the rocker.10. With the camshaft in the block and the head installed,the actual valve lift measured at the valve retainer canbe checked. The camshaft lift multiplied by the designrocker arm ratio should yield the valve lift. However,this is not the case in an actual engine. The actualrocker arm ratio will be less than the design rockerratio, which is typically 1.5 for wedge engines. Thiswill cause the valve lift to be less than the number thatis calculated. This is due to the rocker arm ratio itselfplus the effect of the geometry of the head.“Blueprinted” mechanical rocker arms (those with theexact design ratio) are available for most engines fromvarious high performance machine shops.11. With larger diameter valve springs and heavy dutymechanical pushrods used with high lift racingcamshafts, it is common to have to grind retainerclearance and pushrod cup clearance on the rocker arm.The resulting notch should be kept to an absoluteminimum because it weakens the rocker arm.12. To optimize rocker arm geometry, a cut-to-lengthpushrod kit is recommended, but only to the veryserious racer, or for engines with large amounts of headmilling and block decking. Custom pushrod lengths areused to obtain ideal rocker arm geometry which allowsthe best performance from a given camshaft.The valve gear is attached to the cylinder head and veryclosely related to it as part of the total performance team.There are several theories (engineering considerations)concerning the cylinder head-valve gear area that areinteresting to discuss. Since each theory could have its ownchapter, the discussion will be brief.Valve Gear OilingOiling the valve gear in a standard engine is virtuallyautomatic, as long as the engine has oil pressure. In amodified, high performance engine it can be another story.When recommendations are followed, most racers willhave no oiling problems. When oiling problems dodevelop, they generally manifest themselves as burnedrocker arms, broken pieces, etc. Unfortunately, the piecesthat look the worst aren’t usually the cause of the problem.In the majority of cases relating to valve gear oiling, it’s nota matter of what you should do, but what you should not do.The problems mentioned are the result of poor oiling,assuming the engine is being oiled properly; that is, nofoaming, correct oil pressure, etc.The first thing to check is to be sure a camshaft bearinghasn’t “turned” so that its oiling hole(s) aren’t lined up withthe hole(s) in the block. Next, be sure the passage from thecamshaft to the block’s deck isn’t blocked or restricted.This is usually done with a long handled bottle brush.At the deck surface of the block it is common for racers toinstall a restrictor. THIS IS NOT RECOMMENDED and, iffound, should be removed. If you have “smoked out” yourpushrods or scuffed the valve tips, this is probably thecause. Next, check the head gasket and cylinder head foroiling hole alignment.At this point you can have two different types of problemsdepending on whether your engine uses hydraulic rockers ormechanical rockers. A problem with hydraulics is most likelycaused by an oil leak that prevents the oil from reaching therockers. Spacers used between the rocker stand and the rockershaft will, over an extended period, cause these problems becauseof leakage. Also, the rocker shaft could be installed incorrectly(upside down, reversed, etc.). Adjustable hydraulic pushrods canhelp solve length problems with hydraulic valve gear.

188 MOPAR PERFORMANCE PARTSProblems occurring with mechanical rockers can be muchmore complicated. Since there is no need to put spacersbetween the rocker shaft and the pedestal, a leak there wouldbe unusual. Rocker shaft installation is very critical. Bananagrooves are usually added to mechanical valve gear shafts toimprove oiling of the rocker itself. Bushed rockers are moretolerant of low oil conditions, but standard mechanicalrockers should be adequate for most applications. At thispoint, with oil to the rocker, it must be distributed to thevalve tip and the pushrod tip. Accomplishing this is verytricky. Exactly where and how these holes are located is verycritical, and each engine is unique.Valve Train GeometryThe valve train is everything that connects the valve to thetappet. Valve truin geometry involves knowing where allthese parts are located and how they fit together. Geometryitself is not easy to explain, even if you have taken mathcourses in college. Understanding geometry and applying itto an engine is even more difficult to explain. Although it isquite complicated to work out, DaimlerChrysler/Moparvalve trains are well sorted-out systems, as are mostproduction systems.Weight is very important to ultimate engine speed as arevalve spring loads. Geometry itself can yield rpms with thesame valve spring loads.Valve train geometry directly affects valve train oiling which,in the long run, is the most important consideration. If thevalve gear doesn’t oil properly, you may smoke-out or bumthe pushrod ends, valve tips, etc. Titanium valves or increasedvalve spring pressure will not solve these problems.To help you, we have come up with several valve traingeometry “tips.” However, these tips are only to help youbuild your engine, they are not blueprinting (inspection)standards. Blueprinting standards apply to one part and oneaspect of that part. As you begin to put various parts together,you have a problem that is called “stack-up of tolerances.”Predicting, keeping track of, and controlling stack-up oftolerances is what good engine building is all about.As stated earlier, valve train geometry is related to howparts fit together and where they are located; for example,the number of adjuster threads showing below the rockerarm, or the valve tip-to-rocker arm relationship. Althoughthis may sound relatively straightforward, everythingaffects these relationships: the cylinder head, block,camshaft, valves, valve job, etc. Yes, you can make itperfect for each set of parts, but that would cost thousandsof dollars. And you wouldn‘t go any faster! However, thereare ways to cut down this expense.You could hand select the block, head, etc., but the bestsolution is to use cut-to-length pushrods. Custom cut-tolengthpushrods solve all these problems without all theexpense. Pre-made pushrods work fine but, if you want anexact relationship (geometry) between the rocker arm andthe adjusting screw, you’ll need a cut-to-length pushrod kit.The valve tip-to-rocker arm relationship isn’t as easy.Usually the factory set-up is close. Valve lift is a big factor.Valve lengths and valve jobs also make a big difference.The cylinder head must also be considered. A littlecompromise is best used here. If the rocker arm pad is onthe valve tip with the valve closed, and is still on the valvetip at maximum lift, consider yourself lucky. We don’trecommend cutting the valve tip for any reason. It willremove the hardness on the valve tip and make it soft. Withvery mild camshafts and soft springs, the problem may notbe as obvious, but it’s there!DynamicsDynamics is defined as the engine speed (rpm) potential ofa given camshaft profile when used with a specific valvespring and valve gear set-up.A high performance hydraulic camshaft in a 2-Bbl. enginemight have an ultimate engine speed of 6,400 rpm, but witha high performance spring the engine speed becomes 6,900rpm. Obviously a 2-Bbl. engine with a stock camshaft isn’tgoing to go 6,400, which means the valve gear is better thanthe rest of the engine pieces. This is strictly a valve geartest. In many cases the ultimate speed may be 7,500, butfalse motion may occur at 6,000 or 6,500. The engine willnot achieve the ultimate speed. In any case, the camshaftdictates the engine’s output, and a valve spring must bechosen that will allow the camshaft to do its job.A Super Stock engine might run 6,000 rpm while a LateModel engine might run 7,500 rpm-the same valve springcan’t be used even if the camshaft is the same.Concentration on ultimate speed can lead to overkill results.Note: Titanium valves are usually used to obtain ultimateengine speed, but this would be overkill in most cases.VALVESThe 4.0L Power Tech engine standard production valves aremade of heat resistant steel and have chrome plated stems toprevent scuffing. All valves use a three bead lock keeper toretaining the valve spring and promote valve rotation.The important considerations when choosing valves arediameter, length, stem size, weight, number of lock grooves(Figure 4-25) and valve head shape or profile (Figure 4-26).

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 189Jeep 4.0L Valve Specifications ChartPart Number Location Diameter Length Material ModificationP4529212 Intake std. Std. Std. Std. Back-cut, 8 mmP45292 13 Exhaust Std. Std. Std. Back-cut, 8 mmP5249875 Intake 1.92" 4.91" Stainless 8 mm stemP5249877 Intake 1.97" 4.9 1 " Stainless 8 mm stem-P.5249879 Exhaust 1.50" 4.93" Stainless 8 mm stemP5249880 Exhaust 1 S6" 4.93" Stainless 8 mm stemLength changes the installed spring height and rocker armgeometry. Stem size affects the guide. A smaller stem valvecan be installed in wedge heads by installing the proper sizevalve guides. Smaller stem valves are lighter. Less valveweight increases the engine speed with a given valve spring,but weaker valves break in expensive failures. Therefore,lightweight valves are made of stainless steel or titaniummaterial. Lock groove changes require new keepers.INTAKEVALVEFEXHAUSTVALVEThat leaves valve head diameter and profile. Valve headdiameter is selected by the performance desired as it isrelated to the other parts used. There are two basic valvehead profiles: tulip and nail-head. See Figure 4-26. Actualproduction valves are halfway in between.Wedge heads perform better with nail head valves. Theyalso perform better if the valve seat is high in the headmaking the valve sit high. Sinking wedge valves hurtsperformance. The valve job should be done with only theminimum amount of material removed. One of the bigperformance advantages to oversize valves is that the seatcan be brought up after it has been sunk by repeated valvejobs with the smaller valve. The valve tips should not beground to shorten them or to even them up because the tiphardness is removed. If they are ground or cut, the tipshould be rehardened or the valve tip will wear poorly andmushroom over.In high output race engines we highly recommend installingbronzewall valve guides. If the head to be raced is a usedpiece, bronzewall guides are almost mandatory. Once thebronzewall guides have been installed, the valves and seatscan be ground more accurately and held to closer tolerances(narrower seats, etc.) without sacrificing durability.VALVE SPRINGRETAINER LOCKGROOVESn. Figure 4 - 25Pwo6INail HeadFigure 4 - 26T -- -1 n

-7i-r190 MOPAR PERFORMANCE PARTSStainless Steel ValvesAfter much research Mopar Performance Parts hasintroduced a new line of swirl-polished, stainless steelvalves. Most wedge valves have a “ski jump” on theunderhead part of the valve, which was best removed bybackcutting. Our new valves DO NOT have this so you getbetter flow right out of the box! (Refer to Jeep Engine ValveSpecifications Chart for more information.)Better part, pay more money? Well, in this case MoparPerformance Parts was able to offer all these advantagesand take about $3 per valve out of the list price (and asimilar cut in the dealer price). That’s a price reduction ofapproximately 3 1 percent!Valve Grinding (Valve Job)It is very important that the following specifications aremet: both seat and face angles for intakes and exhausts are45”; seats should be .050” - .070“ wide and kept as close tothe outer edge of the valve as possible; seat approach angleis 70”. See Figure 4-27 for basic production valve job.1. Basic Pei$ormance Valve Job2.It is very important that the valve seat specificationsshown in Figure 4-28 be carefully followed. If valveface and seat run-out is less than .0015”, it is best toleave the seats alone until 50 to 75 hard runs have beenmade. Then, touch-up valves and seats according to thespecifications. Remember that the further the valveseats sink into the ports, the less horsepower the enginewill produce. Never sink valves to equalizecombustion chamber volume. DO NOT grind thevalves or valve seats excessively and DO NOT narrowthe valve seats below specifications. (See Figure 4-29.)NHRA Stock and Super Stock Valve JobFor a NHRA Stock or Super Stock valve job, thefollowing rules apply:The valve must be faced at factory specification angle,and the seat angle must also meet factoryspecifications. The valve seat may be narrowed fromthe top with any angle less than the seat angle, but notto exceed 1/4” larger than the valve head (see Figure 4-29). The seat may be narrowed from the bottom withup to a 70” angle. The maximum width for valve seatand bottom cut may not exceed 1/4“ when measuredtogether (top of seat to bottom of cut).3. Bracket Valve JobIn bracket racing there are no rules regarding valvework, so we can have a special bracket valve job,sometimes referred to as a competition valve job. Thevalve part is relatively easy. Production wedge valveshave a small ski-jump on their backside just below theseat itself. The back cut removes this (see Figure 4-30).Backcut angles vary from 20 to 35 degrees dependingon the engine. Backcutting the valve tends to make thevalve seat narrower, for which we strongly recommendthat bronzewall valve guides be installed in the head.Modification of the valve seat in the head is not as easyto explain. The valve seat itself is 45 degrees, standard.The throat (or approach) angle is 70 degrees, butsometimes 65 degrees is used because the orbitalgrinder used to grind the seats occasionally will“‘chatter” at 70. The 70 degree cut in the throat removesa lot of material, which leaves a sharp edge where thecut transfers to the “as cast” port. (See Figure 4-30 andFigure 4-3 1 .) This sharp edge should be removed verycarefully with a hand grinder so that it blends smoothlyinto both the cast port and the 70 degree machined cut.It is very important to keep to a minimum the metalremoved and to maintain the 70 degree cut, although itmay be narrower than it was originally. Extra cautionshould be used on the port’s “short side” to keep asmuch radius as possible.

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 191Ideal Valve Face And Seat Widths(Seat Should Center As NearAs Possibe On Valve Face):SeatExhaust .07Intake .05FaceIntake .09Exhaust .loSeat Reconditioning1. Grind Valve Faces and Seats to 45"(Runout Not To Exceed .002").2. Bottom Dress with 70" Stone.3. Top Dress with 15"for Light Reconditioning.w v" fi' 45"Figure 4 - 27AA-SEAT WIDTH (INTAKE 1/16 (1.587 mm) TO 3/32 (2.381 mm) INCHEXHAUST: (.080-.100 INCH) - (2-2.5 mm)B-FACE ANGLE (INTAKE & EXHAUST: 44M0-45')C-SEAT ANGLE (INTAKE & EXHAUST: 45"-4554?D-CONTACT SURFACEPU605Figure 4 - 28

--n il192 MOPAR PERFORMANCE PARTSNot over 1/4" larger than valve head114" MaximumFigure 4 - 29m Backcut Valve\ RemoveBACKCUT VALVECenterlinefl Open Up Throat Area 1SeatArea EnlargedFigure 4 - 31Valve TimingFigure 4 - 301.2.3.4.Disconnect spark plug wires and remove spark plugs.Remove the cylinder head cover. Refer to CylinderHead Cover Removal, 'Cylinder Head' section of thischapter, for the procedure.Remove the capscrews, bridge and pivot assembly, androcker arms from above the No. 1 cylinder. Alternatelyloosen each capscrew one turn at a time to avoiddamaging the bridge.Rotate the crankshaft until the No. 6 piston is at topdead center (TDC) on the compression stroke.

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 1935. Rotate the crankshaft counterclockwise (viewed fromthe front of the engine) 90”.6.7.8.9.Install a dial indicator on the end of the No. 1 cylinderintake valve pushrod. Use rubber tubing to secure theindicator stem on the pushrod.Set the dial indicator pointer at zero.Rotate the crankshaft clockwise (viewed from the frontof the engine) until the dial indicator pointer indicates0.305 mm (0.01 2”) travel distance (lift).The timing notch index on the vibration dampershould be aligned with the TDC mark on the timingdegree scale.If the timing notch is more than 13 mm (1/2”) awayfrom the TDC mark in either direction, the valvetiming is incorrect.If the valve timing is incorrect, the cause may be abroken camshaft pin. It is not necessary to replace thecamshaft because of pin failure. A spring pin isavailable for service replacement.Polished Valve StemsFor many years, we have told racers to polish their valvestems. This recommendation comes originally from Mr.Tom Hoover, generally accepted as the father of the 426Hemi. His quote was, “Like a mirror!” This process is quitesimple and doesn’t take very long. You start with verysmooth sand paper-400 to 800 grit. Then you move up tofiner cloths. Remember, you don’t want to remove anymaterial, you just want to make the stem smooth. You canstart the process by hand, but a drill press or similarmachine is generally used for the final polishing. Careshould be exercised to make sure that the valve is securelychucked in the drill press and at the same time no marks areleft in the valve stem by the drill press chuck jaws. Thisshould be done to every valve prior to installation.For most of us, this is just good engine building procedure.For some of us, it may reduce valve guide wear, increasecylinder head and engine durability, and reduce oilconsumption. In rare cases it even keeps valve guides frombeing destroyed, which would also destroy valve seatsresulting in a very expensive head repair or replacement.Valve Stem Lash CapsMopar Performance Parts valve stem lash caps have thefollowing features:Hardened steel for improved rocker tip durabilityFit between the end of the valve and the rocker arm tipLarger area than stock valve tip to help spread therocker loadsSold in sets of 16 pieces~-Valve Stem Lash CapsP4 120626P4 120635P45 29 83 9VALVE STEM OIL SEALSValve stem lash caps, 3/8“ stem.Valve stem lash caps, 5/16” stem.Valve stem lash caps, 11/32” stem.Most expensive, professional race car engines don’t usevalve stem oil seals because they are rebuilt after everyrace. For the rest nf us, valve stem oil seals are veryimportant. The 4.0L engine standard production valve stemoil seals are made of rubber and incorporate a garter springto maintain consistent lubrication control.Valve stem oil seals control oil flow down the valve stem.If they fail to do their job, oil will get into the combustionchamber. This will cause your oil consumption to go up. Oilis poor fuel, so burning it in the combustion chamber willlower the amount of heat made in the combustion cycle andtherefore lower the amount of power made. Oil is also apoor fuel in that it lowers the overall octane of the fuelmixture in the combustion chamber and can causedetonation problems. Detonation problems can lead tospark plug fouling, which may be misinterpreted as anignition problem.For anyone but the “pros,” a valve seal should be used. Thequestion is, which one? The keys to answering this questionare the valve spring and the camshaft.The best valve seal is the Mopar Performance Parts Vitonseal (P4529240). It is called an “umbrella” seal. It is madeof a special high temperature Viton rubber and slips overthe valve stem. The “umbrella” drops over the top of thevalve guide. This requires the inside diameter of the seal tobe larger than the outside diameter of the valve guide. Inthis manner, the seal shrouds the valve stem from the oil.However, the larger outside diameter of the seal means thatit can’t be used with dual valve springs.If you use dual valve springs, you have to use a PerfectCircle race seal. It attaches to the top of the valve guideitself. Therefore, the guide may have to be sized to get theseal to fit properly. Unlike the umbrella seal which movesup and down with the valve, the Perfect Circle race sealdoesn’t move. The valve stem slides by and the seal “wipesoff’ the oil. Since umbrella seal\ have no relativemovement to the valve stem, they are used in productionengines for maximum mileage/durability. The PerfectCircle seal is not used in production engines but isrecommended with dual springs.Valve stem size is the major determining factor whenselecting valve stem seals. All standard production 4.0Lvalves (including oversize) are 8 mm stem. For a singlespring with damper, use heavy duty Viton seals(P4529240). They work well for camshafts up to .5 10” lift.

194 MOPAR PERFORMANCE PARTSFor camshafts with more lift (over .510"), a dual spring isrequired. Viton seals can't be used with dual springsbecause there's not enough room; Perfect Circle seals(P3690963, P4876099, P4876100) must be used. They arenot as durable as Viton seals; however, with newbronzewall valve guides, they are acceptable.Replace valve stem oil seals whenever valve service isperformed or if the seals have deteriorated.Race Valve Stem Oil Seal SetsPerfect Circle valve stem oil seals for use with dual valvesprings in race applications. Set of 16 seals. Includesinstallation tool.P3690963 Race valve stem oil seal set, 3/8"inside diameter.P4876099P4876100Viton Valve Stem Oil Seal SetRace valve stem oil seal set, 11/32"inside diameter.Race valve stem oil seal set, 5/16" insidediameter.Viton heavy duty umbrella seals are specially designed towithstand high temperatures. Helps prevent oil seepagedown valve guides. Good for dual purpose highperformance engines. Includes 6 intake and 6 exhaustseals. Not recommended for dual valve springs. Fits 4.0Lengine valves with 8 mm stems only.P4529240VALVE GUIDESViton valve stem oil seal set.Valve guides are an integral part of the cylinder head andare not replaceable; however, they are serviceable.When the stem-to-guide clearance is excessive, the valveguide bores must be reamed to accommodate the next largeroversize valve stem.Oversize stem service valves are available in 0.0762 mm(0.003"), 0.381 mm (0.0151'), and 0.762 mm (0.030") stemsizes. Ream valve guide bores in steps, starting with the0.0762 mm (0.003") oversize reamer and progress to thesize required.Valve Stem-to-Guide Clearance MeasurementValve stem-to-guide clearance may be measured by eitherof the following two methods.1. Preferred Methoda. Remove the valve from the head. Refer to ValveRemoval section of this chapter for the procedure.b.Clean the valve stem guide bore with solvent anda bristle brush.C.d.e.f.g.Insert the telescoping gauge into the bore of thevalve stem guide approximately 9.525 mm (.375")from the valve spring side of the head with contactscrosswise to the cylinder head (Figure 2-67).Remove and measure the telescoping gauge witha micrometer.Repeat the measurement with contacts lengthwiseto the cylinder head.Compare the crosswise measurement to thelengthwise measurement to determine out-ofroundness.If the measurements differ by morethan 0.0635 mm (0.0025"), ream the guide bore toaccommodate the oversize valve stem.Compare the measured valve guide bore diameterwith the diameter listed in 4.OL Engine Specijicutions,'Engine Assembly' section of this chapter. If themeasurement differs from the specification by morethan 0.0762 mm (0.003"), ream the guide bore toaccommodate the oversize valve stem.Note: Valve seats must be reground after reamingthe valve guides to ensure that the valve seat isconcentric to the valve guide.2. Alternate Methoda. Use a dial indicator to measure the lateralmovement of the valve stem (stem-to-guideclearance) with the valve installed in its guide andjust off the valve seat (Figure 2-68).b. The correct clearance is 0.0025-0.0762 mm(0.001-0.00311). If the indicated movementexceeds the specification, ream the guide bore toaccommodate an oversize valve stem.VALVE SEATSNote: Valve seats must be reground after reamingthe valve guides to ensure that the valve seat isconcentric to the valve guide.With cast iron cylinder heads, all the valve seats aremachined into the head material. (Aluminum heads usevalve seat inserts.) One of the most important items in ahigh output engine is the valve job.Valve Seat Refacing1. Install a pilot of the correct size in the valve guide boreand reface the valve seat to the specified angle with agood dressing stone. Remove only enough metal toprovide a smooth finish.2.Use tapered stones to obtain the specified seat width.when required.3. Control seat runout to a maximum of 0.0635 mm(0.0025"), using a dial indicator (Figure 4-32).r - T i l

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 195Part Number Installed Ht. Description O.D. Wire DiameterP4529214 1.64" Cylindrical 1.31" 177"P45292 1.5 1.64" Conical Prod. Prod.P5249464 1.64" Single w/damper 1.42" .187"Lift Range Material.350/.430" Prod..350/.430" Prod..400/.52S" Chrome-si1A valve spring should never seat directly against analuminum head. A steel spring cup should be used. Thespring seat in a cast iron head should not be cut to increasethe installed height (.030" maximum for clean up).It's best to select valve springs by camshaft choice. Thespring height should be measured after the valve job is doneand with the retainer that is going to be used.Valve spring spacers are used to decrease the installed heightof the spring, thereby raising the closed load of the spring.VALVE SPRINGSFigure 4 - 32The 4.0L engine standard production valve springs aremade of high strength chrome steel. The springs arecommon between intake and exhaust applications. Thevalve spring seat is integral with the valve stem seal.Valve springs are very closely tied to the camshaft and, nextto the camshaft itself, are the most important valve gearperformance parts. The important valve spring selectionconsiderations are camshaft lift and profile, spring outsidediameter, loads, engine rpm, and solid height.Valve springs come in many shapes and sizes for manydifferent applications. Some are interchangeable withproduction pieces and some are not. Some fit only onspecific engines. Most stock production engines use asingle spring; high performance production engines use asingle spring with damper; race engines use either a dualspring (inner, outer, plus damper) or a triple spring (inner 1,inner 2, outer, without a damper). With so manyconsiderations, we wanted to separate the springs intosmaller groups to simplify the discussion. We choseinstalled height. For valve spring specifications, refer to theJeep Engine Valve Spring Speczfications Churt. A typicalrace valve spring is shown in Figure 4-33.Valve Spring Shim PackagesValve spring shims are an aid in the assembling ofperformance or race cylinder heads. Shims are placedunder each valve spring to equalize the installed heightand pressure among springs. On aluminum heads, springshims are required to prevent the valve spring fromgalling the aluminum spring seat. The cup-type shims areused to prevent valve spring movement (walk) about thespring seat. Mopar Performance Parts offers these shimsin packages of 16. For all engines with inner spring seatremoved - .645" inner seat inside diameter.P5249 180P5249 18 1P5249 182PS249183Valve spring shim package, .01.5" thick.Valve spring shim package, .030" thick.Valve spring shim package, .060" thick.Valve spring shim package, .060" thick,cup-type.- -1 n

196 MOPAR PERFORMANCE PARTSIIInnerDamperunder the “if it’s good for Super Stock, it must be good forme” theory. The second way is to have a big camshaft in theengine with its required big valve spring, and then removeit and swap in a medium-sized hydraulic camshaft andforget about replacing the valve springs. Either of theseapproaches on a hydraulic camshaft, or even a smallmechanical camshaft, can cause failures such as scuffedcamshafts, worn out tappets, and broken rocker arms. Thesprings that worked well with a high lift roller just don’twork and cause all kinds of failures when used with smallerprofiles. Always refer to our camshaft application charts forproper valve spring usage.Valve Spring Installation Performance TipsIOuterFigure 4 - 33Big Camshaft Valve Spring ConsiderationsEngine builders have a tendency to forget some basicswhen they are changing camshafts. Camshafts are so easyto change and are changed so frequently it’s easy to miss anitem. The most common mistake is to forget to replace thevalve springs.This can be a problem when bigger camshafts are installedor when smaller camshafts are swapped in. One commonproblem occurs when a stock hydraulic camshaft or smallRV design is replaced with a big, high lift unit. If you don’treplace the valve springs so they match the new camshaft,you’ll have problems ranging from lost performance tobroken parts.Another problem-too much valve spring can be evenworse. This is usually arrived at in one of two ways. First isthe racer who wants the BEST valve spring, and worksAt first thought, the installation of valve springs sounds toosimple to even consider. The valve spring sits between theretainer and the spring seat in the head. For performanceapplications, there are some tricks to this simple system whichshould be considered. Racers can use single springs, dualsprings, or triple springs, each one having special challenges.Production engines typically use single springs, whichsometimes include a damper. The most important itemrelative to valve springs is the installed spring height - thedistance between spring seat in the head to the underside ofthe valve spring retainer. With a single spring, such as usedin production, you can use stock retainers, keepers andgood umbrella (Viton) valve seals (P4529240). Checkingthe installed height assures that it is installed correctly.The next most important item is to select the spring that’sright for the camshaft. Each Mopar Performance Partscamshaft has a specific valve spring, listed by part number,that should be used. If it is not a Mopar Performance Partscamshaft, then the camshaft lift must be known to select theproper valve spring. Once the proper spring is selected and theinstalled height checked, all that remain are some quick tips.1. Basic GuidelinesThe following are some basic guidelines to followwhenever you install valve springs in yourperformance engine:a. Valve springs should be load checked. Weak oneswill have to be replaced. Record loads and heightchecked at.Note: Not all spring testers are the same. Manyare not maintained and calibrated on a frequentbasis. This makes the absolute value of springloads quite unreliable. However it is a very goodcomparative tool; that is, measuring all springs onthe same tester or measuring the same spring newand used.The biggest advantage of load checking is to see ifthe springs have “gone away” or to see if a secondset of the same spring is as “strong” as the firstwhich worked well.

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 197b. With the valves, keepers, and retainers installed,check the valve spring height. This should becompared to the spring load information (la) andthe correct thickness shim chosen to get the sameinstalled spring load on each valve.c.d.Valve spring installed height must be carefullycontrolled to avoid “coil bind” by providing atleast .loo” more height at maximum valve liftthan the solid height of the spring.Caution: DO NOT check solid height with aspring that you intend to use in the engine.Compressing a valve spring to solid height willoverstress it and cause premature load loss orspring breakage.With the same spring height setup as lb, measurethe outer valve spring height, the inner valvespring height, and the keeper-to-valve guideclearance. The camshaft lift (lift of the camshaftmeasured at the lobe or lifter) multiplied by therocker arm ratio plus .050” should be less than thekeeper-to-guide clearance in the valve closedposition or the guide will have to be shortened.Measure the “solid height” of both the inner andouter springs. This solid height plus .loo“ plus thevalve lift (camshaft lift multiplied by the rockerarm ratio) should be equal to or less than theinstalled height for each spring.2. Dual SpringsDual springs are unique in that they are two springsseparated by a damper. These are the most commonvalve springs used in racing. Because the secondspring is installed inside, the inside diameter of thisspring must be measured.Typically the spring seat in a stock production head isonly machined for an outer spring. This requires thatthe spring seat be machined down flush with the outerspring surface. In some cases, the inside diameter ofthe inner spring is less than the outer diameter of thevalve guide. This requires the guide to be machineddown in outside diameter.With the inner spring seat in the head machined evenwith the outer, the inner spring usually will go “solid”after the outer, so the outer spring is still the criticalmeasurement. However, DO NOT overlook the inner.The same thing is true of the damper. It is unusual, butit could go solid before the outer. However, its lengthcan be trimmed to give the necessary clearance. For theinner spring, a new retainer would have to be usedunless the inner spring seat wasn’t flush. To check thesolid height of the inner spring, it should be removedfrom the dual spring assembly, leaving the outer andthe damper together. The solid height of the dampercan be checked in the outer and then removed. Theouter can be checked alone. These two measurementsshould be the same.Dual springs usually require a performance-typeretainer, but many single springs can be used on dualspring retainers. The retainer and valve dictate thekeeper style and type. However, the keeper-to-guideclearance should be measured and compared to thecamshaft’s maximum lift. The guide clearance,including the seal (if used) should be at least .050”greater than the camshaft lift. Dual springs DO NOTallow good umbrella (Viton) valve seals to be used;special Perfect Circle valve seals must be used.3. Triple SpringsTriple spring are the most complicated. They consist ofthree separate springs: two wound in one direction anda middle spring wound in the opposite direction. Manypeople interpret a dual spring with damper as a triplespring, but it’s not. Triple springs require a specialretainer. Otherwise, they install similar to dual springs.They may require a smaller outside diameter on thevalve guide. If not a Mopar Performance Parts triplespring, check the seal outside diameter against theinside diameter of the inner spring. Here you havethree installed heights and three solid heights to check.The outer is again the most critical and most likely tocause problems, but don’t overlook the inner two.VALVES AND VALVE SPRING REMOVAL ANDINSTALLATION(Refer to Figure 4-34.)RemovalNote: This procedure can be done with the cylinder headinstalled on the block.Each valve spring is held in place by a retainer and a set ofconical valve locks. The locks can be removed only bycompressing the valve spring.1. Remove the engine cylinder head cover.2. Remove capscrews, bridge and pivot assembliesand rocker arms for access to each valve spring tobe removed.3. Remove pushrods. Retain the pushrods, bridges,pivots and rocker arms in the same order and positionas removed.4. Inspect the valve springs and retainers for cracks andpossible signs of weakening.5. Remove the spark plug(s) adjacent to the cylinder(s)below the valve springs to be removed...

198 MOPAR PERFORMANCE PARTS6. Connect an air hose to the adapter and apply airpressure slowly. Maintain at least 621 kPa (90 psi) ofair pressure in the cylinder to hold the valves againsttheir seats. For vehicles equipped with an airconditioner, use a flexible air adapter when servicingthe No. 1 cylinder.7.8.9.Tap the retainer or tip with a rawhide hammer to loosenthe lock from the retainer. Use a valve springcompressor tool to compress the spring and remove thelocks (Figure 4-35).Remove valve spring and retainer (Figure 4-34).Remove valve stem oil seals (Figure 4-34). Note thevalve seals are different for intake and exhaust valves.The top of each seal is marked either INT (intake) orEXH (exhaust). DO NOT mix the seals.10. Remove the valves and place them in a rack in theorder in which they are removed.IEXHAUSTVALVEFigure 4 - 341 RETAINERVALVE STEMOIL SEALINTAKEVALVE80bT104bCleaningFigure 4 - 3559009-581. Clean all carbon deposits from the combustionchambers, valve ports, valve stems, valve stem guides,and cylinder head.2.3.Clean all grime and gasket cement from the cylinderhead machined gasket surface.Inspect for cracks in combustion chambers and valve ports.Inspection1.Inspect for cracks on the exhaust seats.2. Inspect for cracks in the gasket surface at eachcoolant passage.3.4.5.Inspect the valve for burned, cracked or warped heads.Inspect for scuffed or bent valve stems.Replace valves displaying any damage.Valve ClearancesProper valve clearances in a race engine are very importantto prevent bent or broken valves.The valve-to-valve clearance should be checked first.This is done with both valves on the seat. This isimportant in all engines.Piston-to-valve clearance is equally important. Thepiston-to-valve clearance is usually measured byplacing modeling clay on the piston and manuallyturning the engine over with the head bolted on andcamshaft, lifters, pushrods, etc., adjusted to zero lash.The clearance between the valve and the block isusually only considered when installing oversizevalves. In some cases, a notch in the side of thecylinder bore below the valve is required.I- --ll iT

T ^ T 74.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 1994. Check rocker arm-to-valve tip relationship foralignment. Improper alignment can place undue sideloads on the valves, causing rapid valve guide wear.Rocker shaft spacers or grinding the rocker can be usedto move the rocker arm up or down the shaft to align iton the valve tip.Valve Refacing1. Use a valve refacing machine to reface the intake andexhaust valves to the specified angle.2.After refacing, a margin of at least 0.787 mm (0.031")must remain (Figure 4-36). If the margin is less than0.787 mm (0.031"), the valve must be replaced.Installed Height and GuideThe installed height can be checked quite easily. However,with high lift camshafts, more care should be taken thanjust measuring the outer spring height. The inner springshould be checked, too. The solid height of the outer spring,inner spring and the damper should also be checked. Mostsprings, including production and dual springs (outer) willgo solid at 1.1-1.2". Race springs will go solid at l", whiledual springs (inner) will go solid at less than 1 ".Note: Be sure to check inner and outer springs separately.While measuring the installed spring height, also check thekeeper-to-guide clearance. If inadequate clearance is found,the guide will have to be shortened. The easiest way to dothis is by grinding it. If dual springs are used, the innerspring seat may have to be dropped even with the outerspring seat, and the outside diameter of the guide itselfdecreased for the inner spring to fit over it.InstallationCORRECTNO MARGININCORRECT J9009-78Figure 4 - 36Valve Spring Tension TestUse a valve spring tester and a torque wrench (Figure 2-66)to test each valve spring for the specified tension value.(Refer to 4.0L Engine Specifications, 'Engine Assembly'section of this chapter, for valve spring tension values.)Replace valve springs that are not within specification.Note: Most people in the performance industry use asimpler, more common valve spring tester that does notrequire a torque wrench to arrive at the tension (load).These simpler to use valve spring testers allow you tocompress the spring to the height (open or closed) that youwant to measure and then read the load directly off a scalethat is on the tester itself. The key to valve spring testers isto obtain the correct installed height.This procedure can be done with the cylinder head installedon the block.Caution: Install oil seals carefully to prevent damage fromthe sharp edges of the valve spring lock groove.1.2.3.4.5.6.7.8.9.Thoroughly clean valve stems and valve guide bores.Lubricate the stem lightly.Install the valve in the original valve guide bore fromwhere it was removed.Lightly push the valve seal over the valve stem andvalve guide boss. Be sure the seal is completely seatedon the valve guide boss.Install valve spring and retainer.Compress the valve spring with a valve springcompressor tool and insert the valve locks. Release thespring tension and remove the tool. Tap the spring fromside-to-side to ensure that the spring is seated properlyon the cylinder head.Release air pressure and disconnect the air hose.Remove the adapter from the spark plug hole andinstall the spark plug.Repeat the procedures for each remaining valve springto be removed.Install the pushrods. Ensure the bottom end of each rodis centered in the plunger cap seat of the hydraulicvalve tappet.

200 MOPAR PERFORMANCE PARTSIIJeep 4.0L Valve Spring Retainer Specifications ChartIRetainer MaterialSingle-Std.P45292 17 Steel 8 mm ConicalJeep 4 and 6 Cylinder Engine Keepers (Locks)Part NumberP4S292 18Valve Stem Size Angle Hardened Groove Use With Retainers Sets8 mm 8” Std. I Single I P4529216, P4529217 I 24 Pieces I10. Install the rocker arms, pivots and bridge at theiroriginal location.11. Tighten the bridge capscrews alternately one turn at atime to avoid damaging the bridge. Tighten thecapscrews to 28.5 Nom (21 ft-lbs) torque.12. Install the cylinder head cover.VALVE SPRING RETAINERS AND KEEPERS(LOCKS)Valve spring retainers are a pretty simple engine part. Theycome in steel, chrome-moly, aluminum, and titanium.Keepers (or locks) are the mating piece between the valvestem and the retainer. The usual design consideration is thenumber of lock grooves on the valve stem- one, two, or three.The valve stem size affects both the keeper and retainer.One specification that hasn’t been mentioned, which affectsboth the keeper and retainer, is the seat angle. For yearswe’ve used 8 degrees as the angle of standard and highperformance keepers and retainers. Other manufacturerscall theirs 7 degrees. There really isn’t any differencebetween these two labels. The actual angle is greater than 7but less than 8. Effectively it’s the same. However, this isn’ttrue of the special IO degree keeper-retainer system. Thetop width of the 10 degree system is much wider than the 7-8 degree system. In either case, keepers and retainers canonly be swapped as a total system. You can’t use 8 degreekeepers with 10 degree retainers or vice versa. Be careful.This isn’t as obvious to spot as it sounds.The retainer should be light and strong. Stock productionsteel retainers are acceptable for most applications. Aserious race engine with a high lift camshaft should usetitanium retainers.Note: NEVER sink the valves deliberately to increase theinstalled height. This results in reduced performance.Mopar Performance Parts valve keepers (locks) are madefroni hardened steel and are available in single and triplegroove styles to meet your application requirements

T - T ?4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 2018" Versus 10" Retainers and Keepers (Locks)Valve spring retainers are attached to the valve by "keepers"or locks. All standard production 4.0L engine valve keeperswere an 8" design. The production retainers, likewise, werean 8" design. Currently there are 10" keepers and retainersavailable, but they are used only in racing. In a high rpmrace engine, an 8" keeper can "pull through' the retainer. Inan expensive race engine this can be disastrous. The 10"keeper and retainer system is a hard-core racer part that isdesigned to keep this from occurring. The 10" retainercannot be used with 8" keepers (locks) and vice-versa.One note of caution. DO NOT assume that you have 10"keepers or retainers. If you accidentally tried to use 10"keepers with 8" retainers, you would instantly recognize thatsomething was wrong. However, if you were to use 8"keepers with 10" retainers, it would not be so obvious, butthe results would be as disastrous. Always be sure to checkthe valves that you'll be using for stem diameter and numberof lock grooves before ordering keepers and/or retainers.Note: Keep in mind that if you have trouble with outer springcoil bind, you have to increase the installed height. But if thedamper inside the outer spring goes solid, the simplestsolution is to trim the damper for the added clearance.ROCKER ARMSJeep 4.0L engine standard production rocker arms are madeof stamped steel and have a operational ratio of 1.6: 1. Whenthe pushrods are forced upward by the camshaft lobes thepushrod presses upward on the rocker arms, the rocker armspivot, forcing downward pressure on the valves forcing thevalves to move downward and off from their seats.The most important considerations in rocker arms arestrength and durability. Strength is required to minimizedeflections and transfer the camshaft motion to the valveaccurately. The most important item regarding a highperformance hydraulic camshaft is that the higher valvespring loads required by the camshaft puts more load on therocker arms, which causes the pushrods to have a tendencyto pierce the rocker arm. Thicker material in the pushrodball or cup area is the only solution to the problem. Theseheavy duty hydraulic rocker arms are available from MoparPerformance Parts.To optimize rocker arm geometry, a cut-to-length pushrodlut is recommended, but only to the very serious racer or forengines with large amounts of head milling and blockdecking. The rocker arm tip should contact squarely overthe tip of the valve.Heavy Duty Rocker ArmHeavy duty stamped rocker arms for use with hydrauliccams (only). Right and left rockers are the same. Can beused to service stock engines. For all 2.5L and 4.0L Jeepengines. (Sold individually.)P452922 1Roller Rocker Arm SetHeavy duty rocker arm.Fits all 2.5L and 4.0L engines. (Must use a spacer forvalve cover clearance.)Contains one cylinder set of two rockers, two supportstands, rocker shaft and screws.Extruded aluminum rockers, anodized blue.Can be used with hydraulic, mechanical or rollercamshafts.Roller tip and center pivot to reduce internal friction.Provides exact geometry; 1.6: 1 ratio.Adjustable, oil through pushrod style.P4529885Roller rocker arm set.Aluminum Rocker Assembly LubeWhen you use aluminum roller rockers, don't take achance with a substandard lubricant. Mopar PerformanceParts assembly lube is a must to complete the job right.P5249099Aluminum rocker assembly lube.

202 MOPAR PERFORMANCE PARTSInstallation1. Install the pushrods in their original locations. Ensurethat the bottom end of each pushrod is centered in thetappet plunger cap seat.2.3.4.5.Install the rocker arms, pivots and bridge above eachcylinder from where they were originally removed.Loosely install the capscrews through each bridge.At each bridge, tighten the capscrews alternately oneturn at a time to avoid damaging the bridge. Tightenthe capscrews to 28.5 Nom (21 ft-lbs) torque.Install the cylinder head cover. Refer to Cylinder HeadCover Instullation, ‘Cylinder Head’ section of thischapter, for the procedure.PUSHRODSRemoval1. Remove the cylinder head cover. Refer to CylinderHead Cover Removal, ‘Cylinder Head’ section of thischapter, for the procedure.2.3.4.Remove the two capscrews at each bridge and pivotassembly (Figure 2-62). Alternately loosen the capscrewsone turn at a time to avoid damaging the bridges.Remove the bridges, pivots and corresponding pairs ofrocker arms and place them on a bench in the sameorder as removed (Figure 2-62).Remove the pushrods and place them on a bench in thesame order as removed (Figure 2-62).Cleaning and InspectionClean all the components with cleaning solvent and usecompressed air to blow out the oil passages in the rockerarms and pushrods.Inspect the pivot surface area of each rocker arm. Replaceany that are scuffed, pitted or excessively worn.Inspect the valve stem tip contact surface of each rockerarm and replace any rocker arm that is deeply pitted.Inspect each pushrod end for excessive wear and replace asrequired. If any pushrod is excessively worn because oflack of oil, replace the pushrod and inspect thecorresponding hydraulic tappet.A wear pattern along the length of the pushrod is notnormal. Inspect the cylinder head for obstruction if thiscondition exists.Length, strength, and weight are the most critical items forpushrods, especially the first two. Length affects geometryand valve gear oiling. Strength keeps deflections minimizedand weight helps engine speed, but a weight loss that causesa sfrength loss will result in a performance loss.The valve train of the Jeep 4.0L engine is oiled through thepushrods. Jeep engine pushrods (all Jeep engines) are hollowso fhat oil can pass through them to oil the valve train.Warning! Because Jeep engine valve trains are oiled viahollow pushrods, solid shaft pushrods cannot be used.Standard Length PushrodThis is a fully assembled, stock diameter hydraulicpushrod. It is hollow to provide valve train oiling (same asproduction pushrod). Factory approved and engineered forrebuild or repairs. For 1987-2000, 4.0L and all 2.5Lengines. (Sold individually.)P45292 19Standard length pushrod.Standard Length Pushrod SetThese are fully assembled, stock diameter pushrods. Theyare hollow to provide valve train oiling (same asproduction pushrods). Complete set of twelve (12). For1987-2000, 4.0L engines only.P4.529675 Standard length pushrod set...T -rrr

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 203Hydraulic PushrodsSince 1964, most Chrysler-Plymouth-Dodge-Jeep engineshave been built using hydraulic camshafts. This means thetappets are hydraulic. It also means the rocker arms arenon-adjustable. (There are a couple exceptions to thisgeneral rule, but it holds true for the majority.) Thehydraulic camshaft, tappet, and non-adjustable rockerrequire a special pushrod. The hydraulic pushrod has twomale ends. Length isn’t critical here as long as the lifter canadjust for the change.Hydraulic camshafts use a zero valve lash setting. Theactual adjustment is done by the hydraulic tappet. If thepushrod doesn’t bend, it does its job without problems andthe engine runs fine.As long as the engine remains “stock,” this holds true. Thatis because the hydraulic tappet has a lot of adjustment builtin.This adjustment takes care of production variations, withsome adjustment room to spare. The total adjustment isapproximately .180“ and it operates normally in the middleof its travel. You’ll have trouble if you get too close to theend of travel (up or down), so the last .010” isn’t usable.Production tolerances will take another .030”, which leavesapproximately ,050’’ in either direction or .loo“ total. This ismore than enough cushion for a stock engine. However, itmay not be enough for modified engines.“Modified engine” really means rebuilt or non-stock, notnecessarily “race.” The modification could be a biggercamshaft, milled or straightened head or deck surface,different tappets from those recommended, different valves,different head, or a change to the rocker stand or itsattachment. This assumes that “broken” pieces such as bentpushrods, scuffed valve tips, bent rocker shafts, wornpushrod socket in the rocker, scuffed rocker tips, etc., arefound and corrected. This is quite a list and obviously noteasy to check out. Do not despair. The pushrod lengthrequired for your “modified” engine can be checked fairlyeasily. The hydraulic tappet must be disassembled anddrained of oil to check the tappet’s collapsed height asinstalled. From this basic measurement you can determineyour “free lash” (too much or not enough) and know howlong your pushrod needs to be and if a stock (production)one will work.Realistically, most racers don’t do this. They quickly putthe engine together and worry about it when they find aproblem trying to start the engine. At this point they’llprobably blame the camshaft or the lifters. Assuming thatthe lifters get oil pressure and they’re recommended MoparPerformance Parts lifters, these pieces aren’t likely to be atfault. Assuming the camshaft choice is up a step or twofrom stock and that it is either a production unit or MoparPerformance Parts design, the camshaft isn’t the problemeither. In truth, the “why” can be very difficult to determine.This sounds like a problem, but it really isn’t. The reason isthat no matter why there’s a “free lash’ problem, thecheapest and easiest solution is adjustable hydraulicpushrods. Using these pushrods can solve all kinds ofproblems with mismatched parts.LlFTERSmAPPETSThere are three types of lifters: hydraulic, mechanical-flattappet, and roller. Their use is dictated by the camshaft. Thereare two types of mechanical tappets: standard and mushroom.The Jeep 4.0L standard production engine valve lash iscontrolled by hydraulic tappets located inside the cylinderblock, in tappet bores above the camshaft. The tappets havea hole in the tappet body. Oil from the cylinder block mainbore enters and flows through the tappet exiting the top ofthe tappet. Oil that exits the tappet enters the hollowpushrod, travels up the pushrod and exits through a smallhole in the rocker arm where it enters the cylinder head andreturns to the oil pan.Hydraulic TappetMopar Performance Parts hydraulic tappets are for usewith general purpose, high performance hydrauliccamshafts. Can be used as production replacement. (Soldindividually.)P4529220Hydraulic tappet.Hydraulic LiftersnappetsHydraulic tappets are standard in all 4.0L Power Tech engines.1. Preliminary Checka. Before disassembling any part of the engine tocorrect tappet noise, read the oil pressure at thegauge (install a reliable gauge at pressure sendingunit). The pressure should be between 255-5 17kPa (37-75 psi) at 1,600 rpm and higher. If vehiclehas no oil pressure gauge, check the oil level in theoil pan.

204 MOPAR PERFORMANCE PARTSb. The oil level in the pan should never be above the“full” mark or below the “add oil” mark on the oildipstick. Either of these two conditions could beresponsible for noisy tappets. Check the oil levelafter the engine reaches normal operatingtemperature. Shut off the engine, allow 5 minutesto stabilize oil level, then check the dipstick. Makesure the vehicle is on level ground.i. Oil Level Too Highii.If the oil level is above the “full” mark on thedipstick, it is possible for the connecting rodsto dip into the oil while the engine is runningand create foam. Foam in the oil pan wouldthen be fed to the hydraulic tappets by the oilpump, causing them to lose length andallowing valves to seat noisily.Oil Level Too LowLow oil level may allow the oil pump to takein air which, when fed to the tappets, causesthem to lose length and allows valves to seatnoisily. Any leaks on the intake side of thepump through which air can be drawn willcreate the same tappet action. When tappetnoise is due to aeration, it may be intermittentor constant, and usually more than one tappetwill be noisy. When oil level and leaks havebeen corrected, the engine should be operatedat fast idle for sufficient time to allow all ofthe air inside of the tappets to bleed out.2. Tappet Noise DiagnosisTo determine the source of tappet noise, operate theengine at idle with valve covers removed. Feel eachvalve spring or rocker arm to detect noisy tappet. Thenoisy tappet will cause the affected spring andorrocker arm to vibrate or feel rough in operation.Note: Worn valve guides or cocked springs aresometimes mistaken for noisy tappets. If this is thecase, noise may be dampened by applying side thruston the valve spring. If noise is not appreciably reduced,it can be assumed the noise is in the tappet. Inspect therocker arm pushrod sockets and pushrod ends for wear.Valve tappet noise ranges from light noise to a heavyclick. A light noise is usually caused by excessive leakdownaround the unit plunger which will necessitatereplacing the tappet, or by the plunger partially stickingin the tappet body cylinder. A heavy click is caused eitherby a tappet check valve not seating, or by foreignparticles becoming wedged between the plunger and thetappet body causing the plunger to stick in the downposition. This heavy click will be accompanied byexcessive clearance between the valve stem and rockerarm as the valve closes. In either case, the tappetassembly should be removed for inspection and cleaning.3. RemovalRetain all components in the same order as removed tofacilitate installation in their original positions.a.b.C.d.e.f.Remove the cylinder head cover. Refer toCylinder Head Cover Removal, ‘Cylinder Head’section of this chapter, for the procedure.Remove the bridge and pivot assemblies and rockerarms by removing the two capscrews at each bridge(Figure 2-62). Alternately loosen each capscrewone turn at a time to avoid damaging the bridges.Remove the pushrods (Figure 2-62).Remove the intake and exhaust manifolds. Referto the service manual for the proper procedure.Remove the cylinder head and gasket. Refer toCylinder Head Removal, ‘Cylinder Head’ sectionof this chapter, for the procedure.Remove the tappets through the pushrod openingsin the cylinder block.4. Disassembly, Cleaning and InspectionPlace the components of each tappet in a separate location.This will greatly assist in the installation operation.a.b.c.d.e.f.Release the snap ring (Figure 2-72).Remove the following from the tappet body(Figure 2-72):i. Plunger capii. Metering valve...111. Plungeriv. Check valve assemblyv. Plunger return springClean the components of each tappet assembly incleaning solvent to remove all varnish, gum andsludge deposits.Inspect for indications of scuffing on the side andbase of each tappet body.Inspect each tappet base for concave wear with astraightedge positioned across the base.If the base is concave, the corresponding lobe onthe camshaft is also worn. Replace the camshaftand tappets.......T --I ’7

4.0L POWER TECH IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 2055. Assemblya. Install the following into the tappet body:b.i. Plunger return springii.Check valve assemblyiii. Plunger6. Installationiv. Metering valvev. Plunger capCompress the plunger assembly by exerting forceon the plunger cap with the pushrod and install thesnap ring.Note: It is not necessary to charge the tappets withengine oil. They will charge themselves within a veryshort period of engine operation.a. Coat each tappet in Mopar Super Oil Conditioner,or equivalent.b.c.d.e.Install each tappet in the same bore from where itwas originally removed.Install the exhaust and intake manifolds. Refer tothe service manual for the proper procedure.Install the cylinder head and gasket. Refer toCylinder Head Installation, ‘Cylinder Head’section of this chapter, for the procedure.Install each pushrod in the same location fromwhere it was removed.f. Install the rocker arms and bridge and pivotassemblies at their original locations.g.h.i.Loosely install the capscrews through each bridge.Tighten the capscrews alternately one turn at atime to avoid damaging the bridges.Pour the remaining Mopar Super Oil Conditionerover the entire valve actuating assembly. TheMopar Super Oil Conditioner must remain withthe engine oil for at least 1,609 km (1,000 miles);however, it does not have to be drained until thenext scheduled oil change.Install the cylinder head cover. Refer to CylinderHead Cover Installation, ‘Cylinder Head’ sectionof this chapter, for the procedure.Hydraulic Tappet Installation TipsThe important thing to keep in mind is that there isn’t aproblem with the camshaft or the tappet individually. Thehydraulic tappet is a sophisticated device. If it has oilinside, then it won’t collapse or adjust. If you deliberatelyfill the inside of the tappet with oil, it won’t collapse. Somesources recommended that you fill it with oil beforeinstallation. For racing or performance we don’t. This hasnothing to do with applying break-in oil on the outside ofthe tappet. Before installation we recommend draining anyoil that may be inside the tappet first by carefullydisassembling the tappet itself. Once drained, the pushrodpivot inside the tappet can be pushed down manuallyagainst the tappet’s internal, light spring. Now you can putoil on the outside and drop it into the engine for assembly.But be prepared. When the engine is started all 12 tappetswill make noise-ticking and clattering like very loosemechanical tappets. As soon as the engine’s oil pressurecomes up, the noise goes away. (Priming the engine beforestarting helps minimize the noise.) Easy enough, but whygo to the extra trouble?Generally the engine starts a little easier (less effectivecamshaft duration) and you know that the tappets areworking properly. But the trick isn’t what this method givesyou, but what problems this method can avoid. With thelifters pumped up, you’ll generally hold the valves off theseat for 360” (all the time). This can cause the valves to hitthe pistons or the pushrods to bend. The tappets will bleeddownbut it can sometimes take a while.With the valves partially off their seats, you don’t get muchcranking compression, which will make the engine hard tostart. If it starts, it won’t want to run at idle until the tappetsbleed-down, which could take some time. If you get a tightone that won’t bleed-down, then you have to disassemblethe engine down to the tappets and manually drain thetappet, if you can determine which one it is. Locating theexact tappet is not easy to do. Otherwise, you’ll have todrain them all. To us, this approach is not a good gamble.Many people manually fill their tappets before installationand have no problems. Stock camshafts and very mildcamshafts have a lot of valve-to-piston clearance, whichhelps if the valve is off the seat all the time. Think aboutit - why take the chance‘?Mushroom LiftersnappetsIf mushroom lifters are used, the underside of the liftersshould be spotfaced. This will require a back-spotfacingtool. Mushroom lifters should only be used with mushroomcamshafts because they have narrowed lobes.If you have a hydraulic camshaft, then you must havehydraulic tappets. That’s pretty easy, but what do you dowith them? Dip the outside in Lubrizol (camshaft break-inoil) and drop them in the engine, right? Sometimes, but thismethod can cause problems that will affect all camshafts,including stock production camshafts... T - 1 1

206 MOPAR PERFORMANCE PARTSINTRODUCTIONOilingThe 4.0L engine uses a pressure feed, full flow filtrationoiling system utilizing a gear-type positive displacementpump is mounted at the underside of the block opposite theNo. 4 main bearing (Figure 4-37). The pump draws oilthrough the screen and inlet tube from the sump at the rearof the oil pan. The oil is driven between the drive and idlergears and pump body, then forced through the outlet to theblock. An oil galley in the block channels the oil to the inletside of the full flow oil filter. After passing through thefilter element, the oil passes from the center outlet of thefilter through an oil galley that channels the oil up to themain galley which extends the entire length of the block.The oiling system has a capacity of 5.7L (6 quarts). (Formore oiling system specifications, refer to 4.OL EngineSpecifications, ‘Engine Assembly’ section of this chapter.)Galleys extend downward from the main oil galley to the uppershell of each main bearing. The crankshaft is drilled internallyto pass oil from the main bearing journals (except No. 4 mainbearing journal) to the connecting rod journals. Eachconnecting rod bearing cap has a small squirt hole. Oil passesthrough the squirt hole and is thrown off as the rod rotates. Thisoil throw-off lubricates the camshaft lobes, camshaft positionsensor drive gear, cylinder walls, and piston pins.The hydraulic valve tappets receive oil directly from themain oil galley. Oil is provided to the camshaft bearingthrough galleys. The front camshaft bearing journal passesoil through the camshaft sprocket to the timing chain. Oildrains back to the oil pan under the No. 1 main bearing cap.The oil supply for the rocker arms and bridged pivotassemblies is provided by the hydraulic valve tappets whichpass oil through hollow pushrods to a hole in thecorresponding rocker arm. Oil from the rocker armlubricates the valve train components and then passes downthrough the pushrod guide holes in the cylinder head, pastthe valve tappet area, and returns to the oil pan.The stock lubrication system will be adequate for normalpassenger car operation. However, in any case whereDaimlerChrysler engines are subjected to unusually highcrankshaft rotational speeds (over 6,000 rpm), acceleration,deceleration, or cornering loads, special precautions mustbe taken with the engine’s oiling system. Not only must anengine’s oiling system be modified for adequatelubrication, but it must also be modified to achieveoptimum engine power output.TroubleshootingOiling the valve gear in a standard engine is virtuallyautomatic, as long as the engine has oil pressure. In amodified, high performance engine, it can be another story.SystemWhen recommendations are followed, most racers will haveno oiling problems. When oiling problems do develop, theygenerally manifest themselves as burned pushrod tips,scuffed valve tips, scuffed and burned rocker arms, brokenpieces, etc. Unfortunately, the pieces that look the worstusually aren’t the cause of the problem. In the majority ofcases relating to valve gear oiling, it’s not a matter of whatyou should do, but what you should not do. The problemsmentioned are the result of poor oiling, assuming the engineitself is being oiled properly (no foam, no zero psi, etc.).The first thing to check is that a camshaft bearing hasn’t“turned’ so that its oiling holes aren’t lined up with theholes in the block. Next, be sure the passage from thecamshaft to the block’s deck isn’t blocked or restricted.This is usually done with a long handled bottle brush.At the deck surface of the block, it is common for racers toinstall a restrictor. This is not recommended and, if found,should be removed. If you “smoked out” your pushrods orscuffed the valve tips, you’ve probably found the cause.Next, check the head gasket and cylinder head itself foroiling hole alignment.At this point you can have two different types of problemsdepending on whether your engine uses hydraulic rockersor mechanical rockers. A problem with hydraulics is mostlikely caused by an oil leak that prevents oil from reachingthe rockers. Spacers used between the rocker stand and therocker shaft will, over an extended period, cause theseproblems because of leakage. Also, the rocker shaft couldbe installed incorrectly (upside down, reversed, etc.).Problems occumng with mechanical rockers can be muchmore complicated. Since there is no need to put spacersbetween the rocker shaft and the pedestal, a leak there wouldbe unusual. Rocker shaft installation is very critical. Bananagrooves are usually added to mechanical valve gear rockershafts to improve oiling of the rocker itself. Bushed rockersare more tolerant of low oil conditions, but standardmechanical rockers should be adequate for most applications.At this point, with oil to the rocker, it must be distributed tothe valve tip and the pushrod tip. Accomplishing this is verytricky. Exactly where and how these holes are located is verycritical and each engine is unique.There is another “trick’ with mechanical rockers that shouldbe considered. The proper (ideal) adjustment for the rockeradjusting screw is to have only one thread showing below therocker arm with the valve lash set properly (two may be okay,three shaky, etc., but high rpm makes one thread showing themost desirable). This requires custom length pushrods forevery engine. If you’ve “smoked” your pushrods and you hadall the threads showing below the rocker (Le., pushrod tooshort), more oil to the valve gear won’t cure the problem.Only longer pushrods will do the job.

4.0L POWER TECH IN-LINE 6 (OILING SYSTEM)207TAPPETGALLERYFigure 4 - 37

208 MOPAR PERFORMANCE PARTSOILING SYSTEM PERFORMANCECONSIDERATIONSChoosing the Correct Oiling SystemThe oiling system to be used on a high performance engineis determined by the output level of the engine and the typeof application that the engine is going to be used for. Oilcapacity is the first consideration in a basically stocksystem used for high performance. This means that the firststep for bracket racing is to deepen the stock pan 2“ alongwith lowering the pick-up the same amount. The next stepis a Super Stock race pan and high volume oil pressurepump. The last step is a dry sump which is particularlyimportant in oval track and high performance drag racevehicles that are built low to the ground. During yourengine build-up, after the camshaft has been chosen and theengine’s application is known, the oiling system typeshould be decided on so that any block modification(especially if a dry sump and roller lifters are to be used)can be done before the block is assembled and it’s too late.Oiling System Passage RequirementsIt is important to note that oil pump performance at highengine speeds can be most easily improved by reducingrestrictions on the suction side of the oil pump. Reducingflow restriction on the suction side of the pump is muchmore significant than reducing flow restriction on thepressure side of the pump. Oil pump suction pipe diametershould be very generous.Caution: Modified oil pump suction pick-ups must befitted with a protective screen to prevent the pump fromingesting debris such as metal shavings, broken valvespring tips, etc.Oil Flow to Connecting Rod BearingsFor increased oil flow to connecting rod bearings, 360”fully grooved main bearing sets should be used.Note: It is NOT recommended that the crankshaft begrooved because that will weaken the crankshaft.Oil RestrictionIt seems that some magazine article or book is alwaysrecommending that an engine’s oil be restricted in someway. Some suggestions have no real effect, but thoserestricting oil to the upper valve gear can be quite harmful.We DO NOT recommend restricting oil flow to the uppervalve gear. Leave all the passages stock size and be surethat they are unobstructed.The usual result of oil restriction to the upper valve gear is“smoked out” pushrod tips, scuffed valve tips, scuffed orburned rockers, or scuffed valve guides. These areexpensive ways to find out what doesn’t work. Full rollerrocker arms can cut down on the valve gear’s oilrequirement but are generally expensive. In racing, as therpm is increased, the valve gear needs more oil. If you haveextra time available in your engine building process,helping the oil in the cylinder head return to the pan can beben’eficial. Helping the oil return past the crankshaftwithout getting on to the crankshaft is the best place tospend your time.Restricting oil to the tappet galley with roller lifters is avery common practice (and required for 3.9L V-6 engineswith high lift roller camshafts). However, restricting oil tothe upper valve gear is NOT recommended. The oil is fedto the upper valve gear through mating passages in theblock and head. Restricting these passages cuts down on theamount of oil available to the valve gear (valves, rockers,pushrods). This causes two problems. At high rpm, rockerarms like to “shake off’ the oil that is used to lubricatevalves and pushrod tips. In most cases, the engine needs allits designed oil flow to keep its durability high and tominimize parts wear. The other problem occurs at lowspeed where the oil pressure drops to its minimum. In thiscondition, the valve gear, being the furthest from the oilpump, gets very little (if any) oil. The loads are low butwith so little oil, any less can cause accelerated wear. Ineither case, scuffed valve tips, burned pushrod ends, andgalled rockers can be the result, which is why oil restrictionto tlhe heads is not recommended.OIL PUMPA gear-type oil pump is mounted at the underside ofthe cylinder block opposite the No. 4 main bearing(see Figure 2-78).Oil pump removal or replacement will not affect distributortiming because the distributor drive gear remains in meshwit11 the camshaft gear.The stock oil pump is adequate for normal operation if it is upto specifications. The pump must turn freely when assembled.Heavy Duty Oil PumpWhen the going gets tough, you’ll want to be sure andsupply as much oil to your engine as possible. This heavydut,y high volume pump will do the job and take the mostsevere punishment. For 4.0L engines only.P4529227Heavy duty oil pump.High Volume Oil Pump AssemblyFor many years, Mopar Performance Parts has suppliedparts for oiling systems. Our previous parts have come askits that the racer had to put together himself, in many casesusing a stock oil pump as a starting point. MoparPerformance Parts now offers a high volume, highperformance oil pump assembly for 4.0L Power Techengines (P4529241). It offers a 25% increase in volumeover the stock pump and comes fully assembled and readyto bolt on the engine.

4.0L POWER TECH IN-LINE 6 (OILING SYSTEM) 209High Volume Oil PumpThis Mopar Performance Parts high volume oil pump issimilar to the heavy duty oil pump (P4529227), exceptthat it has larger rotors for a 25% increase in capacity. For4.0L engine only.P452924 1High volume oil pump.Oil Pressure RequirementsOil pressure requirements for the 4.0L engine are asfollows:At Idle Speed (600 rpm) ............ 13 psi ................... 89.6 kPaAt 1,600+ rpm ........................37-75 psiOil Pressure Relief. ...... 75 psi .................... 517 kPaOil Pump PrimingAfter an engine build (or re-build), the lubrication systemshould be checked to ensure that it is supplying pressure tothe bearings before any attempt is made to start the engine.If the engine is running without oil pressure even for a fewseconds, there will be extensive damage done to the engine.After installing a mechanical oil pressure gauge (only if yourvehicle is not already equipped with an oil pressure gauge),remove all the spark plugs in order to relieve the compressionin the cylinders and to prevent the engine from starting. Theengine should be turned over with the starter motor until theoil pressure gauge shows a reading of over 10 psi.Once you have determined that the engine does have oilpressure, the spark plugs may be reinstalled and the enginemay be started. When the engine starts, the gauge shouldshow a minimum reading of 89.6 kPa (13 psi) at 600 rpm(idle speed).Warning! If the gauge does not register any pressurewhen the engine is cranked with the starter motor, DONOT TRY TO START THE ENGINE. Running an enginewith no oil pressure for even a couple of minutes can causeserious damage.If the gauge does not register any pressure when the engineis cranked with the starter motor, go through yourlubrication system and check it carefully. Make sure thereis sufficient oil in the pan. Also be sure that the pickup isconnected and that the oil pickup is fully submerged. Makesure the pickup tube does not have any leaks where airmight be entering the system. Make sure the oil pump isworking properly.OIL PUMP SERVICE PROCEDURESRemoval1. Drain the engine oil.2. Remove the oil pan. Refer to the proper service manualfor the procedure.Caution: DO NOT disturb the position of the oil inlet tubeand strainer assembly in the pump body. If the tube is movedwithin the pump body, a replacement tube and strainerassembly must be installed to ensure an airtight seal.3.Remove the oil pump retaining bolts, oil pump and gasket.Gear End Clearance MeasurementRemove the cover retaining bolts and cover from the pumpbody.1. Preferred Methoda. Place a strip of Plastigauge (P4286819) across thefull width of each gear (Figure 2-79).b.c.Install the pump cover and tighten the bolts to 8Nom (70 in-lbs) torque.Remove the pump cover and determine theamount of clearance by measuring the widthof compressed Plastigauge with the scale onthe Plastigauge envelope.Correct clearance by this method is 0.051-0.152 mm(0.002-0.006"). The preferred measurement is 0.05 1mm (0.002"). If the gear end clearance is excessive,replace the oil pump assembly.PlastigaugeWhen reassembling your engine you'll need a variety ofPlastigauge to measure bearing clearances. This popularassortment includes one blue strip for .004" - ,009"tolerances, two red strips for .002" - ,006" tolerances, andtwo green strips for .001 I' - ,003" tolerances. Each strip is12" long.P42868 192. Alternate MethodPlastigauge assortment.a. Place a straightedge across the ends of the gearsand the pump body.b.Select a feeler gauge that fits snugly but freelybetween the straightedge and the pump gears(Figure 2-80).Using this method, the correct clearance is 0.051-0.152mm (0.002-0.006"), with the preferred measurementbeing 0.05 I mm (0.002"). If the gear end clearance isexcessive, replace the oil pump assembly..-

-ll721 0 MOPAR PERFORMANCE PARTSGear-to-Body Clearance Measurement1.2.3.4.5.6.7.8.9.Measure the gear-to-body clearance by inserting afeeler gauge between the gear tooth and the pump bodyinner wall directly opposite the point of the gear mesh(Figure 2-81).Select a feeler gauge which fits snugly but freely.Rotate the gears to measure each tooth-to-bodyclearance in this manner.The correct clearance is 0.051-0.102 mm (0.002-0.004”). The preferred clearance is 0.051 mm (0.002”).If the gear-to-body clearance is more than specified,replace the idler gear, idler shaft and drive gearassembly.Remove the cotter pin and slide the spring retainer,spring and oil pressure relief valve plunger out of thepump body.Inspect for binding condition during disassembly.Clean or replace as necessary.The oil inlet tube and strainer assembly must beremoved to allow removal of the relief valve. Install areplacement inlet tube and strainer assembly.AssemblyNote: Two relief valve plunger sizes (standard andoversize) are available. When replacing the valve, ensurethat the correct replacement valve and either the standardsize or 0.254 mm (0.010”) diameter oversize plunger isobtained and installed.1. Install the oil pressure relief valve plunger, spring,retainer, and cotter pin.2.3.4.5.6.7.If the position of the inlet tube in the pump body hasbeen disturbed, install a replacement inlet tube andstrainer assembly. Apply a light film of Permatex No.2 sealant, or equivalent, around the end of the tube.Use an oil pump inlet tube installer tool to drive thetube into the body (Figure 2-82). Ensure that thesupport bracket is properly aligned.Install the idler gear and the drive gear assembly.Inspect the gears to ensure that a binding conditiondoes not exist before installing the oil pump.To ensure self-priming of the oil pump, fill the pumpwith petroleum jelly before installing the oil pumpcover. DO NOT use grease!Apply a bead of Loctite 5 15, or equivalent, and installthe pump cover.Tighten the cover bolts to 8 Nom (70 in-lbs) torque.Installation1. Install the oil pump with a replacement gasket.Tighten the bolts to 23 Nom (17 ft-lbs) torque. (Referto Figure 2-78.)2.3.Install the oil pan with replacement gaskets and seals.Refer to the proper service manual for the procedure.Fill the oil pan with clean engine oil to the specified level.OIL PICK-UPSAn oil pick-up is used in virtually every engine. It’s not afancy device and doesn’t get much attention by the averageracer. In spite of this, the pick-up is very important to yourengine. If it does not do its job, then the engine is in realtrouble and could very easily fail.Once the pan is removed from the engine, the pick-up sticksout away from the crankshaft and bottom of the block. Assuch, it is very vulnerable and can be easily damaged.Removing it from the block, which has to be done to allowthe engine to be rebuilt, can also be tricky and cause thepick-up to be damaged. One common damage is to bend it.Typically, when you try to bend it “back into place” youwill break or crack it. A crack will allow air to get into theoil system and be fed directly to the bearings which willcause the obvious failure. A crack can also cause the oilpump’s “prime” to be lost. Used pick-ups can also be verydifficult to clean. For any of these situations, obtaining newparts will solve your problem. Remember, they aredesigned to work in the stock pan. If the pan is changed,you may have to modify the pick-up, but now you will havea new part to start with for your modification.OIL PANThe 4.0L engine standard production oil pan is made oflaminated steel and has a single plane sealing surface. Theoil pan gasket is a one piece steel backbone silicone coatedgasket. Removal and replacement procedures varydepending on vehicle type and model year. Refer to yourservice manual for removal and replacement procedures.Oil Pan Gasket SetIncludes both the sides and the ends. For 4.0L engine only.P4529244Oil pan gasket set.

4.0L POWER TECH IN-LINE 6 (OILING SYSTEM) 211OIL PAN PERFORMANCE CONSIDERATIONSWindage LossesEvery engine that uses oil for lubrication has windagelosses. Controlling windage loss can help make morepower. This holds true for any engine. The more enginespeed that you use, the worse the windage loss becomes.Remember, less windage means more horsepower!So what is windage and why does less of it make morepower? Windage is the friction caused by the crankshaft andconnecting rod assembly rotating through an air-oilmixture. Windage trays are designed to “scrape” the oil thatis thrown off the crankshaft away from the crankshaft andinto the pan, and keep the oil that is in the pan from comingup for the crankshaft to drag through. Each connecting rodand main bearing has oil and oil pressure in it and, becauseof the oil pressure, some will leak out and get in the way ofthe rotating crankshaft assembly. Then there’s the oil thatgoes to the head to lubricate the valve gear that has to getback to the pan somehow. This usually means that it fallsback past the tappets and on to the crankshaft. Smart racerswill work extra hard to install special drains so that thereturn oil doesn’t fall on to the crankshaft.Windage TrayEvery high performance engine should have a windage tray.It goes between the oil pan and the block. Only the windagetray and two oil pan gaskets are required for installation.The only time a windage tray should not be used is with acustom-made race oil pan. With a custom-made race pan,the windage tray should be removed resulting in increasedvehicle performance. If the vehicle slows down when thetray is removed, the pan has been compromised too muchand the tray should always be used with that particular pan.Stock (Production) Oil Pan ModificationsThe standard pan can be helped by reworking the sump soit is 2” deeper. A longer oil pick-up must also be installedat the same time. A deepened pan can also be used. Withthis pan the pick-up must also be lengthened, or a strainerand pipe assembly, which is designed for use with thedeepened pan, should be purchased. With any oil pancapacity or shape change, the dipstick should be carefullyrecalibrated. Be sure to fill the oil filter before calibrating!With either of these pans installed, the ground clearancewill be reduced and the pan will no longer be protected. Foradded pan protection, a slud plate should be added and thevehicle should be driven with increased care.In a stock pan, especially a deepened pan, the rearacceleration baffle is very important. It keeps oil fromrunning up into the rear cylinders and slowing down the lastrod journal with increased drag. The rear acceleration bafflemust be sealed to three walls of the sump (back and twosides) or it becomes useless.DRY SUMP OILING SYSTEMFor drag racing, a dry sump system should only beconsidered for vehicles that have almost no groundclearance. However, dry sump oiling systems can be veryadvantageous in an oval track vehicles. Dry sumps providemore ground clearance so the vehicle can sit lower. This isbecause dry sump pans are very shallow. This allows thecenterline of the crankshaft to get closer to the ground whilemaintaining the same actual ground clearance. (Groundclearance is usually specified and enforced by thesanctioning body.)All production (stock) oil pans are wet sump designs. Witha dry sump, the oil that is being stored in preparation forbeing pumped back into the engine is stored outside theengine (or remotely), usually in a separate tank (withbaffles, etc.) located ahead of the engine. A race wet sumppan would have a large capacity rear sump located directlyunder the crankshaft.Production wet sumps are small and may be located in thecenter, front or rear. A race wet sump ideally designedwould be 9 to 10 inches deep. But many professionallybuiltrace vehicles are built so low to the ground that thereis no room for this style pan. Enter the dry sump. However,a properly designed dry sump system is expensive.Therefore, a racer who doesn’t have the crankshaftdragging on the ground doesn’t need a dry sump becauseit’s money spent for no gain. Here, look closely at a racewet sump. There is performance in a good wet sump systemrace pan.A dry sump oil system should be used whenever a deep oilpan cannot be used. There is approximately 40 hp lost to ashallow, wet sump pan.The dry sump system consists of an oil tank, scavengepump, and a pressure pump. The oil pump used is a multistage,external assembly with two or three stages forscavenge and a pressure stage. Drag race engines requiretwo scavenge stages, oval track engines require three. Thepump should be run at .5 to .6 engine speed.The oil tank for drag racing use can be as small as 5 qts.,while an oval track racing tank should be 3 gallons.Now that we know all the parts, let’s see how it works. Thepressure stage picks oil up from the tank, then sends it to anexternal oil filter, and then to the engine. The engine then getsoiled and dumps the oil back in the pan where the scavengestages pick up the oil and return it to the tank. The tank isvented to the valve cover to equalize pressures. ContactWeaver Brothers for further details and dry sump hardware.Weaver Brothers1980 Boeing WayCarson City, NV 89706. ..

I- -1 n21 2 MOPAR PERFORMANCE PARTSOIL COOLERSEngine Oil CoolerThis specially engineered, finned radiator design oil coolerprevents engine oil from overheating, thus ruining itslubricating characteristics. This cooler is ideally suited forendurance-type engine applications and utilizes 1/2" pipethread fittings. Measures 1 1 " x 12" x 1 - 1/2".P3690956Engine oil cooler.Heavy Duty Engine Oil CoolerThis heavy duty steel, full flow oil cooler is the best wayto ensure peak engine oil cooling efficiency under heavierthan normal driving conditions. It is thermostaticallycontrolled to provide continuous cooling of your engine'soil. Install in oil filter circuit. Oil circulates in acontinuous loop from the pan, through the pump, then tothe cooler. Includes built-in relief valve. Designed forsimple installation. Cooler is 1-1/2" thick. Measures 6" Wx 18" L.P48769 17Heavy duty oil cooler.Universal Oil Cooler PackagesSpecial universal coolers mount between engine and oilfilter to circulate heater core coolant to reduce oiltemperatures.P4529690P452969 1OILUniversal oil cooler package, standard.Universal oil cooler package, extra cooling.Use only high detergent and additive engine oil. The oilmust meet Mil Spec MS-DG. DO NOT use viscosityimprover oil additives. The only oil additives you shouldconsider using are anti-scuff additives, such as MoparEngine Oil Supplement. Anti-scuff additives should beused only for running in and should be drained from theoiling system before racing (be sure to re-fill the engine oilto the correct level before re-starting the engine).SAE ViscosityAn SAE viscosity grade is used to specify the viscosity ofengine oil. Use only engine oils with multiple viscositysuch as 5W-30 or IOW-30. These are specified with a dualSAE viscosity grade which indicates the cold-to-hottemperature viscosity range. Select an engine oil that is bestsuited to your particular temperature range and variation(Figure 4-38).Il iENGINE OIL VISCOSITY GRADES-29" -18" -12" -7" 0" 16" 27" 38" 1Temperature range anticipated before next oil changeOil Level InspectionFigure 4 - 38Caution: DO NOT overfill crankcase with engine oil,pressure loss or oil foaming can result.Inspect engine oil level approximately every 800kilometers (500 miles). Unless the engine has exhibited lossof oil pressure, run the engine for about five minutes beforechecking oil level. Checking engine oil level on a coldengine is not accurate.To ensure proper lubrication of an engine, the engine oilmust be maintained at an acceptable level. The acceptablelevels are indicated between the ADD and SAFE marks onthe engine oil dipstick.1.2.Position vehicle on level surface.With engine OFF, allow approximately ten minutes foroil to settle to bottom of crankcase, remove engine oildipstick.3. Wipe dipstick clean.4.5.6.Install dipstick and verify it is seated in the tube.Kemove dipstick, with handle held above the tip, takeoil level reading.Add oil only if level is below the ADD mark ondipstick.Engine Oil ChangeChange engine oil at mileage and time intervals described inMaintenance Schedules of your owners or service manual.Run engine until achieving normal operating temperature.1. Position the vehicle on a level surface and turnengine off.2.Hoist and support vehicle on safety stands.3. Remove oil fill cap.4. Place a suitable drain pan under crankcase drain.II

4.0L POWER TECH IN-LINE 6 (OILING SYSTEM) 2135. Remove drain plug from crankcase and allow oil todrain into pan. Inspect drain plug threads for stretchingor other damage. Replace drain plug if damaged.6.7.Install drain plug in crankcase.Lower vehicle and fill crankcase with specified typeand amount of engine oil described in this section.8. Install oil fill cap.9. Start engine and inspect for leaks.10. Stop engine and inspect oil level.Installation1.2.3.Lightly lubricate oil filter gasket with clean engine oil.Thread filter onto adapter nipple. When gasket makescontact with sealing surface (Figure 4-39), handtighten filter one full turn. DO NOT over tighten.Add oil, verify crankcase oil level and start engine.Inspect for oil leaks.ENGINE OIL FILTERAll engines are equipped with a high quality full-flowdisposable type oil filter. DaimlerChrysler recommends aMopar or equivalent oil filter be used.Removal1.2.3.4.5.Position a drain pan under the oil filter.Using a suitable oil filter wrench, loosen the filter.Rotate the oil filter counterclockwise to remove it fromthe cylinder block oil filter boss.When filter separates from adapter nipple, tip gasketend upward to minimize oil spill. Remove filter fromvehicle.With a wiping cloth, clean the gasket sealing surface(Figure 4-39) of oil and grime.... ._FACE GASKET 9100-7Figure 4 - 39

21 4 MOPAR PERFORMANCE PARTSINTRODUCTIONCooling SystemThe cooling system (Figure 4-40 and Figure 4-41) regulatesengine operating temperature. It allows the engine to reachnormal operating temperature as quickly as possible. It alsomaintains normal operating temperature and preventsoverheating.The cooling system also provides a means of heating thepassenger compartment and cooling the automatictransmission fluid (if equipped). The cooling system ispressurized and uses a centrifugal water pump to circulatecoolant throughout the system.The cooling system consists ofIRadiatorMechanical cooling fanFan shroudRadiator pressure capThermostatCoolant reserve/overflow systemTransmission oil cooler (if auto. trans. equipped)CoolantWater pumpHoses and hose clampsAccessory drive beltFANSHROUDFigure 4 - 41Cooling System CapacityCaution: Vehicle may be equipped with long life coolant.Extended life coolant is identified by an orange color.Normal coolant is identified by a greenish color. DO NOTmix the two types of coolant. Refer to your service manualfor coolant recommendations.4.01, 12.3 liters (13.0 quarts)"* Includes 2.2 liters (2.3 quarts) for coolant recovery bottle.Coolant Reservoir/Overflow SystemThis system works along with the radiator pressure cap.This is done by using thermal expansion and contraction ofthe coolant to keep the coolant free of trapped air. Itprovides :A volume for coolant expansion and contraction.A convenient and safe method for checking/adjustingcoolant level at atmospheric pressure. This is donewithout removing the radiator pressure cap.Some reserve coolant to the radiator to cover minorleaks and evaporation or boiling losses.As the engine cools, a vacuum is formed in the coolingsystem of both the radiator and engine. Coolant will then bedrawn from the coolant tank and returned to a proper levelin the radiator.The coolant reservoir/overflow system has a radiatormounted pressurized cap, an overflow tube and a plasticcoolant reservoir/overflow tank mounted to the right innerfender (typical)...

T - T 74.0L POWER TECH IN-LINE 6 (COOLING SYSTEM) 215TroubleshootingThe 4.0L Power Tech engine standard production coolingsystem is adequate at keeping operating temperatures ataccepted levels. However, several components may bechanged to reduce power losses in the system.Not surprisingly, race engine cooling problems arise duringthe summer and tend to disappear in the fall. There arevarious causes: flex-fans, water pumps, radiator size andfunctioning shrouds, grille openings, and fan bladediameter and number. The not so obvious areas areimproper spark advance and too lean fuel mixture.Now, what happens if a racer has fixed all of these problemsand he still overheats or runs too hot? What could thisproblem be? Some people feel this means there is somemysterious design problem with the engine. This is a witchhunt! Generally, engines don’t have an overheatingproblem. Big engines make more heat than small engines,but this just requires a bigger radiator. Put simply, enginesmake heat; cooling systems get rid of heat. Nothing fancy!If your engine overheats, that means the balance betweenthese two functions has been lost somewhere.COOLING SYSTEM HOSES(Refer to Figure 4-40.)Rubber hoses route coolant to and from the radiator, intakemanifold and heater core. The lower radiator hose is springreinforcedto prevent collapse from water pump suction atmoderate and high engine speeds. When performing a hoseinspection, inspect the radiator lower hose for properposition and condition of the internal spring.Warning! Constant tension hose clamps are used on mostcooling system hoses when removing or installing, use onlytools designed for servicing this type of clamp. Always wearsafety glasses when servicing constant tension clamps.Caution: A number or letter is stamped into the tongue ofconstant tension clamps. If replacement is necessary, use onlyan original equipment clamp with matching number or letter.Inspect cooling hoses at regular intervals. Replace hosesthat are cracked, feel brittle when squeezed, or swellexcessively when the system is pressurized.In areas where specific routing clamps are not provided, besure that hoses are positioned with sufficient clearance. Checkclearance from exhaust manifolds and pipe, fan blades, drivebelts and sway bars. Improperly positioned hoses can bedamaged, resulting in coolant loss and engine overheating.SERPENTINE DRIVE BELTCorrect drive belt tension is required to ensure optimumperformance of the belt driven engine accessories. Ifspecified tension is not maintained, belt slippage may causeengine overheating, lack of power steering assist, loss of airconditioning capacity, reduced generator output rate, andgreatly reduced belt life.It is not necessary to adjust belt tension on the 4.0L engines.These engines are equipped with an automatic belttensioner. The tensioner maintains correct belt tension at alltimes. Due to use of this belt tensioner, DO NOT attempt touse a belt tension gauge on 4.0L engines.DiagnosisWhen diagnosing serpentine drive belts, small cracks thatrun across ribbed surface of belt from rib to rib (Figure 4-42) are considered normal. However, cracks running alonga rib (not across) are not normal (Figure 4-42). Any beltwith cracks running along a rib must be replaced. Alsoreplace the belt if it has excessive wear, frayed cords orsevere glazing.Refer to the Serpentine Drive Belt Diagnosis Chart forfurther belt diagnosis.NORMAL-CRACKSBELT OKNOT NORbL CRACKSREPLACE BELTFigure 4 - 42m7-44

21 6 MOPAR PERFORMANCE PARTSSERPENTINE DRIVE BELT DIAGNOSISCONDITION3IB CHUNKING (ONE OR MORE3IBS HAS SEPARATED FROM3ELT BODY)3IB OR BELT WEARLONGITUDINAL BELT:RACKING (CRACKS BETWEENN O RIBS)POSSIBLE CAUSES1. Foreign objects imbedded in pulleygrooves.2. Installation damage.1. Pulley(s) misaligned.2. Abrasive environment.3. Rusted pulley(s).4. Sharp or jagged pulley groove tips.5. Rubber deteriorated.1. Belt has mistracked from pulleygroove.2. Pulley groove tip has worn awayrubber to tensile member.CORRECTION1. Remove foreign objects frompulley grooves. Replace belt.2. Replace belt.1. Align pulley(s).2. Clean pulley(s). Replace belt ifnecessary.3. Clean rust from pulley(s).4. Replace pulley.5. Replace belt.1. Replace belt.2. Replace belt.

4.01. POWER TECH IN-LINE 6 (COOLING SYSTEM) 217IIBELT SLIPSCONDITIONSERPENTINE DRIVE BELT DIAGNOSISPOSSIBLE CAUSES1. Belt slipping because of insufficienttension.CORRECTION1. Replace automatic belt tensioner.“GROOVE JUMPING (BELTDOES NOT MAINTAIN CORRECTPOSITION ON PULLEY)BELT BROKEN (NOTE: IDENTIFYAND CORRECT PROBLEMBEFORE NEW BELT ISINSTALLED)NOISE (OBJECTIONABLESQUEAL, SQUEAK, OR RUMBLEIS HEARD OR FELT WHILEDRIVE BELT IS IN OPERATION)2. Incorrect belt.3. Belt or pulley subjected tosubstance (belt dressing, oil ethyleneglycol) that has reduced friction.4. Driven component bearing failure.5. Belt glazed and h(ardened fromheat and excessive slippage.1. Belt tension either too high or toolow.2. Incorrect belt.3. Pulley(s) not within designtolerance.4. Foreign object(s) in grooves.5. Pulley misalignment.6. Belt cord line is broken.1. Excessive tension.2. Incorrect belt.3. Tensile member damaged duringbelt installation.4. Severe misalignmlent.5. Bracket, pulley, or bearing failure.1. Belt slippage.2. Bearing noise.3. Belt misalignment.4. Belt-to-pulley mismatch.2. Replace belt.3. Replace belt and clean pulleys.4. replace faulty componentbearing.5. Replace belt.1. Replace automatic belt tensioner.2. Replace belt.3. Replace pulley(s).4. Remove foreign objects fromgrooves.5. Check and replace.6. Replace belt.1. Replace belt and automatic belttensioner.2. Replace belt.3. Replace belt.4. Check and replace.5. Replace defective componentand belt.1. Replace belt or automatic belttensioner.2. Locate and repair.3. Replace belt.4. Install correct belt.

21 8 MOPAR PERFORMANCE PARTSWATER PUMPA centrifugal water pump (Figure 4-43) circulates coolantthrough the water jackets, passages, intake manifoldradiator core, cooling system hoses and heater core Thepump is driven from the engine crankshaft by a singleserpentine drive belt on all engines.The water pump impeller is pressed onto the rear of a shaftthat rotates in bearings pressed into the housing. Thehousing has two small holes to allow seepage to escape.The water pump seals are lubricated by the antifreeze in thecoolant mixture. No additional lubrication is necessary.Caution: All 4.0L Power Tech engines are equipped witha reverse (counterclockwise) rotating water pump andthermal viscous fan drive assembly. REVERSE is stampedor imprinted on the cover of the viscous fan drive and innerside of the fan. The letter R is stamped into the back of thewater pump impeller. Engines from previous model years,depending upon application, may have been equipped witha forward (clockwise) rotating water pump. Installation ofthe wrong water pump or viscous fan drive will causeengine over heating.Caution: 160°F thermostats should NOT be used in otherthan high endurance racing vehicles. Use of 160°Fthermostats in vehicles other than this can result in seriousengine damage.For high speed race engines, a small diameter crankshaftpuky and large diameter alternator and water pumppulleys are desirable. Aftermarket sources have thesepulleys available and they feature a deep groove design.For drag strip use only, the water pump can be cut down,200'' for less friction and horsepower loss. There are alsoaftermarket electric fan-water pump kits which replace thestandard fan belt so that the power that is needed to operatethe water pump doesn't come from the crankshaft,increasing the engine's horsepower output. (A mechanicalwater pump requires about 10 hp at 7,000 rpm.) If legal, anelectric drive water pump should always be used.Water Pump Flow TestA quick flow test to tell whether or not the pump is workingis to see if the heater warms properly. A defective pumpwill not be able to circulate heated coolant through the longheater hose.Another flow test to help determine pump operation isas follows:1. Remove radiator cap.'Warning! DO NOT remove radiator cap if the coolingsystem is hot or under pressure.2. ]Remove a small amount of coolant from the system.Start the engine and warm up until the thermostatopens. With the thermostat open and coolant level low,you will see if the water pump is pumping coolantthrough the system.Water Pump InspectionWATER PUMPHUBPerformance TipsWATER PUMPFigure 4 - 43ma7836The water pump is the heart of the cooling system. It isresponsible for pumping coolant through the engine block,cylinder heads, heater core and radiator.For most high performance off-road applications, highengine temperature is undesirable. For these applications,install a 160°F thermostat. It will help the engine run cooler.Replace water pump assembly if it has any of the followingconditions:The body is cracked or damaged.Water leaks from shaft seal. This is evident by traces ofcoolant below vent hole.Loose or rough turning bearing. Also inspect viscousfan drive.Impeller rubs either the pump body or the cylinder block.WATER NECKThe water neck is also called the thermostat housing.However, many racing vehicles DO NOT use a thermostat,so it might be confusing to name it after something that isnot used. The typical water neck exits straight up. Theupper radiator hose fits over the water neck.T -- - "1

T -174.01L POWER TECH IN-LINE 6 (COOLING SYSTEM) 21990 Degree Water Neck OutletThe purpose of the 90 degree outlet is to drop the upperradiator hose down and allow its angle to be changed. Stockoutlets have the water exiting straight up (as installed on theengine). This type of exit requires the top radiator hose tomake a quick 90 degree bend to get to the radiator. In thisconfiguration, it is common to get kinks in the hose,especially replacement hoses. Stock Mopar hoses aremolded with the sharp bend. However, the hose will stillinterfere with any blower drives that may sit on top of themanifold. By having the 90 degree bend in a rigid housingrather than a rubber hose, you can turn the corner muchtighter. This allows for a lower hood line (which can also behelpful in circle track vehicles). It also looks neater andcleaner-a plus for show vehicles.An additional feature is that it has three positions: straightahead, approximately 30 degrees to the right, or 30 degreesto the left, enabling the housing to be rotated to point moredirectly at the top radiator inlet. This allows for moreoptions in clearance items/accessories at the front of theengine. It also makes for a straighter and smaller hose andtherefore a cleaner looking engine compartment.90" Water Neck OutletCast aluminum, 90" water neck outlet provides greaterflexibility in routing cooling system hoses. Threedirectional capability ideal for compact enginecompartments. Improves the appearance of the enginecompartment.P5249 19 1THERM 0 STAT90" water neck outlet.The engine thermostat is a wax pellet driven, reverse poppetchoke-type. It is located on the front of the engine (radiatorside) in the thermostat housing/engine outlet connectorlocated in the flange (Figure 4-44). An O-ring for sealing isincorporated on it. There is a relief in the thermostathousing/outlet connector for the O-ring (Figure 4-45).An arrow, plus the word UP is stamped on the front flangenext to the air bleed. The words TO RAD are stamped onone arm of the thermostat. They indicate the properinstalled position.The engine thermostat is designed to provide the fastestwarm-up possible by preventing leakage through it and toguarantee a minimum engine temperature of 82 to 9 1°C(180 to 195°F). It also automatically reaches wide open soit does not restrict flow to the radiator as temperature of thecoolant rises in hot weather to around 104°C (220°F).Above this temperature the coolant temperature iscontrolled by the radiator, fan, and ambient temperature,not the thermostat.The thermostat's primary purpose is to maintain enginetemperature in a range that will provide satisfactory engineperformance and emission levels under all expected drivingconditions. It also provides hot water (coolant) for heaterperformance. It does this by transferring heat from enginemetal and automatic transmission oil cooler (if equipped) tocoolant, moving this heated coolant to the heater core andradiator and then transferring this heat to the ambient air.The same thermostat is used for winter and summer seasons.An engine should not be operated without a thermostat,except for servicing or testing. Operating without athermostat causes other problems, including longer enginewarm-up time, unreliable warm-up performance, increasedexhaust emissions and crankcase condensation. Thiscondensation can result in sludge formation.The most common type of thermostat failure, usually foundon high mileage vehicles, is a thermostat failed in the shutposition. The temperature gauge (if equipped) will give anindication of this condition. Depending upon length of timethat vehicle is operated pressure cap may vent. This willexpel steam and coolant to coolant reserve/overflow tankand the ground below vehicle.For most high performance off-road applications, highengine temperature is undesirable. For these applications,install a 160°F thermostat. It will help the engine run cooler.Caution: 160°F thermostats should NOT be used in otherthan high endurance racing vehicles. Use of 160°Fthermostats in vehicles other than this can result in seriousengine damage.I LONG'I1 SHORTIBOLTGASKET\Figure 4 - 44THERMOSTAT'THERMOSTATHOUSINGJ9307-13

220 MOPAR PERFORMANCE PARTSOnly when sufficient heat is present will the viscous fandrive engage. This is when the air flowing through theradiator core causes a reaction to the bimetallic coil. It thenincreases fan speed to provide the necessary additionalengine cooling.II GRO~VE J9307-25. COOLANTFigure 4 - 45The presence of aluminum components in the coolingsystem requires strict corrosion protection. Maintaincoolant at specified level with a 50/50 mixture of antifreezeand water. If coolant becomes contaminated or looses color,drain and flush cooling system and fill with correctly mixedsolution.Caution: DO NOT use coolant additives which claim toimprove engine cooling.Once the engine has cooled, the radiator dischargetemperature will drop. The bimetallic coil again reacts andthe fan speed is reduced to the previous disengaged speed.Caution: Engines equipped with serpentine drive beltshave reverse rotating fans and viscous fan drives. They aremarked with the word REVERSE to designate their usage.Installation of the wrong fan or viscous fan drive can resultin engine overheating.Caution: If the viscous fan drive is replaced because ofmechanical damage, the cooling fan blades should also beinspected. Inspect for fatigue cracks, loose blades, or looserivets that could have resulted from excessive vibration.Replace fan blade assembly if any of these conditions arefound. Also inspect water pump bearing and shaft assemblyfor any related damage due to a viscous fan drivemalfunction.IMOUNTING NUTTO WATER PUMPFANSViscous Fan DriveOn 4.0L engines, an electric fan is standard and a thermalviscous fan is added on trailer tow packages only. Thethermal viscous fan drive (Figure 4-46) is a silicone fluidfilledcoupling used to connect the fan blades to the waterpump shaft. The coupling allows the fan to be driven in anormal manner. This is done at low engine speeds whilelimiting the top speed of the fan to a predeterminedmaximum level at higher engine speeds.A thermostatic bimetallic spring coil is located on the frontface of the viscous fan drive unit (Figure 4-46). This springcoil reacts to the temperature of the radiator discharge air. Itengages the viscous fan drive for higher fan speed if the airtemperature from the radiator rises above a certain point.Until additional engine cooling is necessary, the fan willremain at a reduced rpm regardless of engine speed.Figure 4 - 46Mopar Performance Parts Viscous Fan PackageMopar Performance Parts has carried a viscous drive fanpackage for years. Viscous drives allow the engine to run ata higher rpm than the fan: that is, the fan slips at high speed.The purpose of a viscous drive is to save horsepower.We receive many calls concerning fans and cooling. A largenumber of viscous fans have been introduced in theafterrnarket over the last few years. This situation caused usto throw some parts on the dyno. The dyno allows us toknow exactly what’s going on. We selected several viscousunits and several different fans. Some of the new fans lookvery nice - six blade, symmetrical. The one we’ve shown inour parts catalog for years is a five blade, asymmetricaldesign, which we’ve always considered to look “funny.”-31

4.0lL POWER TECH IN-LINE 6 (COOLING SYSTEM) 221The new ones were bound to do better. Well, so much forstyle! The Mopar Performance Parts viscous fan packagewon! It was 5 to 10 horsepower better than the otherviscous fans. Each was run separately so that we didn'tmiss any possible combination.That was reassuring. But the real shocker was the MoparPerformance Parts viscous drive compared to a plastic flexfan. Everyone had always assumed that these two types ofunits were about the same in performance. Additionally, theplastic flex fans are sold as a performance piece and theyhave always looked trick. Well so much for looks! TheMopar Performance Parts viscous drive package was IOhorsepower and 13 Ib-ft of torque better than the flex fan.The flex fan could be as good as some of the other viscousdrives, but the Mopar Performance Parts unit issubstantially better for performance.Note: Although the viscous fan package listed will fit your4.0L Power Tech engine (bolt spacing is the same), caremust be taken to assure sufficient fan-to-radiator clearanceis maintained (minimum 1/2" from the leading edge of thefan to the back edge of the radiator; 3/4" preferred).Viscous Fan PackageIMost late 1960s and early 1970s Chrysler-Plymouth-Dodge muscle cars were equipped with viscous fans forcooling purposes. DaimlerChrysler engineers havedetermined through dyno testing that this viscous fan isthe best replacement package. It provides thermostaticallycontrolled cooling, includes a lightweight balanced fanand takes the least amount of horsepower from the engine.P4 120758Electric FansViscous fan package.12 volt electric cooling fans are highly efficient auxiliarybolt-ons for Street Rods, Street Machines, race cars, trucks,and compact or medium sized vehicles. They can beinstalled in front or in back of your radiator quickly andeasily. Unlike conventional belt drive fans, an electric fanwill not rob engine horsepower.

222 MOPAR PERFORMANCE PARTSINTAKE MANIFOLDThe 4.0L engine standard production intake manifold ismade of cast aluminum and uses eleven bolts to mount tothe cylinder head (Figure 4-48). This mounting styleimproves sealing and reduces the chance of leaks.Removal and InstallationThe engine intake manifold and exhaust manifolds must beremoved and installed together. The manifolds use acommon gasket at the cylinder head. Refer to ExhaustMuni&dolds, ‘Exhaust System’ section of this chapter formore information.MULTI-POINT FUEL INJECTION (MPI)The 4.0L engine uses a sequential Multi-Port Fuel lnjection(MPI) system. Fuel is injected into the intake manifoldbefore the intake valve in precise metered amounts throughelectrically operated injectors. The injectors are fired in aspecific sequence by the Powertrain Control Module (PCM).The PCM constantly adjusts the amount of fuel injected tomeet changing operating conditions by controlling injectorpulse width (the length of time the injector is energized). ThePCM also adjusts ignition timing by controlling the ignitioncoil operation through the Ignition Control Module (ICM).The PCM determines air-fuel mixture and ignition timingbased on inputs it receives from various sensors that monitorengine operating conditions.The PCM receives inputs from sensors that react to exhaustgas oxygen content, coolant temperature, manifold absolutepressure, engine speed (crankshaft position), throttleposition, battery voltage, intake manifold air temperature,engine knock and transmission gear selection. These inputsrepresent the engine’s instantaneous operating conditions.Air-fuel mixture and ignition timing calibrations forvarious driving and atmospheric conditions are preprogrammedinto the PCM. The PCM monitors andanalyzes its various inputs, computes engine fuel andignition timing requirements based on these inputs, andcontrols fuel delivery and ignition timing accordingly. TheEngine Control System is comprised of (1) the sensors andswitches that provide input to the PCM, (2) the PCM itself,and (3) the PCM outputs (engine control devices that thePCM constantly adjusts). The Engine Control Systemconsists ofBattery VoltageManifold Absolute Pressure (MAP) SensorCoolant Temperature SensorManifold Air Temperature (MAT) SensorExhaust Oxygen (0,) SensorInduction SystemEngine Speedcrankshaft Position SensorThrottle Position SensorInjector Synchronization SignalA/C Select SignalAIC Request SignalNeutral Safety SwitchKnock SensorFuel Pump RelayFuel InjectorsIdle Speed Stepper MotorB+ Latch RelayOxygen Sensor Heater RelayEGR Valve SolenoidIgnition Control ModuleShift Indicator Light (manual transmissions only)A/C Clutch RelayPowertrain Control Module (PCM)The Powertrain Control Module (PCM) is a digitalmicroprocessor. Air-fuel mixture calibrations for variousdriving and atmospheric conditions are pre-programmedinto the PCM. The PCM monitors and analyzes its variousinputs, computes engine fuel and ignition timingrequirements based on these inputs, and controls fueldelivery and ignition timing accordingly. As operatingconditions change, the PCM adjusts injector pulse width andignition timing for optimum performance and fuel economy.Jeep High Performance ComputerMopar Performance Parts computer provides more sparkadvance and increased fuel flow for off road racingapplications. This computer will enhance otherperformance modifications. For 1987-90, 4.0L enginesonly.P4529334PCM InputsJeep high performance computer.The PCM is powered by the vehicle’s battery. When theignition is turned to the ON or START position, thefollowing inputs are supplied to the PCM:Battery VoltageManifold Absolute Pressure (MAP) SensorCoolant Temperature Sensor

4.0L POWER TECH IN-LINE 6 (INDUCTION SYSTEM) 223Manifold Air Temperature (MAT) SensorExhaust Oxygen (0,) SensorEngine Speedcrankshaft Position Sensor0 Throttle Position SensorInjector Synchronization SignalA/C Select SignalNeutral Safety Switch (gear selection- automatictransmission)Knock Sensor0 Start SignalPCM OutputsBased upon signals from various input sensors andswitches, the PCM adjusts the following components (PCMoutputs):Fuel Pump RelayB+ Latch Relay0 Oxygen Sensor Heater Relay0 A/C Clutch Relay0 Fuel InjectorsIdle Speed Stepper MotorEGR Valve SolenoidIgnition Control Module (ICM)Shift Indicator Light (manual transmission only)Modes of OperationAs input signals to the PCM change, the PCM adjusts itsresponse to the output devices. For example, the PCM mustcalculate a different injector pulse width and ignition timingfor idle than it does for wide open throttle. There are eightdifferent modes of operation that determine how the PCMresponds to the various input signals.Modes of operation are of two different types: OPENLOOP and CLOSED LOOP.During OPEN LOOP modes the PCM receives inputsignals and responds only according to preset PCMprogramming. Input from the oxygen (0,) sensor is notmonitored during OPEN LOOP modes.During CLOSED LOOP modes the PCM does monitor the0, sensor input. This input indicates to the PCM whether ornot the calculated injector pulse width results in the idealair-fuel ratio (14.7 parts air to 1 part fuel). By monitoringthe exhaust oxygen content through the 0, sensor, the PCMcan ‘fine tune’ the injector pulse width to achieve optimumfuel economy combined with low emission engineperformance.The MPI system has the following modes of operation:Ignition Switch ONEngine Start-up (Crank)Engine Warm-upIdleCruiseDecelerationWide Open ThrottleIgnition Switch OFFThe ignition switch ON, engine start-up (crank), enginewarm-up, deceleration, and wide open throttle modes areOPEN LOOP modes. The idle and cruise modes, with theengine ut operating temperature, are CLOSED LOOP modes.Throttle BodyFiltered air from the air cleaner enters the intake manifoldthrough the throttle body. Fuel does not enter the intakemanifold through the throttle body. Fuel is sprayed into themanifold by the fuel injectors. This throttle body, mountedon the intake manifold, contains an air bypass passage thatis used to supply air for idle conditions, and a throttle valvefor above idle conditions.The throttle position sensor and idle speed stepper motorare attached to the throttle body. The accelerator cable isconnected to the throttle valve through a bellcrank andlinkage mounted to the intake manifold.There are different throttle bodies for automatic and manualtransmission equipped vehicles. The throttle valve is notcontrolled by the PCM.Fuel RailThe fuel rail supplies fuel to the injectors and is mounted tothe intake manifold (Figure 4-47). The fuel pressureregulator is attached to the rail and the fuel pressure testport is integral with the rail. The fuel rail is not repairable.

224 MOPAR PERFORMANCE PARTSI INJ.#l INJ.#2 INJ.#3 INJ.#4 INJ.#5 INJ.#6pressure is exerted to seal the fuel outlet causing systempressure to increase. With high vacuum, such as during idle,fuel pressure on the bottom of the diaphragm is assisted byintake manifold pressure on the spring side of thediaphragm, resulting in lower system fuel pressure. Thefuel pressure regulator is not controlled by the PCM.Racing ModificationsBy their nature, unlike carbureted engine set-ups, fuelinjection systems deliver fuel equally among all sixcylinders. It’s because of this excellent fuel distributioncharacteristic that fuel injection is preferred over carburetors,even over high performance 2 and 4-Bbl. carburetors.\ MOUNTING \BOLTS (4)Fuel Pressure RegulatorFUELPRESSURE TESTPORT CAPFigure 4 - 47F~~CTOR8Ob898e3The fuel pressure regulator used with the MPI fuel systemis a vacuum assisted, non-adjustable type. The regulator ismounted on the output end of the fuel rail and is connectedto intake manifold vacuum. The regulator is calibrated tomaintain fuel system pressure at approximately 214 kPa (3 1psi) with vacuum applied while the engine is at idle. Fuelpressure will be 55-69 kPa (8-10 psi) higher if vacuum isnot applied to the regulator.The pressure regulator contains a diaphragm, calibratedspring and fuel return valve. Fuel pressure operates on thebottom side of the diaphragm while spring pressure andintake manifold vacuum operate on the top side of thediaphragm. Spring pressure tries to force the return valveclosed. Fuel pressure, with assistance from manifoldvacuum on the spring side, acts against the spring pressureto open the return valve. Thus, system fuel pressure is theamount of fuel pressure required to force against springpressure and unseat the fuel return valve.Without vacuum applied to the spring side of the regulator,the spring is calibrated to open the fuel return outlet whenthe pressure differential between the fuel injectors and theintake manifold reaches approximately 269 kPa (39 psi).Since manifold vacuum varies with engine operatingconditions, the amount of vacuum applied to the spring sideof the diaphragm varies. For this reason, fuel pressurevaries depending upon intake manifold vacuum. With lowvacuum, such as during wide open throttle conditions,minimal vacuum assistance is available and full springAnd don’t disconnect those stock fuel injection sensors!Today’s engines run a lot hotter because they run a lotleaner; because of this, fuel injection temperature is verycritical. It is something that has to be constantly monitoredand stabilized to keep the fuel injection and the power levelin their proper places. Mopar Performance Partsrecommends the use of all sensors, even in highperformanceracing set-ups. These sensors constantly inputvital information to the PCM, and the PCM corrects themixture accordingly.And don’t abandon that oxygen sensor, either. Since racingset-ups don’t use catalytic converters, use an EGT probe tolocate the hottest spot in the exhaust system and install theoxygen sensor there.AIR FILTERS~High Performance Air Filter ElementSpecial reusable filter element for high performance.Increases air flow versus stock filters which increasesengine output.P5249792P52499 18P4876273P4876272Air Filter Cleaning FluidHigh performance air filter element,1993-97 Jeep Grand Cherokee 4.0L only.High performance air filter element,199 1-96 Jeep Wrangler 4.0L only.High performance air filter element,1997-98 Jeep Wrangler 4.0L only.High performance air filter element,1987-96 Jeep Cherokee 4.0L only.Mopar Performance Parts long-life high performance airfilters are reusable. This cleaning fluid is designed toremove dirt to extend the life of the filter.P4529392Air filter cleaning fluid.

4.0L POWER TECH IN-LINE 6 (INDUCTION SYSTEM) 225Air Filter OilLong life, high performance air filters trap dirt with aspecial oil on the filter. After cleaning air filters, re-oilthem with this special fluid.P4529393TURBOCHARGINGAir filter oil.Turbocharging is not for the amateur. People who wantturbochargers on their race vehicles are those looking foran added amount of horsepower to their already wellrunningengines.Turbocharging is not a new engineering feature. It has beenused for many years in many applications. Even someproduction models of the mid- 1960s had a turbochargingoption. However, after a year or two in production, theseoptions were dropped.Over the past several years, interest in turbocharging hasincreased rapidly. Much of this interest is centered aroundthe Street Machine, Street Rod, and recreational vehiclesegments of the automotive high performance scene. Wehave been evaluating the turbocharging of Jeep engines forseveral years. We have been primarily interested in gainingexperience and knowledge in the area and have left themarketing of kits, etc., to the aftermarket manufacturers.Turbocharging is best suited to small engines with lowcompression ratios because of the quality of gasolinecurrently available. Turbochargers can add a lot of power toan engine without having to change engine displacement,swap engines, or disassemble the engine. Most aftermarketsystems just bolt right on. Jeep engines are particularlywell-suited to turbocharging because of their heavy dutyconstruction and reliability.Choosing a turbocharger can be a complicated task which isbeyond the scope of this discussion. For details, we suggestthat you contact the various turbo manufacturers. Ingeneral, small engines should use small turbochargers.Also, small turbochargers are best suited for generalpurpose use. The larger turbochargers are designed for highengine speeds and high outputs, which make them bestsuited for actual racing applications. The boost pressurefrom the turbocharger for a general purpose applicationwould be in the 5 to 10 psi range. For boost pressures over10 psi and/or higher compression ratios (over 8.0: l), waterandlor alcohol injection is needed. For general purpose use,a conservative camshaft is an advantage because itimproves low speed response. Also, for general purposeuse, water injection is not recommended because if thewater is allowed to run out, excessive detonation andengine failure would quickly result.In a turbocharging application, the most likely parts to fail inan engine are the pistons and/or rings, which will fail fromdetonation. Therefore, low compression ratios and lowerboost pressures are recommended for general purpose use,and water injection should be used in racing applications.For general purpose turbocharger applications, a sparkadvance retard system sensitive to positive manifoldpressure should be added to the distributor.Some general tips on turbocharging are as follows. Awastegate increases the engine’s performance, especially atlower engine speeds. A turbocharger unit needs to be oiledfrom the engine. It should also have a much larger oil returnline to the sump than the line that is used to supply the oilto the turbo under pressure.If you have further questions on turbocharging, we suggestthat you contact the manufacturer of the turbochargingsystem you are interested in.SUPERCHARGINGSupercharging is not for the amateur. People who wantsuperchargers on their race vehicles are those looking foran added amount of horsepower to their already wellrunningengines.There are many types of superchargers on the market.There are roots blowers and centrifugal blowers. There arenames like Paxton, Latham, Judson, B & M, Weiand, andmany others. But to most racers and performanceenthusiasts, the blower that they want on either their race ordual purpose vehicle is a 6-7 1 . It is a roots blower, but it’sbetter known as the blower the pros have used in Top Fueland Funny Car racing dating back to the late 1960s.The 6-71 roots blower makes power (and torque) by puttinga positive pressure in the intake manifold. In a typical dualpurpose application, this pressure is in the 5 to 7 psi range.6-71 blowers were designed and built originally for dieselengines. They have never been standard production on anygasoline engine. However, they have become very popularadditions for Street Machines and Street Rods. These“automotive” units are remanufactured and/or speciallybuilt for racinghigh performance purposes.There are two general types of 6-71 blowers for highperformance applications - Gas/Fuel “pro” racing and dualpurpose. These two look the same externally but aredifferent internally and use a different drive arrangement.We’ll leave the “Gas/Fuel” racing blowers to the pros. Theyare much more expensive.Dual purpose 6-71 blowers bolt to a specially modifiedintake manifold usually based on a carbureted intake for thespecific engine. In some cases, it is a unique casting...

226 MOPAR PERFORMANCE PARTSOnce you have the special intake manifold, the blower canbe bolted on to your engine. After the carburetor or fuelinjection is added to the top of the blower, a hole is cut inthe hood, fuel lines and throttle linkage added, andeverything is done except for the blower drive, which isadded to the front of the engine. The adaptation of theblower to the intake for your specific engine and the blowerdrive itself are best left to the dual purpose blowerspecialists that make the kits.Note: Due to the increased air flow, supercharging an enginerequires a large increase in fuel delivery. Production fuelinjection systems are not capable of meeting this fueldemand. To supercharge an engine which has production fuelinjection, the injection system must be substantially modifiedor else removed and a carburetion system installed.SourcesThe various engine builders and suppliers in thesupercharging area are very important people to keep intouch with to be able to keep up-to-date. Their addressesare listzed belowKeith Black Racing Engines1 1 120 Scott AvenueSouth Gate, California 90280Milodon Engineering Co.20716 Plummer StreetChatsworth. California 9 13 11B&M9142 Independence AvenueChatsworth, California 9 13 1 1www.bmracing.comCrane Cams530 Fentress BoulevardDaytona Beach, Florida 321 14www.cranecams.com..

T - T TINTRODUCTIONThe fuel delivery system must supply gasoline to thecarburetor/fuel injectors under very hard acceleration,potentially as high as two G. The best carburetor/fuelinjection and intake manifold set-up can’t do its job if itdoesn’t receive the proper supply of fuel. Getting fuel to thecarburetor/fuel injectors efficiently for off-road (racing)applications is the subject of this section.Note: For more information on fuel injection systems,refer to ‘Induction System’ section of this chapter.Drag Racing Fuel SystemA good electric fuel pump, such as the Carter 4.594(P4007038), should be used to make sure that the enginedoesn’t have any fuel starvation problems. It should behooked up so that it only works when the key is in the “ON”position. A separate switch in conjunction with the ignitionkey is optional. See Mopar Chassis-8th Edition (P524944 1 )for more complete details.In Stock Eliminator, one electric pump is sufficient. Infaster categories such as Super Stock or ModifiedProduction, two Carter electric fuel pumps (P4007038) inparallel should be used. Parallel means having two inletsand two outlets rather than one pump feeding into a secondpump. The mechanical pump should also be used.Also available from Mopar Performance Parts for racevehicles is a high capacity, high pressure Holley electricfuel pump (P4 120227 -regulator included) and Holleypressure regulator (P4120228). The Holley pump requiresthe Holley regulator. With the Holley pressure regulator andelectric fuel pump, you don’t use a mechanical pump. Thismeans the pump could be left on with no fuel lines attached,or the pump could be removed and the hole left in the blockcovered with a chrome fuel pump block-off plate(P4529404). The latter approach is recommended.For the majority of bracket racing applications werecommend an electric fuel pump be added next to the gastank in addition to the mechanical fuel pump. For a dual 4-Bbl. tunnel ram system, we recommend two Holley electricfuel pumps (P4120227) with a pressure regulator (includedwith pump) at each carburetor.You should always have at least one fuel filter in the linc. DONOT use a glass or plastic fuel filter. Use only a metal fuelfilter. Glass and plastic filters may be convenient, but theyare usually not legal for racing and are definitely not sqfi..4.0L POWER TECH IN-LINE 6 (FUEL DELIVERY SYSTEM) 227Fuel Delivery SystemWarning! Plastic or glass fuel filters will either melt orbreak in an accident or fire, causing a major fuel fire.MOPAR PERFORMANCE PARTS DOES NOTRECOMMEND THE USE OF GLASS OR PLASTICFUEL FILTERS AT ANY TIME.Carter Electric Fuel PumpIn Stock Eliminator, one pump is sufficient. In fastercategories, two pumps can be used in parallel. Provides 72gph 63 7.0 psi.P400703 8Carter electric fuel pump.Holley Electric Fuel PumpHigh capacity, high pressure. Can be used in parallelwithout mechanical pump for multiple carburetorapplications. Regulator included. Provides 70 gph at 9.0 psi.P4 I20227Holley electric fuel pump.Holley Fuel Pressure RegulatorTo service Holley fuel pump P4120227.P4 I20228Holley fuel pressure regulator.High Capacity Electric Fuel PumpsHigh capacity, high pressure electric fuel pump can beused singularly or in parallel with mechanical pump.Designed for drag race applications.PS249781110 gph.P.5249782 140 gph.P52497832.50 gph.Oval Track Fuel SystemThe fuel system has to keep fuel supplied in adequatevolume and pressure to allow the carburetor/fuel injectorsto function properly at W.O.T. (wide open throttle). If itdoesn’t, the engine will run lean, overheat and fail parts, ornot run at all.Caution: Due to the extreme safety hazards that electricfuel pumps can cause in oval track racing, MoparPerformance Parts does NOT recommend the use ofelectric fuel pumps for oval track vehicles. Refer to Chapter8, Off-Roading and Racing, for more details.

228 MOPAR PERFORMANCE PARTSGenerally, electric pumps are not allowed by circle tracksanctioning bodiedtech officials. This means that the rest ofthe fuel system has to be “right.” The mechanical pump hasto be in top shape. Be sure to use a high volume pump. Thefuel lines must be as straight as possible without kinks, flatspots, pinches, or diameter changes. From the tank to thecarburetor, only one size fuel line should be used. Once yousplit the main fuel line down from one line to multiplecarburetor entries (such as a dual-feed Holley carburetor),you can drop a size in fuel line diameter.You should always have at least one fuel filter in the line.DO NOT use a glass or plastic filter. Use only a metal fuelfilter. Glass and plastic filters may be convenient, but theyare usually not legal for racing and are definitely not safe.Warning! Plastic or glass fuel filters will either melt orbreak in an accident or fire, causing a major fuel fire.MOPAR PERFORMANCE PARTS DOES NOTRECOMMEND THE USE OF GLASS OR PLASTICFUEL FILTERS AT ANY TIME.If you are constructing new fuel lines, they should go underthe floor pan. And don’t forget the gas tank vent. It shouldbe designed to work both on the level ground of thepitdgarage and on the bankedhigh G comers on the racetrack itself. Keep in mind that, in the comers at race speeds,all the gas in the tank is “piled up” on the right side(passenger side) of the tank. (This obviously assumes thatthe race car always turns left.)FUEL PUMPThe fuel pumps of carbureted and fuel injected vehicles aredifferent. Carbureted vehicles have a mechanical fuel pumpdriven by an eccentric lobe on the engine’s camshaft. Fuelinjected engines (such as the 4.0L) have a gearhotor typepump driven by a permanent, magnetic 12 volt electricmotor that is immersed in the fuel tank. This electric pumpis integral with the fuel sender unit and is also installedinside the fuel tank.Note: Electric fuel pumps used with Throttle BodyInjection (TBI) and Multi-Point Injection (MPI) systems,though similar in appearance and function, are different andCANNOT be interchanged.MPI Fuel PumpThe MPI fuel pump has a check valve at the outlet end thatconsists of a steel ball held against a seat by force appliedfrom a spring. When the pump is operating, fuel pressureovercomes spring pressure and forces the ball off its seat,allowing fuel to flow. When the pump is not operating,spring pressure forces the ball back against the seatpreventing fuel back flow through the pump.MPI Fuel Pump ControlsThe fuel pump circuit of the MPI system is equipped witha ballast resistor to reduce fuel pump noise. Voltage tooperate the fuel pump is supplied through the fuel pumprelay, except during engine starting (cranking) and wideopen throttle conditions. Ground for the fuel pump relay iscontrolled by the engine’s Powertrain Control Module(PCM). During engine starting, the fuel pump relay andballast resistor are bypassed and voltage is supplied to thefuel pump through the starter relay. During wide openthrottle conditions the fuel pump relay and ballast resistorare again bypassed and voltage is supplied to the fuel pumpthrough the oxygen (02) sensor relay.MPI system fuel pressure is maintained at 214 kPa (31 psi)when the pump is operating and vacuum is supplied to thefuel pressure regulator. If vacuum is not supplied to the fuelpressure regulator because of a broken or clogged vacuumline, fuel pressure will be 5-69 kPa (8-10 psi) higher. Whenthe fuel pump is not operating, system fuel pressure of 13 1-269 kPa (19-39 psi) is maintained by the fuel pump outletcheck valve and the vacuum assisted fuel pressure regulator.FUEL TANKS AND FUEL CELLSFor the majority of race vehicles, the standard gasoline tankshould be adequate. The typical production gas tank has a15-20 gallon capacity. The stock-type fuel tank willperform best full or close to full. The only real shortcomingof the production fuel tank is the tank vent, especially onnewer vehicles. The quick, economical solution to this is toput a .25“ hole through the gas cap.Warning! DO NOT put a hole through the gas cap with thegas cap on the vehicle. Severe personal injury may result.On a high output race vehicle, an auxiliary tank vent shouldbe added at the top-front and inside-left edge of the tank.The typical upside-down “J” vent will spill gasoline onhard deceleration with a full tank. The vent should also beself-draining or it will be inoperative. An upward spiralvent will do this best if space permits.Note: If the stock gas tank is used, check the gas tanksupport strap(s) and attaching bolts. If you only have onestrap, add a second. If you have two, consider doublethickness straps. If the straps are rusted, replace them. UseGrade 8 bolts to attach the tank support straps to thechassidframe.On gas tanks that are rear fill, the cap will sometimes leakunder hard acceleration. This should be corrected with aleak-proof cap or relocated filler before the vehicle is raced,or replace the tank with a fuel cell.

4.0L POWER TECH IN-LINE 6 (FUEL DELIVERY SYSTEM) 229If an all-out race vehicle is going to have the gas tank size,filler tube, or pick-up modified, then a fuel cell is highlyrecommended. Fuel cells are safer and feed the fuel linebetter for the same amount of work. Before installing a fuelcell, check with your local track and sanctioning body tosee if they are legal. We highly recommend them for bothracing function and safety.FUEL LINEFuel lines should be metallic, not rubber. Rubber fuel linesshould only be used for vibration connections (such asgoing from the body/frame to the engine).Note: Fuel injected engines use specially constructedrubber fuel lines. Only fuel lines marked EFMEFI shouldbe used. Rubber fuel lines should be replaced every coupleof years to avoid cracking. Whenever possible, it isrecommended that rubber fuel lines be replaced with steelbraided lines.Fuel lines should always be routed outside the frame rails inthe bellhousing area. At all times try to use the vehicle’sframe to protect fuel lines. DO NOT place any fuel line onthe bottom of a frame rail. In addition, fuel lines shouldNEVER pass through the driver’s compartment at any point.When installing rubber fuel lines, ensure that they arerouted away from contact with other vehicle componentsthat could rub against them and cause failure. Avoid contactwith clamps or other components that cause abrasions orscuffing. Ensure that all rubber fuel lines are properlyrouted and avoid heat sources. Only use hose clamps whichhave rolled edges. Other types of clamps may cut into thehose and cause high pressure fuel leaks. Rubber fuel lineson race vehicles should be replaced every couple of yearsto avoid cracking.FUEL FILTERThe fuel filter protects the fuel injectors from dirt, waterand other foreign matter. The filter is located under thevehicle along the driver’s side frame rail. Replace filter atintervals specified on the Maintenance Schedule in theservice manual.Caution: Fuel filters designed for carbureted systems areNOT interchangeable with filters designed for fuel injectionsystems. Using fuel filters designed for carbureted systemson fuel injection systems will cause damage to systemcomponents andor fuel system shut down. For proper fuelinjection system fuel filter availability and pricing, contactyour local Chrysler-Plymouth-Dodge-Jeep dealer.FUEL HOSES AND CLAMPSInspect all hose/clamp connections for completeness andensure that no leaks are present. Hoses that are cracked,scuffed, swollen, have rubbed against other vehiclecomponents or show any other signs of wear that could leadto failure must be replaced.When installing hoses, ensure that they are routed awayfrom contact with other vehicle components that could rubagainst them and cause failure.Quick Connect Fuel Tube FittingsMPI fuel injected engines utilize quick-connect fuel tubefittings at the ends of nylon reinforced hoses. These fittingsconsist of two O-rings, a spacer (installed between the 0-rings) and an O-ring retainer.Note: The O-ring and spacer assembly must be replacedwhenever the quick-connect fittings are disassembled.On MPI equipped vehicles, the fittings are used at the inletside of the fuel rail, the pressure regulator end of the fuelrail, and at the end of the tube/hose assembly that connectsthe pressure regulator to the return tube (located below theEGR valve transducer).FUELFuel DefinitionsThere are many types of fuels. The following are the mostpopular or common in racing. It is important to note that notall fuels are hydrocarbons (a compound of carbon andhydrogen). There are others such as butane, benzene, andaniline which are sometimes used in small quantities forspecial applications. Then there are the fuels that carry theirown oxygen which are considered “super fuels.” This is afield that is rapidly changing. Racing has always been aleader in the fuel development field.GasolineA hydrocarbon. The most common fuel used in racing.0 MethanolThe simplest alcohol, commonly called wood alcohol.It is a colorless, flammable liquid used as an antifreeze,solvent, fuel, and denaturant for ethanol. Themost commonly used alcohol fuel in racing.EthanolCommonly called grain alcohol. This is the alcohol thatis added to ‘‘pump’’ gas, especially in the MidwesternUnited States.

230 MOPAR PERFORMANCE PARTSPropaneEither a gas or a liquid, propane is used in some fleetvehicles that operate within large cities. Typicallyrequires a special tank and throttle body to convert astandard vehicle.NitromethaneGenerally considered a nitrate in the same family asnitroglycerin. It has nitrogen and oxygen added to thebase carbon and hydrogen compound. Because it hasits own oxygen in the compound, it is a “super fuel”since it can give up the oxygen in the combustionprocess and drastically increase an engine’s output.Nitromethane is used in NHRA Top Fuel and FunnyCar racing. It is generally not legal to use outside ofdrag racing.HydrazineA nitrogen and hydrogen compound commonly called“rocket fuel.” Very dangerous! Was used in NHRA TopFuel racing in the late 1960s and early 1970s. Has sincebeen banned for automotive use.TolueneA hydrocarbon generally used as an additive togasoline. Tends to reduce engine “knocking” byincreasing the fuel’s octane rating or number.Propylene OxideAnother gasoline additive; usually used in smallamounts. Just as with Nitromethane, it carries its ownoxygen which will make gasoline burn like a “superfuel.” Used to increase horsepower.FUEL ECONOMYThe first “energy crisis” occurred in late 1973 through 1974with subsequent gasoline shortages. This resulted in, for thefirst time, serious considerations being given to fueleconomy by the American car-buying public. The 1973-74crisis started Americans thinking about fuel economy, but itdidn’t convince buyers that they needed to double their fueleconomy or purchase 30 to 40 mpg small cars. 1979 wasthe year of giant gas lines, closed gas stations, odd-evenrationing, and minimum-or-maximum sales limits. The“energy crisis” of 1979 resulted not only in shortages, butgreatly increased prices as well. In 1978 a gallon could bepurchased for 50-60 cents, which most people already feltwas too high. In 1979 the price went past $1.00 per gallonquickly, and on up to $1.30 per gallon or higher. (For thelast several years prices have stabilized, but they couldshoot up again at any time.) These two aspects of the 1979crisis made fuel economy the number one buyer interest.This was a new area for the American buyer that neverthought about fuel economy before. Some buyers fell backon 10-20 year old information that foreign cars had the bestfuel economy. American companies countered withcomparison ads showing better fuel economy for Americancars. The fuel economy contest was on and shows no signsof letting up.To this end, we have prepared the following tune-up tipswhich will help you optimize the fuel economy of yourDaimlerChrysler vehicle. Keep in mind that a good tune-upand constant maintenance are the best choices for good fueleconomy. All the “trick” gadgets that the market now has tooffer together are worthless on a poorly tuned andmaintained vehicle.

4.OL POWER TECH IN-LINE 6 (FUEL DELIVERY SYSTEM) 231EngineNote: The following information refers to all engines as agroup, unless specifically stated otherwise.Complete engine fuel economy performance is a verycomplicated and lengthy topic. Therefore, this section issplit into three subsections: 1) simple tune-ups that don’trequire any nonstandard parts; 2) minor rework andmodification requiring some nonstandard parts; and, 3) amore extensive rework which requires removal of thecylinder head and the installation of some nonstandard parts.1. Tune-up and Check-OutThere are many times when fuel is wasted or used at agreater rate than is desirable because the engine is inneed of a simple tune-up. There are also a few simpleadjustments and changes that can be made to improveyour engine’s fuel economy. We will cover these simpletune-up items first before moving onto the morecomplex and expensive modifications. Therecommendations in this section should be studied firstregardless of what further modifications are considered.a. Spark Plugs and Ignition CablesNew spark plugs should always be installed whenperforming a major tune-up. Examine the oldplugs carefully. They can tell you a lot about thecondition of your engine and/or ignition system.Spark plugs should be a light tan color. If they areblack, they are probably misfiring. Oily blackindicates oil fouling. Sooty black generallyindicates ignition problems or the fuel-air mixtureis too rich. Always check the plug gap wheninstalling new spark plugs.While changing the plugs, inspect the ignitioncables and ends carefully to see that they are ingood condition. If any plug condition indicatesthat the ignition cable may be broken, or if anyignition cable or end looks cracked or in poorcondition, that cable should be replaced.There are sophisticated electrical instrumentsavailable in some tune-up shops that can tell if theplugs are firing efficiently or if the plug wires needto be replaced. These instruments can be a big aidin doing tune-ups.b. Distributor Cap and RotorThe distributor cap and rotor are the next items tocheck. Inspect the distributor cap’s terminals forcorrosion or pitting and the cap itself for cracks orcarbon tracking. If any of these conditions arefound to exist, the cap should be replaced. Wheninstalling a new cap, be sure it fits securely againstthe distributor housing.The distributor rotor should also be checked forpitting or corrosion and should fit tightly on theend of the distributor shaft. The rotor should bereplaced if it does not meet these requirements.Air FilterThe air cleaner filter element should be removed,checked, and replaced if dirty. Even if it looksclean but has been used, blow it out from theinside with compressed air.Fuel LeaksCheck the carburetodthrottle body and fuel linesfor external fuel leaks with the air cleanerremoved. The fuel pump and fuel filterconnections should also be checked for leaks. Allleaks should be repaired.Carburetor AdjustmentsAfter the engine has been thoroughly warmed, thechoke should be “off’ or perfectly vertical. Thiscan be checked by removing the air cleaner whilethe engine is idling. If the choke blade isn’tvertical, adjust it so it is. With the engine shut-offand the air cleaner removed, inspect theaccelerator pump linkage. On most vehicles thereare three adjustment holes in the pump arm. Thebest driveability will be obtained with the linkagein the hole closest to the arm’s pivot. The besteconomy will be obtained using the hole farthestaway from the pivot. The economy setting maymake the engine “stumble” or “pause”; i.e., makethe driveability poorer. If the poorer driveability isobjectionable, try the adjustment in the center holeon the pump arm as a compromise.The idle circuit usually has an “enrichment” screwon the outside of the carburetor. This screw has arestricted adjustment range to enable the engine’sidle to be set as smoothly as possible. Be carefulthat this screw wasn’t over adjusted. This wouldresult in poor fuel economy.Check the trap doors in the air cleaner snorkels toensure that they open once the engine is warmedup. Also check the air cleaner and carburetor forvacuum leaks, cracked hoses (especially vacuumhoses), or hoses that have come off.. . T - 7 7

232 MOPAR PERFORMANCE PARTSf. Ignition Timing (if adjustable)Ignition timing or spark advance is very importantto fuel economy. It is very important that it be setcorrectly. Most late model vehicles have a tag inthe engine compartment that provides the correctspark advance setting for that vehicle’s engine.This initial timing should be set at the specifiedidle speed and with the vacuum advance hosedisconnected. In the interest of fuel economy, youshould always run the maximum allowable sparkadvance.g. Lipht Engine OilsRunning a light engine oil will also help fueleconomy. Caution must be used with light oil as itmay not lubricate the engine properly under highload or temperature conditions. It is mostimportant that a multi-viscosity, high quality oil beused. Avoid aftermarket additive “viscosityimprovers” and heavy oils such as SAE 40W or50W. Engine oils lighter than SAE 10W30 are notgenerally recommended for six cylinder cast ironengines. If in doubt, check your owners or servicemanual.2. Rework (Simple Modifications)With the basic tune-up and check-out operationsperformed, we have a solid foundation for makingfurther improvements. These improvements requirespecial parts but offer further fuel economy gains overthe best stock package. Since these changes do use newand different parts, be sure to check your warranty andlocal track regulations BEFORE you make any change.3. Rebuild (Major Modifications)With all the easy to reach items completed, furtherimprovements can be obtained by more extensivemodifications, which will require greater time and effort.These modifications require removing the cylinder headand/or intake manifold. If you do your own work, thecost of these modifications is relatively low.a. Blueprint Compression RatioBlueprinting the engine compression ratio willprovide an increase in fuel economy. To blueprintthe compression ratio, the cylinder head must beremoved and milled at a machine shop. After thehead is removed from the engine, clean it andvolume check combustion chamber volumes.b. Valve JobA good valve job is very important to fueleconomy. The valve job and cylinder head millingshould be done at the same time for simplicity andto reduce cost. The head will have to be taken to amachine shop or valve grinder to have the valvesground, providing the best possible cylindersealing. Any valve in poor condition should bereplaced. Always reassemble the head with newvalve stem seals.c. CamshaftChanging camshafts rarely improves fueleconomy. If a high performance camshaft has beeninstalled in the engine, better fuel economy maybe obtained by using the standard productioncamshaft that came with the engine. Since mostproduction engines are built with mild camshafts,there is very little, if any, fuel economy advantagein replacing the production camshaft.ChassisIn general, when trying to compare camshaftsfrom different sources, cam lift is the mostvaluable piece of information. More lift, moreperformance (horsepower); less lift, lessperformance (but more fuel economy). For moreinformation, refer to ‘Camshaft and Valve Gear’section of this chapter.With the engine adjustments and modifications covered, wecan turn our attention to the rest of the vehicle.Tire PressureThe air pressure in a tire affects fuel economy.Generally, higher tire pressures will provide better fueleconomy by reducing the tire’s rolling resistance.Fluid LevelsOperating the transmission and rear axle at less thantheir “full” fluid capacity will help fuel economy. Anautomatic transmission can be run one pint below fullwhile a manual transmission and rear axle can be run a1/2 pint below full. Caution must be used. Loweringfluid levels below these recommendations may causetransmission or axle damage.Front End AlignmentHaving the vehicle’s front end aligned properly willprovide improved fuel economy and reduced tire wear.The vehicle’s front end toe-idtoe-out condition has thegreatest effect on fuel economy. It is important that thetires point straight ahead when the vehicle is travelingin a straight line. Stock caster and camber settingsshould also be used.. ..._

-r --T 74.0L POWER TECH IN-LINE 6 (FUEL DELIVERY SYSTEM) 2334. WeightAny increase in vehicle weight will adversely affect fueleconomy. The vehicle’s basic weight is hard to decrease;therefore, it is important not to carry any unnecessaryweight. While any weight reduction is beneficial interms of improved fuel economy, weight differentials ofless than 100 lbs. will provide improvements too smallfor the average driver to notice.5. Torque ConvertersHigh stall torque converters are a detriment to fueleconomy. If a special high stall converter has beeninstalled, reinstalling the stock converter will result inimproved fuel economy.6. Manual TransmissionA 4 or 5-speed manual transmission will providebetter fuel economy than an automatic. However, theconversion of an automatic transmission vehicle to amanual transmission is extremely complicated andnot recommended.Cost EffectivenessIncreasing a vehicle’s fuel economy “at any cost” canresult in an expensive project and one that is a poorinvestment. Basic rebuild modifications and tune-ups arealways a good buy because they not only increase your fueleconomy, they also increase the usable life of theenginehehicle. Cost effectiveness should be considered inmodifications that cost over $200. These modifications fallinto three groups: drivetrain parts, engine swap, or avehicle rebuilt from the ground-up.DrivingAll of the previously discussed engine and chassismodifications will improve your overall fuel economy.However, the single most important factor in overallmileage is the driver. The subject of “how to driveeconomically” can be discussed at great length. There are,however, only three primary considerations to be kept inmind: speed, acceleration, and braking.Only accelerate as hard as is necessary to keep up withtraffic and to attain your desired speed; drive slowly anduse your brakes as little as possible, yet maintain safety.Jack rabbit starts and jerky, on and off the acceleratordriving wastes gasoline. Slower vehicle speeds will resultin better mileage. For example, a car or truck will get betterfuel economy at 65 mph than it will at 75 mph. Finally,coasting to a stop rather than braking hard will result inimproved mileage. Obviously, this requires that you allowmore distance between you and the vehicle ahead. It alsorequires you to plan further down the road in order toanticipate occasions which may require braking. Theultimate fuel economy improvement is smooth, steady,slower driving. Your trips should also be planned such thatshort, single trips are avoided.There are many other books and pamphlets from othersources that offer fuel economy tips. If you are serious aboutfuel economy, we suggest that you obtain as many of theseas possible because they contain many good suggestions.

~ ~T -1 '1234 MOPAR PERFORMANCE PARTSExhaust SystemINTRODUCTIONThe basic exhaust system consists of an exhaust manifold,exhaust pipe with oxygen sensor, catalytic converter, heatshield(s), muffler and tailpipe.The 4.0L engine uses a seal between the exhaust manifoldand exhaust pipe to assure a tight seal and strain-freeconnection, a single muffler, and a single, monolithic-typecatalytic converter.The exhaust system must be properly aligned to preventstress, leakage, and body contact. If the system contacts anybody panel, it may amplify objectionable noises originatingfrom the engine or body.When inspecting an exhaust system, critical items to lookfor are cracked or loose joints, stripped screw or boltthreads, corrosion damage, and worn, cracked or brokenhangers. Replace all components that are badly corroded ordamaged. DO NOT attempt to repair. When replacement isrequired, use original equipment parts (or their equivalent).This will assure proper alignment and provide acceptableexhaust noise levels.All exhaust systems should be checked for leaks. A leak inthe exhaust system is unsafe and will cost you power. DONOT, under any circumstances, use flexible tubinganywhere in the exhaust system as the efficiency of theflow will be reduced.Caution: Avoid application of rust prevention compoundsor undercoating materials to exhaust system floor pan heatshields. Application of coating will result in excessive floorpan temperatures and objectionable fumes. Light overspraynear the edges is permitted.I nta ke/Ex haust Man if old GasketThe 4.0L engine uses a common intake and exhaustmanifold gasket. This gasket is designed for originalreplacement. For 4.0L engine only.P4529243IntakeExhaust manifold gasket.Intake/Exhaust Manifold Race GasketMade from special high temperature material for addeddurability in racing. Can be used as a service replacement.4.0L engine only.P4876 1 12Intake/Exhaust manifold race gasket.~Intake/Exhaust Manifold Attaching PackagePackage of factory original nuts and bolts to attach intakeand exhaust manifolds. Includes 15 bolts, 12 washers, twostuds, two spacers, two pins and one tube. For 1986-89,4.0L engines only.P4529680Catalytic ConverterIntakeExhaust manifold attachingpackage.There is no regularly scheduled maintenance on anyDaimlerChrysler catalytic converter. If damaged, theconverter must be replaced.The stainless steel catalytic converter body is designed tolasi the life of the vehicle. Excessive heat can result inbulging or other distortion, but excessive heat will not bethe fault of the converter. A fuel system, air injectionsystem or ignition system malfunction that permitsunburned fuel to enter the converter will usually causeoverheating. If a converter is heat-damaged, correct thecause of the damage at the same time the converter isreplaced. Also, inspect all other components of the exhaustsystem for heat damage.Caution: Due to exterior physical similarities of somecatalytic converters with pipe assemblies, extreme careshould be taken when selecting replacement parts. Foravailability and pricing, contact your local Chrysler-Plymouth-Dodge-Jeep dealer.The combustion reaction caused by the catalyst releasesadditional heat in the exhaust system, causing temperatureincreases in the area of the reactor under severe operatingconditions. Such conditions can exist when the enginemisfires or otherwise does not operate at peak efficiency.DO NOT remove spark plug wires from plugs or by anyother means short out cylinders if exhaust system isequipped with a catalytic converter. Failure of the catalyticconverter can occur due to temperature increases caused byunburned fuel passing through the converter.Unleaded gasoline MUST be used to avoid poisoning thecatalyst core. DO NOT allow engine to operate above 1,200rpm in neutral for extended periods over 5 minutes. Thiscondition may result in excessive exhaust system/floor pantemperatures because of no air movement under the vehicle.

4.01. POWER TECH IN-LINE 6 (EXHAUST SYSTEM) 235CONDITIONEXCESSIVE EXHAUST NOISELEAKING EXHAUST GASESPOSSIBLE CAUSE1. Leaks at pipe joiints.2. Burned or blown out muffler.3. Burned or rustedl-out exhaustpipe.4. Exhaust pipe leaking at manifoldflange.5. Exhaust manifold cracked orbroken.6. Leak between exhaust manifoldand cylinder head.7. Restriction in muffler or tailpipe.8. Exhaust system contacting bodyor chassis.1. Leaks at pipe joints.2. Damaged or improperly installedgaskets.CORRECTION1. Tighten clamps at leaking joints.2. Replace muffler assembly. Checkexhaust system.3. Replace exhaust pipe.4. Tighten connection attachingnuts.5. Replace exhaust manifold.6. Tighten exhaust manifold tocylinder head stud nuts or bolts.7. Remove restriction, if possible.Replace muffler or tailpipe, asnecessary.8. Re-align exhaust system to clearsurrounding components.1. Tightenheplace clamps at leakingjoints.2. Replace gaskets as necessaryHeat ShieldsHeat shields are needed to protect both the vehicle and theenvironment from the high temperatures developed in thevicinity of the catalytic converter. The combustion reactionfacilitated by the catalyst releases additional heat in theexhaust system. Under severe operating conditions, thetemperature increases in the area of the reactor. Suchconditions can exist when the engine misfires or otherwisedoes not operate at peak efficiency. DO NOT remove sparkplug wires from plugs or by any other means short outcylinders. Failure of the catalytic converter can occur due toa temperature increase caused by unburned fuel passingthrough the converter.DO NOT allow the engine to operate at fast idle forextended periods (over five minutes). This condition mayresult in excessive temperatures in the exhaust system andon the floor pan.Exhaust Gas Recirculation (EGR)To assist in the control of oxides of nitrogen (NO x ) inengine exhaust, all engines are equipped with an exhaustgas recirculation (EGR) system. The use of gas to diluteincoming aidfuel mixtures lowers peak flame temperatureduring combustion, thus limiting the formation of NOX.Exhaust gases are taken from openings in the exhaust gascrossover passage in the intake manifold. Refer to theservice manual for complete description, diagnosis andproper service procedures.EXHAUST AND INTAKE MANIFOLDSThe two exhaust manifolds are log style and are made ofhigh silicon molybdenum cast iron. The exhaust manifoldsshare a common gasket with the intake manifold. Theexhaust manifolds also incorporate ball flange outlets forimproved sealing and strain free connections.RemovalNote: The engine intake and exhaust manifold must beremoved and installed together. The manifolds use acommon gasket at the cylinder head.1.2.3.4.5.Disconnect the battery negative cableRemove air cleaner inlet hose from throttle bodyassembly.Remove the air cleaner assembly.Remove the throttle cable, vehicle speed control cable(if equipped) and the transmission line pressure cable(if equipped).Disconnect the following electrical connections andsecure their harness out of the way:Throttle Position SensorIdle Air Control Motor.. T --ll 7

. .‘236 MOPAR PERFORMANCE PARTS6.7.8.9.Coolant Temperature Sensor (at thermostat housing)Intake Air Temperature SensorOxygen (02) SensorCrank Position SensorSix (6) Fuel Injector ConnectorsDisconnect the MAP sensor, HVAC, and brake boostervacuum supply hoses at the intake manifold.Perform the fuel pressure release procedure. (Refer tothe proper service manual for correct procedure,)Disconnect and remove the fuel system supply linefrom the fuel rail assembly. (Refer to the proper servicemanual for correct procedure,)Loosen the accessory drive belt and tensioner. (Referto the proper service manual for correct procedure.)10. Remove the power steering pump and bracket from theintake manifold and set aside.11. Raise the vehicle.12. Disconnect the exhaust pipe from the engine exhaustmanifold. Discard the seal.13. Lower the vehicle.14. Remove the intake manifold and engine exhaustmanifold.InstallationIf the manifold is being replaced, ensure all fittings, etc., aretransferred to the replacement manifold.1.2.3.4.5.6.Install a new engine exhausthntake manifold gasketover the alignment dowels on the cylinder head.Position the engine exhaust manifold to the cylinderhead. Install fastener Number 3 and finger tighten atthis time (Figure 4-48).Install intake manifold on the cylinder head dowels.Install washer and fastener Numbers I, 2, 4, 5, 8, 9, IOand 11 (Figure 4-48).Install washer and fastener Numbers 6 and 7(Figure 4-48).Tighten the fasteners in sequence and to the specifiedtorque (Figure 4-48):Fastener Numbers 1 through 5 - Tighten to 33 Nom(24 ft-lbs) torque.Fastener Numbers 6 and 7 - Tighten to 31 Nom(23 ft-lbs) torque.Fastener Numbers 8 through II - Tighten to 33Nom (23 ft-lbs) torque.7.8.9.IO.11.12.13.Install the power steering pump and bracket to the intakemanifold. Tighten the belt to specification. (Refer to theproper service manual for correct procedure.)Install the fuel system supply line to the fuel rail assembly.Before connecting the fuel supply line to the fuel railinspect the O-rings and replace if necessary. (Refer to theproper service manual for correct procedure.)Connect all electrical connections on the intake manifold.Connect the vacuum hoses previously removed.Install the throttle cable and vehicle speed controlcable (if equipped).Install the transmission line pressure cable (if equipped).(Refer to the proper service manual for correctprocedure.)Install air cleaner assembly.1 ‘I. Connect air inlet hose to the throttle body assembly.15. Raise the vehicle.16. Using a new exhaust manifold seal, connect theexhaust pipe to the engine exhaust manifold. Tighten -the bolts-to 3 1 Nom (23 ft-lbs).1.7. Lower the vehicle.18. Connect the battery negative cable.19. Start the engine and check for leaks.rFRONTEXHAUST MANIFOLDFigure 4 - 48EXHAUST MAN’FoLD 8oM)986a

4.0L POWER TECH IN-LINE 6 (EXHAUST SYSTEM) 237EXHAUST SYSTEM MODIFICATIONSUsing straight-through type mufflers and steel tubingheaders on your stock vehicle doesn't mean that you willgain horsepower. Today's car and truck exhaust systems arespecifically tuned to the engines they come with. In otherwords, the best all-around, dual purpose exhaust set-up isthe stock set-up that came with your vehicle. OK, youmight gain 5 extra horsepower by using a header and astraight-through type muffler, but the noise level, thedisturbance in engine back pressure (via the exhaustsystem) and the high cost of these performance parts do notjustify making these modifications. However, if the vehicleis to be raced and the modifications to that vehicle includea high performance camshaft and valve train set-up, then aheader and straight-through type muffler can be verybeneficial, and the cost justified.Note: All exhaust systems should be checked for leaks. Aleak in the exhaust system is unsafe and will cause you tolose power.HeadersSteel tubing headers are a very popular exhaust systemmodification. When shopping for headers, the mostimportant thing to remember is to match the headers to boththe engine AND the vehicle. This will save you a lot of timewhen installing the headers.Mopar Performance Parts Exhaust HeadersBolt on a set of our Mopar Performance Parts headers andfeel the power. Manufactured from heavy 14 gauge tubingwith 3/8" thick flanges, mandrel bent, and triple nickelchromefinish makes these headers the most durable onthe market. Each header is engineered to achieveminimum back pressure and maximum flow, resulting inincreased horsepower and torque. Headers carry a lifetimewarranty and are emissions exempt. Kits include allnecessary installation hardware. For 4.0L engines only.(Vehicle application as listed.)P5249972 Wrangler, 1995.P4876260 Wrangler, 1997-98.P4529530Wrangler (all), stainless steel.P48769 18 Cherokee, 1986-91.P524997 1 Cherokee and Grand Cherokee, 1996-98.Exhaust Collector and Feeder GasketsThese exhaust collector and feeder gaskets are madefrom special extra high temperature material for addedstrength and durability. For use with Mopar PerformanceParts headers.P487635 1P4876352P4876353MufflersExhaust collector gasket, 2-1/2", 3-bolt.Exhaust collector gasket, 3", %bolt.EGR feeder gasket(1995 and prior models).Cat-Back Performance ExhaustOur Mopar Performance Parts cat-back exhaust systemsare specifically engineered to fit your vehicle - nomodifications are required. These kits simply bolt into theOE hangers and brackets. Features include heavy wall, 16gauge aluminized tubing with true mandrel bendsallowing for maximum flow and minimum back pressure.A low restriction, aluminized case, flow-through mufflerwith a 3" core produces a deep mellow exhaust tone. Nofiberglass packing to burn out. Kits include all necessaryinstallation hardware. For 4.0L engines only.P5249739P4876277P4876359P4876089P4876627Cat-Back performance exhaust,1993-95 Wrangler.Cat-Back performance exhaust,1997-98 Wrangler.Cat-Back performance exhaust,1986-96 Cherokee.Cat-Back performance exhaust,1997-98 Cherokee.Cat-Back performance exhaust,1993-98 Grand Cherokee.Note: For maximum performance, this system should beused in conjunction with Mopar Performance headers... T --T 7

238 MOPAR PERFORMANCE PARTSINTRODUCTIONIgnitionNote: Some newer 4.0L Power Tech engines (modelspecific -check your service manual) use a distributor-lessignition system. For information on this system, refer toDistributorless Ignition System, later in this section.For any type of racing, a good electronic ignition system isa must. The Mopar Performance Parts Chrome Box IgnitionControl Module (P4120534) is perfect for those of youracing low to moderately high performance engines. Forextreme high performance, the Super Gold ICM(P4120600) is the preferred choice.The area of ignition systems and components has beenchanging rapidly in the last few years. Further developmentis expected to continue well into the future, providing Jeepracers with the best high performance ignition systemsavailable for their race vehicles.Older ignition systems, such as point-type, will not becovered because we no longer produce or recommend thesepieces for high performance race vehicles. We will try tocover all the new electrical modifications, systems andhardware that have been developed recently for racevehicle use.Ignition EnergyThe purpose of the ignition system on an internal combustionengine is to start the combustion of the fuel/air mixture. Itmust ignite a flame that will be self-sustaining and it mustignite it at the proper time so that combustion will becompleted at the proper time for best engine efficiency.One way of comparing ignition systems is by the amount ofenergy that they can deliver to the spark plug. There areseveral different types of energy “curves.” The two mostimportant characteristics are peak energy and duration(time). Capacitive-discharge systems tend to have very highpeak energy but very short duration. Multi-fire systemshave long durations and fire the plug several times perrevolution. Chrysler-Plymouth-Dodge-Jeep ignitionsystems, such as the Super Gold ICM (P4120600), featurehigh peak energy, long duration, and one of the highest totalenergies (area under the curve) delivered to the plugbecause they don’t go to zero during their duration in aneffort to fire the plug more than once. Race engines needhigh total energy systems to deliver maximum power,especially at high rpm.Variations in fuel composition, air-to-fuel ratio,distribution, internal turbulence in the cylinder, andcombustion chamber shape are a few of the factors that canmake the combustion process less than ideal. They all havethe common characteristic that poor fuel burning mayresult. The factors mentioned produce effects that, althoughSystemthey can’t be corrected by a more powerful ignition system,may be overcome by one. In other words, an ignitionsystem will not change these factors (aidfuel ratio,turbulence, etc.), but the proper system can cause ignitionof the mixture in spite of their presence. A productionsystem is called on to do this to some extent; however, asmore severe requirements are placed on the engine, theproduction system will quickly reach its limit.A general rule of thumb is that at least 30 millijoules ofenergy are required to ignite the typical mixture. Mostsystems exceed this amount (even production systems) inthe lower rpm ranges. However, this is for a typicalcondition. As more performance and higher speeds aredemanded of an engine, these conditions are no longer true.There are many indications that a stronger spark is needed.Many replacement systems are available that try to answersome of these requirements.With some of the less than ideal mixture conditionsmentioned, there will be times when the mixture is notignitable no matter how much energy is pumped into thespark plug. Multiple Spark Discharge is the answer to theproblem. It not only produces a very strong first spark, butit also repeats this spark. This is important because if thelack of ignition is caused by such things as turbulence ornon-uniform distribution of the mixture in the cylinder, theneventually an ignitable mixture will be available in theregion of the plug. One of the MSD repetitive sparks willignite the mixture.ELECTRONIC IGNITION SYSTEMThe 4.0L engine is a multi-point fuel injected engine. Theelectronic ignition system used consists of the followingcomponents:A solid-state Ignition Control Module (ICM) togenerate the voltage for spark plug firingAn Powertrain Control Module (PCM) to process inputinformation to fire the ICMAn engine speed sensor with flywheel trigger to inputcrankshaft position for the PCMA synchronization pulse (stator) for firing order inputto the PCMNote: Ignition timing (advancehetard) is controlled by thePClM and is not adjustable.

4.01. POWER TECH IN-LINE 6 (IGNITION SYSTEM) 239Powertrain Control Module (PCM)The 4.0L engine ignition system is controlled by theengine’s Powertrain Control Module (PCM). The PCM is adigital microprocessor (computer). Air-fuel mixturecalibrations for various driving and atmospheric conditionsare pre-programmed into the PCM. The PCM monitors andanalyzes its various inputs, computes engine fuel andignition timing requirements based on these inputs, andcontrols fuel delivery and ignition timing accordingly. Asoperating conditions change, the PCM adjusts injectorpulse width and ignition timing for optimum performanceand fuel economy.Jeep High Performance ComputerMopar Performance Parts computer provides more sparkadvance and increased fuel flow for off road racingapplications. This computer will enhance other performancemodifications. For 1987-90, 4.0L engines only.P4529334Jeep high performance computer.Ignition Control Module (ICM)The Ignition Control Module (TCM) is mounted to theignition coil. Based on control system inputs, the PCMtriggers the ignition coil via the ICM. The PCM is able toadvance or retard ignition timing by controlling the ignitioncoil through the ICM.The ICM consists of a solid-state ignition circuit and anintegrated ignition coil that can be removed and servicedseparately if necessary.The PCM provides an input signal to the ICM. The ICMhas only two outputs:1. Tachometer signal to the tachometer and diagnosticconnector2.High voltage from the ignition coil to the distributorcapIgnition CoilThe ignition coil does not require special service other thanmaintaining the terminals and connectors.When an ignition coil is suspected of malfunctioning, test iton the vehicle. A coil may “break down” after the engine hasheated it to a high temperature. It is important that the coilbe at operating temperature when tested. Perform the testaccording to the test equipment manufacturer’s instructions.DistributorThe 4.0L engine distributor does not have built-incentrifugal or vacuum assisted advances. Ignition timingadvance is controlled by the Powertrain Control Module(PCM). The distributor is locked in place by an ear on thedistributor housing that a hold down bolt passes throughwhen the distributor is installed.For those of you who are contemplating an ignition systemmodification for racing, we will briefly discuss distributorsin more detail.There are two different electronic distributors, one forvacuum advance models and one for mechanical tach drivemodels. The vacuum advance model has a vacuum controlunit on the side. Interior parts (such as the reluctor) are notinterchangeable between the two distributors.Referring to the two types of distributors as being“mechanical” or “vacuum” is somewhat of a misnomersince the two distributors function basically the same. Themechanical distributor refers to the mechanical tach drivetake-off that this distributor features. It has no vacuumadvance unit. The mech-tach units are commonly referredto as “race” units. They also feature a more accurateregulator and a faster advance curve (full advance by 1,200rpm). The vacuum advance distributor has the vacuumadvance unit and must be used with an electrical tach(because it does not have the mech-tach drive feature).Vacuum advance units are less expensive and are designedfor dual purpose applications. The advance curve offersmore flexibility than the “race” unit, not being fullyadvanced until 2,000 rpm.The advance curve in the distributor is important to bothperformance and economy. There are two advance springs,one light and one heavy, in production units to reach thscurve. Some high performance vacuum advance models haveonly the light spring in the distributor and the advance curveis reshaped to give more advance at lower engine speed.As a general rule, a multi-purpose high performance machineshould have a fast advance curve. This means full centrifugaladvance by 2,000 rpm of engine speed. For a full-race dragcar such as a Pro Stock, a faster curve can be used.Note: At this time, Mopar Performance Parts does notoffer a vacuum advance distributor for the 4.0L engine.Since the mechanical distributor (stock on the 4.0L) is thepreferred racing piece, we recommend not modifying thesystem to a vacuum advance system, but rather thatemphasis be placed on obtaining a higher performancePowertrain Control Module (PCM) or Ignition ControlModule (ICM).

240 MOPAR PERFORMANCE PARTSElectronic Ignition DistributorThis replacement electronic ignition distributor comescomplete with cap and rotor. For 1987-90,4.0L engineswith MPI only.P4529683I. Distributor CupElectronic ignition distributor.Remove the distributor cap and wipe it clean with adry, lint free cloth. Visually inspect the cap for cracks,carbon paths, broken towers, white deposits on theinside (caused by condensation entering the capthrough cracks), or damaged rotor button. Replace anycap that displays charred or eroded terminals. Themachined surface of a terminal end (faces towardrotor) will indicate some evidence of erosion fromnormal operation. Examine the terminal ends forevidence of mechanical interference with the rotor tip.If replacement of the distributor cap is necessary,transfer spark plug wires from the original cap to thenew cap one at a time. Ensure that each wire isinstalled into the tower of the new cap that correspondsto its tower position in the original cap. Fully seat thewires into the towers.2. Distributor RotorVisually inspect the rotor for cracks, evidence ofcorrosion and the effects of arcing on the metal tip, andevidence of mechanical interference with the cap.Some charring is normal on the end of the metal tip.The silicone dielectric compound applied to the rotortip for radio interference noise suppression will appearcharred. This is normal. (DO NOT remove the charredcompound.) Test the spring for insufficient tension.Replace a rotor that displays any of these adverseconditions. Coat the tip of a replacement rotor withMopar Performance Parts Silicone DielectricCompound or equivalent.Distributor Cap and Rotor SetReplacement cap and rotor set. For 4.0L engine only.P4529686Distributor cap and rotor set.Mopar Performance Parts Electronic IgnitionComponentsHigh Performance Electronic Control UnitsFor a hotter spark and more rpm capability, use one of MoparPerformance Parts' high performance ECUs. For generalhigh performance and usage up through 6,000 rpm, use theOrange Box ECU. For higher rpm output requirements upthrough 8,000, select the Chrome Box ECU.P4 I20505P4 120534Orange Box ECU.Chrome Box ECU.Super Gold Electronic Control UnitThe Super Gold Electronic Control Unit is the culminationof eight years of high performance ignition systemsdevelopment. Designed to out perform any ignition unitpreviously offered to Mopar racers, it will handle the highcurrent demand by the P3690560 (Accel) highperformance coil, while keeping dwell variation to lessthan 1" from 1,000 to 10,000 rpm. Dwell is set formaximum spark output at low and high engine speeds.The Super Gold ECU provides outstanding performancefrom idle to 12,000 rpm.P4 I 20600Super Gold ECU - race only.Ballast Resistor - Electronic DistributorP2,44464 1 Use with mechanical advance distributorusing P3690560 coil. 114 Ohm.P5206436lgnition coilsP4 120889P3690560-~~~ ~Use with electronic ignition systemsusing P4120505 Orange Box ECU andproduction coil, or with P4120889 coil.1 Ohm.Accel Super Coil for all 12-voltapplications. Not recommended forengine speeds over 6,500 rpm. (Use withballast resistor P5206436.)Accel Race Coil specifically designed tobe used with race electronic ignitionkits. Designed for racing applicationsonly. Not recommended for continuedoperation at speeds below 3,000 rpm formore than 30 minute periods. (Use withballast resistor P244464 1 .)Control Wiring Harness Kit for ElectronicIgnitionsKit used to convert to a new electronic ignition system.P3690152Control wiring harness kit for electronicignitions.

T -7 74.01- POWER TECH IN-LINE 6 (IGNITION SYSTEM) 241Chrome Ignition Coil BracketAnother underhood piece to dress-up your enginecompartment. Includes special clamp screw.P4286728Tach AdapterChrome ignition coil bracket.Designed for applications when high capacitive dischargecoils interfere with tachometer or fuel injection signals.This device provides a clear 12 volt square wave signaloutput with a 30% duty cycle.P487673 8Tach adapter.DISTRIBUTORLESS IGNITION SYSTEMSome newer 4.0L Power Tech engines use what is referredto as a distributorless ignition system (model yearspecific-check your service manual). This system iscomprised of a one-piece coil rail containing threeindependent coils.Although cylinder firing order is the same as 4.0L enginesof previous years, spark plug firing is not. The 3 coils dualfire the spark plugs on cylinders 1-6, 2-5 andor 3-4. Whenone cylinder is being fired (on compression stroke), thespark to the opposite cylinder is being wasted (on exhauststroke). The one-piece coil bolts directly to the cylinderhead. Rubber boots seal the secondary terminal ends of thecoils to the top of all 6 spark plugs. One electrical connector(located at the rear end of the coil rail) is used for all threecoils. Because of coil design, spark plug cables (secondarycables) are not used. A distributor is also not used.The ignition system consists ofSpark PlugsIgnition Coil(s)Powertrain Control Module (PCM)Crankshaft Position Sensor0 Camshaft Position SensorThe MAP, TPS, IAC and ECT also have an effect onthe control of the ignition system.Powertrain Control Module (PCM)The ignition system is controlled by the Powertrain ControlModule (PCM).The PCM opens and closes the ignition coil ground circuitto operate the ignition coil(s). This is done to adjust ignitiontiming, both initial (base) and advance, and for changingengine operating conditions.The amount of electronic spark advance provided by thePCM is determined by five input factors: engine coolanttemperature, engine rpm, intake manifold temperature,manifold absolute pressure and throttle position.Ignition CoilA one-piece coil rail assembly containing the individualcoils is used on the 4.0L engine (Figure 4-50). The coil railmust be replaced as one assembly. The bottom of the coil isequipped with 6 individual rubber boots (Figure 4-50) toseal the 6 spark plugs the coil. Inside each rubber boot is aspring. The spring is used for a mechanical contact betweencoil and the top of the spark plug. These rubber boots andsprings are a permanent part of the coil and not servicedseparately. One electrical connector (located at the rear ofthe coil) is used for all three coils (Figure 4-51).Although cylinder firing order is the same as Jeep enginesof previous years, spark plug firing is not. The 3 coils dualfirethe spark plugs on cylinders 1-6, 2-5 and/or 3-4 (Figure4-49). When one cylinder is being fired (on compressionstroke), the spark to the opposite cylinder is being wasted(on exhaust stroke).Battery voltage is supplied to the three coils from the ASDrelay. The Powertrain Control Module (PCM) opens andcloses the ignition ground circuit for ignition coil operation.Base ignition timing is not adjustable. By controlling thecoil ground circuit, the PCM is able to set the base timingand adjust the ignition timing advance. This is done to meetchanging engine operating conditions.The ignition coil is not oil filled. The windings areembedded in an epoxy compound. This provides heat andvibration resistance that allows the ignition coil to bemounted on the engine.Because of coil design, spark plug cables (secondary cables)are not used. The cables are integral within the coil rail.II II ’IFRO)o1 -5-3-6-2-4COILS PAIRED:CYLINDERS 1-6CYLINDERS 2-5CYLINDERS 3-4Figure 4 - 49

242 MOPAR PERFORMANCE PARTSCYL. CYL. CYL. CYL. CYL. CYL.I #6 #5 #4 #3 #2 #1The engine will not operate if the PCM does not receive acrankshaft position sensor input.Camshaft Position SensorThe camshaft position sensor contains a hall effect devicecalled a sync signal generator to generate a fuel sync signal.This sync signal generator detects a rotating pulse ring(shutter) on the oil pump drive shaft. The pulse ring rotates180 degrees through the sync signal generator. Its signal isused in conjunction with the crankshaft position sensor todifferentiate between fuel injection and spark events. It isalso used to synchronize the fuel injectors with theirrespective cylinders.IMOUNTINGBOLTS (4)Figure 4 - 50Figure 4 - 51Automatic Shutdown (ASD) Relay8Ob76118The Automatic Shutdown (ASD) relay is located in thePower Distribution Center (PDC). Refer to label on PDCcover for relay location.As one of its functions, the ASD relay will supply batteryvoltage to the ignition coil(s). The ground circuit to operatethe ASD relay is controlled by the Powertrain ControlModule (PCM). The PCM regulates ASD relay operationby switching its ground circuit on and off.Crankshaft Position SensorEngine speed and crankshaft position are provided throughthe crankshaft position sensor. The sensor is a hall effectdevice combined with an internal magnet. The sensorgenerates pulses that are sent to the Powertrain ControlModule (PCM). The PCM interprets the sensor input todetermine the crankshaft position. The PCM then uses thisposition, along with other inputs, to determine injectorsequence and ignition timing.SPARK PLUGSSpark plugs tend to be taken for granted. Once installed inthe engine, they all look the same. Plugs are sold byekeryone, not just auto parts stores and dealers, andtherefore are readily available. We assume that anythingthat fits, works. We extend this assumption to include that,if it fits and works, then that’s all the plug can do. In a stockengine used for “stock” purposes this may be true. In aperformance engine, it’s a long way from the truth and canlead directly to problems. It’s obvious in a race engine thatif the plug doesn’t do its job, we have trouble. We’llprobably blame the ignition system first and then thecarburetor (if equipped). These can be expensivemisdirections. Before we get into these problem areas, let’sback up and identify our plug.Each plug has a “part number” reference or an I.D. number.The basis of this numbering system is the heat range of theplug. Unfortunately, all manufacturers don’t use the samenumbering system for their various heat ranges. This makesit difficult to understand. However, Chrysler-Plymouth-Dodge- Jeep has used mostly Champion plugs andChampion is our current production source. All of our techbooks base their recommendations on Champion plugs. Allthe other manufacturers compare their heat range toChampion’s. With the common base of heat rangeinformation being Champion’s, we’ll concentrate on thisgroup for our discussion. A typical Champion plug for aDaimlerChrysler-built engine would be an RN12YC. Theheat range is 12, but what do the letters mean? Let’s look atthem one at a time. We’ll concentrate on the letters that areused on DaimlerChrysler applications. There are manymore “specials” which are available from Champion.The first letter “R’ stands for resistor. Most newer plugs are“R’ rated as well as all production plugs. The resistor cutsdown on radio interference. If there is no letter in thisposition, then it’s a standard plug. Today, standard plugs areonly used in racing.-- ..T --I 7

4.0L POWER TECH IN-LINE 6 (IGNITION SYSTEM) 243The second letter, or the first one before the two digits of theheat range, defines the “reach” of the plug. This is dictatedby the number of spark plug threads in the cylinder head.For most engines there are only three. The “N’ stands for the“long-reach” plug (.750”), the “J” is the “short-reach’’ plug(3/8”), and the combination prefix BL or single V stands fora .460” reach plug. There are special plugs available fromChampion that use 10 and 18 mm threads, also.The two number digit used in the middle is the heat rangeof the plug. The heat range is basically its performancenumber. This is what determines whether the plug is goingto perform at its best in your application. For the momentwe’ll skip over the discussion of heat ranges and return toit later.The first letter to the right of the heat range defines the“nose shape” or configuration. There are three basictypes -regular, retracted, and projected. The projected corenose (electrode) is defined by a “Y.” All our plugs are“Y’s -projected nose.On older, standard design plugs, the last position is blank.Most of the newer plugs use a “C” which stands for “CopperPlus Design.” This copper feature can’t be seen by casuallylooking at the plug, but it allows the plug to be moreversatile. “C” plugs are able to cover more heat ranges or,stated somewhat differently, the “C” allows the plug of agiven heat range to do its job plus the job (performancecharacteristics) of a one or two step colder plug.That brings us back to the heat range. Before we get into thepractical side of heat ranges, let’s cover the theory. Thereare three basic heat range groups that are used for specificapplications. The numbers from 1 to 25 are used forautomotive applications. Numbers 26 to 50 are used foraviation, and 51 and up are used for racing, competition,and other special applications. Since we’re concerned withautomotive racing and performance, we only have toconcern ourselves with the first and last categories.Basic heat ranges are quite easy to figure out-the higherthe number the hotter the plug, the lower the number thecolder the plug. For example, a JlOY plug is colder than aJ12Y. The exception to this is racing plugs. ALL racingplugs are colder than production plugs although they havebigger numbers. Once into the racing plug category, the“lower the number the colder the plug” rule still holds.Why all the fuss about heat range? In performanceapplications, the heat range is key to the plug’s overallperformance. The hotter the plug’s heat range, the better itperforms at low speed. The hotter plug offers betterdriveability. On the other hand, the colder plug offers betterhigh rpm operation. The colder plug performs better in highoutput engines and at W.O.T. (wide open throttle). Coldplugs used on the “street” (low rpm use) will foul quickly.Hot plugs used at high rpm or high output will “miss” andcause the engine not to put out its peak power or allow it toreach peak rpm.So, how do you pick the best heat range? It can be done bytrial and error. DaimlerChrysler racing books give variousrecommendations as to the best performance approach.DaimlerChrysler service and owners manuals specifyproduction plugs. In general, if you don’t have morespecific information available, a performance engineshould use plugs two heat ranges colder than the productionrecommendation. A race engine should be one or two stepscolder than the performance plug.Re-gapping standard spark plugs to a wide gap can be doneeasily with the Accel plug gapping tool. If this tool isn’tused, extreme care should be used when opening up a largeplug gap. The best way is to file down the center electrode.This approach has the drawback of short plug life.Champion makes plugs specially designed for the largergaps. Otherwise, use the Accel tool.

~ ~244 MOPAR PERFORMANCE PARTSMopar Performance Parts Spark PlugsNEW! These spark plugs are specifically designed for the optimum performance of your Moparengine. Each package contains 4 spark plugs.Race & Tuning Application Plugs (J-Strap Type)Pack PINP4876939P4876940P4876941P4876942P4876943P4876944P4876945Cross ReferenceC 63CC 61C to C 59Cc 57c to c 55cc 53c to c 5 ICC 51CC 61C to C 59Cc 57c to c 55cApplicationAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesPack P/NP4876928P4876929P4876930P487693 1P4876932P4876933P4876934P4876935I 1Cross ReferenceC 61C to C 59Cc 57c to c 55cC 53C to C 51CC 51CS 61C to S 59Cs 57c to s 57cS 53C to S 51Cs 51cApplicationAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race Applicationsr --H -r

4.0L. POWER TECH IN-LINE 6 (IGNITION SYSTEM) 245Spark Plug and Ignition Wire RemovalRemove the ignition wire by grasping it at the spark plugboot, and then turn (1/2 turn) and pull it straight back in onesteady motion.1. Prior to removing the spark plug, spray compressed airaround the spark plug hole and the area around thespark plug.2.3.Remove the spark plug using a quality socket with arubber or foam insert.Inspect the spark plug. (Refer to Inspection.)InspectionFaulty and fouled plugs may perform well at idle speed, butat higher engine speeds they frequently fail. Faulty plugscan be identified in a number of ways: poor fuel economy,power loss, decrease in engine speed, hard starting and, ingeneral, poor engine performance. Spark plugs alsomalfunction because of carbon fouling, excessive air gap,or a broken insulator.Examine the spark plugs for burned electrodes and fouled,cracked or broken porcelain insulators. Keep plugsarranged in the order in which they were removed from theengine. An isolated plug displaying an abnormal conditionindicates that a problem exists in the correspondingcylinder. Replace spark plugs at the intervals recommendedon the Maintenance Chart in the service manual.Spark plugs that have low mileage may be cleaned and reusedif not otherwise defective. After cleaning, file the centerelectrode flat with a small point file or jewelers file. Adjustthe gap between the electrodes to the specified dimensions.SpecificationsNote: Due to model year differences, refer to the properservice or owners manual for spark plug type, gap, andtightening specifications.Gap AdjustmentCheck the spark plug with a gap (feeler) gauge. If the gapis not correct, adjust it by bending the ground electrode.Refer to the proper service or owners manual for spark pluggap specifications.Installation1. Start the spark plug into the cylinder head by hand toavoid cross threading.2.3.Tighten the spark plug to specified torque. Refer to theproper service or owners manual for torquespecifications.Install ignition wires over spark plugs.Always tighten spark plugs to the specified torque. Overtightening can cause distortion resulting in a change in thespark plug gap. Tighten all spark plugs to 35 Nom (27 ft-lbs).When replacing the ignition wires, route the wirescorrectly and secure them in the proper retainers. Failure toroute the wires properly can cause ignition noise radioreproduction, cross ignition of the spark plugs or shortcircuitthe wires to ground.SPARK PLUG CABLES (IGNITION WIRES)Check spark plug cable connections for good contact at theignition coil, distributor terminals, and spark plugs.Terminals should be fully seated. The nipples and spark plugcovers should be in good condition. Nipples should fittightly. Spark plug boot should completely cover the sparkplug hole in the cylinder head cover. Install the boot until theterminal snaps over the spark plug. A snap must be felt toensure the spark plug cable terminal engaged the spark plug.Loose cable connections will corrode, increase resistance,and permit water to enter. These conditions can causeignition malfunction. Plastic clips in various locationsprotect the cables from damage. When cables are replaced,the clips must be used to prevent damage to the new cables.If you don’t have top quality ignition wires you aren’tconducting maximum spark. Production spark plug wire is7 mm. For dual purpose and race-only applications, werecommend larger 7.5 mm spark plug wires. MoparPerformance Parts high performance 7.5 mm spark plugwires (P4286742) feature high quality insulation and boots(ends). If more insulation is required, neoprene hose of theproper inside diameter is recommended.Note: Using spark plug wires larger than 7.5 mm is NOTrecommended because of potential compatibility problemswith on-board computers and electronics.High Performance 7.5 mm Ignition Wire SetThis special high performance plug wire set features largerwire while maintaining compatibility with on-boardcomputer and electronics found in current productionvehicles. Package uses high tech production-style bootends at both the distributor and plug end of the wire. Wireis imprinted with the Mopar Performance Parts name. Thiscomplete set is pre-cut and fits all 1991-97 Jeep 4.0Lengines (only).P4286742High performance 7.5 mm ignitionwire set.

I.~~~~246 MOPAR PERFORMANCE PARTSAccessoriesUsually, once the spark plug wire is installed, pulling on thewire to remove the boot from the plug is the most commoncause of failure. This is especially true of non-standardproduction or “cheap” wires. Using the Mopar PerformanceParts spark plug wire boot puller (P524971S) will help plugwire removal without damaging the connector. The bootpuller will probably double the wire life, making it one ofthe best deals in the ignition area.MOpar Performance Parts spark plug wires have straightends at the spark plug, which is the most common style.Having been in racing for many years, we know thatstraight ends are not best for all applications, especiallywith headers. In an effort to solve this problem, we haveintroduced vari-angle plug adapters (P4286742) whichadjust easily from straight to right angles.Our plug wire separator package (P4007667) keeps thewires separated from the cap to the plug. This helpsperformance by preventing cross firing and makes theengine compartment look much more organized.Spark Plug Wire Boot PullerHere’s the tool you need for easy removal of spark plugwires without pulling the wire out of the terminal end andboot. Saves on knuckles, too.P.5249718 Spark plug wire boot puller.Vari-Angle Plug AdaptersHere’s a convenient way to steer spark plug wires aroundheaders, brackets, and other tight areas, in any directionyou want. Vari-angle plug adapters have a built-in swiveldevice which maintains the position you bend them in. Ahandy set-up for any racer. Sold two per set.P4286742Van-angle plug adapters.Ignition Wire Separator SetIgnition wire separators. 8 pieces per set.P4007667IGNITION SWITCHIgnition wire separator set.In race vehicles, the production ignition switch issometimes replaced by a toggle switch. This can causeproblems if a high-amp rated switch (such as P3690282)isn’t used. P3690282 is an 18-20 amp rated switch, whilemost readily available switches are 14-16 amp rated. Thelower rating causes more resistance in the ignition circuit,which cuts down on the voltage available to the ignition’s:ontrol unit. The lower voltage can cause the ignitionystem to perform poorly or develop a miss which can beery difficult to analyze.Ignition SwitchesP3690282P3690823“On-Off’ micro switch assembly(20 amp).Push button starter switch assembly.GENERAL IGNITION SYSTEM PERFORMANCE TIPSOne of the most important items in ignition is to check theTDC timing mark on the vibration damper to be sure that itreads zero when the piston is at TDC.Problems such as “pinging,” flat spots, poor idle andmisfires can be caused by a bad ignition system, but theymay also be caused by problems with the MPI system.Problems caused by a poor fuel system or ignition systemhave many similar symptoms. There is no substitute for agood mechanic when these problems are encountered.On any vehicle that is being converted to a race vehicle, westrongly recommend the steering column lock be removed.If things go wrong with the engine with the vehicle movingand the column lock is working, the drives wouldn’t be ableto steer and could have an accident.Grounds are very important, especially in a race vehicle.The engine should be grounded to the body and to theframe. The control box should be grounded to the engine.Painted surfaces make poor grounds - sand paint or othersurface material off and ground metal-to-metal.There are 2 special switches that are helpful in wiring a racevehicle: “On-Off’ Micro Switch Assembly (20 amp-P3690282); and, Push Button Starter Switch Assembly(P3690823). The “On-Off’ Micro Switch Assembly is themost important. Other “econo” switches aren’t rated as highon amperage and therefore put resistance between thebattery and the ignition and can cause misfiring.A volt meter is recommended for a race vehicle so that thebattery’s power can be checked frequently. If the battery’svoltage gets to be less than 12.0 volts, the ignition systemmay function inadequately resulting in poor performanceand lost races. Also measure what the voltage is at theignition system itself.

- -'7INTRODUCTIONThe starting system is designed to provide the vehicleoperator with a convenient, efficient and reliable means ofcranking and starting the internal combustion engine used topower the vehicle and all of its accessory systems from withinthe safe and secure confines of the passenger compartment.The starting system consists of the following components:BatteryStarter relayStarter motor (including an integral starter solenoid)Ignition switch0 Parkheutral position switchWire harnesses and connections (including the batterycables).OperationThe starting system components form two separate circuits.A high-amperage feed circuit that feeds the starter motorbetween 150 and 350 amperes, and a low-amperage controlcircuit that operates on less than 20 amperes. The highamperagefeed circuit components include the battery,battery cables, the contact disc portion of the startersolenoid, and the starter motor. The low-amperage controlcircuit components include the ignition switch, theparWneutra1 position switch, the starter relay, theelectromagnetic windings of the starter solenoid, and theconnecting wire harness components.Battery voltage is supplied through the low-amperagecontrol circuit to the coil battery terminal of the starter relaywhen the ignition switch is turned to the momentary Startposition. The parkheutral position switch is installed inseries between the starter relay coil ground terminal andground. This normally open switch prevents the starterrelay from being energized and the starter motor fromoperating unless the automatic transmission gear selector isin the Neutral or Park positions.When the starter relay coil is energized, the normally openrelay contacts close. The relay contacts connect the relaycommon feed terminal to the relay normally openterminal. The closed relay contacts energize the startersolenoid coil windings.The energized solenoid pull-in coil pulls in the solenoidplunger. The solenoid plunger pulls the shift lever in thestarter motor. This engages the starter overrunning clutchand pinion gear with the starter ring gear on the automatictransmission torque converter drive plate.4.0L POWER TECH IN-LINE 6 (STARTING SYSTEM) 247Starting SystemAs the solenoid plunger reaches the end of its travel, thesolenoid contact disc completes the high-amperage starterfeed circuit and energizes the solenoid plunger hold-in coil.Current now flows between the solenoid battery terminaland the starter motor, energizing the starter.Once the engine starts, the overrunning clutch protects thestarter motor from damage by allowing the starter piniongear to spin faster than the pinion shaft. When the driverreleases the ignition switch to the On position, the starterrelay coil is de-energized. This causes the relay contacts toopen. When the relay contacts open, the starter solenoidplunger hold-in coil is de-energized.When the solenoid plunger hold-in coil is de-energized, thesolenoid plunger return spring returns the plunger to itsrelaxed position. This causes the contact disc to open thestarter feed circuit, and the shift lever to disengage theoverrunning clutch and pinion gear from the starter ring gear.Following are general descriptions of the majorcomponents in the starting system.STARTER MOTOR(Refer to Figure 4-52.)The starter motor incorporates several features to create areliable, efficient, compact, lightweight and powerful unit.The electric motor of the starter features fourelectromagnetic field coils wound around four pole shoes,and four brushes contact the motor commutator. The startermotor is rated at 1.4 kilowatts (about 1.9 horsepower)output at 12 volts.The starter motor is serviced only as a unit with its startersolenoid and cannot be repaired. If either component isfaulty or damaged, the entire starter motor and startersolenoid unit must be replaced.OperationThe starter motor is equipped with a planetary gearreduction (intermediate transmission) system. Theplanetary gear reduction system consists of a gear that isintegral to the output end of the electric motor armatureshaft that is in continual engagement with a larger gear thatis splined to the input end of the starter pinion gear shaft.This feature makes it possible to reduce the dimensions ofthe starter. At the same time, it allows higher armaturerotational speed and delivers increased torque through thestarter pinion gear to the starter ring gear.

248 MOPAR PERFORMANCE PARTSPower RatingVoltageStarter Motor and SolenoidManufacturer I MitsubishiEnaine ADDlication 2.5L. 4.0LNumber of FieldsNumber of PolesNumber of BrushesDrive TypeFree Running Test VoltageFree Running Test Maximum Amperage DrawFree Running Test Minimum Speed2.5L - 1.2 Kilowatt (1.6 Horsepower)4.0L - 1.4 Kilowatt (1.9 Horsepower)12 Volts444Planetary Gear Reduction11.2 Volts90 Amperes2.5L - 2600 rpm4.0L - 2500 rpmI Solenoid Closing Maximum Voltage Required I 7.8 Volts I2.5L 130 AmperesI *Cranking Amperage Draw Test4.0L - 160 AmperesI*Test at operating temperature. Cold engine, tight (new) engine, or heavy oil will increase starter amperage draw.Figure 4 - 52The starter motor is activated by an integral heavy dutystarter solenoid switch mounted to the overrunning clutchhousing. This electromechanical switch connects anddisconnects the feed of battery voltage to the starter motorand actuates a shift fork that engages and disengages thestarter pinion gear with the starter ring gear.The starter motor uses an overrunning clutch and starterpinion gear unit to engage and drive a starter ring gear thatis integral to the torque converter drive plate mounted onthe rear crankshaft flange.STARTER RELAYThe starter relay is an electromechanical device thatswitches battery current to the pull-in coil of the startersolenoid when the ignition switch is turned to the Startposition. The starter relay is located in the PowerDistribution Center (PDC) in the engine compartment. Seethe fuse and relay layout label affixed to the inside surfaceof the PDC cover for starter relay identification andlocation. The starter relay cannot be repaired or adjustedand, if faulty or damaged, it must be replaced.BATTERYIt is very important that the battery be fully charged inracing applications with an electronic ignition. A volt metershould be used to check the battery voltage before thevehicle is raced. The voltage should not be allowed to dropbelow 12.0 volts. Lower voltage will cause poor ignitionperformance such as misfires and will result in slowing thevehicle down. It may also cut down on the electric fuelpump’s efficiency.Brass Battery TerminalsHere’s a variety of brass terminals in different styles thatoffer maximum conductivity. Feature positive threadedattachments. Designed for large gauge wire used in batteryrelocation kits with features best liked and required byracers.P4349575P4349576P4349577P4349578P4349579P4349580Battery terminal with left or right cableconnection - 1 gauge wire.Ring terminal, 318“ eye - 1 gauge wire.Battery terminal with left or right cableconnection - 4 gauge wire.Ring terminal, 318” eye - 4 gauge wire.Quick disconnect “positive” batteryterminal with 318” stud.Quick disconnect “negative” batteryterminal with 3/8” stud.*. - - T -7

4.0L POWER TECH IN-LINE 6 (STARTING SYSTEM) 249Battery RelocationMost race vehicles begin life with the battery in theengine compartment.Mounting the battery in the trunk of a RWD race vehiclehelps by shifting weight over the drive wheels (improvingtraction) and by making the engine compartment lesscluttered. But there’s more to a trunk mounted battery kitthan just putting the battery in the trunk. Physically movingthe battery is easy. The problem is that the battery must stilloperate the engine’s ignition and fuel delivery systems, andwith the battery eight feet away from the ignition system(usually a high output electronic race unit), minimizingvoltage drop is critical.To minimize voltage drop, the Mopar Performance Partstrunk mounted battery kit (P4349500) uses #1 gauge wire,while the competition uses #4 gauge. The smaller the gaugenumber the bigger the wire size. The bigger the wire sizethe less voltage drop occurs. To provide the best electricalconductor available, Mopar Performance Parts suppliescopper wire-the competition uses aluminum. Copper is abetter electrical conductor than aluminum. The better theconductor, the less voltage drop occurs in the samedistance; that is, trunk to engine compartment. Handcrimpedterminals can lead to problems such as voltagelosses, loose connections, and so on. That’s why the MoparPerformance Parts cable has factory-installed threadedbrass terminals.Some people feel that a full length ground cable is required.This is acceptable, but it adds a lot of weight and isn’tnecessary. The engine is already grounded from the blockto the firewall of the bodylframe (unibody). Check to besure. The Mopar Performance Parts package includes aground strap to ground the battery to the frame in the trunkarea. The Mopar Performance Parts package also includesmany convenience items such as starter to relay andsolenoid wires, terminals, firewall grommets, and batterycover. Other kits don’t include these items. However, itdoes not include a battery.Trunk Mounted Battery KitThis improved kit is designed for moving the battery tothe trunk. Improves weight distribution which is soimportant for drag racers. It means less clutter in theengine compartment, and helps provide better traction. Itwill even contribute to improved braking and lessundersteer in hard turns for oval trackers and rallyers. Kitwill fit nearly any vehicle. Does not include battery.P4 349 5 00Trunk mounted battery kit..-

250 MOPAR PERFORMANCE PARTSIn this section we will review the entire engine buildingprocedure. This includes detailed blueprinting techniques,as well as all start-up, tune-up and troubleshootingprocedures necessary.Engine AssemblyCylinder Head Gasket Failure DiagnosisA leaking engine cylinder head gasket usually results inloss of power andlor coolant and engine misfiring.An engine cylinder head gasket leak can be located betweenadjacent cylinders or between a cylinder and the adjacentwater jacket.An engine cylinder head gasket leaking betweenadjacent cylinders is indicated by a loss of powerandor engine misfire.An engine cylinder head gasket leaking between acylinder and an adjacent water jacket is indicated bycoolant foaming or overheating and loss of coolant.Cylinder-to-Cylinder Leakage TestTo determine if an engine cylinder head gasket is leakingbetween adjacent cylinders, follow the procedure outlined inCylinder Compression Pressure Test. An engine cylinderhead gasket leaking between adjacent cylinders will result inapproximately a 50-70% reduction in compression pressure.Cylinder-to-Water Jacket Leakage TestINSPECTION AND TESTINGCylinder Compression Pressure TestThe results of a cylinder compression pressure test can beutilized to diagnose several engine malfunctions.Ensure the battery is completely charged and the enginestarter motor is in good operating condition. Otherwise theindicated compression pressures may not be valid fordiagnosis purposes.1. Disconnect ignition coil tower electrical connectorsand remove ignition coil towers.2. Remove spark plugs.3.4.5.6.Clean spark plug recesses with compressed air.Secure the throttle in the wide-open position.Disable the fuel system. (Refer to the proper servicemanual for correct procedure.)Insert a compression pressure gauge and rotate theengine with the engine starter motor for threerevolutions.7. Record the compression pressure on the 3rd revolution.Continue the test for the remaining cylinders.Refer to 4.0L Engine Specifications, later in this yection, forthe correct engine compression pressures.AWarning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or the fan. DONOT wear loose clothing.Remove the radiator cap. Start the engine and allow it towarm up until the engine thermostat opens.If a large combustionkompression pressure leak exists,bubbles will be visible in the coolant. If bubbles are notvisible, install a radiator pressure tester and pressurize thecoolant system. If a cylinder is leaking combustion pressureinto the water jacket, the tester pointer will pulsate withevery combustion stroke of the cylinder.Cylinder Combustion Pressure Leakage TestThe combustion pressure leakage test provides an accuratemeans for determining engine condition. Testing will detectexhaust and intake valve leaks (improper seating), leaksbetween adjacent cylinders or into water jacket, as well asany causes for combustionkompression pressure loss.1. Check the coolant level and fill as required. DO NOTinstall the radiator cap.2.3.Start and operate the engine until it attains normaloperating temperature, then turn the engine OFF.Disconnect ignition coil tower electrical connectors.4. llemove ignition coil towers.5. Kemove spark plugs...

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 2516. Remove the oil filler cap. I Oil Leak Inspection7. Remove the air cleaner.8. Calibrate the tester according to the manufacturer’sinstructions. The shop air source for testing shouldmaintain 483 kPa (70 psi) minimum, 1,379 kPa (200psi) maximum (552 kPa [80 psi] recommended).9.Perform the test procedures on each cylinder accordingto the tester manufacturer’s instructions. While testing,listen for pressurized air escaping through the throttlebody, tailpipe and oil filler cap opening. Check forbubbles in the radiator coolant.All gauge pressure indications should be equal, with nomore than 25% leakage.Example: At 552 kPa (80 psi) input pressure, a minimumof 414 kPa (60 psi) should be maintained in the cylinder.Refer to the Cylinder Combustion Pressure Leakage TestDiagnosis Chart.Begin with a thorough visual inspection of the engine,particularly at the area of the suspected leak. If an oil leaksource is not readily identifiable, the following steps shouldbe followed:1. DO NOT clean or degrease the engine at this timebecause some solvents may cause rubber to swell,temporarily stopping the leak.2. Add an oil soluble dye (use as recommended bymanufacturer). Start the engine and let idle forapproximately 15 minutes. Check the oil dipstick tomake sure the dye is thoroughly mixed as indicatedwith a bright yellow color under a black light.3.4.Using a black light, inspect the entire engine forfluorescent dye, particularly at the suspected area of oilleak. If the oil leak is found and identified, repair perservice manual instructions.If dye is not observed, drive the vehicle at variousspeeds for approximately 24 km (15 miles), andrepeat inspection.5.If the oil leak source is not positively identified at thistime, proceed with the Air Leak Detection Test Method.CYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHARTCONDITIONAIR ESCAPES THROUGHTHROTTLE BODYAIR ESCAPES THROUGHTAI LPl PEAIR ESCAPES THROUGHRADIATORMORE THAN 50% LEAKAGEFROM ADJACENT CYLINDERSMORE THAN 25% LEAKAGE ANDI AIR ESCAPES THROUGH OILFILLER CAP OPENING ONLYPOSSIBLE CAUSEIntake valve bent,, burnt, or notseated properlyExhaust valve bent, burnt, or notseated properlyHead gasket leaking or crackedcylinder head or blockHead gasket kaking or crack incylinder head or block betweenadjacent cylindersStuck or broken piston rings;cracked piston; worn rings and/orcylinder wallCORRECTIONInspect valve and valve seat.Reface or replace, as necessaryInspect valve and valve seat.Reface or replace, as necessaryRemove cylinder head and inspect.Replace defective partRemove cylinder head and inspect.Replace gasket, head, or block asnecessaryInspect for broken rings or piston.Measure ring gap and cylinderdiameter, taper and out-of-round.ReDlaCe defective Dart as necessary

252 MOPAR PERFORMANCE PARTSAir Leak Detection Test Method1. Disconnect the breather cap to air cleaner hose at thebreather cap end. Cap or plug breather cap nipple.2.3.Remove the PCV valve from the cylinder head cover.Cap or plug the PCV valve grommet.Attach an air hose with pressure gauge and regulator tothe dipstick tube.Caution: DO NOT subject the engine assembly to morethan 20.6 kPa (3 psi) of test pressure.4.5.6.7.Gradually apply air pressure from 1 psi to 2.5 psimaximum while applying soapy water at the suspectedsource. Adjust the regulator to the suitable test pressurethat provide the best bubbles which will pinpoint theleak source. If the oil leak is detected and identified,repair per service manual procedures.If the leakage occurs at the rear oil seal area, refer toInspection for Rear Seal Area Leaks.If no leaks are detected, turn off the air supply andremove the air hose and all plugs and caps. Install thePCV valve and breather cap hose.Clean the oil off the suspect oil leak area using asuitable solvent. Drive the vehicle at various speedsapproximately 24 km (15 miles). Inspect the engine forsigns of an oil leak by using a black light.Inspection for Rear Seal Area LeaksSince it is sometimes difficult to determine the source of anoil leak in the rear seal area of the engine, a more involvedinspection is necessary. The following steps should befollowed to help pinpoint the source of the leak.If the leakage occurs at the crankshaft rear oil seal area:1. Disconnect the battery.2. Raise the vehicle.3. Remove the torque converter or clutch housing coverand inspect the rear of the block for evidence of oil.Use a black light to check for the oil leak:a. Circular spray pattern generally indicates sealleakage or crankshaft damage.b. Where leakage tends to run straight down,possible causes are a porous block, camshaftposition sensor seal, camshaft bore cup plugs, oilgalley pipe plugs, oil filter runoff, and mainbearing cap-to-cylinder block mating surfaces.4. If no leaks are detected, pressurize the crankcase asoutlined Air Leak Detection Test Method.Caution: DO NOT exceed 20.6 Wa (3 psi).5. If the leak is not detected, very slowly turn thecrankshaft and watch for leakage. If a leak is detectedbetween the crankshaft and seal while slowly turningthe crankshaft, it is possible the crankshaft seal surfaceis damaged. The seal area on the crankshaft could haveminor nicks or scratches that can be polished out withemery cloth.Caution: Use extreme caution when crankshaft polishingis necessary to remove minor nicks and scratches. Thecrankshaft seal flange is especially machined tocomplement the function of the rear oil seal.6. For bubbles that remain steady with shaft rotation, nofurther inspection can be done until disassembled.BUILDING A NEW ENGINESooner or later you’ll build a new engine for your racevehicle. Mopar engines typically last a long time, even inracing. Our Mopar Performance Parts racers will use thesame engines for two or three years. The GM racers alwayshavc two or three at any one time and build or rebuild themall at least once during the race season. We all know whythey need so many! However, the point is that some dayyou’ll build a new engine. We’ll assume that you want abasic engine, nothing fancy. In the early steps you’ll need tocheck over the basic parts -block, head, crankshaft. You’llneed to gather your technical information - servicemanuals, parts catalogs, and racing books - and then lay outa plan for horsepower level and determine which parts youmust use. (This book will help answer these questions.) Nomatter which parts you use, the engine must be prepped andbuill.. This is where racers tend to make errors - in the formof spending money on the wrong things.On your engine build-up plan, list all the basic buildingblocks (big parts) of your engine: block, crankshaft, head,etc. Under each item list the major operations that have tobe clone to that piece. (For example, the block has to bebored, honed, milled.) Then, on a separate piece of paper,make two columns: operations that you can do andoperations that must be sent out. Next to each item on the“sertd out” list, put down an estimated cost. Then add up allthe costs and compare the total to your basic budget.The “send out” column generally consists of machining,milling, boring, etc. The most important of these is blockhoning. You must have a dial-bore gauge to hone. You alsomust have a honing plate for your engine. So, when yousend your block out to be honed, pick a shop that has ahoning plate for your engine or supply the honing plate withthe block.The crankshaft can be polished at home, using extra care. Ifit’s used and is scratched up and needs to be groundundersize, it will have to be sent out.

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 253On the cylinder head, the valve work is the most importantaspect and is usually sent out. The special equipment that isrequired to do valve jobs is not usually found in the homeshop. This is an area where the extra money spent willresult in more Performance. Like the block, the head will besent out for milling. If new guides or seats are required inthe head, these operations should also be sent out to aqualified shop. (Not all valve grinders do guides.) Lappingthe valves can be done at home but, a word of caution-iftoo coarse a lapping compound is used, you’ll destroy agood valve job. It’s best left to the headhalve expert.Once the machine operations are performed, assembly of theengine can be done at home. Certain basic tools are required.Take your time and be extra careful. Never hurry or try tobuild an engine quickly. Leave that to the professionals.What Parts to UseThe most commonly asked question in the engineperformance business is, “What parts should I use?”Typically, the question is asked in the following manner:“I’ve got a 4.0L Power Tech engine-what parts do yourecommend?” Obviously, there is more than one answer. Inreality, the answers are almost infinite. The parts inquestion are the induction system, exhaust manifolds,camshaft, and ignition system. The easiest way to answerthis general question is to refer to earlier sections of thischapter.To develop a list of general engine parts recommendations,the important questions to answer are as follows:What type of fuel is going to be used?0 What’s the engine’s compression ratio?0 What type of transmission is to be used?What type of induction system is desired?Do you want to use headers?The answer to the fuel question (typically gasoline) willdictate the maximum compression ratio that can be used andis the most important of the five questions. It will determinewhich piston can be used and how the heads and block canbe modified, if at all. The transmission type (manual orautomatic) will affect both the carburetor and the camshaft.Remember that automatic transmission pieces will workwith a manual, but manual transmission pieces won’t workwith an automatic without other changes. The inductionsystem can be fuel injection or carburetion. If carburetion isselected, an intake manifold that will work with thecarburetor must be selected. Most performance applicationswill use exhaust headers. The ignition system should alwaysbe a high performance electronic. In general terms that givesyou the “what parts to use” answer, except for the camshaft,which is covered in its own section of this chapter.Engine Torque vs. HorsepowerTorque and horsepower relative to performance engines arenot the same thing, but they are very closely related. Theactual equation is as follows:Bhp =brake horsepowerT = torque in lbs-ftrpm = engine speed in revolutions per minutek = constantIn racers language, horsepower refers to the high rpm scaleand torque refers to the low rprn scale. Usually, the dividingline for mild performance engines is 3,000 to 3,500 rpm.Unfortunately, in practice, parts that help horsepowergenerally hurt torque and vice-versa. This is true when onlyone engine part is changed, keeping the rest of the enginethe same. Racing engines with drastically modified rprnscales are much too complicated to analyze in this manner.However, it can be useful for dual purpose machines.Let’s choose a specific example-camshafts. Here the ruleis: the bigger the camshaft, the more horsepower it makes.However, this can also be stated as: the bigger the camshaft,the less torque it makes. The question you should askyourself is, “Does my engine need more torque or morehorsepower?’ You can answer this question easily bydeciding whether you want to improve your performanceabove 3,500 rpm or below 3,500 rpm. Keep in mind that animprovement in one area comes at the expense of another;that is, more torque, less horsepower (and vice versa). Thesesimple guidelines can be very helpful in making many partsselections, but remember that you must have abaseline - some standard you want to compare against. (Themost common baseline is some version of a stock engine.)

254 MOPAR PERFORMANCE PARTSBefore You StartWhen an engine building project is in its early stages, thereare several basic decisions that must be made or at leastconsidered early on. The most important of these decisionsis whether the engine is going to be built from the groundup, so-to-speak, or will it just have pieces bolted-on; that is,swapped. A camshaft change or intake manifold swapobviously doesn’t require a complete engine rebuild. We dosuggest strongly that even the racer who is just in the boltonstage read this book completely, without skipping theengine building information, so that he is sure to have allthe facts and information required for a more completeunderstanding of his modification.The next consideration is how the engine is going to beused; that is, drag racing, off-road racing, or dual purpose?Special aspects of each type are covered in Chapter 8, Off-Roading and Racing.Please keep in mind that a good engine in one area of racinghas many things in common with good engines from otherareas of racing. They are not completely different. Somespecific parts may change, but the technique of good enginebuilding will be the same.Other areas to which thought and planning should bedevoted are the overall budget that is available, the amountof time that you can devote to the project, and the manpowerthat you have at your disposal. Plan to match your basiccomponents such as axle ratio, transmission, and overallvehicle weight to your engine package, or vice versa.Reference MaterialOne of the most important items to have before you start is aservice manual for your particular engine. A current MoparPei$ormance Parts Catalog is also strongly recommended. Anotebook in which you can write all your measurements, partnumbers, plans, etc., is also recommended.EquipmentHaving the proper engine building equipment is asimportant as what you plan to do to the engine. Once thereference material has been obtained and read, the rest ofthe equipment consists of tools such as an engine stand, dialindicator and base, degree wheel (P4452990), valve springcompressor, steel scale, cc’ing equipment and burette, dialboregauge, torque wrench, quality hone, basic sockets andwrenches, snap gauges, micrometers, and Plastigauge(P4286819).A dial-bore gauge is a very useful tool in precision enginebuilding. If you are going to hone the engine yourself, thena dial-bore gauge is an absolute necessity. If you don’t haveone, the block should be honed at a reputable machine shop,or by a professional engine builder. It is very important thatthe bores be straight (without taper) and round.It is also recommended that you or your selected machineshop have a honing plate. It is one of the most importanttools you can use. (For more information, refer to ‘Block’section of this chapter.)PlastigaugeWhen reassembling your engine you’ll need a variety ofPlastigauge to measure bearing clearances. This popularassortment includes one blue strip for .004” - .009”tolerances, two red strips for ,002” - .006” tolerances, andtwo green strips for .OO 1 I’ - .003” tolerances. Each strip is12” long.P42868 19Degree WheelPlastigauge assortment.Durable Mopar Performance Parts aluminum plate 0”-180’-0” degree wheel for centerlining camshafts. Featuresstep-by-step installation instructions printed on back side.P445 2990RecordsDegree wheel.One of the most important items in engine building is thekeeping of accurate records of how each engine was built.All clearances such as bearings, ring gaps, etc., and all theother measurements such as head cc’s, 1/2” down fillvolume, etc., should be carefully written down. Allmachining operations such as head milling, piston notches,etc., as well as all items, part numbers, or special parts usedshould be recorded. No item should be omitted. Theserecords will help in building future engines and also insolving engine failure problems (as well as preventing themin future engines).ENGINE BLUEPRINTINGTo obtain maximum performance and durability for aproduction engine, it is necessary to first “blueprint” theengine to provide a solid foundation for subsequentmodifications. “Blueprinting” is the term used to describethe process wherein every part of the engine is checked forconformity to its specified dimensions. If it is a moving part,it will also have a specified working clearance which mustbe checked. This is necessary because all dimensions andworking clearances have a plus and minus tolerance whichallows them to function properly even though the figure maynot be quite exact. These tolerances are what make thealmlost fully automated modern production line possible,all0 wing for the huge volumes that are produced today.-- a --- 7 -

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 255This production line system is more than adequate for stockpassenger vehicle engines. However, an engine that will beused for performance work requires more precision.Blueprinting provides this precision by ensuring that alldimensions, working clearances, and settings are brought tothe point where they produce the best results, both fromperformance and reliability standpoints. The worth of thisprocedure has been proven many times on thedynamometer and the race track, with fully blueprintedengines always producing more horsepower than theirproduction line counterparts.It is now time to make the final decisions on your basicengine racing plan. A lot of consideration should be givento the camshaft, carburetion system, and actualcompression ratio that are going to be used in the engine.These three decisions will greatly influence many aspectsof the basic preparation. Waiting until the last minute tomake these decisions may result in extra work, added cost,or poor engine performance.Keep in mind as you build your engine that there are placesto spend your time that are very important to your engine’sperformance. However, there are also many areas that DONOT affect engine performance, and some that mayadversely affect it. The two most important considerations inengine building are to have straight and round cylinder boresand to have these bores in a “good” block. Cleanliness isalso very important. Therefore ALL used and new partsshould be cleaned before anything further is done.I 1IDuration . ....................One problem with identifying production camshafts for agiven engine is that all are ground from the same casting.At this point, camshaft identification is best done bymeasuring the camshaft lift at the lifter. The usually reliablecasting number fails on camshafts.Casting numbers and forging numbers are as valuablefor new parts as they are for old ones. Write both inyour notebook.IIBlock casting number .....................Cylinder head casting numberIntake manifold number ....................Rod forging number .....................Crankshaft number (if available)Dynamic BalancingDynamic balancing of an engine assembly seems to be alost art. Many racers appear to be trying to build theirengine deliberately without balancing it. This seemscounter-productive. Balancing is strongly recommendedfor racing engines and performance purposes, but itrequires the engine to be totally disassembled to allow youto balance it. There are several “stages” to consider.Balancing is a dynamic process. However, it begins with manystatic processes that can generally be classified as weighing. Eachpiston, pin, and both the small and big end of each connecting rodis weighed. Once weighed, each individual piece is lighteneddownto the weight of the lightest piece in the set. Once matchedsets are created, the balance shop adds a “bob-weight” to thecrankshaft rodthrows. Now the crankshaft and vibration damper(if desired) can be spun and balanced dynamically. Heavy pieces(connecting rods or pistons) and externally balanced productionengines will require weight to be added. Lightweight pieces willtypically require weight to be removed.Any serious race engine, especially a high rpm version,should be internally balanced as an assembly. There isperformance to be gained from balancing the engine. It alsohelps the engine last longer. Cast crankshaft engines areexternally balanced and therefore should be balanced withthe offset vibration damper, which is a stock part of thepackage. It is recommended that if the engine is externallybalanced it also be internally balanced, which will requireMallory metal (see Figure 4-5). (For more information,refer to ‘Crankshaft’ section of this chapter.)Note: It is common on cast crankshaft engines to offsetbalance the torque converter (or flywheel) as part of theoverall balance; however, this is not recommended.When production parts are used, no balancing is required ifthe engine is being used in a production-style application.In this case, production balance is adequate. In someproduction engines the engine is externally balanced. If youplan to balance these engines, balance them as an assemblywith any external balancing components, such as dampers,torque converters, and flywheels included, or adjusted for.You can’t really balance (spin) torque converters with theengine, but you can do the flywheel and damper.For a low-cost race engine, production balance isacceptable as long as the original parts haven’t beenswitched, mixed, or modified.

T ‘11256 MOPAR PERFORMANCE PARTSNominal NumbersNumbers are fun to play with. However, they can be usedin more than one way. We all know what a number is, sowhat is a nominal number? A nominal number is similar toan average. Nominal numbers are used to describespecifications that are found in production manufacturing.In the automotive industry, we use them to describe enginespecifications such as compression ratio. The advertisedcompression ratio of any production engine is a nominalnumber. If you measure the size of the combustion chamberin cc’s for hundreds of production engines, you end up witha nominal number for the combustion chamber. If youmeasure the size of the intake port (port volume) forhundreds of production engines, you end up with a nominalnumber for the intake port (port volume).A nominal number does not mean that it is the biggest orsmallest, just the most common. Although it isn’t a trueaverage, it indicates the range that you can expect. The keyto all this is not to consider nominal numbers as absolute.They can go up or down (plus or minus). In most cases,much of the total variation (or observed variation) is notdue to the part itself. For example, let’s assume that thenominal (or advertised) port volume for a head is 170 cc’s.Let’s also assume that you want a large port volume foryour race engine, and the reason that you bought this headis because of the 170 number. You measure it at the shopand your new head measures 170.1 cc’s. You’re happy andtake the part home. A week later you measure the same portin the same head again in your own shop at home and find165 cc’s. Now you’re mad! What happened? Temperature?Maybe. Different burette? Maybe. Most likely youswitched valves. Originally you measured it with anail-head or flat valve, but at home you measured it with astock valve which was semi-tulip (for example). The portdidn’t change. Valve shape changes can affect themeasurement of the combustion chamber. A nail-head orflat valve makes the chamber smaller, and an undercut tulipvalve makes the chamber larger.Remember, nominal numbers are for reference only. Forcomplete accuracy, measure the part itself with all the partsthat you are actually going to use in the final engineassembly. If you change parts at a later date, don’t forget tomeasure again!Dynamometers (Dynos)A short example may help illustrate the point. If you builtan engine that made 200 horsepower and you took it toDyno service A and it made 225 hp, you’d be pleased. Ifyou took the same engine to Dyno service B and it made245 hp, you’d be even more pleased. Dyno service C - 260hp. But if you took it back to Dyno service A and it made225 hp you’d be disappointed. Unfortunately, you havenow spent thousands of dollars, used up your engine, andlearned nothing. You’ve been racing dynos. However, all isnot lost. If you stay at one dyno service and make yourchanges, relative gains should translate to real at-the-trackperformance gains. You just can’t get too hung up onabsolute numbers.DISASSEMBLYBefore the engine assembly and blueprinting procedure isstarted, the engine has to be disassembled. This disassemblyprocedure is usually considered only a necessary evil and is,therefore, usually done as quickly as possible. This is notrecommended. The correct way to disassemble an engine isslowly. During teardown you should check for fluidcontamination (mixing of oil and water), cross-threaded orstripped bolts and nuts, bolt holes that aren’t tapped deepenough, and be sure to turn the crankshaft withoutconnecting rods (but with all the main bearings in place) tosee if there are any tight spots. Careful disassembly can giveyou a lot of clues as to what has to be fixed, replaced, orchanged in the engine when you rebuild it.Things to CheckWhen building a new engine assembly, which for most of usreally means rebuilding a used assembly with some newparts, there is a lot of information the parts can tell us thatwill help us with our project. Unfortunately, we have tocheck these things ourselves. To this end, there are severalmeasurements that should be made during disassembly, orwhen the new parts are received, which should be recordedin the notebook that you should keep on each engine that youbuild. They will be helpful when the engine is rebuilt. Someof these measurements are crankshaft end play, connectingrod side clearance, deck height (top of piston to top of block),camshaft lift, and actual installed camshaft centerline. Youshould check the camshaft lobes and valve guides forexcessive wear and check the pushrods for straightness.Dynamometers (dynos) allow you to measure an engine forhorsepower and torque output without putting it in avehicle. This has many advantages but it also has manyshortcomings. You don’t want to end up “racing dynos”because dyno testing can be very expensive and uses up lotsof parts.

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 257Crankshaft End Play . ......................Rod Side Clearance . ......................Deck Height: Above BelowCamshaft LiftAt Valve: Intake Exhaust ________At Camshaft: IntakeInstalled Camshaft CenterlineCamshaft I. D.Exhaust ________(or part number, if available) _________________At this point we’ll assume that we’re rebuilding the enginefor added power and that there was nothing wrong with iton its last pass; that is, it isn’t broken. So why are thesemeasurements important?Let’s look at each one individually. Crankshaft end play canindicate that the crankshaft is worn and needs to bereplaced. It may also indicate that you have anengine/drivetrain mount problem that needs to be fixedbefore you break the engine. If the connecting rod sideclearance is high, you may need connecting rods or thecrankshaft journal may be worn. Deck height affects thepiston selection and directly relates to the engine’scompression ratio.The easiest way to identify a camshaft by measuring the liftboth at the valve and at the camshaft lobe. This allows us tocalculate the rocker arm ratio. The camshaft centerlinecheck allows us to put the camshaft in the engine in theexact same location as before. If we don’t do this, we canlose some power/performance with the same pieces we had.The camshaft I.D. is sometimes stamped on the end of thecamshaft that goes into the engine. This is sometimeshelpful with aftermarket grinds. But, if it isn’t there, thenthe camshaft lift will get us what we need. One of the mostimportant items is to write this information down.Pari IdentificationCasting numbers can be used to identify new or usedcylinder heads and cylinder blocks, even new or used intakemanifolds. Forging numbers can be used to identifyconnecting rods. In either case, these numbers cannot beused to purchase the part from a dealer, speed shop, etc. Inmost cases, the service number (number used to obtain theitem) will be one or two digits different from the castingforgingnumber. This doesn’t usually cause a problem, onlyconfusion, except for production camshafts. Camshaftshave a casting number, but it’s of no use in identifying thecamshaft except to tell you which engine it came out of,which you usually already know.The problem is that all production cams (2 to 3 designs in agiven year) for a given engine are all ground from the samecasting. At this point, cam identification is best done bymeasuring the cam lift at the lifter. This is much morereliable than casting numbers.Otherwise, casting numbers and forging numbers are asvaluable for new parts as they are for old ones. Write bothin your notebook.INSPECTION AND PREPARATIONCylinder BlockThe basic block should be checked and reworked inaccordance with the following procedures:1. Before disassembling the block, the deck height of thepistons must be checked. Deck height is the distancefrom the top of the piston to the top of the deck surfaceof the block. This is an important dimension since ithas a direct influence on compression ratio. If thepiston is a flat top style, it will usually be below thedeck and this is the distance that must be measured. Adomed piston will stick up above the deck surface andthe distance is measured from the deck to the top of thedome. Mark this figure down for future reference andcompletely disassemble the block.Optional Step: Stress Relieving (refer to ‘Block’section of this chapter).2.3.4.All the head bolts should be screwed into the blockwithout the head. Visually inspect the rows of bolts forany that may be bent, drilled at any angle, or for holesthat are not drilled deep enough. When the head boltsare screwed in, the depth of thread engagement shouldbe checked and recorded.The main bearing bores must be checked for bothspecified diameter and alignment with each other. Ifeither is off, a Tobin-Arp align boring machine (or anysimilar type machine) must be used to align bore theblock. A crankshaft-turning tight spot indicates that thebores are out of alignment.Sonic Testing (refer to ‘Block’ section of this chapter).

258 MOPAR PERFORMANCE PARTS5.6.7.8.9.10.11.12. Honing Plates (refer to ‘Block’ section of this chapter).13.14.Once the main bearing bores are known to be inalignment, the deck surfaces of the block should bechecked to make sure they are parallel with the axis ofthe crankshaft. The distance from the centerline of thecrankshaft to the deck surface of the block should beexactly the same in the front and rear. If not, the decksurfaces will have to be milled. At this time the deckheight can be machined to the proper dimension.Note: Deck heights that are above the block surfacewill be increased by milling the block. Check theblueprint specifications on the engine before milling.The resulting machined surface of the deck must be onthe rough side to produce a good gasket seal andprevent the head gasket from moving.A bottoming tap should be run down all head and mainbearing bolt holes. The head bolt holes should bechamfered slightly to prevent the top thread frompulling up when the head bolts are torqued.Use a small, fine file to remove burrs and break allsharp edges in the main bearing bores and around thecylinder bore chamfers, along with other sharp edgeson the block.The tappet bores may be shined with #400 paper toremove any rough spots or burrs. A brake cylinderhone may also be used with care.If a big flat-tappet camshaft that requires .loo”oversize mushroom lifters is going to be used, thebottoms of the lifter bores should be spot-faced to aslightly larger diameter than the diameter of themushroom lifter bottom.Ensure that all cylinder head dowel pins used foraligning purposes are the proper height (not too high),and also check to be sure that the dowel pins locate thehead properly so that the combustion chamber iscentered over the cylinder bore. Check to be sure thatthe dowel pins don’t hold the head up off the block.Honing (refer to ‘Block’ section of this chapter).The rear main bearing oil seal machined groove shouldbe roughed slightly with a center punch, and the ropeseal must be seated all the way in. The rubber rear mainseal should be held in place with Permatex (RTV).A chemical kit belongs in every workshop before you startbuilding the engine. It will be useful in coping with life’smechanical frustrations, such as baked-on gaskets,assuring proper seal, assembly lubing, freeing up nuts, anddozens of other uses. Chemical products to be usedfrequently are: Silicone RTV, Gasket Remover, Lubriplate,Spray White Lube, Anaerobic Gasket Maker, Lock ’NSeal, Brake and Carburetor Cleaner, Penetrating Fluid,Spray Gasket Adhesive, Thread Sealant with Teflon, andHand Cleaner. Everything you’ll need to spare a headache!15. When installing camshaft bearings, make sure that theoil holes in the bearings line up with the oil holes in theblock. DO NOT replace camshaft bearings unless theyare bad.16. When all machine operations are complete, the blockshould be thoroughly washed out with solvent. Usebottle brushes of suitable size to clean out all bolt holes,oil passages, etc. Finish off with another thoroughwashing using a good, common detergent and warmwater. Blow or wipe dry and oil to prevent rust. Engineparts can’t be too clean. Many early engine failures canbe traced to dirt or foreign objects (metal chips, etc.)that were left in the engine when it was reassembled.Crankshaft1.2.3.4.5.6.Check crankshaft end play (refer to Crankshaft EndPlay, ‘Crankshaft’ section of this chapter).Crankshaft bearing journals should be checked forspecified diameter and clearance. If it is a hardenedcrankshaft, it shouldn’t be ground for clearance. Thesecrankshafts are hard only to a depth of .0003”. The mainbearing clearances should also be checked. The best wayto measure crankshaft journals is with a micrometer.Main bearing clearances can be measured directly or byusing Plastigauge. The main bearing clearances shouldbe 0.03-0.06 mm (0.001 -0.0025”). For completeprocedure, refer to Measuring Main BearingClearances, ‘Crankshaft’ section of this chapter.The bearing journals may be polished by hand, firstwith #400 and then with #600 paper. Any nicks, burrsor scratches should be polished out. Chamfer oil holesin journals and use a wet stone to break edges. Checkthe oil passages to each journal.Caution: With nodular cast iron crankshafts, it isimportant that the final paper or cloth polish after anyjournal regrind be in the same direction as normalrotation in the engine.Before assembly, make sure crankshaft, includinginternal oil passages, is clean. Also be sure all oilingpassages are drilled through.When assembling the crankshaft into the block, oil thebearings and journals.When installing the crankshaft, locate the main capscarefully so that the crankshaft spins freely, and torque allcaps to specification. Then spin the crankshaft by handthrough several revolutions before installing the rear mainseal. It should be fairly free, requiring very little effort.Remove the caps and check for any burrs. If present, theycan be removed by gently scraping with a bearing knife.When installing the rear main seal, make sure it is properlyseated improper seating can cause the crankshaft to bind.-~

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 2597. For better race engine oiling with a high capacity oilpump, 360” main bearing oiling is desired. 360” fullygrooved main bearing sets should be used. It is NOTrecommended that the crankshaft itself be groovedbecause grooves weaken the crankshaft.8.A degreed damper is a must for racers since they mustset their timing by total degrees advanced at a fairlyhigh rpm (for example, 35” total at 2,500 rpm). Adegreed damper is the easiest, most accurate, and mostconvenient tool for doing this. It also aids in setting thevalve lash by giving 90” reference marks.Note: Damper degree timing tape is P4529070.Measuring Main Bearing and Connecting RodBearing Clearances(Refer to ‘Crankshaft’ and ‘Connecting Rods’ sections ofthis chapter for detailed instructions.)Cylinder Head1.2.3.4.5.6.7.8.The cylinder head should be “cc’d’ and the volumescompared to specifications. Any milling that isrequired should be done, and the chamber volumesrechecked.The cylinder head should be checked for squarenessand for any cracks or flaws. The valve guides shouldalso be checked for wear and replaced if necessary.The cylinder head should have a valve job done if theseat runout does not meet specifications: 0.064 mm(0.0025”). Refer to ‘Camshaft and Valve Gear’ and‘Cylinder Head’ sections of this chapter for moreinformation.The cylinder head should be installed on the blockwithout the head gasket to check dowel pin height.Dowel pins should NOT hold the cylinder head up offthe block surface; they should only locate it over thecylinder bores.When high lift camshafts are installed in productionbasedengines, the keepers may hit the valve guide. Thisshould be checked at the cam’s maximum lift. The guideshould be shortened to give .100“ clearance between thetop of the guide and the bottom of the keepers.When dual valve springs are used, the inner spring seatmay have to be cut down flush with the outer spring seat.With the crankshaft, pistons, and connecting rodsremoved, check the alignment of the combustionchamber over the cylinder bore. If it needs to becorrected, use offset dowel pins in the block.The latest tech trend in Stock and Super Stock racing isto “cc” the ports-both intake and exhaust. This isn’t atechnique to increase performance; rather, it’s ameasurement technique used by the NHRA and IHRAat the tech barn. They have a cc number for the portvolume and your cylinder head will be checked againstthat number. Refer to the ‘Cylinder Head’ section ofthis chapter for complete information.Connecting RodsNote: The following information is for the preparation ofsteel connecting rods only.I. Connecting rods should be checked for alignment; boresshould be parallel. Check big and small ends for size.2. Using a small file, deburr the connecting rods, payingparticular attention to the mating surfaces and tabgroove. You need the clamping effect of a 60 microbore. The sides should be polished by hand on a flatplate using #600 paper. Proper side clearance should be0.25-0.48 mm (0.010-0.019”). DO NOT increase sideclearance past .019” as this increases the oil demand ofthe engine. It will also allow too much oil on thecylinder walls which will overload the rings and allowexcess oil in the combustion chambers.3.In an engine that is to be used in a high rpm situation,the connecting rods and connecting rod bolts should beMagna-Glo checked for cracks or forging flaws.4. A race engine should always use heavy dutyconnecting rod bolts and nuts.5.6.7.8.9.The connecting rod bearing clearance is 0.25-0.76 mm(0.001-0.003”). Preferred bearing clearance is 0.044-0.050 mm (0.0015-0.0020”).The connecting rod bolt head should be seated againstthe flat, machined surface in the connecting rod.For a race engine, the big end of the connecting rodshould be sized to the minimum diameter to get themaximum crush from the bearing.Shot-peening the rods is recommended if they haven’tbeen already.Some race engines use floating piston pins. On theseengines, the pin-to-connecting rod clearance shouldbe checked. On standard production engines that usea pressed pin, the amount of interference should bechecked. (Refer to 4.0L Engine Specifications, inthis section.)10. Connecting rods with full floating pins to be used inracing applications should have the small end of theconnecting rod drilled with a small hole(approximately 3/32”) for increased piston pin oiling.The best location for this oiling hole is the top of theconnecting rod above the pin (Figure 4-11). Pin oilingholes in the sides (5 o’clock or 7 o’clock, for example)weaken the connecting rod itself and therefore areNOT recommended. One hole in the top does the bestjob of oiling the pin and maintaining the connectingrod’s strength...- ‘IT1-

260 MOPAR PERFORMANCE PARTSPistons and Rings1.2.3.4.5.6.7.8.9.10.Check ring grooves for burrs, then for proper sideclearance.Check ring end gap against specification. DO NOT inany case exceed specifications as this will allow toomuch blow-by, causing power loss and/or allowing toomuch oil to reach the combustion chamber which cancause detonation. The ring gap ends must be squareand parallel.Use a fine stone to deburr rings and to just barely breakedges on end gaps. Break the edges using #600 paper,but DO NOT chamfer.Pistons and Piston Rings - General Selection (refer to‘Pistons and Rings’ section of this chapter forselection information).Production pistons will perform well with standardproduction clearance. Solid skirt, racing-type pistonswill need more clearance (check with the manufacturerof the pistons you are using). This clearance ismeasured just below the oil ring and perpendicular tothe pin centerline.Production pistons are designed with an offset pin tokeep piston slap to a minimum. Internal friction can bereduced by reversing this offset. On flat top pistons itis only necessary to reverse the piston on theconnecting rod to accomplish this. The location notchor groove on the top of the pistons should be pointingtoward the rear of the engine when you finish.Pistons should be clearance checked in the bores thatthey will be run in. Also, piston ring end gaps shouldbe checked in the cylinders that they will be in.With either flat or domed pistons there will most likelybe valve notches or reliefs cut to provide sufficientvalve clearance. The edges of these notches as well asother edges on the tops of the pistons should be sandedlightly with #400 paper so they are not sharp.High lift camshafts will require the pistons to benotched or the existing notches to be deepened.High compression pistons have a large dome that sticksinto the combustion chamber. In some cases this domewill strike the spark plug and close it up. Therefore, theend of the plug should be given 1/4” clearance in theshape of a spherical cup. This will also aid in flamepropagation because the plug will be less shrouded.Seal and CoverWith the engine parts preparation completed, parts shouldbe sealed in paper and then covered with a plastic bag. Thecarburetor/throttle body flange, exhaust ports, etc., shouldbe taped over until the engine is installed and thesecomponents are actually bolted on.SUB-ASSEMBLY OF BASIC GROUPSWith the individual pieces of the engine prepared, we cannow proceed to put together larger assemblies, such as theshort block and cylinder head assemblies. Also, beforestarting work in this area, certain basic engine decisionsshould be made such as engine compression ratio andcamshaft design and specifications. With these decisionsmade, there are some specific procedures that you shouldbe familiar with when you are assembling the individualpieces. These procedures will be discussed separately in thefollowing sections before going on to the final engineassembly.The most important areas in the performance andhorsepower output of any engine are as follows. Straightand round cylinder bores are the most important with theirrelated area of sealing the ring to the cylinder wall and thepiston. The valve work (valve job) is also very important toall engines. Cylinder head ports are important to highoutput engines. Lightweight rotating engine pieces willhelp the performance of all engines as long as their use isnot at the expense of durability. Having a good valveassembly that works well together to do the required job isoften overlooked, but is very important in engineperformance. (For more information on valve traingeometry, refer to ‘Camshaft and Valve Gear’ section ofthis chapter.)Preliminary AssemblyIt is recommended at this point that a preliminary assemblyof the short block be made and various measurementstaken. This preliminary assembly should consist ofinstalling the main bearings, crankshaft, and piston andconnecting rod assemblies (no rings required).After this preliminary assembly has been made, measurethe actual deck height, dome height (if a domed piston isused) or depth of the “dish’ (if a dished piston is used), andgasket thickness. With this information, you can thende1.ermine your initial compression ratio.

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 261Cylinder Head and Intake ManifoldWith the short block ready to be assembled, the cylinderhead and intake manifold can be checked in the preliminarystages of assembly.The intake manifold should be checked for port alignment.The intake manifold’s angle should be the same as thecylinder head and it should fit such that with the gasketinstalled the intake manifold bolt holes line up.For more intake manifold information, refer to ‘InductionSystem’ section of this chapter.Camshaft and Valve GearChoosing the camshaft is the last of the three major enginebuilding decisions (the three being carburetion,compression ratio, and cumshaf), and it is easier to makeonce the other two decisions have been finalized. Thecamshaft directly affects the pistons, block, head, andcomplete valve gear, so it should not be taken lightly.Camshaft choice is often difficult because of the vastnumber of options available. However, once carburetionand compression ratio decisions are made (along with whatthe engine is going to be used for), the total number ofchoices will be narrowed down to a handful or less, whichis a lot easier to select from than hundreds.With head, valves, and springs initially assembled, the headassembly can be bolted to the block and preliminary checkson camshaft and valve gear can be made.1. General Camshaft SelectionThere are literally thousands of camshaft designs tochoose from. Picking the correct one for you and yourengine without spending too much money is a verytough job. Selecting the type of camshaft (hydraulic,mechanical, roller) is usually the hardest job. MoparPerformance Parts has specific recommendations forvarious engines. However, you must still decide on thetype that best suits your application. Once you havedecided to go hydraulic, solid, or roller, MoparPerformance Parts can make recommends that willwork best in your application. The easiest way toidentify the type of camshaft is by lift. Each categoryhas a lift range in which it works best. For completeinformation and performance applicationrecommendations, refer to ‘Camshaft and Valve Gear’section of this chapter.2. Valves and Valve Springsa. Valves should be measured (to be sure they are theproper size) and inspected for flaws or otherdamage. Measure the actual outside diameter ofthe valves to be used and record the measurement.b. Valve springs should be load checked. Weaksprings will have to be replaced. Record loads andheight checked at. The biggest advantage of loadchecking is to see if the springs have “gone away”or to see if a second set of the same spring is as“strong” as the first which worked well.c.d.e.Note: Not all spring testers are the same. Manyare not maintained and calibrated on a frequentbasis. This makes the absolute value of springloads quite unreliable. However it is a very goodcomparative tool; that is, measuring all springs onthe same tester or measuring the same spring newand used.With the valves, keepers, and retainers installed,check the valve spring height. This should becompared to the spring load information (#2b) andthe correct thickness shim chosen to get the sameinstalled spring load on each valve. Valve springinstalled height must be carefully controlled toavoid “coil bind” by providing at least .loo“ moreheight at maximum valve lift than the solid heightof the spring.Caution: DO NOT check solid height with aspring that you intend to use in the engine.Compressing a valve spring to solid height willoverstress it and cause premature load loss orspring breakage.With the same spring height setup as #2c, measurethe outer valve spring height, the inner valvespring height, and the keeper-to-valve guideclearance. The camshaft lift (lift of the camshaftmeasured at the lobe or lifter) multiplied by therocker arm ratio plus .050” should be less than thekeeper-to-guide clearance in the valve closedposition or the guide will have to be shortened.Measure the “solid height” of both the inner andouter springs. This solid height plus .loo“ plus thevalve lift (camshaft lift multiplied by the rockerarm ratio) should be equal to or less than theinstalled height for each spring.The valve spring installed height can be increasedwithout installing longer valves. Usually, specialretainers are used to do this. The increasedinstalled height stresses the spring less so that itlasts longer. It also allows for higher lift camshaftswith the same basic parts.Note: DO NOT sink the valve or machine theouter spring seat down into the head to increasethe installed height. This would result in decreasedperformance.

262 MOPAR PERFORMANCE PARTSd. Check the pushrod-to-block clearance with highlift camshafts or large diameter pushrods.4.5.Additional clearance can be obtained by using asmall electric or air grinder, a drill motor with arotary file, or a rat-tail file. Grind to yourindividual need.Pushrod LengthTo optimize rocker arm geometry, a cut-to-lengthpushrod kit is recommended, but only to the veryserious racer or for engines with large amounts of headmilling and block decking. Custom length pushrods areused to obtain ideal rocker arm geometry which allowsthe best performance from a given camshaft.For additional information, refer to Pushrods,‘Camshaft and Valve Gear’ section of this chapter.Additional Camshaft Installation Performance TipsWhen installing a new camshaft, there are several itemsbesides the camshaft that should be replaced. First,you’re probably going to replace the valve springs toget the most out of the new camshaft. It’s always a goodidea at this point to install new valve seals.While the camshaft is out, it’s recommended that thestandard silent chain be replaced with a roller timingchain and sprocket set. Refer to ‘Crankshaft’ section ofthis chapter for more information.The 4.0L engine needs offset bushings to centerlinecamshafts (P3 6909 3 6).When centerlining the camshaft, we recommend usinga degree wheel. Once the engine is put back together,you should use damper degree timing tape (P4529070).Refer to ‘Camshaft and Valve Gear’ section of thischapter for complete camshaft centerlining information.Notes Before Final Assembly3. Rocker Arms and Pushrodsa. Check rocker arm-to-valve tip relationship foralignment. Improper alignment can place undueside loads on valves, causing rapid valve guidewear. Rocker shaft spacers or grinding the rockercan be used to move the rocker arm up or down theshaft to align it on the valve tip.b.c.Check valve tips for scuffing or high wear.Check pushrods for straightness and length. If theyare too short, they can’t be adjusted to workproperly. If they are too long, they will over-anglethe rocker arm and, with high lift camshafts, hitthe bottom of the rocker.1. Make sure all parts have been cleaned, and are kept asclean as possible.2.3.Observe factory torque specifications for all fasteners,and also factory specified tightening sequences forcylinder head and intake manifold bolts to reduce thepossibility of cylinder head or intake manifold warpage.The engine should be assembled using oil, gasketsealer, white grease, etc., on the appropriate points.FINAL ASSEMBLYNow that we’ve gathered all our parts, the next step is toclean everything, especially the used parts that are going tobe reused. Clean them before they go to the machine shop,unless you’re going to pay extra to “tank” them. A machineshop will do a better job with clean parts than with greasyparts. You don’t have to polish them-just degrease them...

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 263Earlier we said we were going to rebuild our engine. This isactually a common misnomer. It would be more correct tosay that we are going to assemble the engine or, in ourspecific case, reassemble. There are certain operations thatwe can’t do. For these special operations, we have to selecta machine shop. Typically these operations are:1. Bore block2.Hone block with honing plate3. Valve job:4.5.- Grind valves- Grind seats in head- Install valve seats, if requiredDeck cylinder head andor blockInstall bronzewall guides, if required6. Rebuild connecting rods7. BalancingOnce all these parts come back from the machine shop, weget to do our thing-assemble the engine-slowly, veryslowly! The first step is to clean everything AGAIN-newparts, old parts, and machined parts. When completed, drythoroughly and wipe or spray light oil onto the parts to keepthem from rusting, then cover or wrap in newspaper untilactual assembly time. All the measurements, clearances andfine tuning prep have to be done prior to final assembly. Thisusually requires parts of the engine to be sub-assembledtwo, three, or four times before final assembly. At this point,we’ll assume all this preparation has been done.To put the complete engine together we should consider threesub-assemblies that should be put together separately. Becauseof this, they may also be assembled at different times. They are:1.Connecting rod and piston assembly2. Cylinder head assembly3. Rocker shaft assemblyOur final assembly steps are:1.2.3.4.5.6.7.8.Block on to engine standMain bearings added to blockCrankshaft installed and mains torquedConnecting rods attached to pistons:- Pressed pin (machine shop)- Floating pin (add snap rings)Rings added to piston and connecting rod assembliesConnecting rod bearings added to connecting rodsConnecting rod and piston assemblies inserted into blockCamshaft installed9. Timing chain and sprockets added10. Tappets inserted11. Cylinder head assembly:- Valves inserted- Valve seals added- Springs installed- Retainers added- Keepers installed12. Head gasket added13. Cylinder head installed14. Head bolts torqued (in proper sequence)15. Rocker shaft assemblies:- Rocker arms added in order- Rocker bolts inserted- Oiling holes checked for alignment16. Rocker shaft assemblies installed17. Pushrods installed18. Rocker shafts torqued down19. Camshaft centerline checked20. Intake and exhaust manifolds installed21. Intake and exhaust manifold bolts torqued (inproper sequence)22. Distributor installed23. Valve covers, oil pan, timing covers added, as required24. All open holes, such as carburetor/throttle body pad andexhaust ports, taped in preparation for paint or installation25. Old spark plugs installed26. Engine stored, painted, or installed27. After installation, old plugs swapped for new plugs andsealing tape removed28. Engine dress-up completed -plug wires, hoses,headers, etc.29. Before actual engine start-up, refer to Engine Start-up,later in this sectionAnd you thought this was going to be easy! Take your timeand it’s not so bad. If you can work on the engine full-time,allow one month. If you do the work part-time, allow twomonths or more. This doesn’t include machine shop or partsgathering time. Be careful and don’t hurry. You’ll besuccessful. There’s a lot of pride in the successfulcompletion of an engine building project.*.

264 MOPAR PERFORMANCE PARTSCamshaft into Block1.2.3.4.5.Before installation, the camshaft and tappets should beliberally coated with Mopar Engine Oil Supplement.This lubricant will stick to the surfaces withoutdraining off and will prevent scuffing when the engineis fired up for the first time. It has been determined thatthis is when the most camshaft damage takes place.When installing the camshaft sprocket, use at leastGrade 8 bolts, along with Loctite and safety wire. It ispossible for high speed engine harmonics to causethese bolts to loosen if precautions aren’t taken.Because of production tolerances, it is possible for thecrankshaft-to-camshaft relation to be several degreesoff, either advanced or retarded. It is important that thistiming be correct to produce maximum performance.While the engine is still without the head, the timingmarks on the crankshaft damper and the timing chaincover should be checked for accuracy of the “0’ TDCmark.Advancing or retarding a camshaft should only be doneto install the camshaft at its designed centerline. It isvery important to have the centerline correct. Mostcamshafts will have the design centerline stated as partof the specifications along with duration and lift. If itisn’t given, it can be calculated (refer to ‘Camshaft andValve Gear’ section of this chapter). Advancing orretarding a camshaft from its designed centerline is notrecommended because it will reduce the overallefficiency of the engine.Cylinder Head onto BlockWhen the block was honed using a honing plate, a certaincylinder head bolt thread engagement depth was used for eachbolt. It is important that the cylinder head be attached usingthe same thread engagement depth as the honing plate did.With the block ready to be assembled, the cylinder head andintake and exhaust manifolds can be checked in thepreliminary stages of assembly.Use the correct torque sequence when installing head bolts(refer to Installation, ‘Cylinder Head’ section of thischapter for complete procedure). Be sure to torque the boltsa second time after you’ve run the engine.Valve Gear onto EngineWith the camshaft in the block and the head installed, theactual valve lift measured at the valve retainer can bechecked. The camshaft lift multiplied by the design rockerarm ratio should yield the valve lift. However, this is not thecase in an actual engine. The actual rocker arm ratio will beless than the design rocker ratio which is typically 1.5 forwedge engines. This will cause the valve lift to be less thanthe number that is calculated. This is due to the rocker armratio itself plus the effect of the geometry of the head.“Blueprinted” mechanical rocker arms (those with an exactdesign ratio) are available for most engines from varioushigh performance machine shops.Intake ManifoldThe intake manifold should be checked for port alignment.The intake manifold’s angle should be the same as thecylinder head and it should fit such that with the gasketinstalled the intake manifold bolt holes line up.The intake manifold attaching holes in some cylinder headsare shallow. Check to be sure the manifold screws areproperly torqued and that the manifold is actuallycompressing the gaskets. If the holes are shallow, a rathersevere oil leak may result.Carburetion System (if equipped)The carburetion system directly affects the cylinder head,but only to a minor degree. All the same, the carburetionsystem is rated as the number two engine building decisionbecause of its indirect effect on camshaft selection. In manycastzs, the carburetion system is determined by the rules ofthe governing body that runs the race track. Without that toguide us, a single 3-barrel is preferred because of itssimplicity.Oiling SystemRefer to ‘Oiling System’ section of this chapter for detailedinformation and parts listing.Accessory DrivesA typical drag race vehicle has a very limited accessorydrive at the front of the engine. It may consist totally of onedry sump pulley and belt. This is very simple and has neverbeen known to cause any problems except for those whoforget to charge their batteries between runs! However,othler types of race vehicles typically have a water pumpdrive, an alternator drive, a power steering pump drive,and/or a dry sump drive. If you take the “stack it on thefront and use a longer bolt” approach, you could have someproblems, especially during long, high speed races. You’dlike to keep the drives as close to the front of the engine asyou can. However, you can’t take the drag racing approacheither. If you use the water pump drive to drive thealternator, you can save one separate drive. The powersteering can be driven off the water pump so that it doesn’tload the crankshaft and push the bolt out further. Thissirnple approach can take several inches off the bolt length.Valve ClearancesPrloper valve clearances are very important to prevent bentor broken valves. Valve clearances to be checked includevalve-to-valve, valve-to-piston, valve tip-to-rocker arm tip,and valve-to-block. For complete information, refer to‘Camshaft and Valve Gear’ section of this chapter.

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 265Boring and Milling SpecificationsFor information, refer to ‘Block’ section of this chapter.Engine PaintThe completed engine is now ready to be painted. Seal offthe open holes and machined surfaces such ascarburetor/throttle body flanges and exhaust port openings.Tape over or cover all items that you don’t want painted,such as chrome valve covers. Nine colors are availablefrom Mopar Performance Parts.Seal and CoverWhen the engine assembly is completed it should be sealedwith duct tape (covering exhaust ports, etc.) and then coveredwith a plastic bag. The carburetor/throttle body flange,exhaust ports, etc., should be taped over until the engine isinstalled and these accessories are actually bolted on.Engine Enamel Spray PaintBlack (P4120753)Race Hemi Orange (P4120751)Street Hemi Orange (P4349216)Turquoise (P4120752)Red (P4349218)Blue (P4349217)Yellow (P4529144)Aluminum Silver (P4529148)Gold Metallic (P4529149)All 2.2L engines since 198 I, and 3 18 and 360 engines since 1983, have been painted black.A bright orange color used on cars equipped with Max Wedge engines (413 and 426Wcross-ram) during 1962-64. Also used on 426 Race Hemis built in 1964-65.A red-orange color used on 426 Street Hemis built in 1966-7 1. Commonly referred to as“Hemi Orange.” 1969-71 high performance 383 and 440 engines and 1970-71, 340 ‘A’engines were also painted this color.This medium blue-green color was used on all ‘B-RB’ big block engines during 1962-7 1(with the exception of 1969-71 high performance 383 and 440 engines-they were paintedStreet Hemi Orange).This bright red color was used on all 273 ‘A’ engines from 1964-69. Also, 1968-69, 340engines and most mid-1960s 318 ‘A’ engines were finished in this color.This medium blue color was used on all production engines from 1972-83 with theexception of the 2.2L engine. Most 318 ‘A’ engines built from the late 1960s through 1972were painted this color.Used on many early 1960s Slant Six engines, including trucks.This color was used as far back as the 1940s and as late as the early 1960s. Most of theearly 300 series Hemis and 1950s engines were painted this color.The “Golden Lion” engines of the late 1950s and early 1960s as well as the “GoldenCommando” and DeSoto “Adventurer” engines used the color.

l- --TI a266 MOPAR PERFORMANCE PARTSEngine Building ChecklistDo you own and have youstudied the service manual foryour engine?Did you read this chaptercompletely?Did you select your parts basedon Mopar Performance Partsrecommendations?Did you take your time andcarefully check everything?Did you clean the parts aftereach operation?Did you check all the variousclearances?Did you re-check all torques?Do you know your exactcompression ratio?Did you record all measuremer..;and parts used?How many "tricks" were added tothe engine? (Put number in "NO"column .)Did you select your camshaft forits intended use?Was the octane of the gasavailable considered with thecompression ratio?Did you use oil, gasket sealer,white lithium grease, etc., duringassembly?- YES - NODo you know your exactcamshaft centerline (asinstalled)?Did your cylinder bores measureround and straight?Did you use a dial-bore gauge tomeasure the cylinder bores?Did you measure the camshaftlift at the valves (intake andexhaust)?Did you check the connectingrod bolts for the head flush withthe spot-face?Did you check TDC on thedamper after assembly?Was the engine builder presentat engine start-up?Was the piston pin clearance orpress checked?Was the valve job done by aprofessional?

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 267Engine Start-upWith the new engine built-up and installed in the racevehicle, you’re ready to start the engine for the first time.This sounds simple enough but should not be taken lightly.The first step is to be sure that there’s oil in the pan. Neverassume that someone else did it. Check it yourself! Next isto add water. Check for leaks before starting. Double checkthe firing order, plug wires and basic timing.In addition to these items, make sure that:1. The oil pump and oiling system are supplying oilpressure. After installing a mechanical oil pressuregauge (only if your vehicle is not already equippedwith an oil pressure gauge), remove all the spark plugsin order to relieve the compression in the cylinders andto prevent the engine from starting. The engine shouldbe turned over with the starter motor until the oilpressure gauge shows a reading of over 10 psi.2.3.4.5.Once you have determined that the engine does haveoil pressure, the spark plugs may be reinstalled and theengine may be started. When the engine starts, thegauge should show a minimum reading of 89.6 Wa (13psi) at 600 rpm (idle speed).The fuel pump(s) is supplying fuel to the engine, andthere are no fuel leaks at the various fittings.The throttle linkage operates freely.The ignition timing is set properly (conservatively forbreak-in).The tach and engine shutoff (on manual transmissions)is functioning properly.TRACK TESTING“Track testing” can be critical to the maximum efficiency ofthe overall vehicle. These tests are grouped into three areas:garage, the race track itself, and pits. Obviously the title“track” is slightly misleading. The term “track” implies thatthe race vehicle is completed and ready-to-go, which isrequired for these tests. So in this sense, “track” is more acondition than a location.Before TestingBefore any test is run, certain preparations have to be madeor the test may fail. You should always test specific things,preferably one at a time.Be sure that you have read this chapter completely. Takethis book as well as the appropriate service manual withyou to the test.PreparationMake sure that the enginehehicle is fully prepped beforegoing to the test. Engine full of oil, coolant, etc. Vehicle fullof gas. Test the brakes, steering, transmission shifters, etc.Also write down exactly what you’re going to test and inwhich order.Pack all the spare parts (gaskets, sealers, etc.) that may berequired in portable containers such as the MoparPerformance parts tote (P4529181). Mark each tote withwhat’s inside. Always take extra bearings, pushrods, rockerarms, valve springs, retainers and keepers. Take all yourextra ignition pieces (especially plugs and wires) and (ifequipped) carburetor parts (especially jets).Be sure that the “test parts” fit before going to the track.Generally on a seasoned race vehicle, the vehicle is taken tothe track with the new parts installed. Then you canbaseline the new parts and switch to the old parts withoutproblems because they’ve been on the vehicle already.Also, separate plug wires using P4007667 kit. Shield nonplugwires with convolute tubing for protection andneatness. Choose size by the size and number of wiresbeing covered.~Parts ToteParts and tool storage can be a real hassle when you goracing or even at home in the garage. This handy parts toteis designed to hold your tools and parts neatly and safely.Made of durable impact resistant plastic that will stand upto a rugged treatment. Stackable so you can maximizespace. Molded in blue. 21-1/8” x 15-1/4” x 12-3/4”.P4529 18 1Parts tote.Self-Locking Cable Tie PackageKeep your engine compartment neat and free of loosewires with these handy, self-locking nylon cable ties.Available in ladder or solid locking design. Just looparound loose wires, tighten, and cable locks in placeautomatically. Ten each of the following lengths and stylesare included: 8” and 5- 1/2“ solid design; 11” and 7” ladderdesign.P4286521Self-locking cable tie package.~Screw-On Cable Tie PackageScrew-on cable ties have a built in grommet for screw orbolt attachment to firewall, fenderwall, etc. Screws andbolts not included. Sold five per package. 12-1/2” length.P4286522Screw-on cable tie package.*. T 7 n

~268 MOPAR PERFORMANCE PARTSConvolute Tubing PackagesHere’s the best way to protect loose wires, cables andvacuum hoses. Convolute tubing is specially designedarmor for protection against heat and corrosive substances.Made of black polyurethane that’s ribbed for curving intight areas and slit for easy installation over existingwiring harnesses. Keeps wires out of the way and makes avery neat underhood appearance. Each package includes25 feet of material which can be cut to length. Select fromfour popular diameters.P4286576* 1/4“ convolute tubing.P42865777/16“ convolute tubing.P4286578” 5/8” convolute tubing.P4286579 1” convolute tubing.* Package includes 24 retaining clips.ENGINE SPECIFICATIONSBefore you run any engine test (track or shop), you shouldknow and have written down the following information:Camshaft Centerline . .....................Valve Spring Installed Height:Valve-to-Piston Clearance:___Intake _______ Exhaust ________Total Spark Advance ......................TDC on Damper Checked __________________Optional items to this list are cylinder head cc’s and deckheight. This information should be based on actualmeasurements and written down as the actual number,not “stock.”At the TrackWhen taking the vehicle to the race track. the “trick” is forthe driver-mechanic to get the most out of the package thathe is testing. You learn nothing if something is wrong withone or several of the parts.Once the vehicle is at the track and unloaded, warm up theengine. Check all the fluids. Check engine for leaks. Besure all the gauges work. If it is a new engine, break it ineasy-don’t hurry. Fill the gas tank and check plug wires.Be sure that the vehicle goes straight - tire pressures equal,etc. Always use helmets and seatbelts during test.BASIC TUNE-UP AND TROUBLESHOOTINGBasic Tuning1.2.3.4.5.6.7.Test battery specific gravity; add water if necessary.Clean and tighten battery connections.Test cranking amperage draw. See Starting MotorCranking Amperage Draw, ‘Electrical System’ sectionof the service manual.Tighten intake and exhaust manifold bolts in propersequence to specification.Perform cylinder compression test:a.b.C.d.e.f.g.Warm up engine, if possible, to normal operatingtemperature. If not possible, perform cold.Remove all spark plugs from engine. As sparkplugs are being removed, check electrodes forabnormal firing indicators - fouled, hot, oil, etc.Record cylinder number of problem spark plug forfuture reference.Disconnect coil wire from distributor and secure togood ground to prevent a spark from starting a fire.If equipped with a carburetor, be sure choke andthrottle blades are fully open during thecompression check.Insert compression gauge adapter into the No. 1spark plug hole in cylinder head. Crank engineuntil maximum pressure is reached on gauge.Record this pressure as No. 1 cylinder pressure.Repeat step e for all remaining cylinders.Compression should not vary much from cylinderto cylinder. Refer to engine specifications.The recommended compression pressures are tobe used only as a guide when diagnosing engineproblems. An engine should not be disassembledto determine the cause of low compression unlesssome malfunction is present.Clean or replace spark plugs as necessary and adjustgap as specified. Tighten to specifications.Test resistance of spark plug cables. Refer to ‘ElectricalSystem’ section of your service manual for procedure.Inspect the primary ignition wire and vacuum advanceoperation (if equipped). Test coil output voltage, primaryand secondary resistance. Replace parts as necessary.Refer to ‘Ignition System’ section of your service manualfor procedure and make necessary adjustment...

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 2698. Reset ignition timing with vacuum advance linedisconnected. Ignition timing should be set tospecifications. Performance applications should settotal spark advance with vacuum disconnected.9. Set carburetor idle mixture adjustment (ifequipped). Adjust throttle stop screw tospecifications. Bigger camshafts require more idlefuel. Bigger jets may be required.10. Test fuel pump for pressure and vacuum.11. Air filter element should be replaced as specified in‘Lubrication and Maintenance’ section of your servicemanual. Replace more often when vehicle is driven industy or sandy areas.12. Inspect crankcase ventilation system as outlined in‘Lubrication and Maintenance’ section of yourservice manual.13. Inspect and adjust accessory drive belts.14. Road test vehicle as a final test.Basic TroubleshootingThe first step in troubleshooting is to define your problem.What does it do, when does it do it, etc? If it comes and goesor if it changes, then it can be very difficult to solve.Surprisingly, many of these apparently tough problems aresolved by simply going back to the basics. We’ll stick to thebasics because of our space limitations and let the “pros” whohave on-the-scene access to the vehicle work on the others.If a loss of performance is noticed while running theengine, ignition timing should be checked. If ignitiontiming is retarded about 16”, camshaft and accessory shafttiming with the crankshaft should be checked. The timingchain may have “jumped” a tooth. This is a nice way ofsaying check the camshaft centerline!We’d also suggest, at this point, to check TDC using theMopar Performance Parts positive stop TDC indicator tool(P4349737) and compare with the marks on the damperbeing used.Check fuel delivery system (electric pumps, etc.). Checkthe carburetor for wide open throttle and other functionsalong with vacuum leaks from hoses in the area. Also checkplug wires and wire ends.Next, run through the steps of the basic tune-up andcompare readings to initial ones. If you have no initialreadings, it is much more difficult to find a problem easily.You may want the engine leak tested to get better data.PERFORMANCE TROUBLESHOOTINGUnlike basic troubleshooting, in performance troubleshootingthere really isn’t anything “wrong.” The engine just isn’trunning as fast as it should be. Obviously, if there issomething wrong, it will make the vehicle go slow. But this isperformance troubleshooting. We are only going to concernourselves in this short discussion with the problems of usingthe wrong parts, using the right parts in the wrongapplications, or mixing the right parts for one application withthe right parts from a different application and ending up withthe wrong package. To illustrate this last point, assume thatyou install a high lift hydraulic camshaft in your standardproduction engine and use the stock valve springs. It isn’tgoing to work properl-no spring load, spring likely to gosolid, break, etc. There’s nothing wrong with the camshaft orthe springs, they just aren’t going to work together.In performance troubleshooting, the first step in finding anyproblem is to read as much about it as you can so that youbetter know what to expect. Note that defining yourproblem isn’t the first step.Refer to ‘Camshaft and Valve Gear’ section of this chapterfor camshaft and valve gear performance tips. These tipsare particularly good for finding which spring to use withvarious camshafts, and which camshaft to use for variousapplications. For many years Mopar Performance Parts hasput together parts packages for racing at variousperformance levels. These packages appear in Chapter 8,Off-Roading and Racing. All the parts needed to achieveeach level are listed by part number as they apply.Unfortunately, not all racers seem able to reach theperformance level listed when they use the parts. Then, ofcourse, the vehicle, engine, or Mopar Performance Parts isblamed. Troubleshooting race vehicles can be very difficultand, in many cases, an expert is required on the spot. Who’sthe “expert” going to be? Well, if you want to solve yourproblem without spending a lot of money and in areasonable amount of time, you’ll use this book.YEAR-END CHECKSAt the end of the race year there are several things that youshould check. Some items can change and should bechecked on all engines, while other items don’t reallychange but need to be known exactly. Any of the followingitems that you don’t know specifically, be sure to find outbefore you put the race vehicle into storage.The list is as follows: exact TDC, total timing as run (novacuum), as-installed camshaft centerline, finish line rpmas-raced, electric fuel pump delivery rate, as-raced batteryvoltage, torque converter stall speed, weight distribution.Each one should be recorded on your enginelvehicle logsheet for future reference.

270 MOPAR PERFORMANCE PARTSTDC CheckAs you approach the end of the racing season, youhopefully have a completed, running engine. It may havebeen running for one year or carried over for the last yearor two. In any case, you’ll be putting it away shortly. Sincethe engine is probably running well, you wouldn’t likelycheck much on the engine. However, because it is runningcorrectly, this is the best time to check things out.One of the things to check is the TDC mark. This isparticularly critical if the damper has been off the engine orreplaced. Most people don’t check TDC on a race-readyengine because the cylinder head is on. Mopar PerformanceParts positive stop TDC indicator tool (P4349737) isdesigned to check TDC with the head in place. Althoughusing a degree wheel is best, we’ll just use masking tapebecause it’s simple and cheap.Install masking tape (about one inch wide) on the damperwith at least three inches of tape on either side of the timingmark. Remove all the spark plugs and install the positivestop TDC indicator tool in the No. 1 spark plug hole withthe piston near the bottom. Rotate the engine clockwise andgently bring the piston up against the stop. On the maskingtape, place a mark directly opposite the “0’ on the timingtab. Then rotate the engine counterclockwise and repeat theprocedure by placing a second mark on the tape. Measurethe distance from the timing mark on the damper to eachmark on the masking tape. The two distances should beexactly the same. If not, re-mark the damper as required anduse timing tape (P4.529070) to line up with the new mark.Lleak CheckingAt the end of the race season, it’s a good idea to check theoverall condition of the engine. This is best done using aleak checking gauge. If the engine was leak tested when it*as built, or last year during the racing season, then thenew numbers can be compared to the old ones for addedinformation. Always use the same leak tester. You can befooled by switching gauges.L.eak checking is a valuable tool that can reveal a great dealabout engine condition, but it doesn’t provide all the answers.To leak test your engine, you’ll need a source of 90-100 psicompressed air, a couple of hoses and a leak tester. All thespark plugs should be removed from the engine. Startingwith the No. 1 cylinder, the piston is brought to TDC on thecompression stroke so that both valves are closed. The sparkplug fitting is screwed into the plug hole and sealed. A quickdiisconnect fitting is usually used to connect the plug fittingto the leak tester. Then compressed air is connected to thetester and the gauge zeroed to give an accurate reading. Thenthe cylinder fitting is connected and the gauge will read thepercent of cylinder leakage.With everything still connected, any severe leakage can bepinpointed by removing the radiator cap, air cleaner, andcrankcase oil filler cap.I. Air escaping through the carburetor or throttle bodyindicates a poorly seated or bent intake valve.2.:3.‘4.Air escaping through the tail pipe or headers indicatesa bad, bent, or burned exhaust valve.Air bubbling into the radiator indicates a leaking orblown head gasket.Air escaping through the oil filler pipe indicates badpiston rings.

- -1-74.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 271Where it is convenient, the exhaust and intake manifoldsmay be removed and the ports taped over with masking tapeto give a better reading on where the air is escaping.BIow-BYBlow-by is a loss of compression pressure and the resultingincrease in oil consumption and smoking. This is very badand should be minimized. It is a good indication that thereis room for improvement in the engine’s output and power.Portable blow-by meters are available.STORAGEIn StorageAt the end of the racing season, it’s time to consider puttingthe engine away. This usually amounts to five or six monthsof storage. This length of storage should not be takenlightly, relative to a precision racing engine. Since theengine is built and maintained with care, it should be storedwith care.To this end, there are several steps that we’d recommend.First, remove all the plugs and add a teaspoon of oil to eachcylinder through the plug hole. Then rotate the engine withthe starter and reinstall the plugs. Drain the water from theradiator and the block. Disconnect both leads from thebattery (it should be charged once a month during itsstorage). Drain the gas out of the carburetor/throttle body(if equipped) and the fuel tank. Next, cover thecarburetor/throttle body and the collector exits (options). Ifthe engine has a S.50“ lift or higher camshaft, then therocker arms or rocker arm and shaft assemblies should beremoved and stored separately. This allows all the springsto sit on the valve seat (closed position) instead of severalbeing open and possibly losing spring load. It also allowsall the valves to be closed, which helps keep moisture(condensation) out of the cylinders. Finally, store theengine (vehicle) in a warm and dry area that is maintainedat room temperature. Second choice would be an area thatis heated and kept above 4.5 degrees (approx.). In colderareas you might consider storing the vehicle on top ofplywood sheets instead of directly above a concrete floor.You can also place a large sheet of Styrofoam insulation onthe floor (below the engine, transmission, and axle areas).We’ll assume that the engine has been in storage for 4 or 5months and is being readied for the upcoming race seasonwithout being rebuilt. It’s also assumed that the engine willbe raced consistently once the season starts. In this case, themajor thing to check is the bearings - both rods and mains.You should also leak test the engine to make sure that oneof the rings didn’t “stick” during the winter. The next itemis to replace the distributor cap and rotor. Chances are theyran all last year without being replaced. It’s also a good ideato replace the oil filter after winter storage. It can be donebefore start-up or after start-up when the oil is changed, butbefore it’s taken to the track. Also, check all the rubberhose? for cracks or hardness (loss of flexibility). Finally,check the spark plug wires, especially the ends. Plug wiresget dirty or corroded, insulation gets cracked and the endsget torn up. If there’s any question, replace the wire. It’llonly cause trouble later on that you may not be able todiagnose properly in the heat of battle.Engine RestartingThe lubrication system should be checked to ensure that itis supplying pressure to the bearings before any attempt ismade to start the engine. If the engine is run, even for a fewseconds, without oil pressure, there will be extensivedamage done to the engine.After installing a mechanical oil pressure gauge, all thespark plugs should be removed in order to relieve thecompression in the cylinders and to prevent the engine fromstarting. The engine should be turned over with the startermotor until the oil pressure gauge shows a reading of atleast 6 psi.Once you have determined that the engine does have oilpressure, the spark plugs may be reinstalled and the enginemay be started. When the engine starts, the gauge shouldshow a minimum reading of 13 psi at curb idle (600 rpm),and 37-7.5 psi at 1,600+ rpm.Out of StorageWhen bringing your race vehiclehace engine out of storagein preparation for the racing season, it is time to considerrebuilding the engine, reworking the chassis to installbigger tires, improving weight distribution, and otherperformance changes. These are basically major projects.There are many minor items that are often overlooked.Even though they may be “minor” relative to rebuilding thevehicle or engine, their negative effects on performance canbe very high!

272 MOPAR PERFORMANCE PARTS1989, 4.0L ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1989 Jeep Cherokee Service Manual.CamshaftTappet Clearance ..........................End Ploy. ..............................Zero Lash (Hydraulic tappets)Zero (engine operating)Bearing Clearance .........................0.025-0.076 mm 0.001 -0.003 in.Bearing Journal DiameterNo. 1No. 2No. 3No. 4Base Circle Runout ....................Cam Lobe Lift. ...........................Valve Lift. . .............................Intake Valve TimingOpens ...............................Closes ...............................Exhaust Valve TimingOpens ...............................Closes ...............................Valve Overlap .........................Intake Duration ...........................Exhaust Duration ..........................51.54-51.56 rnm 2.029-2.030 in.51.28-51 31 mm 2.019-2.020 in.51 .03-51 .05 mm 2.009-2.010 in.50.78-50.80 mm 1.999-2.000 in.0.03 mm (max) 0.001 in. (max)6.43 rnm 0.253 in.10.76 mm15" BTDC75'ABDC59' BBDC31 O ATDC46'270"270"0.424 in.CrankshaftEnd Play. .............................. 0.038-0.165 mrn 0.0015-0.0065 inMain Bearing JournalDiameter .......... ... ... ...........Main Bearing Journal WidthNo.1 . ...............................No.3 ................................NO. 2-4-5-6-7 ...........................Main Bearing Clearance ......................63.489-63.502 mm 2.4996-2.5001 in.27.58-27.89 mrn 1.086-1.098 in.32.28-32.33 mm 1.271 -1.273 in.30.02-30.18mm 1.182-1.188 in.0.03-0.06 mm 0.001 -0.0025 in.(0.051 mm (0.002 in.preferred) preferred)Connecting Rod JournalDiameter ........... ... ....... ........ 53.1 7-53.23 mrn 2.0934-2.0955 in.Connecting Rod JournalWidth ........................ 27.18-27.33 mm 1.070-1.076 in........IMaximum Out-of-Round(All Journals) ......................Maximum Taper(All Journals)...........................0.013 mm0.01 3 rnrn0.0005 in.0.0005 in.

- . P F l4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 273ICylinder BlockDeck Height. ............................Deck Clearance. ..........................Cylinder Bore Diameter(standard) .............................Maximum Taper. .........................Maximum Out-of-Round .....................Tappet Bore Diameter. .......................Cylinder Block Flatness . ......................239.49-239.64 rnm0.546 mm (below block)98.42-98.48 mm0.025 mm0.025 mm23.000-23.025 mm0.03/25-0.05/152 mm(0.20 mm mox)9.429-9.435 in.0.0215 in. (below block)3.8751 -3.8775 in0.001 in.0.001 in.0.9055-0.9065 in.0.001 /1-0.002/6 in.(0.008 in. mox)Conndng RodsTotal Weight (less bearings) .....................Total Length(renter-to-center) .........................Piston Pin Bore Diameter. .....................Connecting Rod Bore(less bearings) . ..........................Bearing Clearance .........................Side Clearance ...........................Maximum Twist ...........................Maximum Bend ...........................155.52-1 55.62 mm23.59-23.62 mm56.09-56.08 mm0.03-0.08 mm(0.044-.05 rnrn preferred)0.25-0.48 mm0.025 rnrn per 25.4 mm0.01 27 rnrn per 25.4 mm657-665 grams6.123-6.127 in.0.9288-0.9298 in.2.2085-2.2080 in.0.001 -0.003 in.(0.0015-0.002 in. preferred)0.01 0-0.01 9 in.0.001 in. per inch0.0005 in. per inchICylinder HeadCombustion Chamber Volume ...................Valve Arrangement .........................64.45-67 A ~CCEl-IE-IE-El-El-IEValve Guide ID (Integral) ...................... 7.9 mm , 3.12 in.Valve Stem-to-Guide Clearonce .................. 0.03-0.08 mm0.001 -0.003 in.Intake Valve Seat Angle. .......................Exhaust Valve Seat Angle. .....................Valve Seat Width .......................... 1.02-1.52 mm 0.040-0.060 in.Valve Seat Runout. ......................... 0.064 mm 0.0025 in.Cylinder Head Flatness ....................... 0.03/25-0.05/152 mm 0.001/1-0.002/6 in.(0.20 mm max) (0.008 in. max)44.5'44.5"Oil ProssuroAt Idle Speed (600 rprn) . ...................... 13 psi 89.6 kPaAt 1600+ rpm . ........................... 37-75 psi 255.1-517.1 kPaOil Pressure Relief. .........................75 psi51 7.1 kPa

--I -I274 MOPAR PERFORMANCE PARTSOil PumpGear-to Body Clearance(Radial)..............................0.051 -0.102 0.002-0.004 in.(0.051 mm preferred) (0.002 in. preferred)IGear End Clearance, Plastigage .................. 0.051 -0.152 0.002-0.006 in.(0.051 mm preferred) (0.002 in. preferred)Gear End ClearanceFeeler Gauge. ..........................0.1 01 6-0.2032 mm(0.1 778 preferred)0.004-0.008 in.(0.007 in. preferred)PistonsWeight (less pin) ...........................51 0-51 4 gromsPiston Pin BoreCenterline-to-Piston Top .....................41.94-42.04 mm1.651 -1.655 in.Piston-to-Bore Clearance ......................0.023-0.043 mm 0.0009-0.0017 in.(0.030-0.033 mm preferred) (0.0012-0.0013 in. preferred)Piston Ring Gap Clearance -Compression (both) ...................... .. 0.25-0.51 mm 0.010-0.020 in.Piston Ring Gap Clearance -Oil Control Steel Rails ............. ....... 0.25-0.64 mm 0.010-0.025 in.Piston Ring Side Clearance -No. 1 Compression. ....................... 0.043-0.081 mm 0.0017-0.0032 in.No. 2 Compression ........................(0.043 mm preferred)0.043-0.081 mm(0.0017 in. preferred)0.001 7-0.0032 in.Oil Control ............................(0.043 mm preferred)0.03-0.20 mm(0.0017 in. preferred)0.001 -0.008 in.(0.08 mm preferred)(0.003 in. preferred)Piston Ring Groove HeightCompression (both)........................Oil Control ............................2.019-2.045 mm4.78-4.80 mm0.0795-0.0805 in.0.1 88-0.1 895 in.IPiston Ring Groove DiameterNo. 1 and No. 2. .........................Oil Control ............................Piston Pin Bore Diameter. .....................88.30-88.55 mm90.35-90.60 mm23.642-23.655 mm3,476-3.486 in.3.557-3.566 in.0.9308-0.931 3 in.Piston Pin Diameter ......................... 23.632-23.645 mm 0.9304-0.9309 in.Piston-to-Pin Clearance .......................0.008-0.01 3 mm loose(0.01 3 mm preferred)0.0003-0.0005 in. loose(0.0005 in. preferred)Piston-to-Pin Connecting Rod .................... 8.9kN press-fit 2000 Ibf press-fit

- --T 74.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 275Rocker Arms, Push Rods and TappetsRocker Arm Ratio ..........................1.6:l..........................Push Rod Length. 244.856-245.364 mm 9.640-9.660 in.Push Rod Diameter .........................7.92-8.00 mm 0.312-0.315 in.Hydraulic Tappet Diameter .....................22.962-22.974 mm0.904-0.9045 in......................Tappet-to- Bore Clearance 0.03-0.05 mm 0.001 -0.0025 in.ValvesValve Length(Tip-to-Gauge Dim. Line)(Intake) .............................(Exhaust) ............................Valve Stem Diameter ........................Stem-to-Guide Clearance ......................Intake Valve Head Diameter. ...................Intake Valve Face Angle ......................Exhaust Valve Head Diameter ...................Exhaust Valve Face Angle ......................Maximum Allowable Removed farTip Refinishing ..........................122.4-122.8 mm 4.822-4.837 in.122.8-123.2 mm 4.837-4.852 in.7.9 mm 3.12 in.0.03-0.08 mm 0.001 -0.003 in.48.5 mm 1.91 in.45'38 mm 1.50 in.45"0.25 mm 0.010 in.Valve SpringsFree Length ............................. 46.22 mm opprox. 1.82 in. approx.Spring TensionValve Closed ........................... 293-329 N at 41.266-74 Ibf at 1.625Valve Open ............................ 91 1-978 N at 30.4Inside Diameter ...........................205-220 Ibf at 1.20024.08-24.59 mm 0.948-0.968 in.

~~~276 MOPAR PERFORMANCE PARTS1989,4.0L ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the IY8Y Jeep Cherokee Service Munuul.ComponentTorqueA/C Compressor Brocket-to-Engine BoltsA/C Low Pressure Service Valve NutAlternator Adjusting BoltAlternator Pivot BoWNutCamshaft Sprocket BoltConnecting Rod Bolt NutsCrankshaft Main Bearing BoltsCrankshaft Pulley-to-Damper NutCylinder Head Bolts (#1-10&#12-14)(#IllCylinder Heod Cover BoltsExhaust Manifold-to-Downpipe NutsFlywheeVConverter Housing BoltsFuel Pump BoltsOil Pan Bolts - 1 /4-20- 5/16-18Oil Pan Drain PlugOil Pump Attaching Bolts (Short)Oil Pump Attaching Bolts (Long)Oil Pan Cover BoltsPower Steering Pump Pressure Hose HutRocker Arm Assembly-to-Cylinder HeadSpark PlugsStarting Motor-to-Cylinder Block BoltsTiming Case Cover-to-Block BoltsVibration Damper Bolt (Lubricated)34 N-rn38 N-rn24 Nom38 N-rn108 Nom45 Nom108 N-rn27 Nm149 N-rn135 Nm6 N-rn27 N*rn38 Nvn22 Nom9 Nm15 Nm41 Nm14 Nm23 Nom8 Nrn52 N-rn26 Nom38 Nm45 Nom7 Nom108 Nom(25 ft-lbs)(28 ft-lbs)(18 ft-lbs)(28 ft-lbs)(80 ft-lbs)(33 ft-lbs)(80 ft-lbs)(20 ft-lbs)(1 10 ft-lbs)(100 ft-lbs)(55 in-lbs)(20 ft-lbs)(28 ft-lbs)(16 ft-lbs)(7 ft-lbs)(1 1 ft-lbs)(30 ft-lbs)(10 ft-lbs)(1 7 ft-lbs)(70 in-lbs)(38 ft-lbs)(19 ft-lbs)(28 ft-lbs)(33 ft-lbs)(62 in-lbs)(80 ft-lbs).*

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 2771999, 4.0L ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1999 Jeep Cherokee Sewice Munuul.Engine DescriptionEngine Type. ................ In-line 6 CylinderBore and Stroke ............... 98.4 x 86.69 mm(3.88 x 3.413 in.)Displacement. ................ 4.0L (242 cu. in.)Zompression Ratio ...................... 8.8: 1Firing Order .................... 1-5-3-6-2-4Lubrication .... Pressure Feed-Full Flow FiltrationCooling System .. Liquid Cooled-Forced CirculationCylinder Block ..................... Cast IronCrankshaft ................. Cast Nodular IronCylinder Head. ..................... Cast IronCamshaft ......................... Cast IronAluminum AlloyPistons ......................Combustion Chamber ............. Dual-QuenchConnecting Rods ............ Cast Malleable Ironrngine SpecificationsCamshaftHydraulic Tappet Clearance ......... Zero LashBearing Clearance .......... 0.025 to 0.076 mmBearing Journal Diameter(0.001 to 0.003 in.)No. 1 ..... 51.54 to 51.56 mm (2.029 to 2.030 in.)No. 2 ..... 51.28 to 51.31 mm (2.019 to 2.020 in.)No. 3 ..... 51.03 to 51.05 mm (2.009 to 2.010 in.)No. 4 ..... 50.78 to 50.80 mm (1.999 to 2.000 in.)Base Circle Runout ........... 0.03 mm - max.(0.001 in. - max.)Valve Lift ............... 10.29 mm (0.405 in.)Intake Valve TimingOpens ........................Closes ........................Exhaust Valve Timing12.4" BTDC60.9" ABDCOpens ......................... 49.8 BBDCCloses. ........................ 29.2" ATDCValve Overlap ........................ 41.6"Intake Duration ..................... 253.3"Exhaust Duration ..................... 259."CrankshaftEnd Play ................. 0.038 to 0.165 mm(0.0015 to 0.0065 in.)Main Bearing JournalDiameter No. 1-6. ........ 63.489 to 63.502 mm(2.4996 to 2.5001 in.)Main Bearing JournalDiameter No. 7 .......... 63.449 to 63.487 mm(2.4980 to 2.4995 in.)CamshaftMain Bearing JournalWidth No. 1 .............. 27.58 to 27.89 mm(1.086 to 1.098 in.)Main Bearing JournalWidth No. 3 .............. 32.28 to 32.33 mm(1.271 to 1.273 in.)Main Bearing JournalWidth No. 2-4-5-6-7 ......... 30.02 to 30.18 mm(1.182 to 1.188 in.)Main Bearing Clearance ....... 0.03 to 0.06 mm(0.001 to 0.0025 in.)Main Bearing Clearance (Preferred) ... 0.051 mm(0.002 in.)Connecting Rod JournalDiameter. ................ 53.17 to 53.23 mm(2.0934 to 2.0955 in.)Connecting Rod JournalWidth ................... 27.18 to 27.33 mm(1.070 to 1.076 in.)Out-of-Round (Max. All Journals) ..... 0.013 mm(0.0005 in.)Taper (Max.-All Journals) ......... 0.013 mm(0.0005 in.)Cylinder BlockDeck Height ............. 240.03 to 240.18 mm(9.450 to 9.456 in.)Deck Clearance (Below Block) ........ 0.546 mm(0.0215 in.)Cylinder Bore Diameter-Standard. ................ 98.45 to 98.48 mm(3.8759 to 3.8775 in.)Cylinder Bore Diameter-Taper (Max.). .................... 0.025 mm(0.001 in.)Cylinder Bore Diameter-Out-of-Round .................... 0.025 mm(0.001 in.)Tappet Bore Diameter ..... 23.000 to 23.025 mm(0.9055 to 0.9065 in.)Flatness ................ 0.03 mm per 25 mm(0.001 in. per 1 in.)Flatness ............... 0.05 mm per 152 mm(0.002 in. per 6 in.)Flatness Max. .... 0.20 mm max. for total length(0.008 in. max. for total length)Main Bearing BoreDiameter ............. 68.3514 to 68.3768 mm(2.691 to 2.692 in.)Connecting RodsTotal Weight (Less Bearing) ... 657 to 665 grams(23.17 to 23.45 oz.)Length (Center-to-Center) . . 155.52 to 155.62 mm(6.123 to 6.127 in.).-

1- -7i-l278 MOPAR PERFORMANCE PARTSCamshaftPiston Pin Bore Diameter .... 23.59 to 23.62 mm(0.9288 to 0.9298 in.)Bore (Less Bearings) ........ 56.08 to 56.09 mm(2.2080 to 2.2085 in.)Bearing Clearance .......... 0.025 to 0.076 mm(0.001 to 0.003 in.)Bearing Clearance(Preferred) ............... 0.044 to 0.050 mm(0.0015 to 0.0020 in.)Side Clearance .............. 0.25 to 0.48 mm(0.010 to 0.019 in.)Twist (Max.). .............. 0.001 mm per mm(0.001 in. per inch)Bend (Max.) ............... 0.001 mm per mm(0.001 in. per inch.)Cylinder Compression Pressure8.8:lRatio ...............................Pressure Range ............. 827 to 1,034 Wa(120 to 150 psi)Max. Variation Between Cylinders ..... 206 WaCylinder Head(30 psi)Combustion Chamber ......... 52.22 to 58.22 cc(3.37 to 3.55 cu. in.)Valve Guide 1.D. (Integral) ..... 7.95 to 7.97 mm(0.313 to 0.314 in.)Valve Stem-to-GuideClearance ................ 0.025 to 0.076 mm(0.001 to 0.003 in.)Intake Valve Seat Angle ................ 44.5"Exhaust Valve Seat Angle .............. 44.5"Valve Seat Width. ............ 1.02 to 1.52 mm(0.040 to 0.060 in.)Valve Seat Runout ....... 0.064 mm (0.0025 in.)Flatness ................ 0.03 mm per 25 mm(0.001 in. per 1 in.)Flatness ............... 0.05 mm per 152 mm(0.002 in. per 6 in.)Flatness Max. ... 0.20 mm . max. for total length(0.008 in. max. for total length)Rocker Arms, Push Rods & TappetsRocker Arm Ratio ..................... 1.6: 1Push Rod Length ....... 244.856 to 245.364 mm(9.640 to 9.660 in.)Push Rod Diameter ........... 7.92 to 8.00 mm(0.312 to 0.315 in.)Hydraulic Tappet Diameter . . 22.962 to 22.974 mm(0.904 to 0.9045 in.)Tappet-to-Bore Clearance .... 0.025 to 0.063 mm(0.001 to 0.0025 in.)ValvesLength (Tip-to-Gauge Dimension Line)Intake ............... 122.479 to 122.860 mm(4.822 to 4.837 in.)Length (Tip-to-Gauge Dimension Line)Exhaust. ............. 122.860 to 123.241 mm(4.837 to 4.852 in.)VaJve Stem Diameter. ....... 7.899 to 7.925 mm(0.311 to 0.312 in.)Stem-to-Guide Clearance ..... 0.025 to 0.076 mm(0.001 to 0.003 in.)Valve Head Diameterntake.................. 48.387 to 48.641 mm(1.905 to 1.915 in.)Valve Head Diameter-Exhaust. ............... 37.973 to 38.227 mm(1.495 to 1.505 in.)Valve Face Angle-Intake ................ 45"Valve Face Angle-Exhaust ............... 45"Tip Refinishing (Max. Allowable) ...... 0.25 mm(0.010 in.)Valve SpringsFree Length (Approx.) ..... 47.65 mm (1.876 in.)Spring Tension-Valve Closed ....... 316 to 351 N @ 41.656 mm(71 to 79 lbf. @ 1.64 in.)Spring Tension-Valve Open ........ 898.6 to 969.7 N 30.89 mm(202 to 218 lbf @ 1.216 in.)Inside Diameter ......... 21.0 mm to 21.51 mmPistons(0.827 to 0.847 in.)Weight (Less Pin) ........... 417 to 429 grams(14.7 to 15.1 02.)Piston Pin Bore(Centerline to Piston Top) .... 40.61 to 40.72 mm(1.599 to 1.603 in.)Piston-to-Bore Clearance ..... 0.018 to 0.038 mm(0.0008 to 0.0015 in.)Ring Gap ClearanceopCompression Ring ....... 0.229 to 0.610 mm(0.0090 to 0.0240 in.)Ring Gap Clearance-4!nd Compression Ring ...... 0.483 to 0.965 mm(0.0190 to 0.0380 in.)Ring Gap Clearance-Oil Control Steel Rails ...... 0.254 to 1.500 mm(0.010 to 0.060 in.)RCing Side Clearance-Compression Rings ......... 0.042 to 0.084 mm(0.0017 to 0.0033 in.)Fling Side Clearance-Oil Control Rings ............ 0.06 to 0.21 mm(0.0024 to 0.0083 in.)Piston Ring Groove Height-Compression Rings ......... 1.530 to 1.555 mm(0.0602 to 0.0612 in.)

4.0L POWER TECH IN-LINE 6 (ENGINE ASSEMBLY) 279Piston Ring Groove HeightOil Control Ring ........... 4.035 to 4.060 mm(0.1589 to 0.1598 in.)Piston Ring Groove Diameter-No.1 Compression Ring ...... 88.39 to 88.65 mm(3.48 to 3.49 in.)Piston Ring Groove Diameter-N0.2 Compression Ring. ..... 87.63 to 87.88 mm(3.45 to 3.46 in.)Piston Ring Groove Diameter-Oil Control Ring ........... 89.66 to 89.92 mm(3.53 to 3.54 in.)Piston Pin Bore Diameter . . 23.650 to 23.658 mm(0.9312 to 0.9315 in.)Piston Pin Diameter ...... 23,637 to 23.640 mm(0.9306 to 0.9307 in.)Piston-to-Pin Clearance : ... 0.0102 to 0.0208 mm(0.0005 to 0.0009 in.)Piston-to-Pin Connecting Rod(Press Fit). ................ 8.9 kN (2000 lbf.)Oil PumpGear-to-Body Clearance(Radial) .................. 0.051 to 0.102 mm(0.002 to 0.004 in.)Gear-to-Body Clearance(Radial) (Preferred) ....... 0.05 1 mm (0.002 in.)Gear End Clearance-Plastigage ................ 0.051 to 0.152 mm(0.002 to 0.006 in.)Gear End Clearance-Plastigage (Preferred) ..... 0.051 mm (0.002 in.)Gear End Clearance-Feeler Gauge ............ 0.1016 to 0.2032 mm(0.004 to 0.008 in.)Gear End Clearance-Feeler Gauge (Preferred) . . 0.1778 mm (0.007 in.)Oil PressureAt Idle Speed (600 rpm) ....... 89.6 kPa (13 psi)At 1600 rpm & Higher ......... 255 to 517 kPa(37 to 75 psi)Oil Pressure Relief ........... 517 kPa (75 psi)

280 MOPAR PERFORMANCE PARTS1999, 4.0L ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1999 Jeep Cherokee Service Manual.TORQUE SPECIFICATIONSDESCRIPTIONTORQUEAIC Compressor Bracket-to-Engine34 N.m (25 ft. lbs.)Bolts ....................AIC CompressorMounting Bolts ............ 27 N.m (20 R. lbs.)AIC Low Pressure Service ValveNut ..................... 38 N-m (28 R. lbs.)Block HeaterNut- ..................... 2 N.m (16 in. lbs.)Camshaft Sprocket68 N-m (50 R. lbs.)Bolt .....................Camshaft Thrust Plate to Cylinder BlockScrews. .................. 24 N-m (18 R. lbs.)Clutch Cover to FlywheelBolts ....................Coil Bracket to BlockBolts ...................Connecting Rod54 N.m (40 R. lbs.)22 N-m (192 in. lbs.)Nuts .................... 45 N.m (33 R. lbs.)Cylinder BlockDrain Plugs ............... 34 N-m (25 R. lbs.)Cylinder HeadBolts .................. 135 N-m (100 R. lbs.)Cylinder Head CoverBolts .................... 10 N-m (85 in. lbs.)Distributor ClampBolt ................... 23 N.m (204 in. lbs.)Engine Mounts-FrontSupport Bracket Bolts ....... 61 N-m (45 R. lbs.)Support Cushion BoltdNuts .. 41 N-m (30 R. lbs.)Support Cushion Bracket Bolts. ........ 54 N.m(40 R. lbs.)Support Cushion Bracket Stud Nuts ...... 41 N-m(30 R. lbs.)Support Cushion Thru-Bolt ... 65 N.m (48 ft. lbs.)Engine Mounts-RearCrossmember-to-Sill Bolts (Automatic) ... 41 N-m(30 R. lbs.)Insulator Stud Assembly Nut . 41 N.m (30 R. lbs.)Support CushiodCrossmember Nuts .... 22 N.m(192 in. lbs.)Support Cushion/Bracket Nuts (Manual) . 75 N-m(55 R. lbs.)Transmission Support Bracket Bolt(Manual). ................ 46 N-m (34 R. lbs.)Transmission Support Bracket'Cushion Bolt(4WD Auto) .............. 75 N-m (55 R. lbs.)Transmission Support Adaptor Bracket Bolts(2WD Auto) .............. 75 N-m (55 R. lbs.)Exhaust ManifoldPipeNuts .................... 27 N-m (20 R. lbs.)Flywheel to Converter HousingBolts .................... 38 N-m (28 R. lbs.)Flywheel to CrankshaftBolts .................. 143 N.m (105 R. lbs.)Front Cover-to-BlockBolts 1/4-20 ............... 7 N-m (60 in. lbs.:Bolts 5/16-18 ............ 22 N.m (192 in. lbs.:Fuel RailBolts/Stud. .............. 12 N-m (108 in. lbs.'GeneratorFixed Bolt ................ 24 N-m (18 fi. lbs.Thru BoltLNut ............. 38 N-m (28 R. lbs.Main Bearing CapBolts ................... 108 N.m (80 R. lbs.)Main Bearing BraceNuts ....................Oil Filter47 N-m (35 R. lbs.)Filter .................. 18 N-m (156 in. lbs.)Connector (to adaptor) ...... 47 N-m (35 R. lbs.)Connector (to block) ........ 68 N-m (50 ft. lbs.)Adaptor Bolts ............ 102 N-m (50 R. lbs.)Oil GalleyPlug ....................Oil Pan41 N.m (30 R. lbs.)1/4-20 Bolts .............. 9.5 N-m (84 in. lbs.)5/16-18 Bolts ............ 15 N-m (132 in. lbs.)Ilrain Plug ............... 34 N.m (25 ft. lbs.)Oil PumpShort Attaching Bolts ...... 23 N-m (204 in. lbs.)Long Attaching Bolts ...... 23 N-m (204 in. lbs.)Cover Bolts ............... 8 N-m (70 in. lbs.)Power Steering Pump Pressure HoseNut ..................... 52 N-m (38 R. lbs.)Rocker Arm Assembly-to-Cylinder HeadCapscrews ................ 30 N-m (21R. lbs.)Spark PlugsPlugs .................... 37 N.m (27 R. lbs.)Starter MotorMounting Bolts ............ 45 N.m (33 R. lbs.)Thermostat HousingBolts ................... 18 N.m (156 in. lbs.)Throttle BodyBolts ....................Vibration DamperBolts ...................Water Pump/BlockBolts ....................10 N.m (90 in.lbs.)108 N-m (80 R. lbs.)23 N-m (17 R. lbs.)T - 7 7

T - T 7Chapter 54.2L In=Line 6

I- - 7 7282 MOPAR PERFORMANCE PARTSIntroduction ........... .................................................. 283..................................... ... 284Crankshaft ...................................................... 286... ..................... 292Cylinder Head .................... ................................................... 298Camshaft and Valve Gear ................................................................. .302Oiling System ....................................... ............................... 308Induction System ............................................. .. .. . .312Ignition System ................................ .. ............................... 327Engine Assembly . .................................................... ............. 333

~ ~r -1-74.2L IN-LINE 6 (INTRODUCTION) 283Note: Due to the similarity of 4.2L and 4.0L Jeep engines, only those procedures specific to the 4.2L engine will becovered in this chapter. All other 6-cylinder procedures, techniques and modification tips can be found in Chapter 4, 4.OLPower Tech In-line 6. Therefore, in addition to this chapter, we highly recommend that all 4.2L engine owners readChapter 4 in its entirety.For additional 4.2L engine general service information, refer to the proper service manual.The 4.2L is an In-line 6 cylinder, carbureted engineequipped with a micro-computer controlled Fuel Feedbacksystem. It was produced in 232 and 258 CID versions.Introduction81128A4.2L Engine Assembly (Cut-Away View)8112864.2L Engine Assembly (Typical)

284 MOPAR PERFORMANCE PARTSINTRODUCTIONThe 4.2L is an In-line 6 cylinder, carbureted engineequipped with a micro-computer controlled Fuel Feedbacksystem. It was produced in 232 and 258 CID versions.(Refer to the specifications that follow.)The 4.2L engine has a bore and stroke of 95.25 x 98.93 mm(3.88 x 3.44") and incorporates an overhead valve system inBlockThe cylinders are numbered from front to rear with a firingorder of 1-5-3-6-2-4. The crankshaft rotates in acounterclockwise direction, viewed from the rear of theengine.Seven two-piece main bearings are used to support thecrankshaft. The camshaft is supported by four one-pieceline bored bearings.I4.2L Short Block Assembly (Exploded View)T - 7 - 1

4.2L IN-LINE 6 (BLOCK) 285Disassembly1.2.3.4.5.6.7.8.9.10.11.Remove the water pump and fuel pump from thecylinder block.Remove the vibration damper.Remove the crankshaft oil seal.Remove the timing case cover.Remove the oil slinger from the crankshaft.Remove the camshaft retaining bolt and remove thesprockets and chain as an assembly.Remove the camshaft.Remove the oil pan, the gaskets, and the seals.Thoroughly clean the pan and engine block gasketsurfaces.Remove the oil pump.Remove the connecting rods and the pistons. Removethe connecting rod and piston assemblies through thetop of the cylinder bores.Caution: Be sure that the connecting rod bolts DONOT scratch the crankshaft journals or cylinder walls.Short pieces of rubber hose slipped over the connectingrod bolts will provide protection during removal.Remove the crankshaft.Cylinder Bore Measurement1.2.3.4.5.6.Use a bore gauge to measure each cylinder borediameter. If a bore gauge is not available, use an insidemicrometer.Measure the cylinder bore diameter crosswise to thecylinder block near the top of the bore. Repeat themeasurement at the bottom of the bore.Determine the taper by subtracting the smallerdiameter from the larger diameter.Rotate the measuring device 120" and repeat stepsabove. Finally, rotate the device another 120" andrepeat the measurements.Determine out-of-roundness by comparing thedifference between each 120" measurement.If the cylinder bore taper does not exceed 0.025 mm(0.001 ") and the out-of-roundness does not exceed0.025 mm (0.001"), the cylinder bore can be trued byhoning. If the cylinder bore taper or out-of-roundcondition exceeds these maximum limits, the cylindermust be bored and then honed to accept an oversizepiston. A slight amount of taper always exists in thecylinder bore after the engine has been in use for aperiod of time.Cylinder Bore ResurfacingCaution: DO NOT use rigid type hones to removecylinder wall glaze.1. Use an expanding type hone to true the cylinder boreand to remove the glaze for faster piston ring seating.Move the hone down and up (stroke) at sufficientspeed to produce a uniform 60" angle crosshatchpattern on the cylinder walls. DO NOT use more thanten strokes per cylinder (one stroke is one down-andupmovement). Refer to "Block' section of Chapter 4for more information.2. Scrub the cylinder bores clean with a solution of hotwater and detergent.3.Immediately apply light engine oil to the cylinderwalls. Wipe with a clean, lint-free cloth.Assembly1.2.3.4.5.6.7.8.9.Install the crankshaft.Install the connecting rods and the pistons through thetop of the cylinder bores.Caution: Be sure that the connecting rod bolts DONOT scratch the crankshaft journals or cylinder walls.Short pieces of rubber hose slipped over the connectingrod bolts will provide protection during removal.Install the oil pump.Install the oil pan, gaskets and seals.Install the camshaft.Install the camshaft retaining bolt and install thesprockets and chain as an assembly.Install the oil slinger on the crankshaft.Install the timing case cover.Install the crankshaft oil seal.10. Install the vibration damper.11. Install the water pump and fuel pump to the cylinderblock.ENGINE MOUNTSResilient rubber cushions support the engine andtransmission at three points: at each side on the centerlineof the engine and at the rear between the transmissionextension housing and the rear support crossmember.Replacement of a cushion may be accomplished bysupporting the weight of the engine or transmission at thearea of the cushion.

286 MOPAR PERFORMANCE PARTSCRANKSHAFTThe 4.2L crankshaft has twelve counterweights; thecrankshaft is counterweighted and balanced independently.It has seven main bearings and six connecting rod journals.The crankshaft has a main bearing journal diameter of63.489-63.502 mm (2.4996-2.500 1 'I), and main bearingjournal widths of (No. I) 27.58-27.89 mm (1.086-1.098"),(No. 2) 32.28-32.33 mm (1.271-1.273"), and (Nos. 3, 4, 5,6 and 7) 30.02-30.18 mm (1.182- 1.188").The crankshaft has a connecting rod journal diameter of53.17-53.23 mm (2.0934-2.0955") and a connecting rodjournal width of 27.18-27.33 mm (I ,070- 1.076").The component parts of the crankshaft assembly areindividually balanced; then the complete assembly isbalanced as a unit.Note: On automatic transmission equipped engines, thetorque converter and converter flexplate must be markedprior to removal and installed in this position uponassembly.Service replacement dampers, crankshafts, flywheels,torque converters and clutch components are balancedindividually and, therefore, may be replaced as requiredwithout rebalancing the complete assembly.If the crankshaft is damaged to the extent thatreconditioning is not feasible, it must be replaced. Theengine must be removed from the vehicle for crankshaftreplacement.For more crankshaft specifications, refer to 4.2L EngineSpecificutions, 'Engine Assembly' section of this chapter.CRANKSHAFT MAIN BEARINGSThe main bearings are steel backed, sintered copper, leadalloy precision type.Each bearing is selectively fit to its respective journal toobtain the desired operating clearance. In production, theselect fit is obtained by using various-sized, color-codedbearing inserts.When required, different sized upper and lower bearinginserts may be used as a pair; therefore, a standard sizeupper insert is sometimes used in combination with a .001"undersize lower insert.Service replacement bearing inserts are available as pairs inthe following undersizes: standard, .001",.002",.010", and,012". The size is stamped on the back of the inserts.It may be necessary, in some instances, to use differentsized upper and lower inserts to reduce clearance by .0005".C ran ks haf tThe bearing insert nearest to standard should always beinstalled in the upper location.Caution: Never use bearing inserts with greater than .001"difference in size in pairs.Upper - Std.Lower - .OO 1 'I undersizeRemovalUpper - S td..Lower - .002" undersizeI. Disconnect the battery negative cable.2. Remove the spark plugs.3. Raise the vehicle.4. Remove the oil pan and oil pump. Refer to Oil PumpRemoval and Oil Pun Removal, 'Oiling System'section of this chapter, for the procedures.5. Remove the main bearing caps and lower inserts.6. Remove the lower insert from the bearing cap.7. Remove the upper insert by loosening (DO NOTremove) all of the other bearing caps and inserting asmall cotter pin tool in the crankshaft journal oil hole.Bend the cotter pin as illustrated to fabricate the tool(Figure 2-13). With the cotter pin tool in place, rotatethe crankshaft so that the upper bearing insert willrotate in the direction of its locking tab.Note: Because there is no hole in the No. 3 mainjournal, use a tongue depressor or similar soft-facedtool to remove the bearing insert. After moving theinsert approximately 25 mm (l"), it can be removed byapplying pressure under the tab.8. Using the same procedure just described, remove theremaining bearing inserts (one at a time) forinspection.

4.2L IN-LINE 6 (CRANKSHAFT) 287Inspection1. Wipe inserts clean and inspect for abnormal wearpatterns and for metal or other foreign materialimbedded in the lining. Normal main bearing insertwear patterns are shown in Figure 2-14.2.3.4.5.If any of the crankshaft journals are scored, remove theengine for crankshaft repair.FittingInspect the back of the inserts for fractures, scrapings,or irregular wear patterns.Inspect the upper insert locking tabs for damage.Replace all damaged or worn bearing inserts.The main bearing caps, numbered (front to rear) from 1through 7 have an arrow to indicate the forward position.The upper main bearing inserts are grooved to provide oilchannels while the lower inserts are smooth.Each bearing insert pair is selectively fit to its respectivejournal to obtain the specified operating clearance. Inproduction, the select fit is obtained by using various-sizedcolor-coded bearing insert pairs. The bearing color codeappears on the edge of the insert. The size is not stamped onbearing inserts used for engine production.The main bearing journal size (diameter) is identified inproduction by a color-coded paint mark on the adjacentcheck toward the flanged (rear) end of the crankshaft,except for the rear main journal, which has the mark on thecrankshaft near the flange.When required, upper and lower bearing inserts of differentsizes may be used as a pair. A standard size insert issometimes used in combination with a 0.025 mm (0.001")undersize insert to reduce the clearance by 0.013 mm(0.0005"). Never use a pair of bearing inserts with greaterthan a 0.025 mm (0.001") difference in size.Note: When replacing inserts, the odd size inserts must beeither all on the top (in cylinder block) or all on the bottom(in main bearing cap).Main Bearing-to-Journal Clearance - CrankshaftInstalledWhen using Plastigauge, check only one bearing clearanceat a time.1. Install the grooved main bearings into the cylinder blockand the non-grooved bearings into the bearing caps.2.3.4.Install the crankshaft into the upper bearings dry.Place a strip of Plastigauge (P4286819) across the fullwidth of the crankshaft journal to be checked.Install the bearing cap and tighten the bolts to 108 N*m(80 ft-lbs) torque.5.6.7.8.9.Note: DO NOT rotate the crankshaft. This will causethe Plastigauge to shift, resulting in an inaccuratereading. Plastigauge must not be permitted to crumble.If it is brittle, obtain fresh stock.Remove the bearing cap. Determine the amount ofclearance by measuring the width of the compressedPlastigauge with the scale on the Plastigauge envelope.The correct clearance is 0.0254 to 0.0635 mm (.0010 to.0025") for all main bearing journals, with 0.051 mm(0.002") preferred.Plastigauge should indicate the same clearance acrossthe entire width of the insert. If clearance varies, it mayindicate a tapered journal or foreign material trappedbehind the insert.If the specified clearance is indicated and there are noabnormal wear patterns, replacement of the bearinginserts is not necessary. Remove the Plastigauge fromthe crankshaft journal and bearing insert. Proceed toCrankshaft Main Bearing Installation.If the clearance exceeds specification, install a pair of0.025 mm (0.001") undersize bearing inserts andmeasure the clearance as described in the previous steps.The clearance indicated with the 0.025 mm (0.001")undersize insert pair installed will determine if thisinsert size or some other combination will provide thespecified clearance.Example: If the clearance was 0.0762 mm (0.003")originally, a pair of 0.0254 mm (0.001") undersizeinserts would reduce the clearance by 0.0254 mm(0.001"). The clearance would then be 0.0508 mm(0.0021') and within the specification. A 0.0508 mm(0.002t1) undersize bearing insert and a 0.0254 mm(0.001") undersize insert would reduce the originalclearance an additional 0.0127 mm (0.0005") and theclearance would then be 0.0381 mm (0.0015'l).Caution: Never use a pair of inserts that differ morethan one bearing size as a pair. For example, DO NOTuse a standard size upper insert and a 0.051 mm(0.002") undersize lower insert.If the clearance exceeds the specifications using a pairof 0.051 mm (0.0021t) undersize bearing inserts,measure the crankshaft journal diameter with amicrometer. If the journal diameter is correct, thecrankshaft bore in the cylinder block may bemisaligned, which requires cylinder block replacementor machining to true bore.If the diameter for journals 1 through 6 is less than63.4517 mm (2.4981") or journal 7 is less than 63.4365mm (2.4975"), replace the crankshaft or grind it downto accept the appropriate undersize bearing inserts.Once the proper clearances have been obtained, remove thecrankshaft and proceed to Installation.

288 MOPAR PERFORMANCE PARTSMain Bearing Journal Diameter - CrankshaftRemoved1.2.3.Clean the main bearing journal of oil.Determine the maximum diameter of the journal with amicrometer. Measure at two locations 90" apart at eachend of the journal.Compare the measured diameter with the journaldiameter specification listed in the Main Bearing FittingChart located in your service manual, and select insertsrequired to obtain the specified bearing-to-journalclearance.Installation1.2.3.4.5.6.7.8.9.Lubricate the bearing surface of each insert with engine oil.Install the main bearing upper inserts to the cylinder block.Install the lower bearing inserts into the main bearing caps.Carefully lower the crankshaft into the cylinder block.Install the main bearing caps and lower inserts.Tighten all the bolts to 54 Nom (40 ft-lbs) torque, thentighten to 95 Nom (70 ft-lbs) torque.Finally, tighten the main bearing cap bolts to 108 Nom(80 ft-lbs) torque.Rotate the crankshaft after tightening each mainbearing cap to ensure the crankshaft rotates freely.Install the oil pan with replacement gaskets and seals.Refer to the Oil Pan Installation, 'Oiling System'section of this chapter, for the procedure.IO. Tighten the drain plug securely.1 1. Lower the vehicle.12. Install the spark plugs. Tighten the plugs to 38 Nom(28 ft-lbs) torque.13. Fill the oil pan with engine oil to the full mark on thedipstick level.14. Connect the battery negative cable.Crankshaft End PlayI.2.3.4.5.Attach a magnetic base dial indicator to the cylinderblock at either the front or rear of the engine.Position the dial indicator rod so that it is parallel to thecenterline of the crankshaft.Pry the crankshaft forward, and position the dialindicator to zero.Pry the crankshaft forward and backward. Note the dialindicator readings. End play is the difference betweenthe high and low measurements. Correct end play is0.038 to 0.16.5 mm (0.0015 to 0.0065"). The desiredspecifications are 0.05 1 to 0.064 mm (0.002 to 0.0025").If end play is not within specification, inspectcrankshaft thrust faces for wear. If no wear is apparent,replace the thrust bearing and measure end play. If endplay is still not within specification, replace thecrankshaft..-

~~~~ ~4.2L IN-LINE 6 (CRANKSHAFT) 289REAR MAIN OIL SEALThe crankshaft rear main bearing oil seal consists of twohalf pieces of neoprene with a single lip that effectivelyseals the rear of the crankshaft. Replace the upper andlower seal halves as a unit to ensure leak-free operation.RemovalTo replace the rear main oil seal, the transmission must beremoved. Refer to the service manual for the properprocedure.1.2.3.4.5.Remove the tlywheel or torque converter drive plate.Remove the oil pan. Refer to the Oil Pan Removal,'Oiling System' section of this chapter, for theprocedure.Remove the rear main bearing cap (No. 7).Push the upper seal out of the groove. Ensure that thecrankshaft is not damaged.Remove the lower half of the seal from the bearing cap.Installation1.2.3.4.5.6.7.8.9.Wipe the seal surface area of the crankshaft until itis clean.Apply a thin coat of engine oil.Coat the lip of the seal with engine oil.Position the upper seal into the groove in thecylinder block. The lip of the seal faces toward thefront of the engine.Place the lower half of the seal into the bearing cap.Coat both sides of the lower seal end tabs with MoparGasket-in-a-Tube, or equivalent. DO NOT applysealant to the lip of the seal.Coat the outer curved surface of the lower seal withsoap and the lip of the seal with engine oil.Position the lower seal into the bearing cap recess andseat it firmly.Coat both chamfered edges of the rear main bearingcap with Mopar Gasket-in-a-Tube, or equivalent.Caution: DO NOT apply sealant to the cylinder blockmating surfaces of the rear main bearing cap becausethe bearing-to-journal clearance will be altered.IO. Install the rear main bearing cap.11, Tighten all main bearing bolts to 108 Nom (80 ft-lbs)torque.VIBRATION DAMPERThe vibration damper is balanced independently and thenrebalanced as part of the complete crankshaft assembly. DONOT attempt to duplicate original damper balance holeswhen installing a service replacement.The vibration damper is not repairable and is serviced onlyas a complete assembly.A loose vibration damper or damage to the dampercushions may be misdiagnosed as engine bearing noise.4.2L Vibration DamperReplacement damper compatible with productioncrankshaft and piston-rod weight. For 4.2L engine withstandard belt (only).PS249535Vibration damper.4.2L MPI Vibration DamperA damper kit for use with Jeep 4.2L MPI fuel injection kits.P.5249687 1981-90 CJ and YJ with V-belt.P.5249688 1981-90 CJ and YJ with serpentine belt.Removal1. Remove the drive belt(s).2. Remove the retaining bolts and separate the vibrationdamper pulley (V-belt ONLY) from the vibrationdamper.3. Use a vibration damper removal tool to remove thedamper from the crankshaft.InstallationWith the key in position, align the key slot of thevibration damper hub with the crankshaft key and tapthe damper onto the crankshaft.Install the vibration damper retaining bolt and washer.Tighten the bolt to 108 Nom (80 ft-lbs) torque. If thecrankshaft turns before the damper bolt torque valve isattained, the crankshaft can be prevented from turningby placing two 5/16 x 1-1/2" bolts into the damperfront pulley holes and wedging a bar between them.Rotate the bar until it contacts the frame member toprevent the crankshaft from turning.Install the damper pulley (V-belt only) and retainingbolts. Tighten the bolts to 27 Nom (20 ft-lbs) torque.Install the drive belt(s) and tighten to the specifiedtension. Refer to the service manual for the properspecifications and procedures.r -T-Ic

290 MOPAR PERFORMANCE PARTSTIMING CASE COVERThe timing case cover is provided with a seal and oil slingerto prevent oil leakage at the vibration damper hub.It is important that the timing case cover is properly alignedwith the crankshaft to prevent damage to the oil seal. Theoil seal may be replaced without removing the timing chaincover.Removal1.2.3.4.5.6.7.8.Remove the drive belt(s), engine fan and hub assembly,fan shroud, vibration damper, pulley and key. Refer toVibration Damper Removal, in this section, for theprocedure.Remove the A/C compressor and alternator bracketassembly, if equipped. Refer to the service manual foradditional information pertaining to the A/C system.Remove the oil pan-to-timing case cover bolts andcover-to-cylinder block bolts.Remove the timing case cover, front seal and gasketfrom the engine.Cut off the oil pan side gasket end tabs flush with thefront face of the cylinder block. Remove the gasket tabs.Clean the timing case cover, oil pan and cylinder blockgasket surfaces.Remove the crankshaft oil seal from the timing casecover.Remove the oil seal from the timing case cover.Installation1.2.3.4.5.6.7.Apply sealing compound (Mopar Gasket-In-A-Tube, orequivalent) to both sides of the replacement timing casecover gasket and position the gasket on the cylinderblock.Cut the end tabs off of replacement oil pan side gasketscorresponding to those cut off the original gasket.Cement the end tabs on the oil pan.Coat the front cover end tab recesses generously withRTV sealant (Mopar Gasket-In-A-Tube, or equivalent)and position the seal on the timing case cover. Applyengine oil to the seal-oil pan contact surface.Position the timing case cover on the cylinder block.Place a timing case cover alignment and sealinstallation tool in the crankshaft opening of the cover.Install the cover-to-cylinder block bolts and the oilpan-to-cover bolts.Tighten the cover-to-cylinder block bolts to 7 Nom (62in-lbs) torque and the oil pan-to-cover bolts to 13 Nom(11 ft-lbs) torque.8. Remove the cover alignment tool and position thereplacement oil seal on the tool with the seal lip facingoutward.9. .4pply a light film of Perfect Seal, or equivalent, on theoutside diameter of the seal.10. ]Lightly coat the crankshaft with engine oil.11. Position the tool and seal over the end of the crankshaftand insert a screw tool into timing case coveralignment and seal installation tool. Tighten the nutagainst the tool until the tool contacts the cover.12. Remove the tools and apply a light film of engine oilon the vibration damper hub contact surface of the seal.13. 'With the key inserted in the keyway in the crankshaft,install the vibration damper, washer and bolt. Lubricateand tighten the bolt to 108 Nom (80 ft-lbs) torque.14. Install the A/C compressor and alternator bracketassembly.15. Install the damper pulley, if removed. Tighten the boltsto 27 Nom (20 ft-lbs) torque.16. Install the engine fan and hub assembly. Install the fanshroud.17. Install the drive belt(s) and tighten to the specifiedtension. Refer to the service manual for the properprocedures.TIMING CHAIN AND SPROCKETSInstalllation of the timing chain with the timing marks of thecrankshaft and camshaft sprockets properly aligned assurescorrect valve timing. A worn timing chain will adversely affectvalve timing. If the timing chain deflects more than 1/2", itshould be replaced. The correct timing chain has 48 pins. Achain with more than 48 pins will cause excessive slack.Jeep Gear DrivesReplace conventional Jeep timing chain and gear sets andeliminate chain induced cam timing fluctuations with thisMopar Performance Parts dual idler gear drive camshaftcenterlining drive system. Rugged and durable for off-roadapplications. Fits all 4.0L, 4.2L, and 2.5L Jeep engines.P5249009RemovalJeep gear drives.1. Remove the drive belt(s).2. Remove the engine fan and hub (or Tempatrol fan)assembly.3. Remove the vibration damper pulley (V-belt drive only).4. Remove the vibration damper. Refer to VibrationDamper Removal, in this section, for the procedure.*.

4.2L IN-LINE 6 (CRANKSHAFT) 2915. Remove the timing case cover. Refer to the TimingCase Cover Removal, in this section, for the procedure.6.7.8.9.Remove the oil seal from the timing case cover.Remove the camshaft sprocket retaining bolt and washer.Rotate the crankshaft until the zero timing mark on thecrankshaft sprocket is closest to and on the centerline withthe timing mark on the camshaft sprocket (Figure 5-1).Remove the crankshaft sprocket, camshaft sprocketand timing chain as an assembly. Disassemble thechain and sprockets.InstallationAssemble the timing chain, crankshaft sprocket andcamshaft sprocket with the timing marks aligned.CAMSHAFTSPROCKETTIMINGMARKS1.With the key in the keyway on the crankshaft, installthe assembly on the crankshaft and camshaft.Figure 5 - 12.3.Install the camshaft sprocket retaining bolt and washerand tighten to 108 Nom (80 ft-lbs) torque.To verify the correct installation of the timing chain,turn the crankshaft to locate the camshaft sprockettiming mark at approximately the one o’clock position.This positions the crankshaft sprocket timing markwhere the adjacent tooth meshes with the chain at thethree o’clock position. Count the number of chain pinsbetween the timing marks on both sprockets (Figure 5-2). There must be 15 pins.15 PIYS4.Install the crankshaft oil slinger.5.Install the timing case cover and replacement oil seal.Refer to Timing Case Cover Installation, in thissection, for the procedure.-J9009-716.With the key in the keyway on the crankshaft, installthe vibration damper, washer and bolt. Lubricate andtighten the bolt to 108 Nom (80 ft-lbs) torque.Figure 5 - 27.Install the damper pulley (if removed). Tighten thebolts to 27 Nom (20 ft-lbs) torque.8.Install the engine fan and hub (or Tempatrol fan)assembly.9.Install the drive belt(s) and tighten to the specifiedtension. Refer to the service manual for the properprocedure.

292 MOPAR PERFORMANCE PARTSPiston and Connecting Rod AssemblyCast Pistons and Rings for Jeep 4.2L EnginesPart NumberP5249906 3.810"REMOVAL AND INSTALLATION PROCEDURESRemoval1.2.3.4.5.6.7.8.9.Remove the cylinder head cover. Refer to CylinderHead Cover Removal, 'Cylinder Head' section of thischapter, for the procedure.Remove the capscrews, bridge and pivot assemblies,and rocker arms. Alternately loosen the capscrews, oneturn at a time, to avoid damaging the bridge.Remove the pushrods.Remove the cylinder head and gasket. Refer toCylinder Head Removal, 'Cylinder Head' section ofthis chapter, for the procedure.Position the pistons one at a time near the bottom of thestroke and use a ridge reamer to remove the ridge fromthe top end of the cylinder walls. Use a protective clothto collect the cuttings.Drain the engine oil.Remove the oil pan, gasket and seals. Refer to Oil PanRemoval, 'Oiling System' section of this chapter, forthe procedure.Remove the connecting rod bearing caps and inserts.Retain them in the same order as removed to facilitateinstallation in the original location. The connectingrods and caps are stamped with the correspondingcylinder number.Caution: Ensure that the connecting rod bolts DONOT scratch the crankshaft journals or cylinder walls.Short pieces of rubber hose, slipped over theconnecting rod bolts, will provide protection duringremoval.Remove the connecting rod and piston assembliesthrough the top of the cylinder bores.Inspection1. Connecting Rod BearingsInspect the connecting rod bearings for scoring andbent alignment tabs. Check the bearings for normalwear patterns, scoring, grooving, fatigue and pitting.Replace any bearing that shows abnormal wear.Inspect the connecting rod journals for signs ofscoring, nicks and burrs.2. #Connecting RodsMisaligned or bent connecting rods can cause,abnormal wear on pistons, piston rings, cylinder walls,'connecting rod bearings and crankshaft connecting rodjournals. If wear patterns or damage to any of thesecomponents indicates the probability of a misalignedconnecting rod, inspect it for correct rod alignment.Replace misaligned, bent or twisted connecting rods.Bearing-to-Journal Clearance Measurement1.2.3.4.5.6.7.Wipe the journal clean of oil.Use short rubber hose sections over rod bolts duringinstallation.Lubricate the upper bearing insert and install inconnecting rod.Use piston ring compressor to install the rod and pistonassemblies with the oil squirt holes in the rods facingthe camshaft and the arrow on the piston crownpointing to the front of the engine. Verify that the oilsquirt holes in the rods face the camshaft and that thearrows on the pistons face the front of the engine.Install the lower bearing insert in the bearing cap. Thelower insert must be dry. Place a strip of Plastigaugeacross the full width of the lower insert at the center ofbearing cap. Plastigauge must not crumble in use. Ifbrittle, obtain fresh stock.Install bearing cap and connecting rod on the journaland tighten nuts to 45 Nom (33 ft-lbs) torque. DO NOTrotate crankshaft. Plastigauge will smear, resulting ininaccurate indication.Remove the bearing cap and determine the amount ofbearing-to-journal clearance by measuring the width ofcompressed Plastigauge by using the scale on thePlastigauge envelope. The correct clearance is 0.025 to0.076 mm (0.001 to 0,003").Note: Plastigauge should indicate the same clearanceacross the entire width of the insert. If the clearancevaries, the variation may be caused by either a taperedjournal, bent connecting rod, or foreign materialtrapped between the insert and cap or rod.

TT74.2L IN-LINE 6 (PISTON AND CONNECTING ROD ASSEMBLY) 2938. If the correct clearance is indicated, replacement of thebearing inserts is not necessary. Remove thePlastigauge from crankshaft journal and bearing insert.Proceed with installation.9. If bearing-to-journal clearance exceeds thespecification, install a pair of 0.0254 mm (0.001")undersize bearing inserts. Measure the clearance asdescribed in the previous steps.10. The clearance measured with a pair of 0.0254 mm(0.001 'I) undersize bearing inserts installed willdetermine if two 0.0254 mm (0.001 ") undersize inserts oranother combination is needed to provide the correctclearance.Example: If the initial clearance was 0.0762 mm(0.003"), 0.025 mm (0.00 1 ") undersize inserts wouldreduce the clearance by 0.025 mm (0,001"). Theclearance would be 0.002" and within specification. A0.05 1 mm (0.002") undersize insert would reduce theinitial clearance an additional 0.01 3 mm (0.0005").The clearance would then be 0.038 mm (0.001 5").11. Repeat the Plastigauge measurement to verify yourbearing selection prior to final assembly.12. Once you have selected the proper insert, install theinsert and cap. Tighten the connecting rod bolts to 45Nem (33 ft-lbs) torque.Side Clearance MeasurementSlide snug-fitting feeler gauge between the connecting rodand crankshaft journal flange. The correct clearance is0.254 to ,482 mm (0.010 to 0.019"). Replace the connectingrod if the side clearance is not within specification.I. Clean the cylinder bores thoroughly. Apply a light filmof clean engine oil to the bores with a clean lint-freecloth.2. Install the piston rings on the pistons, if removed.3. Lubricate the piston and rings with clean engine oil.Caution: Ensure that connecting rod bolts DO NOTscratch the crankshaft journals or cylinder walls. Shortpieces of rubber hose slipped over the connecting rod boltswill provide protection during installation.4. Use a piston ring compressor to install the connecting rodand piston assemblies through the top of the cylinderbores.5. Ensure the arrow on the piston top points to the frontof the engine.6. Raise the vehicle.Caution: Verify that the oil squirt holes in the connectingrods face the camshaft and that the arrows on the pistonsface the front of the engine.7. Install the connecting rod bearing caps and inserts inthe same positions as removed.8. Install the oil pan and gaskets. Refer to Oil PunInstullution, 'Oiling System' section, for the properprocedure.9. Lower the vehicle.10. Install the cylinder head, pushrods, rocker arms,bridges, pivots and cylinder head cover. Refer to'Cylinder Head' section for the proper procedures.1 1. Fill the crankcase with engine oil.InstallationEach bearing insert is selectively fitted to its respectivejournal to obtain the specified operating clearance betweenthe bearing and the journal. In production, the select fit isobtained by using various-sized, color-coded bearing inserts.The color code appears on the edge of the bearing insert. Thesize is not stamped on inserts used for production of engines.The rod journal is identitied during the engine production bya color-coded paint mark on the adjacent check orcounterweight toward the flanged (rear end of the crankshaft).When required, upper and lower bearing inserts of differentsizes may be used as a pair. A standard size insert issometimes used in combination with a 0.025 mm (0.001")undersize insert to reduce clearance 0.0 13 mm (0.0005").Caution: DO NOT intermix bearing caps. Each connectingrod and its bearing cap are stamped with the associatedcylinder number on a machined surface adjacent to the oilsquirt hole that faces the camshaft side of the cylinder block.

T - T i l294 MOPAR PERFORMANCE PARTSCONNECTING RODSThe 4.2L engine's connecting rods are made of cast ironwith a total weight (less bearings) of 695-703 grams (24.5-24.9 oz.), and a total length (center-to-center) of 149.17-149.28 mm (5.873-5.877").Connecting rod bore diameter (less bearings) is 56.08-56.09 mm (2.2080-2.2085").For more connecting rod specifications, refer to 4.2LEngine Specifications, 'Engine Assembly' section.Connecting Rod Installation Tips1.2.3.4.5.The connecting rods and caps are stamped with thecylinder numbers in which they were assembled.The numbers are on the same machined surface as thesquirt holes.The numbered sides and the squirt holes must face thecamshaft.Whenever new rings are installed or piston pins arereplaced, it is necessary to check the alignment of theconnecting rod and piston assemblies to ensure trueoperation in the cylinder bore.Misaligned rods will cause uneven piston and ringwear which will result in oil consumption. Theconnecting rod should be inspected for a twisted orbent condition.CONNECTING ROD BEARINGSCaution: Never use bearing inserts with greater than .001"difference in size in pairs.Upper - Std.Lower- .001" U.S.Removal and Inspection1.2.3.4.5.IncorrectUpper - Std.Lower- .002" U.S.Drain the engine oil and remove the oil pan.Rotate the crankshaft as required to position twopistons at a time at the bottom of their stroke.Remove the bearing caps and upper and lower inserts.The upper insert can be readily removed by spinning itout of the connecting rod.Note: DO NOT mix bearing caps. Each connectingrod and its matching cap is stamped with the cylindernumber on a machined surface which faces thecamshaft side of the engine block.Inspect the bearing inserts for abnormal wear ordamage. Bearing inserts exhibiting either conditionshould be replaced.Wipe the connecting rod journals clean and use amicrometer to check for an out-of-round condition.Refer to specifications. If any rod journal is beyondspecifications, it must be reconditioned and fit withnew undersize bearing inserts.The connecting rod bearings are steel-backed, sinteredcopper, lead alloy precision-type. Each bearing isselectively fit to its respective journal to obtain the desiredoperating clearance. In production, the select fit is obtainedby using various-sized, color-coded bearing inserts.When required, different sized upper and lower bearinginserts may be used as a pair; therefore, a standard sizeupper insert is sometimes used in combination with a .001"undersize lower insert.Service replacement bearing inserts are available as pairs inthe following undersizes: standard, .001 'I, .002", .010", and.012". The size is stamped on the back of the inserts.It may be necessary, in some instances, to use differentsized upper and lower inserts to reduce clearance by .0005".The bearing insert nearest to standard should always beinstalled in the upper location.

4.2L IN-LINE 6 (PISTON AND CONNECTING ROD ASSEMBLY) 295InstallationLubricate the bearing surface of each insert with cleanengine oil. Install the bearing inserts, cap and retainingnuts. Tighten to the specified torque.Caution: Care must be exercised when rotating thecrankshaft with bearing caps removed. Be sure the connectingrod bolts DO NOT accidentally come in contact with the rodjournals and scratch the finish. Bearing failure would result.Install the oil pan using new gaskets and seal. Tighten thedrain plug securely.Use new engine oil to fill the crankcase to the specified level.PISTONSAluminum alloy “Autothermic” pistons, steel reinforcedfor strength and controlled expansion, are used. Eachpiston has three piston rings, two compression and one oilcontrol ring above the piston pin.The piston pin boss is “offset” from the piston centerline toplace it nearer the thrust side of the piston.To ensure correct installation of the piston in the bore, anotch is cast into the top perimeter of the piston head. Thenotch must face forward.Piston FittingPistons are fit to their respective bores by measuring theinside diameter of the cylinder bore and the diameter of thepiston.1. Micrometer Methoda. Measure the inside diameter of the cylinder boreat a point 58.725 mm (2-5/16”) below the top ofthe bore.b. Measure outside diameter of the piston. Becausepistons are cam ground, measure at right angle topiston pin at centerline of pin (Figure 5-3).The difference between cylinder bore diameter andpiston diameter is piston-to-bore clearance.I1 - 1GROOVE HEIGHTA 2.01 93-2.0447 mrn (0.0795-0.0805 in)B 4.7752-4.8133 mm (0.1880-0.1895 in)GROOVE DIAMETERD-E 84.4296-84.5566 mm (3.324-3.329 in)F 84.5566-84.8106 mm (3.329-3.339 in)2. Feeler Gauge MethodFigure 5 - 3(Not recommended for racing.)a. Remove the rings from the piston.AMEASURE PISTONAT THIS AREAFOR FITTINGJ9009-73b. Insert a long 0.025 mm (0.001”) feeler gauge intothe cylinder bore.c. Insert the piston, top first, into cylinder borealongside the feeler gauge. With entire pistoninserted into cylinder bore, the piston should notbind against feeler gauge.d. Repeat steps with a long 0.05 I mm (0.002”) feelergauge. The piston should bind.e. If the piston binds on 0.025 mm (0.001”) feelergauge, the piston is too large or cylinder bore is toosmall. If the piston does not bind on 0.051 mm(0.0021t) feeler gauge, the piston is too small forcylinder bore. Pistons up to 0.102 mm (0.004”)undersize may be enlarged by knurling or shotpeening.Replace pistons that are 0.102 mm (0.004”)or more undersize.PISTON RINGSCarbon must be cleaned from all ring grooves. The oil drainopenings in the oil ring grooves and pin boss must becleared. Care must be exercised not to remove metal fromeither the grooves (since this will change their depth) orfrom the lands (since this will change the ring grooveclearance and destroy ring-to-land seating).Side clearance between land and compression rings shouldbe as listed in 4.2L Engine Spec$cution.s, ‘EngineAssembly’ section.. ..T -1 n

296 MOPAR PERFORMANCE PARTSPiston Ring Fitting1.2.3.4.5.6.7.8.9.Carefully clean the carbon from all ring grooves. Oildrain openings in the oil ring grooves and pin bossmust be clear. DO NOT remove metal from thegrooves or lands. This will change ring-to-grooveclearances and will damage the ring-to-land seating.Measure the ring side clearance with a feeler gaugefitted snugly between the ring land and ring (Figure 5-4). Rotate the ring in the groove. It must move freelyaround the circumference of the groove.Place ring in the cylinder bore and push down withinverted piston to position near lower end of the ringtravel. Measure ring gap with a feeler gauge fittingsnugly between ring ends. The correct compressionring end gap is 0.25-0.51 mm (0.010-0.02011). Thecorrect oil control ring end gap is 0.381-1.397 mm(0.015-0.055").Refer to Figure 2-44 for position of the ring gaps wheninstalling piston rings.Install the oil control rings according to instructions inthe package. It is not necessary to use a tool to installthe upper and lower rails. Insert expander ring first,then side rails.The two compression rings are different and cannot beinterchanged. The top ring is a moly ring (the scrapingedge is gray in color). The second ring is a black castiron ring (the scraping edge is black in color when new).The compression rings can be identified by a chamferof either the top or bottom inside edge. The rings mayalso be identified by one or two dots on the top surfaceof the ring.The second compression ring (black cast iron) has achamfer on the BOTTOM of the inside edge. This ringmay also have two dots located on the top surface.Using a ring installer, install the ring with the chamferfacing down. If the ring has dots, the dots will befacing up.10. The top compression ring (the scraping edge is gray incolor) has a chamfer on the TOP of the inside edge.This ring may also have one dot located on the topsurface.11. Using a ring installer, install the top ring with thechamfer facing up. If the ring has a dot, the dot will befacing up.12. Position the ring end gaps on the piston as shown(Figure 2-44).LMillim.t.rrInchesNo. 1 Compression 0.030-0.081 0.0012-0.0032(0.043 Preferred) (0.0017 Preferred)No. 2 Compression0.030-0.081 0.0012-0.0032(0.043 Preferred) (0.0017 Preferred)Oil Control 0.025-0.203 0.001-0.008(0.08 Preferred) 10.003 Preferred)PISTON PINRemovalFigure 5 - 4. -ELERGAUGEPiston pins are press-fit into the connecting rods andrequire no locking device.1. Position the piston and connecting rod assembly on anarbor press.2.Apply force to a piloted driver and press the pincompletely out of the connecting rod and pistonassembly. Note position of the pin through the gaugewindow of removal support tool.Inspection1. Inspect the new piston pin and the connecting rod pinbore for nicks and burrs. Remove as necessary. Neverreuse a piston pin.2.3.4.With the pin removed from the piston and connectingrod, clean and dry piston pin bore and the replacementpiston pin.Position the piston so that the pin bore is in a verticalposition. Insert the pin in the bore. At roomtemperature, the replacement pin should slidecompletely through the pin bore in the piston by forceof gravity.Replace piston if pin jams in the pin bore.

T -TTT4.2L IN-LINE 6 (PISTON AND CONNECTING ROD ASSEMBLY) 297InstallationInsert the piston pin pilot through the piston andconnecting rod pin bores. Ensure that the arrow on thepiston crown is pointing up (Figure 2-50).Position the pin pilot, piston and connecting rod on asupport with the squirt hole of the connecting rod to theleft-hand side.Insert piston pin through the upper piston pin bore andinto the connecting rod pin bore.Position the piloted driver inside the piston pin(Figure 2-49).5. Using an arbor press, press the piston pin through theconnecting rod and piston bores until pin pilot indexeswith mark on the support. The piston pin requires an8900 N (2,000 pounds) press-fit. If little effort isrequired to install the piston pin in a connecting rod orif the rod moves laterally on the pin, the connecting rodmust be replaced.6.Remove the piston and connecting rod assembly fromthe press. The pin should be centered in the connectingrod (+0.792 mm or +0.03 12").

l- - T r l298 MOPAR PERFORMANCE PARTSCYLINDER HEADThe 4.2L engine uses a cast iron cylinder head with acombustion chamber volume of 64.45-67.45 cc.The cylinder head has a quench-type combustion chamberthat creates turbulence and faster burning of the aidfuelmixture, resulting in good fuel economy.Cylinder HeadIntake and exhaust valve lengths are 121.653- 122.034 mmI (4.7895-4.8045").For more cylinder head specifications, refer to 4.2L EngineSpecijications, 'Engine Assembly' section of this chapter.2617I1 - Oil Filler Cap2 - Ventilation Valve3 - Grommet4 - Cylinder Head (Rocker) Cover5 - Bridge6 - Pivot7 Rocker Arm8 - Push Rod9 Cylinder Head Bolt10 - Cylinder Head Core Plug11 - Cylinder Head12 - Snap Ring13 - Tappet14 - Intake Manifold Gasket15 - Hose Fitting16 - Plug17 - Exhaust Manifold18 - Heat Stove19 - Intake Manifold Heater20 - Gasket21 - 0-Ring22 - Intake Manifold23 - Valve24 - Dowel Pin25 - Plug26 - Cylinder Head Stud27 - Oil Deflector28 - Valve Spring29 - Retainer30 - Valve Locks4.2L Engine Cylinder Head (Exploded View)86157

4.2L IN-LINE 6 (CYLINDER HEAD) 299RemovalWarning! DO NOT remove the cylinder block drain plugsor loosen the radiator draincock with the system hot andpressurized because serious burns from the coolant canoccur.1.2.3.4.5.6.7.8.9.10. Disconnect the ignition wires and remove the spark plugs.11. Disconnect the temperature sending unit wireconnector and battery negative cable.12.13.Drain the coolant. Disconnect the hoses at thethermostat housing.Note: DO NOT waste reusable coolant. If the solutionis clean and is being drained only to service the engineor cooling system, drain the coolant into a cleancontainer for reuse.Remove the air cleaner.Remove the fuel pipe and vacuum advance hose.Remove the cylinder head cover. Refer to CylinderHead Cover Removal, in this section, for theprocedure.Remove the capscrews, bridge and pivot assembliesand rocker arms. Alternately loosen each capscrew,one turn at a time, to avoid damaging the bridge.Remove the pushrods. Retain the pushrod, bridges,pivots and rocker arms in the same order as removed tofacilitate installation in the original locations.Disconnect the power steering pump bracket. Set thepump and bracket aside. DO NOT disconnect thehoses.Remove the intake and exhaust manifolds from thecylinder head. Refer to the service manual for theproper procedures.If equipped with air conditioning, perform thefollowing:a. Remove the air conditioner compressor drive beltidler pulley bracket from the cylinder head.b. Loosen the alternator drive belt and remove thealternator bracket-to-cylinder head mounting bolt.The serpentine drive belt tension is released byloosening the alternator.c. Remove the bolts from the A/C compressormounting bracket and set the compressor aside.Remove the ignition coil and bracket assembly.Remove the cylinder head bolts, cylinder head andgasket.Cleaning and InspectionThoroughly clean the machined surfaces of the cylinderhead and block. Remove all gasket material and cement.Remove any carbon deposits from the combustionchambers and top of the pistons.Use a straightedge and feeler gauge to check the flatness of thecylinder head and block mating surfaces. Refer to 4.2L EngineSpecijkations, ‘Engine Assembly’ section of this chapter.InstallationIf the cylinder head is to be replaced and the original valvesused, measure the valve stem diameter. Only standard sizevalves can be used with a service replacement cylinder headunless the replacement head valve stem guide bores arereamed to accommodate oversize valve stems. Remove allcarbon buildup and reface the valves. Refer to ValveRefacing, ‘Camshaft and Valve Gear’ section of thischapter, for the proper procedure.1. Install the valves in the cylinder head usingreplacement valve stem oil deflectors (Figure 5-5).Refer to Installation-Cylinder Head Removed,‘Camshaft and Valve Gear’ section of this chapter, forthe proper procedure.2. Use all of the components from the original cylinderhead that are not included with the replacement head.DO NOT install the temperature sending unit untilcoolant is installed. This permits trapped air to escapefrom the cylinder block and head. Refer to the servicemanual for the proper procedure.Caution: DO NOT apply sealing compound on thecylinder head and block gasket surfaces. DO NOT allowsealing compound to enter the cylinder bore.3.4.5.6.7.8.9.Position the composition gasket on the cylinder blockwith the word TOP facing up.Install the cylinder head. Tighten the bolts in thesequence shown to 115 Nom (85 ft-lbs) torque(Figure 4- 18).Note: The head gasket is made of aluminum-coatedembossed steel and does not require the head bolts tobe re-tightened.Connect the battery negative cable.Install the ignition coil and bracket assembly.Install the spark plugs and connect the ignition wires.Tighten the spark plugs to 38 Nem (28 ft-lbs) torque.Attach the air conditioner compressor mountingbracket to the cylinder head, if removed.Install the intake and exhaust manifolds. Use thecorrect tightening sequence. Refer to the servicemanual for the proper procedures.

l- --r ‘7300 MOPAR PERFORMANCE PARTS10. Install the alternator bracket bolt on the head. Installthe alternator belt and adjust the tension.RETAINERS11. Install the power steering bracket and pump. Adjust thebelt tension. Refer to the service manual for drive belt(including serpentine) adjustment procedures.12. Install the pushrods in the same order they wereremoved.13. Install the rocker arms and the bridge and pivotassemblies in the order removed. Loosely install thecapscrews for each bridge and tighten alternately, oneturn at a time, to avoid damaging the bridge. Tightenthe capscrews to 26 Nam (1 9 ft-lbs) torque.14. Install the cylinder head cover.15. Connect the hoses to the thermostat housing and fill thecooling system to the specified level. Refer to theservice manual for the proper procedure.16. The automatic transmission throttle linkage and cablemust be adjusted after completing the cylinder headinstallation. Refer to the service manual for the properprocedures.17. Install the temperature sending unit and connect thewire connector.18. Connect the fuel pipe and vacuum advance hose.Warning! Use extreme caution when the engine isoperating. DO NOT stand in direct line with the fan.DO NOT put hands near the pulleys, belts or fan. DONOT wear loose clothing.19. Operate the engine with the radiator cap off. Inspect forleaks and continue operating the engine until thethermostat opens. Add coolant, if required.20. Install the air cleaner.VALVE STEM)IL DEFLECTORS\I I\Figure 5 - 5CYLINDER HEAD COVERCrankcase BreatherCYLINDERHEADA universal high performance re-usable crankcase breather(must have stand pipe on valve cover). Washes clean withE’4529392 cleaning fluid for extra miles of service.F’4529394 Crankcase breather.RemovalDisconnect the battery negative cable.Remove the air cleaner and the PCV molded hose.Disconnect the distributor vacuum advance hose at thedistributor.Disconnect the fuel pipe at the fuel pump. Rotate thepipe as necessary to provide clearance for the cylinderhead cover removalhstallation.Remove the PCV valve from the cylinder head covergrommet and disconnect the PCV shutoff valvevacuum hose (Figure 5-6).Remove the vacuum switch and bracket assembly fromthe cylinder head cover.

4.2L IN-LINE 6 (CYLINDER HEAD) 3017. Remove all the necessary vacuum and air hoses toprovide clearance for the cylinder head coverremovalhnstallation. Identify and tag the hoses forinstallation reference.8.9.Remove the cylinder head cover retaining bolts.Detach the cover from the cylinder head by breakingthe silicone rubber seal with a putty knife or razorblade. DO NOT attempt to pry the cover up until theseal has been completely broken.10. Rotate the cylinder head cover toward the passengerside and remove the cover.Inspection and CleaningReplace the cover if it is cracked or damaged in any way. Ifthe pre-cured RTV seal is damaged, replace the cover.If a replacement cover is installed, transfer the PCV valvegrommet and oil filler cap from the original cover to thereplacement cover.Remove any original sealer from the cover sealing surfaceof the cylinder head and clean the surface using a fabriccleaner. Remove all residue from the sealing surface usinga clean, dry cloth.InstallationCYLINDER H'EADCOVER1.2.3.4.5.6.7.Install and tighten the cylinder head cover bolts to 8Nem (70 in-lbs) torque.Connect the fuel pipe and the distributor vacuumadvance hose.Reposition and/or connect all the air and vacuum hosesthat were moved for cover removal clearance.Connect the PCV valve and the PCV shutoff valvehose.Install the air cleaner hoses.Connect the battery negative cable.Check the engine oil and add oil, if necessary.Figure 5 - 6

302 MOPAR PERFORMANCE PARTSCAMSHAFTCamshaft and Valve GearThe 4.2L engine uses a cast iron camshaft with intake andexhaust valve lifts of 10.29 mm (0.405”), intake andexhaust cam lobe lifts of 6.43 mm (0.253”), and intake andexhaust durations of 262”.The camshaft is supported by four steel-shelled, Babbitlinedbearings which have been pressed into the block andline reamed. The camshaft bearings are step bored, beinglarger at the front bearing than at the rear, to permit easyremoval and installation of the camshaft. All camshaftbearings are lubricated under pressure.Note: It is not advisable to replace camshaft bearings unlessyou are equipped with special removing, installing andreaming tools.Camshaft end play is maintained by the load placed on thecamshaft by the oil pump and distributor drive gear.The helical cut of the gear holds the camshaft sprocketthrust face against the cylinder block face. Therefore,camshaft end play is zero during engine operation.Jeep Gear DrivesReplace conventional Jeep timing chain and gear sets andeliminate chain induced cam timing fluctuations with thisMopar Performance Parts dual idler gear drive camshaftcenterlining drive system. Rugged and durable for off-roadapplications. Fits all 4.0L, 4.2L, and 2.5L Jeep engines.PS249009RemovalJeep gear drives.Warning! The coolant in a recently operated engine is hotand pressurized. Release the pressure before removing thedraincock, cap and drain plugs.1.2.3.4.5.6.Disconnect the battery negative cable.Drain the cooling system.Note: DO NOT waste reusable coolant. If the solutionis clean, drain it into a clean container for reuse.Remove the radiator. Refer to the service manual forthe proper procedure.Remove the air conditioner condenser andreceiveddriver assembly as a charged unit, if equipped.Refer to the proper service manual for additionalinformation pertaining to the N C system.Remove the distributor and ignition wires.Remove the fuel pump. Refer to the proper servicemanual for the procedure.7. Remove the cylinder head cover. Refer to CylinderHead Cover Removal, ‘Cylinder Head’ section, for theprocedure.8. Remove the capscrews, bridge and pivot assemblies,and rocker arms.9. Alternately loosen each capscrew one turn at a time toavoid damaging the bridges.10. Remove the pushrods. Position all components on aworkbench in the same order as removed to facilitateinstallation at the original locations.1‘1. Remove the cylinder head and gasket. Refer toCylinder Head Removal, ‘Cylinder Head’ section ofthis chapter, for the procedure.1’2. Remove the hydraulic valve tappets. Refer toHydraulic Valve Tappet Removal, in this section, forthe procedure.13. Remove the vibration damper. Refer to VibrationDamper Removal, ‘Crankshaft’ section of this chapter,for the procedure.14. Remove the timing case cover. Refer to Timing CaseCover Removal, ‘Crankshaft’ section of this chapter,for the procedure.15. Remove the timing chain and sprockets. Refer toTiming Chain and Sprockets Removal, ‘Crankshaft’section of this chapter, for the procedure.16. Remove the grille. Refer to the proper service manualfor the procedure.17. Remove the camshaft.Inspection1.2.3.4.5.Inspect the cam lobes for wear.Inspect the bearing journals for uneven wear patternor finish.Inspect the bearings for wear.Inspect the distributor drive gear for wear.If the camshaft appears to have been rubbing against thetiming case cover, examine the oil pressure relief holes inthe rear cam journal to ensure that they are free of debris.Installation1. Lubricate the camshaft with Mopar Super OilConditioner, or equivalent.2.Carefully install the camshaft to prevent damage to thecamshaft bearings.T - T 1

~4.2L IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 3033.4.5.6.7.8.9.1011Install the timing chain, crankshaft sprocket andcamshaft sprocket with the timing marks aligned.Refer to Timing Chain and Sprockets Installation,‘Crankshaft’ section of this chapter, for the procedure.Install the camshaft sprocket retaining bolt and tightento 108 Nom (80 ft-lbs) torque.Install the crankshaft oil slinger.Install the timing case cover with a replacement oilseal. Refer to Timing Case Cover Installation,‘Crankshaft’ section of this chapter, for the procedure.Install the vibration damper. Refer to VibrationDamper Installation, ‘Crankshaft’ section of thischapter, for the procedure.Install the damper pulley, if removed.Install the fan assembly and shroud.Install the drive belt(s) and tighten to the specifiedtension. Refer to the proper service manual for theprocedure.Install the fuel pump.12. Rotate the crankshaft until the No. I piston is at theTDC position on the compression stroke.13. Install the distributor, cap and ignition wires. Install thedistributor so that the rotor is aligned with the No. 1cylinder spark plug terminal on the cap when thedistributor housing is fully seated on the cylinderblock.Lubricate the hydraulic valve tappets and all valveactuating components with Mopar Super OilConditioner, or equivalent, during installation. TheMopar Super Oil Conditioner must remain with theengine oil for at least 1,609 km (1,000 miles); however,it does not have to be drained until the next scheduledoil change.14. Install the hydraulic valve tappets.15. Install the cylinder head. Refer to Cylinder HeadInstallation, ‘Cylinder Head’ section of this chapter,for the procedure.16. Install the pushrods.17. Install the rocker arms and pivot and bridgeassemblies. Tighten each of the two capscrews foreach bridge alternately, one turn at a time, to avoiddamaging the bridge.18. Install the cylinder head cover. Refer to Cylinder HeadCover Installation, ‘Cylinder Head’ section of thischapter, for the procedure.19. Install the fuel pump. Refer to the service manual forthe proper procedure.20. Install the A/C condenser and receiveddrier assembly,if equipped. Refer to the proper service manual foradditional information pertaining to the A/C system.Caution: Both service valves must be opened beforethe air conditioning system is operated.21. Install the radiator, connect the hoses and fill thecooling system to the specified level. Refer to theservice manual for the proper procedure.22. Check the ignition timing and adjust as necessary.23. Install the grille. Refer to the service manual for theproper procedure.24. Connect the battery negative cable.Measuring Cam Lobe LiftCam lift is a function of camshaft lobe dimensions and maybe checked with a dial indicator.To check cam lift, remove the cylinder head cover andgasket, rocker arm assembly and spark plugs. Install a dialindicator on the end of the pushrod. A piece of rubbertubing may be used to secure the dial indicator plunger tothe pushrod.Rotate the crankshaft until the cam lobe base circle(pushrod down) is under the valve tappet. Set the dialindicator to zero and rotate the crankshaft to a point wheremaximum upward movement of the pushrod occurs.Read the travel at the dial indicator. An excess of minus.006“ from the specified dimensions indicates a defectivecam.VALVES AND VALVE SPRINGSRemoval -Cylinder Head Removed1. Use a valve spring compressor tool to compress eachvalve spring.2.3.Remove the valve locks, retainers, valve springs andvalve stem oil deflectors. Discard the oil deflectors.Remove the valves and place them in a rack in theorder in which they were removed.CleaningClean all carbon deposits from the combustionchambers, valve ports, valve stems, valve stem guidesand head.Clean all grime and gasket cement from the cylinderhead machined gasket surface...

304 MOPAR PERFORMANCE PARTSInspection0 Inspect for cracks in combustion chambers and valveports.0000Inspect for cracks on the exhaust seats.Inspect for cracks in the gasket surface at each coolantpassage.Inspect the valves for burned, cracked or warpedheads.Inspect for scuffed or bent valve stems.Replace valves displaying any damage.Valve RefacingI. Use a valve refacing machine to reface the intake andexhaust valves to the specified angle.2.After refacing, a margin of at least 0.787 mm (0.03 1")must remain. If the margin is less than 0.787 mm(0.03 1 'I), the valve must be replaced.Valve Seat Refacing1. Install a pilot of the correct size in the valve guide boreand reface the valve seat to the specified angle with agood dressing stone.2.3.Remove only enough metal to provide a smooth finish.Use tapered stones to obtain the specified seat widthwhen required.4. Control seat runout to a maximum of 0.0635 mm(0.0025"), using a dial indictor.Valve Spring Tension Test(Refer to Valve Spring Tension Test, 'Camshaft and ValveGear' section of the 4.0L engine chapter, for the properprocedure.)Installation - Cylinder Head Removed1.2.3.4.5.6.7.Thoroughly clean the valve stems and the valveguide bores.Lubricate the stem lightly.Install the valve in the original valve guide bore fromwhere it was removed.Install the replacement valve stem oil deflector on thevalve stem. If the oversize valve stems are used,oversize oil deflectors are required.Position the valve spring and retainer on the cylinderhead and compress the valve spring with a valve springcompressor.Install the valve locks and release the tool.Tap the valve spring from side to side with a hammerto ensure that the spring is properly seated on thecylinder head.VALVE STEM OIL DEFLECTORRubber valve stem oil deflectors are installed on each valvestem to prevent the oil used for rocker arm lubrication fromentering the combustion chamber through the valve guides.The oil deflectors should be replaced whenever valve serviceis performed or if the rubber has become hard and brittle.The valve spring is held in place on the valve stem by aretainer and a set of valve locks. The locks can be removedonly by compressing the valve spring. Whenever valvesprings are removed, they should be tested for correcttension and replaced if not within specifications.ReplacementNylon valve stem oil deflectors are installed on each valvestem to prevent lubricating oil from entering thecombustion chamber through the valve guide bores.Caution: Ensure that the valve stem is free of burrs or sharpedges before replacing the oil deflectors.Replace the oil deflectors whenever valve service isperformed or if the oil deflectors have deteriorated.Oil deflector replacement requires removal of the valvesprings. Refer to Valve and Valve Spring Removal - CylinderHead Removed, in this section, for the removal procedure...l- - i 7

4.2L IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 305VALVE GUIDESThe valve guides are an integral part of the cylinder headand are not replaceable. When the stem-to-guide clearanceis excessive, the valve guide bores must be reamed toaccommodate the next larger oversize valve stem. Reamvalve guide bores in steps, starting with a 0.0762 mm(0.003") oversize reamer and progress to the size required.Valve Stem-to-Guide Clearance MeasurementValve stem-to-guide clearance may be measured by eitherof the following two methods.1. Preferred Methoda. Remove the valve from the head. Refer to Valveand Valve Spring Removal - Cylinder HeadRemoved, in this section, for the procedure.b. Clean the valve stem guide bore with solvent and abristle brush.c. Insert the telescoping gauge into the bore of thevalve stem guide approximately 9.525 mm (375")from the valve spring side of the head with contactscrosswise to the cylinder head.d. Remove and measure the telescoping gauge with amicrometer.e. Repeat the measurement with contacts lengthwiseto the cylinder head.f. Compare the crosswise to lengthwisemeasurements to determine out-of-roundness. Ifthe measurements differ by more than 0.0635 mm(0.0025"), ream the guide bore to accommodate theoversize valve stem.g. Compare the measured valve guide bore diameterwith the diameter listed in 4.2L EngineSpecifications, 'Engine Assembly' section of thischapter. If the measurement differs from thespecification by more than 0.0762 mm (0.003"),ream the guide bore to accommodate the oversizevalve stem.2. Alternate Methoda. Use a dial indicator to measure the lateralmovement of the valve stem (stem-to-guideclearance) with the valve installed in its guide andjust off the valve seat. The correct clearance is0.00250.0762 mm (0.001-0.0031').b. If the indicated movement exceeds thespecification, ream the guide bore to accommodatean oversize valve stem.VALVE TIMING1.2.3.4.5.6.7.Disconnect the spark plug wires and remove the sparkplugs.Remove the cylinder head cover. Refer to CylinderHead Cover Removal, 'Cylinder Head' section of thischapter, for the procedure.Remove the capscrews, bridge and pivot assembly, androcker arms from above the No. 1 cylinder.Alternately loosen each capscrew, one turn at a time, toavoid damaging the bridge.Rotate the crankshaft until the No. 6 piston is at topdead center (TDC) on the compression stroke.Rotate the crankshaft counterclockwise (viewed fromthe front of the engine) 90".Install a dial indicator on the end of the No. 1 cylinderintake valve pushrod. Use rubber tubing to secure theindicator stem on the pushrod.8. Set the dial indicator pointer at zero.9. Rotate the crankshaft clockwise (viewed from the frontof the engine) until the dial indicator pointer indicates0.305 mm (0.012") travel distance (lift).10. The timing notch index on the vibration damper shouldbe aligned with the TDC mark on the timing degreescale.1 1. If the timing notch is more than 13 mm (1/2") awayfrom the TDC mark in either direction, the valvetiming is incorrect.12. If the valve timing is incorrect, the cause may be abroken camshaft pin. It is not necessary to replace thecamshaft because of pin failure. A spring pin isavailable for service replacement.

306 MOPAR PERFORMANCE PARTSROCKER ARMSRemoval1. Remove the cylinder head cover. Refer to CylinderHead Cover Removal, ‘Cylinder Head’ section of thischapter, for the procedure.2.3.4.Remove the two capscrews at each bridge and pivotassembly. Alternately loosen the capscrews one turn ata time to avoid damaging the bridges.Remove the bridges, pivots and corresponding pairs ofrocker arms and place them on a bench in the sameorder as removed.Remove the pushrods and place them on a bench in thesame order as removed.Cleaning and InspectionClean all components with cleaning solvent and usecompressed air to blow out oil passages in rocker armsand pushrods.Inspect the pivot surface area of each rocker arm.Replace any that are scuffed, pitted or excessively worn.Inspect the valve stem tip contact surface of each rockerarm and replace any rocker arm that is deeply pitted.Inspect each pushrod end for excessive wear andreplace as required. If any pushrod is excessively wornbecause of lack of oil, replace the pushrod and inspectthe corresponding hydraulic tappet.A wear pattern along the length of the pushrod is notnormal. Inspect the cylinder head for obstruction if thiscondition exists.Installation1. Install the pushrods in their original locations. Ensurethat the bottom end of each pushrod is centered in thetappet plunger cap seat.2.3.4.5.Install the rocker arms, pivots and bridge above eachcylinder from which they were originally removed.Loosely install the capscrews through each bridge.At each bridge, tighten the capscrews alternately oneturn at a time to avoid damaging the bridge. Tightenthe capscrews to 25 Nom (19 ft-lbs) torque.Install the cylinder head cover. Refer to Cylinder HeadCover Installation, ‘Cylinder Head’ section of thischapter, for the procedure.HYDRAULIC TAPPETS (LIFTERS)The hydraulic valve tappet consists of a body, plunger,plunger return spring, cap and lock ring.The tappet operates in a guide bore which has an oilpassage drilled into the adjoining main oil gallery.When the tappet is on the heel of the cam lobe, the plungerreturn spring indexes with an oil hole undercut in theplunger and allows the oil supply to be admitted through thetappet body. Oil under pressure flows into the body throughthe check valve assembly, maintaining the tappet fullycharged. This cycle of operation occurs when the tappetleaks some oil during the normal valve opening events.Contact with the cam lobe causes tappet body movement,closing the check valve and transmitting “zero-lash”movement of the pushrod to open the intake or exhaust valve.Noise DiagnosisA loud clicking noise is usually the result of the plungerstuck below its operating position or a check valve heldopen. A light clicking noise at idle is usually the result ofexcessive “leak-down” caused by wear or slight leakage atthe check valve and its seat.An intermittent noise is the result of dirt or chips stoppingthe check valve action or a lack of oil flow into the body. Ageneral tappet noise is, in most cases, due to a lack of oilvolume, pressure or aeration.A clickmg noise heard upon starting the engine, reducing inlevel and disappearing after a short period of time, isnormal. This noise is due to a slight oil leak-down conditioncaused by valve spring pressure exerted on the tappets.An individual noisy tappet can readily be located by placingone end of a length of heater hose at the pushrod end of therocker arm and the other end to the ear.The valve tappets should be cleaned and serviced at time ofengine overhaul or whenever excessive noise exists.RemovalRetain all the components in the same order as removed tofacilitate installation at the original positions.1. Remove the cylinder head cover. Refer to CylinderHead Cover Removal, ‘Cylinder Head’ section of thischapter, for the procedure.2,.Remove the bridge and pivot assemblies and rockerarms by removing the two capscrews at each bridge.Alternately loosen each capscrew one turn at a time toavoid damaging the bridges.3. Remove the pushrods.4. Remove the intake and exhaust manifolds. Refer to theservice manual for the proper procedure.

-r -nn4.2L IN-LINE 6 (CAMSHAFT AND VALVE GEAR) 3075. Remove the cylinder head and gasket. Refer toCylinder Head Removal, ‘Cylinder Head’ section ofthis chapter, for the procedure.6.Remove the tappets through the pushrod openings inthe cylinder block.Disassembly, Cleaning and InspectionPlace the components of each tappet in a separate location.This will greatly assist in the installation operation.1. Release the snap ring.2. Remove the following from the tappet body:3.4.5.6.a. plunger capb. metering valvec. plungerd. check valve assemblye. plunger return springClean the components of each tappet assembly incleaning solvent to remove all varnish, gum and sludgedeposits.Inspect for indications of scuffing on the side and baseof each tappet body.Inspect each tappet base for concave wear with astraightedge positioned across the base.If the base is concave, the corresponding lobe on thecamshaft is also worn. Replace the camshaft andtappets.AssemblyInstallationIt is not necessary to charge the tappets with engine oil.They will charge themselves within a very short period ofengine operation.1. Coat each tappet in Mopar Super Oil Conditioner, orequivalent.2. Install each tappet in the same bore from where it wasoriginally removed.3. Install the exhaust and intake manifolds. Refer to theservice manual for the proper procedure.4. Install the cylinder head and gasket. Refer to CylinderHead Installation, ‘Cylinder Head’ section of thischapter, for the procedure.5.6.7.8.9.Install each pushrod in the same location from whereremoved.Install the rocker arms and bridge and pivot assembliesat their original locations.Loosely install the capscrews through each bridge.Tighten the capscrews alternately, one turn at a time, toavoid damaging the bridges.Pour the remaining Mopar Super Oil Conditioner overthe entire valve actuating assembly. The Mopar SuperOil Conditioner must remain with the engine oil for atleast 1,609 km (1,000 miles); however, it does not haveto be drained until the next scheduled oil change.Install the cylinder head cover. Refer to Cylinder HeadCover Installation, ‘Cylinder Head’ section of thischapter, for the procedure.1. Install the following in the tappet body:2.a. plunger return springb. check valve assemblyc. plungerd. metering valvee. plunger capCompress the plunger assembly by exerting force on theplunger cap with the pushrod and install the snap ring.

308 MOPAR PERFORMANCE PARTSSYSTEM OVERVIEWA full pressure-type lubrication system is used, except forthe piston pins, which are lubricated through the connectingrod squirt holes and oil throw-off.Pressure is applied by a gear-type, positive pressure pumpmounted on a boss adjacent to the No. 4 main bearing location.Oil, drawn through the inlet screen and tube to the inlet sideof the oil pump, is driven between the gears and pump bodyto the pressure outlet portion of the oil pump where it isrouted through on oil galley to the inlet side of the full flowoil filter, and on into the main oil galley.Each main bearing and camshaft bearing is lubricated by oilfrom the main oil galley.Holes drilled in each connecting rod journal directlubrication to the connecting rod bearings. Oil throw-offfrom each connecting rod bearing lubricates the cylinderwalls and piston pins.Oiling SystemA small channel (squirt hole) located on the numbered side ofthe connecting rods and caps allows oil to lubricate thecamshaft lobes, tappets, piston pins and distributor drive gear.The hydraulic valve tappets are fed directly from the mainoil galley.Lulbrication is supplied to the timing chain and gears fromthe front camshaft bearing and returned to the crankcasethrlough a cavity under the front main bearing cap.Thlz oil supply for rocker arms and pushrods is obtained fromthe No. 3 cam bearing location, where oil from the mainlubrication galley is metered through a groove in thecamshaft bearing surface to a galley extending upwards tothe cylinder head gasket surface. At this point, the cylinderhead gasket forms a seal joining the cylinder block galleywith the adjoining galley in the cylinder head. Commencingat {he No. 5 rocker arm support, oil then flows into the rockerarrn shaft supplying lubrication to rocker arms and pushrods.Holes cast in the cylinder head return the oil to thecrankcase through the valve tappet area, which in turnlubricates the tappets.

4.2L IN-LINE 6 (OILING SYSTEM) 309SIX CYLINDER ENGINE ASSEMBLY -OIL PAN AND PUMP101 - Oil Filter By-Pass Valve Retainer2 - Oil Filter By-Pass Valve Spring3 - Oil Filter By-Pass Valve4 - Dowel Pin5 - Oil Pump-to-Cylinder Block Gasket6 - Oil Pump Body7 - Oil Pump Drive Shaft and Gear8 - Oil Pump Idler Gear9 - Oil Pump Cover10 - Oil Pan Timing Case Cover Seal11 - Oil Pan12 - Oil Pan Drain Plug13 - Oil Pan Drain Plug Gasket14 - Oil Pan Gasket Set15 - Oil Pan-to-Bearing Cap Seal16 - Oil Pump Idler Gear Shaft17 - Colter Pin18 - Release Valve Plunger19 - Oil Pump Strainer and Inlet Tube Assembly20 - Oil Pump Release Valve Spring21 - Valve Spring Release Cap22 - Oil Filter Element23 - Oil Filter By-Pass Connector881804.2L Engine Oil Pan and Pump (Exploded View)

31 0 MOPAR PERFORMANCE PARTSOIL PANRemoval1.2.3. Drain the engine oil.4. Remove the starter motor.5.6.7.8.Disconnect the battery negative cable.Raise and support the vehicle at the side sills.Remove the flywheel/torque converter housing accesscover.It may be necessary to raise the engine in order toremove the oil pan.Remove the oil pan bolts.Remove the oil pan by sliding it to the rear.CleaningClean the gasket and seal surfaces.Remove all sludge and residue from the oil pan sump.9. Lower and secure the engine if it was raised.10. Install the flywheel/torque converter housing accesscover.11. Install the starter motor.12. Raise the vehicle to remove the jackstands. Lower thevehicle.13, Connect the battery negative cable.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or fan. DO NOTwear loose clothing.14. Fill the oil pan with clean engine oil to the specifiedlevel. Start the engine and inspect for leaks.-OIL PAN-TO-BEARING OIL PAN OLL PANCAP SEAL GASKET SET TIMINGCASE COVERSEALInstallation(Refer to Figure 5-7.)1. Install a replacement oil pan front seal on the timing casecover and apply a generous amount of Mopar Gasket-ina-Tube(or equivalent) to the recesses in the tab ends.2. Cement the replacement oil pan side gaskets intoposition on the cylinder block.3. Apply a generous amount of Mopar Gasket-in-a-Tube(or equivalent) to the end tabs of the gaskets.4. Coat the inside curved surface of the replacement oilpan rear seal with soap.5. Apply a generous amount of sealant such as MoparGasket-in-a-Tube (or equivalent) to the gasketcontacting surface of the seal end tabs.6. Install the seal in the recess of the rear main bearingcap. Ensure that it is fully seated. Either one of twosealing methods may be used.7.8.a. A sealant such as Mopar Gasket-in-a-Tube (orequivalent) may be used instead of a gasket.b. If a gasket is used, coat both sides with a quickdrying adhesive such as Mopar Gasket Compound(or equivalent).Apply engine oil to the oil pan contacting surface ofthe front and rear oil pan seals.Install the oil pan. Tighten the 1/4-20 oil pan bolts to 9N*m (80 in-lbs) torque and tighten the 5/16-18 oil panbolts to 15 N*m (11 ft-lbs) torque. Tighten the drainplug securely.-OIL PANOIL PUMPFigure 5 - 7JEW-165A positive displacement, gear-type oil pump is used and isdriven by the distributor shaft, which in turn is driven by agear on the camshaft. The pump incorporates a pressurerelief valve to regulate maximum pressure. Crankcase oilenters the pump through a pick up tube and screenassembly which is press fit into the pump body.Oil pump removal or replacement will not affect distributortiming as the distributor drive gear remains in mesh withthe camshaft gear.Rerrtoval1. Drain the engine oil.2. Remove the oil pan. Refer to Oil Pan Removal, in thissection, for the procedure...

4.2L IN-LINE 6 (OILING SYSTEM) 31 1Caution: DO NOT disturb the position of the oil inlet tubeand strainer assembly in the pump body. If the tube is movedwithin the pump body, a replacement tube and strainerassembly must be installed to ensure an airtight seal.3. Remove the oil pump retaining bolts, oil pump andgasket (Figure 2-78).Gear End Clearance MeasurementRemove the cover retaining bolts and cover from the pumpbody.1. Preferred Methoda. Place a strip of Plastigauge across the full width ofeach gear (Figure 2-79).b. Install the pump cover and tighten the bolts to 8N*m (70 in-lbs) torque.c. Remove the pump cover and determine the amount ofclearance by measuring the width of compressedPlastigauge with the scale on the Plastigaugeenvelope.The correct clearance by this method is 0.05 1-0.152mm (0.002-0.006"). The preferred measurement is0.051 mm (0.002''). If the gear end clearance isexcessive, replace the oil pump assembly.2. Alternate Methoda. Place a straightedge across the ends of the gearsand the pump body (Figure 2-80).b. Select a feeler gauge that fits snugly but freelybetween the straightedge and the pump gears (Figure2-80).Using this method the correct clearance is 0.05 1-0.152mm (0.002-0.006"), with the preferred measurementbeing 0.051 mm (0.002"). If the gear end clearance isexcessive, replace the oil pump assembly.Gear-to-Body Clearance MeasurementWith both gears in place, measure the gear-to-bodyclearance by inserting a feeler gauge between the gear toothand the pump body inner wall, directly opposite the point ofgear mesh (Figure 2-81). Select a feeler gauge which fitssnugly but freely. Rotate gears to measure each tooth-tobodyclearance in this manner.Correct clearance is 0.051-0.102 mm with 0.051 mmpreferred (0.002-0.004" with 0.002" preferred). If the gear-tobodyclearance is more than specified, replace the oil pump.DisassemblyRemove the cotter pin and slide the spring retainer, springand oil pressure relief valve plunger out of the pump body.Inspect for binding condition during disassembly. Clean orreplace as necessary.Note: The oil inlet tube and strainer assembly must bemoved to allow removal of the relief valve. Install areplacement inlet tube and strainer assembly.AssemblyNote: Two relief valve plunger sizes (standard and oversize)are available. When replacing the valve, ensure that thecorrect replacement valve, standard size or 0.254 mm(O.OIOll) oversize plunger diameter, is obtained and installed.1.2.3.4.5.6.7.Install oil pressure relief valve plunger, spring, retainer,and cotter pin.If the position of the inlet tube in the pump body hasbeen disturbed, install a replacement inlet tube andstrainer assembly. Apply a light film of Permatex No. 2sealant, or equivalent, around the end of the inlet tube.Use an oil pump inlet tube installer tool to drive thetube into the body (Figure 2-82). Ensure the supportbracket is properly aligned.Install the idler gear and the drive gear assembly.Inspect the gears to ensure that a binding conditiondoes not exist before installing the oil pump.To ensure self-priming of the oil pump, fill the pumpwith petroleum jelly before installing the oil pumpcover. DO NOT use grease.Apply a bead of Loctite 515, or equivalent, and installthe pump cover.Tighten the cover bolts to 8 N*m (70 in-lbs) torque.Installation1. Install the oil pump with a replacement gasket. Tightenthe short bolts to 14 Nom (10 ft-lbs) torque and the longbolts to 23 Nom (17 ft-lbs) torque (Figure 2-78).2.3.Install the oil plan with replacement gaskets and seals.Refer to Oil Pan Installation, in this section, for theprocedure.Fill the oil pan with replacement engine oil to thespecified level.Oil Pressure Relief ValveThe oil pressure relief valve is not adjustable. A setting of75 pounds maximum pressure is built into the tension of thespring.In the relief position, the valve permits oil to by-pass througha passage in the pump body to the inlet side of the pump.The oil pump pick-up tube and screen assembly is a pressfit in the oil pump body.Caution: DO NOT disturb the position of the tubeassembly in the pump body unless absolutely necessary.In the event the tube is disturbed, it must be replaced witha new tube assembly.

31 2 MOPAR PERFORMANCE PARTSINDUCTION SYSTEMVehicles with the 4.2L (258 CID) six cylinder engine wereoriginally equipped with a model BBD two venturi,feedback-type carburetor (stock).The stepper motor included with this carburetor has twotapered metering pins. Each metering pin is moved in and outof the carburetor air cavity to achieve the proper aidfuel ratio.Induction Systemdiaphragm, which is held in its extended position by fuelpressure. Fuel flow from the pump remains halted untilexcess pressure is released through the fuel return tube oruntil the carburetor float needle moves off its seat. Thisprocedure continues as long as the engine is running.Mechanical fuel pumps cannot be overhauled. Replace anymlschanical fuel pump that fails either a pressure, capacity(volume) or vacuum test.Chrome Fuel Pump Block-Off PlateThis good looking chrome plate covers the hole left whenreimoving the mechanical fuel pump for replacement withan electric pump. Gasket included.P4.529404 Chrome fuel pump block-off plate.Fuel PumpEXHAUSTMANIFOLD /OXYGENSENSOR4.2L Intake and Exhaust Manifolds60116AThe 4.2L engine uses a single action, mechanical fuelpump. The fuel pump is comprised of an actuating lever, adiaphragm and spring, an inlet valve, and an outlet valve.An eccentric lobe on the engine camshaft operates the fuelpump lever, which is linked to the pump diaphragm. Thelever pulls the diaphragm to its extended position to pumpfuel into the inlet valve. When the carburetor float needlevalve closes, fuel pump output is limited to the amount thatreturns to the fuel tank through the fuel return tube. Thefuel accumulated in the fuel pump chamber prevents thediaphragm from relaxing. The actuating lever continues tomove up and down, but it is prevented from operating theComputerized Emission Control (CEC) FuelFeedback SystemThe CEC Fuel Feedback System on 4.2L six cylinderengines controls undesirable emission in to the atmosphereand maintains the ideal aidfuel ratio to provide an optimumbalance between emission control and engine performance.This is accomplished by use of a Micro-Computer Unit(MCU), several MCU input components and several MCUoutput components.The MCU monitors various engine operating conditions.Based on these conditions, the MCU may, depending on themode of operation, generate output signals to provide theproper aidfuel mixture, proper ignition timing and engineidle speed. Each system operates in two modes ofoperation: CLOSED LOOP and OPEN LOOP.Closed loop operation occurs when the aidfuel ratio isvaried according to the oxygen content in the exhaust gas.During open loop operation, the aidfuel ratio ispredetermined by the MCU for several engine operatingconditions, such as:Start-upCold engine operationWide open throttle (W.O.T.) engine operationWhen the engine is started, the MCU determines whichmode of operation (closed loop or open loop) is correct. Itcan determine this by monitoring the input signals from thevarious input components. Air and coolant temperatureinformation, engine rpm information and vacuum levels areall provided to the MCU for this determination.The MCU operates the system in the open loop mode basedon a priority rating for the various predetermined engineoperating conditions. It continues to operate the system andoutput components in the open loop mode until such time

4.2L IN-LINE 6 IlNDUCTlON SYSTEM) 313as the engine operating conditions indicate that the closedloop mode of operation is appropriate. At this time, theMCU shifts the operation to closed loop. Based upon theoxygen content in the exhaust gas and other inputs, itcontinues to operate the system in the closed loop mode andconstantly vanes the aidfuel ratio to maintain an optimum14.7: 1 ratio.As the engine operating conditions are constantlymonitored by the MCU, any change in condition such as theengine being placed in wide open throttle, is quicklydetected by the MCU. The MCU then places the systemback into the appropriate open loop mode of operation.JEEP 4.2L MULTIPOINT FUEL INJECTIONCONVERSION KIT INSTALLATIONINSTRUCTIONS~~Jeep 4.2L MPI Conversion KitThe Mopar Performance Parts 4.2L electronic fuelinjection kit is designed to make your 1981-90 Jeep moreefficient and powerful. The kit replaces the stockcarburetor, intake manifold, and other major componentswith multi-point fuel injection (MPI). Each cylinder hasits own injector that is activated sequentially with thefiring order to precisely control individual fuelrequirements. The MPI kit is self-compensating and runsequally well from sea level to terrain above 12,000 feet.Mechanical components are based from production 1995Jeep parts. Emissions exempt in CA under CARB E.O.D265-14.Note: Use of these MPI packages requires either damperkit P5249687 or P5249688.P52496 IOP52496 10198 1-90 manual transmission, CJ andYJ models.1981-90 automatic transmission, CJ andYJ models.Note 1: This product is intended for use on stock,unmodified, well maintained 1981-90 4.2L (258 CID)engines. Installation on engines with modified camshafts,increased compression ratio, or engines that are in poormechanical condition (such as low cranking compression orexcessive oil consumption) is NOT recommended.Note 2: This kit is emissions exempt in the State ofCalifornia under C.A.R.B. Executive Order D265-7. Thetune-up procedures and engine service are the same as a1994-95 4.0L Jeep Wrangler.Note 3: Please read these instructions thoroughly prior toinstallation of this kit. Check your parts against the bill ofmaterial included in the kit.Note 4: If spark knock (detonation) occurs, it isrecommended that 92 octane or better premium fuel be used.The use of Mopar combustion chamber cleaner will reducecarbon deposits and help reduce spark knock.Note 5: This is a universal kit. Some part(s) in this lut maynot be used in every installation.Note 6: Keep all parts removed from the engine untilinstallation is complete. You may need them later.Disassembly1.2.3.4.5.6.Disconnect the ground cable from the battery and drainthe coolant from the radiator.Loosen the power steering pump and the alternator andremove the drive belts. Remove the two bolts that holdthe power steering pump to the water pump. Removethe two nuts from the rear power steering pump bracket(DO NOT throw this bracket away-you will need tomodify and re-install later), then slide the pumpforward to disengage it from the rear bracket. Removethe rear bracket from the intake manifold.Remove the air cleaner assembly as a unit and discard it.Remove all of the production emissions controls fromthe engine, including the three (3) solenoids located ontop of the valve cover, the vacuum switch assemblyand any lines and delay valves connected to thecarburetor. All the wiring that goes to all the emissioncontrols including the wires connected to the oldcarburetor can be completely removed. You can alsoremove the small computer that controls the carburetor.Note 1: CJ models have the carburetor computermounted behind the glove box. If you want to removethe computer by taking it out the glove box, you can. Ifyou do not remove the computer, it will not hurtanything. Just be sure to cut the wires going throughthe firewall, push the wires in toward the computer andseal up the hole (silicone/RTV works great).Note 2: Refer to the Production Emissions Schematicor the proper service manual for your particular yearvehicle.Remove the pulse air valves, which inject fresh airupstream and downstream of the catalytic converter,and all associated fittings.Disconnect the heater hose from the fitting on theintake manifold. Remove the throttle linkage andthrottle cable. Remove the carburetodintake manifoldassembly. This will require removing the tube thatconnects the exhaust manifold to the EGR valvemounted on the intake manifold. DO NOT throw thisEGR tube away - you will need later at installation.Note: It is not necessary to remove the exhaustmanifold.

31 4 MOPAR PERFORMANCE PARTSRemove the stock mechanical fuel pump and fuel linesfrom the engine. Make sure to mark the linesPRESSURE and RETURN where you disconnect themat the fender well. Double check your marking-thePRESSURE line is the larger of the two lines!Caution: GASOLINE IS HAZARDOUS! WEAR eyeprotection and never work on a HOT engine or aroundFIRE OR FLAME!Disconnect the upper and lower radiator hoses andremove the radiator, fan shroud, engine fan, thermostathousing and crankshaft pulley. On engines with aserpentine belt drive, do not remove the crank pulley(dampener) at this time. Only V-belt engines get thefront pulley removed at this time, but not thedampener.Before you start removing any parts in this step, clearlymark on the distributor cap where the number one (#1)spark plug wire connects to the distributor. The #1 sparkplug is the plug at the front of the engine-the oneclosest to the radiator. Remove the plug wires anddistributor cap. Remove the #1 spark plug and rotate theengine in its normal direction until the #1 piston is onthe compression stroke. Make doubly sure that you areon the compression stroke when finding TDC. THIS ISVERY IMPORTANT. Note - we recommend removingall 6 plugs because it makes the engine much easier toturn over. The timing mark on the dampener should lineup with the “0” mark on the timing tab. Note-theengine does this twice per cycle! Looking through thestock fuel pump mounting boss, rotate the enginebackwards until the camshaft moves and note theamount of slack in the timing chain as degrees on thetiming tab. If the slack is more than 10 degrees, replacethe timing chain. Rotate the engine in the direction ofrotation to the “0” of the timing tab. Note the clockedposition of the distributor rotor (before removal).Loosen the hold down clamp and remove thedistributor. Remove the ignition coil and bracket anddiscard them. After removing the old distributor refer toFigure 5-11. Looking down the distributor hole, youwill see the oil pump slot. Position the oil pump slot tothe 11 o’clock position. This is very important and willmake the new distributor easier to install in the correctposition. Note the yellow indexing lock pin on thebottom of the distributor. DO NOT remove this pinuntil the distributor is installed. At this time, werecommend installing the new distributor. Be suredistributor gasket is located properly. This gasket islocated in the small parts box. After you have installedthe distributor correctly (Figure 5-12), make sure thatthe old dampener (still on the engine) is at “0” on thetiming tab. Now remove the indexing lock pin from thebottom of the distributor. It is very important that youremove this pin before you try to remove the olddampener from the engine.10. Using a suitable puller, remove the crankshaftdampener. You will need a new dampener: P5249688for serpentine belt, or P5249687 for V-belt drivenpulleys. See Figure 5-8 and Figure 5-9.11. Remove the brake booster fitting from the old manifoldand install it in the new manifold.12. Remove the windshield washer bottle and the charcoalfuel canister. Be sure to mark the vacuum lines that gofrom the fuel canister to the intake manifold and the fueltank.13. Remove the front three (3) driver’s side oil pan bolts.14. Remove the oxygen sensor from the exhaust manifold.15. If the vehicle has a catalytic converter, it will benecessary to seal the air injection tubes at the CAT andheader pipe. Seal by bending the end of the tube andcrimping..* . VIBRATION DAMPERFigure 5 - 8

4.2L IN-LINE 6 (INDUCTION SYSTEM) 315Figure 5 - 9Assembly1.2.Install the new oxygen sensor in the exhaust manifold.Cut off one end of the tube that went from the exhaustmanifold to the EGR valve and remove the tube nutfrom it. Install the saucer-shaped freeze plug into thehole in the exhaust manifold where you removed theEGR tube. Secure the freeze plug by tightening thenow free tube nut down against the freeze plug.3. Install the new distributor. (The distributor is shippedwith an indexing lock pin and will not rotate. DO NOTREMOVE THE PIN UNTIL THE DISTRIBUTOR ISINSTALLED .)Note: If you think the engine may have moved fromTDC, make sure the engine is at TDC on the crankshaftbalancer (Figure 5- lo). The oil pump should be in theposition shown in Figure 5-11. Install the hold downclamp and remove the white locking pin (Figure 5-12).CRANKSHAFTVIBRATION DAMPERTIMING MARKFigure 5 - 70

31 6 MOPAR PERFORMANCE PARTS/11 O'CLOCK POSITIONOllPUMPSLOTFigure 5 - I1Figure 5 - 12

4.2L IN-LINE 6 (INDUCTION SYSTEM) 3174. Install the combination fuel pump block-offplatehgnition coil bracket where you removed theoriginal fuel pump. Make sure that the block-off platehas a gasket. Install the coil with the plug wire terminaltoward the distributor (Figure 5- 13).5.Install the new crankshaft dampener. Torque the bolt to120 ft-lb.6. Install the pickup sensor bracket. The bracket bolts tothe oil pan where you removed the three (3) bolts instep #13 of the disassembly instructions. Install thepickup sensor on the bracket with the bolt provided(Figure 5-26).Note: There should be between .020" and .060"clearance between the sensor and the crankshaftdampener. This clearance is the thickness of the paperbutton on the end of the sensor. You push the sensor upagainst the dampener, then tighten the mounting screw.This will set the initial clearance (Figure 5-14 andFigure 5-26).Figure 5 - 13ICRANKSHAFTVIBRATION DAMPERTIMING MARK\ CRANKSHAFTSENSORFi!gure 5 - 14r

31 8 MOPAR PERFORMANCE PARTS7. Install the crankshaft pulley, the fan, and the radiator.Install the new 195 degree thermostat. This is critical.Temperature level of 195 degrees is critical for fuelsystem operation. Double check the thermostat andmake sure that it is installed in the housing correctly.Make sure that the thermostat itself does not dropdown when installing the housing onto the engine. Ifthat happens, the housing will leak. Just a smallamount of heavy grease will hold the thermostat inplace while you install the housing. Install the coolantsensor supplied into the new thermostat housing in the3/8“ pipe hole, then reinstall this new assembly on theengine. When installing radiator and heater hoses,reroute the new heater hose supplied, as it no longergoes through the intake manifold.Figure 5 - 158.9.Note: On some serpentine belt engines, the CoolantTemperature Sensor will not fit in the thermostathousing. The idler pulley bracket is too close. If youhave this problem, you can install a 3/8“ pipe plug inthe thermostat housing and relocate the temp sensorinto the heater hose. You will need to splice an adapterinto the heater hose. The adapter is a “4 Seasons” partnumber 84540, should be available at your localhardware store or air conditioning supplier, or perhapsat your local auto parts store.Install the new intake manifold. You will only be ableto reinstall one of the power steering pump bracketbolts and you may have to trim the top lip off of thepower steering pump bracket to make it fit the newmanifold. With the new intake manifold, this bracketdoes not actually bolt to the manifold itself. Thebracket does not need to be bolted to the manifold andwill not cause any power steering pump mountingproblems. For a cleaner look to the engine, you mightwant to modify the bracket a little more beforeinstalling it to the back of the power steering pump.Just cut the bracket horizontally above the powersteering pump top bolt hole. This will eliminate theportion of the bracket that bolts to the intake manifold.DO NOT over tighten the intake manifold bolts! Bolttorque is 23 ft-lb (Figure 5-15). Take your timeinstalling these bolts. Make sure that all the intakemanifold cup washers are seated properly.Install the throttle cable and bracket (Figure 5- 16 andFigure 5-17).Figure 5 - 16

4.2L IN-LINE 6 (INDUCTION SYSTEM) 319Figure 5 - 1710. On automatic transmission vehicles, the kickdownlinkage must be installed (Figure 5- 18, Figure 5-19 andFigure 5-20). Once these parts are assembled, youshould set the adjustment. Rotate the throttle body towide open throttle. This will cause the cable to ratchetto the proper zero clearance (Figure 5-19). At this time,verify that the throttle linkage works smoothly andreturns to IDLE (closed throttle).11. Reinstall power steering pump bracket and belts.Tension the belts. The hole in the bracket may need tobe enlarged slightly.12. Connect the new fuel lines to the fuel rails and attach tothe mounting bracket on the new intake manifold. Findthe fuel inlet line where it was connected to the stockmechanical fuel pump (Note: Some CJ models have thefuel supply line routed down the right passenger side ofthe vehicle.) Trace this line back across the engine bay tothe driver's side frame rail. Cut this line and the fuelreturn line a few inches behind the front leaf spring eye.Bend them up slightly to align with the new fuel linesthat come from the MPI fuel rail. Connect the lines withthe 5/16" fuel hose and clamps provided. Note: The newfuel lines look almost identical. You will note that onehas an orange dust cap over the quick connect. This is thereturn line, or fuel out, and has the smaller O-rings inside.It connects to the new fuel rail on the forward end of theline coming out of the fuel pressure regulator. Thepressure line has a yellow dust cap over the quickconnect which has the larger O-rings inside andconnects to the second connection on the fuel rail. IT ISIMPERATIVE THAT THESE LINES ARECONNECTED PROPERLY. Improper connection cancause damage to the fuel pump. THE RETURN FUELLINE GOES FROM THE FUEL REGULATOR (on thefuel rail) BACK TO THE FUEL TANK.Note: On models with the fuel supply line on the rightside, carefully route the line around to the fuel railsimilar to the O.E. setup.Note: (CJ Models Only): If you have a CJ model thathas the pressure line running down the passenger side ofthe vehicle, the best way to route this line is to use a5/16" fuel injection hose. 1.) Look to see how much5/16" fuel injection hose you are going to need. 2.)Attach one end of the fuel injection hose to the hard linethat runs down the passenger side of the vehicle from thefuel tank. 3.) Route this line forward toward the radiator.4.) Then route the line under the radiator toward thedriver's side, and then back down the driver's side framerail. When you have reached the end of the pressure linecoming off the fuel rail, attach the 5/16" fuel injectionhose to the hard line (again using two small hoseclamps). Be very careful with the routing of this fuelline. Make sure that your bends are not restricting anyfuel flow and fuel lines are not routed near the exhaust.Caution: If you buy any fuel line to hook up the fuelpump, make sure it is rated to handle EFI pressures!

T - T 7320 MOPAR PERFORMANCE PARTSFigure 5 - 18Figure 5 - 1977IFigure 5 - 20I

4.2L IN-LINE 6 (INDUCTION SYSTEM) 32113. Install the fuel pump as follows:a. Jack up the rear of the vehicle and place on jackstands. From under the vehicle looking to the rearyou will notice a crossmember in the frame aboveand behind the axle housing. On the driver's side ofthis crossmember you will notice a rubber blockwith three (3) flexible fuel lines emerging from it.The lines turn 90 degrees toward the frame and areconnected to hard lines with clamps. On the flangeof the crossmember are three (3) bolts that attachthe fuel tank skid pan to the crossmember.Note: (CJ Models Only): If you have a CJ withthe fuel line running down the passenger side of thevehicle, jack up the rear of the vehicle and place onjack stands. From under the vehicle looking towardthe rear, you will notice a crossmember in theframe where the skid plate for the gas tank isattached. On the driver's side of this crossmemberyou will notice the hard fuel lines coming through.The best way to mount the fuel filter and pump isas follows-with the fuel pump and filter in hand,use about 4 or 5 inches of the fuel hose supplied inthe kit and connect the outlet side of the fuel filterto the inlet side of the fuel pump (use hose clampson both connections). Now look at the existinghard fuel line on the vehicle. You will need to takeoff the small clamps holding the fuel line to thecrossmember and to the passenger side frame rail.Once you have the fuel line free, use a small pipecutter to cut the hard line close to the bend on therear of the passenger frame rail. This is where theoutlet side of the fuel pump will be attached withsome of the supplied fuel hose. Now use the smallpipe cutter to cut the fuel line at the rearcrossmember before the hard line goes through thecrossmember to the fuel tank. This is where theinlet side of the fuel filter is attached with the restof the supplied fuel hose. Take the bolt in the centerof the crossmember and the bolt closest to thepassenger side frame rail out. Now mount the fuelpump and fuel filter assembly. Make sure that thefuel pump bracket nut is facing the front of theJeep. Put the bolts you removed back in facingtoward the ground. This will make them easier totighten. The fuel pump is mounted on thepassenger side bolt hole and the fuel filter ismounted in the center bolt hole.Note: Look at the terminals on the fuel pump(before installing). There is a positive and negativeterminal. Mark them so you can find the properterminal when you wire them. They are hard to seeafter the pump is installed.b. Remove the center bolt.c. Disconnect the center fuel line from its hard line atthe clamp. Reconnect this flexible line to the outletside of the new fuel pump.d. Mount the fuel pump assembly to the crossmemberflange using the nut and lock washer provided.e. Connect the 5/16'' flexible fuel line from the newfuel pump inlet to the outlet of the new fuel filter.Connect the inlet side of the fuel filter to the fueltank outlet, in the same manner. This location ofthe fuel filter is important to keep debris from thetank out of the fuel pump. The fuel filter is not tobe located downstream from the pump.14. Install the new charcoal canister in the stock locationand hook up the new vacuum lines. (Figure 5-21,Figure 5-22 and Figure 5-23.) Some engines will notuse the plastic valve cover fittings. The many differentvalve covers have different PCV and fresh air fittings.Make sure to use the stock 258 PCV valve or orifice atone end of the valve cover and provide fresh air at theother end of the cover. It is important that the engine isventilated properly to meet emissions and reduce oilleaks caused by crankcase pressure.Note: This kit supplies a new mounting bracket for thecharcoal canister. Do not get frustrated trying to makethis bracket fit your vehicle. If the charcoal canisterworks better where the old canister mounted, just usethe old canister mount. Try to get the new canister asfar down as possible so there is room to mount thePCM (Powertrain Control Module).15. Install the new Powertrain Control Module (PCM)right above the charcoal canister on the bulkhead withthe supplied hardware. Figure 5-24 shows thecomputer being mounted vertically. If the computerwill not fit vertically, you can mount the computerhorizontally (Figure 5-25). If you mount the PCMhorizontally, make sure that the connector plugs intoward the bottom of the PCM.Note: Some models may vary in the space to mountthe PCM, however, it should fit in this approximatelocation. DO NOT OVER TIGHTEN SCREWS.16. Plug in the wiring harness to the PCM using the 60-pinconnector. DO NOT OVER TIGHTEN THECONNECTOR! Drape the harness over the top of themaster cylinder, then around the back side of theengine.Caution: THE HARNESS MUST NOT BE CLOSETO THE EXHAUST; USE TIE WRAPS TO SECUREIT OVER THE MASTER CYLINDER (Figure 5-24).

322 MOPAR PERFORMANCE PARTSCCV HOSEFRESH \AIR -1CLEANERFigure 5 - 21ORIFICE/IIFigure 5 - 22.. T -17

4.2L IN-LINE 6 (INDUCTION SYSTEM) 323IIFigure 5 - 23Figure 5 - 2417. Find the two relays on the harness a short distancefrom the PCM. Mount them to the bulkhead with thescrews provided. Note: Mount the relays with the wirespointed down. This is to prevent water build-up withinthe relays. The PCM may be mounted at any angle,however, do NOT mount it with the wire connectorfacing up. This would allow water to pool in theconnector! The PCM is waterproof. The 60-pinconnector is splash proof, but will not work whenimmersed in water.18. Mount the MAP sensor to the bulkhead right behindthe engine with the screws provided. Plug the greenthree (3) prong plug from the harness into the MAPsensor.Figure 5 - 2519. Route the harness down along the valve cover towardthe front of the engine. Connect the fuel injectors. Eachone is marked where it goes.20. In the center of the harness between injector plugs #3and #4 is a group of four plugs. Connect three (3) ofthese to the throttle body in their respectivereceptacles, and the fourth one to the Manifold AirTemperature (MAT) sensor (Figure 5-22).21.22.In the harness at the front of the engine is anothergroup of three (3) plugs. One of them is very long; thisis the Oxygen Sensor plug. The three (3) prong plug inthis group is the pickup sensor plug. The other (twoprong) plug is the coolant sensor plug. These will onlyplug in to the correct sensors. Secure the cables with tiewraps provided. Make sure the pick up sensorconnector is tied away from the exhaust manifold.Bend the harness toward the passenger side of theJeepB and down along the spark plug side of the head.The next plug is the ignition coil connection. Thencomes the harness ground with the distributor plug.Connect the harness ground under the bolt that holdsthe dipstick tube to the engine block. (It has otherground wires on it. Do not remove any.) Connect thedistributor.23. Route the rest of the harness along the top of thetransmission. The next plug will be the vehicle speedsensor. Route the remaining harness along the framerail to the rear of the JeepB to connect the fuel pumppower (+) to the green wire with the black stripe. Theground wire is black with an orange stripe. Secure theharness all along its length in strategic locations withthe tie wraps provided. Make sure that there isclearance between any moving parts or areas of hightemperature, such as the vehicle exhaust. You maywant to use dielectric grease on the connections toprevent corrosion (Mopar part number 58 126688).

324 MOPAR PERFORMANCE PARTS24. To supply a switched 12 volt power supply to the twobulkhead mounted relays, locate the old positive (+)side coil wire (usually a yellow color). Connect thiswire to the relay wire. Now connect the red relay wireto the starter relay, battery plus (+). The starter relay(also known as the starter solenoid) is usually locatedunder the battery box or mounted on the fender panel.Mount the system fuse.Note: Make sure that the switched 12 volt wire is notrouted through a ballast resistor or resistance wire.Also make sure that 12 volts are present on this wireduring cranking!25. Install the 7.5 amp diode (supplied) in the field wire ofthe alternator. This is the smaller of the two wires,usually brown in color, that plugs into the alternator.Note-the field wire is a solid wire not a stranded wire.Cut the wire and install the diode with the pink crimponconnector facing toward the alternator. It isimperative that this diode be in the field circuit toprotect the new electronics.26. You may wish to install a new windshield washerbottle and bracket. These can be obtained through yourlocal JeepEagle dealer. Washer bottle part number is55 154744; bracket is 55026288. This washer bottleand bracket are supplied with this kit. You can mountthis anywhere you would like, but the correct place tomount it is on the back side of the driver’s side fenderwell. The fit is very tight but it does fit.27. Install the new air filter and bracket. It attaches to thedriver’s side body support rod. Connect the two 1/2”hoses, from the aluminum connectors, to the valvecover vent and the fuel canister vent line. Note-thelarge flexible intake hose can be cut off to the lengthyou need. In some vehicles, this flexible (CAT) hose istoo long.Figure 5 - 26

--T T-I4.2L IN-LINE 6 (INDUCTION SYSTEM) 32528. OPTIONAL: If you wish to install a tachometer or anengine light, the wires for these are already in theharness, located close to the relays. They will behanging out of the harness. The tachometer wire islight gray with a yellow stripe. This is the tachometertrigger wire. The O.E. 198 1-90 Jeep tachometer WILLNOT work with this system.Note 1: In most cases the tach on the 1988-90Wranglers will work with this MPI kit by connectingthe tach wire to the negative side of the coil. Thenegative coil wire is gray or gray with a black tracer.The tach wire switches a 5V signal two times perengine revolution. Set your aftermarket tach on the 4-cylinder scale to achieve a true rpm reading. Sometachs will not work with this 5V signal, or they mayhave needle flutter at low rpm. If this is the case, youwill have to splice into the coil negative side to operateyour tach. If you hook up to the coil, use the 6-cylindersetting on your tach. The coil negative side wire isgray. (Hook up the tach last, after the engine is running,because some tachs have a low impedance and willshort the coil to ground. This will not harm anything,but will prevent the engine from running.)Note 2: Earlier year models will have to purchase anaftermarket tach like P4529160-a 4-6-8 tach. Followthe tach instructions for installation. If the checkengine light comes on, please call the MoparPerformance Technical Assistance Hotline at 1-248-969- 1690.29. The “check engine light” wire runs directly to thePCM. The PCM grounds this wire to turn on a light todisplay fault codes (Figure 5-27).The light bulb holders are available at any localelectronics supply.30. On automatic transmission Jeeps, the brown wire that iscoiled near the PCM connector must be connected tothe neutral safety switch. This wire can be connected tothe bottom of the starter relay, or to the center terminalon the neutral safety switch. On Chrysler automatics,this is the center terminal. If you choose to connect it tothe starter relay, make sure that the terminal is for theneutral start switch. It should be grounded in park andneutral. This wire is for improved idle quality when in“Drive.”

T -- i ‘7326 MOPAR PERFORMANCE PARTS12v+ BlacWioletThe light bulb holders are available at any local electronics supply.Figure 5 - 273 1. Reconnect the battery and turn on the ignition key. Youshould hear the electric fuel pump run for a fewseconds and then shut off. Start the engine andIMMEDIATELY CHECK FOR FUEL LEAKS.Depending on the ambient temperature, the idle rpmmay be high initially, and decrease as the engine warmsup. This is normal! DO NOT try to adjust the rpm bychanging the opening of the throttle blade. Test Drive!Recheck all connectors and fuel lines!32. Be sure to apply the CARB E.O. decal supplied in theIut in a visible location under the hood.Troubleshooting NotesThe following hints we have found to be useful:1. This system is the same as used on the 1994 4.0LWrangler. If you need service parts or are checkingfault codes, refer to the 1994 Jeep@ Wrangler ServiceManual. The wiring is also the same as a 1994Wrangler in function and color. You may call 1-800-626- 1523 to order a service manual.2.3.The crankshaft sensor is very sensitive. Make sure it issolidly mounted. Make sure that your engine does nothave too much crankshaft end play. The paper buttonon the sensor will wear off with use of the engine.The distributor should not be turned to change timing. Itwill not. The distributor is set to have the rotor tip ,020”past #I spark plug terminal with the engine at TDC.4. The fuel return line to the tank must be unrestricted.Check this carefully before you hook up the returnhose.5.6.You may see fault codes for charging system too highor too low. This is normal and should be ignored.The PCM does take some time (15-30 minutes) afterfirst use to “learn” the best settings for your engine. Youwill notice better idle quality and acceleration after thislearning period. For this reason, the battery should beleft connected if this vehicle is to be driven daily. If youuse a kill switch, do not interrupt the B+ circuit or thePCM will need to “re-learn” every time you start theengine.Special Note: If your engine has been rebuilt and thecompression has been raised too far above stock, then youare probably going to experience some detonation.Installing headers, too large a camshaft, bigger valves,excessive porting or a combination of the above will alsocreate a detonation problem that cannot be adjusted outthrough the computer.If you have questions or experience problems, call theMopar Performance Technical Assistance Hotline forassistance at 1-248-969- 1690.

4.2L IN-LINE 6 (IGNITION SYSTEM) 327SOLID STATE IGNITION SYSTEMIgnitionA Solid State Ignition (SSI) system is used on the 4.2L sixcylinderengine. The SSI system is controlled by the engineMicro-Computer Unit. The SSI system consists of thefollowing components:Ignition moduleIgnition coilResistance wireDistributor0 Knock sensorDistributor cap and rotorSpark plugs and wiresSystem OperationThe ignition module is activated by the MCU when theignition switch is in the START or ON position. Theprimary circuit is closed and current flows through the coilprimary winding. When the engine begins turning thedistributor, the trigger wheel teeth rotate past the pickup,coil assembly. As each tooth aligns with the pickup coil, theresulting pulse triggers the MCU which in turn signals theignition module which closes the primary circuit. A highvoltage is then induced in the coil secondary winding andcurrent flows to the distributor cap and rotor. The rotorconnects the high voltage to the proper spark plug. Thetiming of the ignition is constantly changed by the MCU,and vacuum and centrifugal advance mechanismsaccording to engine operation.Ignition AdvanceCentrifugal (mechanical) advance is controlled by enginespeed. Flyweights connected to the distributor shaft arethrown outward by centrifugal force. Higher engine rpmthrows the weights further out. Calibrated rate springs areused to control this movement. The outward motion of theflyweights causes the rotor and trigger wheel to beadvanced on the distributor shaft several degrees in thedirection of normal rotation. This is referred to ascentrifugal ignition advance.When the engine is operating under light load, thecarburetor throttle plates restrict airflow, causing arelatively lean mixture to enter the combustion chambers.Ignition must occur earlier because the lean mixturerequires a longer time to bum. The vacuum ignitionadvance mechanism is used for this purpose. Whencarburetor ported or manifold vacuum is high, the vacuumadvance mechanism moves the pickup coil assemblyseveral degrees opposite to the direction the distributor isSystemrotating. This causes the pickup coil to react to the presenceof the trigger wheel teeth earlier. This process is referred toas vacuum ignition advance. With low vacuum operatingconditions, such as wide open throttle acceleration, a springin the vacuum advance mechanism pushes the pickup coilback to a position of zero advance.IGNITION SYSTEM COMPONENTSMicro-Computer Unit (MCU)The 4.2L engine’s ignition system is controlled by theMicro-Computer Unit (MCU). The MCU monitors variousengine sensors that indicate engine operating conditions.One of these inputs originates from the distributor andrepresents engine speed which is used to determine ignitiontiming. The MCU processes ignition signals and then sendsthem to the ignition module. By modifying the signal itsends to the ignition module, the MCU can retard ignitiontiming in response to the various inputs it receives. TheMCU also controls air-fuel ratio and the pulse air system.The MCU is a completely sealed module which is locatedbehind the glove box next to the radio. It is not repairableand must be replaced as a unit if service is required.Inputs:Outputs:Coolant temperature switchThermal electric switchFour and ten inch Hg vacuum switchesOxygen (02) sensorWide open throttle (W.O.T.) switchKnock sensorDistributor0 Stepper motorIdle relaySole-vac throttle positionerUpstream and downstream solenoidsPCV solenoidIgnition ModuleThe electronic ignition module is located in the enginecompartment behind the bottom of the radiator overflowbottle. It is a permanently sealed, solid state module that is notrepairable and must be replaced as a unit if service is required.

T - T l328 MOPAR PERFORMANCE PARTSThe Micro-Computer Unit (MCU) controls ignition coiloperation through the ignition module. The MCU processesthe ignition signals it receives and then sends a signal to theignition module. The ignition module then interrupts theprimary circuit to the ignition coil causing spark to occur.Dwell is adjusted automatically.Note: When disconnecting SSI system connectors, pullthem apart with a firm, straight pull. DO NOT attempt to prythem apart with a screwdriver. When connecting them, presstogether firmly to overcome hydraulic pressure caused bythe silicone dielectric compound. If the connector lockingtabs weaken or break off, DO NOT replace the associatedcomponent. Bind the connectors together with tape or aharness tie strap to assure good electrical connection.Ignition CoilThe ignition coil is mounted to the engine block next to thedistributor. Coil operation is dictated by the ignition modulewhich is controlled by the MCU maintaining the terminalsand connectors.When an ignition coil is suspected of malfunctioning, test iton the vehicle. A coil may “break down” after the enginehas heated it to a high temperature. It is important that thecoil be at operating temperature when tested. Perform thetest according to the test equipment manufacturer’sinstructions.Ignition Coil ConnectorThe ignition coil terminals and connector are of uniquedesign. The connector is removed from the coil by graspingboth sides and pulling away from the coil.When a tachometer is required for engine testing or tuneup,connect it using an alligator jaw type connector.Resistance WireA wire with 1.35 ohms resistance is provided in the ignitionwiring to supply less than full battery voltage to the ignitioncoil after the starter motor solenoid is de-energized. Duringengine starting, the resistance wire is bypassed and fullbattery voltage is applied to the ignition coil. The bypass isaccomplished at the I-terminal on the starter motor solenoid.DistributorThe distributor used with the 4.2L engine is equipped withcentrifugal and vacuum assisted advances. Ignition timing iscontrolled through the engine Micro-Computer Unit (MCU).The distributor consists of three groups of components:pickup coil and trigger wheel, ignition advancemechanisms, cap and rotor. The distributor drive gear isinstalled in the distributor shaft and meshes with a spiral cutgear on the camshaft. The end of the distributor shaft isflattened and fits into a slot in the top of the oil pump andprovides the force to drive the oil pump.Pickup Coil and Trigger WheelThe ignition coil primary circuit is opened and closedelectronically by the ignition module. The distributorpickup coil and trigger wheel provide the input signal forthe MCU.The trigger wheel, which is installed on the distributor shaft,has one tooth for each engine cylinder. The wheel is mountedso that the teeth rotate past the pickup coil one at a time.Thle pickup coil has a magnetic field that is intensified bythe presence of ferrous metal (contains iron-can be pickedup with an ordinary magnet). The pickup coil reacts to thetrigger wheel teeth as they pass. As a trigger wheel toothapproaches and passes the pole piece of the pickup coil, itreduces the reluctance (compared to air) to the magneticfield and increases field strength. Field strength decreasesas the tooth moves away from the pole piece. This increaseand decrease of field strength induces an alternating current(pulse) into the pickup coil, which triggers the MCU, whichin turn signals the ignition module. The control unit opensand closes the coil primary circuit according to the positionof the trigger wheel teeth.There aren’t any contacting surfaces between the triggerwheel and pickup coil assembly. The dwell angle isdetermined electronically by the control unit and is notadjustable. When the ignition coil primary circuit isswitched open, the MCU sends a signal to the ignitionmodule that starts an electronic timer in the ignition modulewhich keeps the coil primary only long enough for theelectromagnetic field within the coil to collapse and thevoltage to discharge. The ignition module thenautomatically closes the coil primary circuit. The period oftime the circuit is closed is referred to as dwell.Carp and RotorThe central tower on the distributor cap is connecteddirectly to the high voltage at the coil. The current flowsthrough the spring-loaded contact on the rotor to the carbonbutton in the cap. The rotor tip aligns with a contact in thecap that corresponds to the cylinder to be ignited just as theignition coil output high voltage is applied to the rotor. Inthis way, each spark plug is “fired’ in turn.A unique feature of the SSI is the silicone applied to therotor blade during the manufacture. Radio interference isgreatly reduced by the presence of a small quantity ofsilicone dielectric compound on the rotor blade. After a fewthousand miles, this compound becomes charred by the highvoltage current flowing through the rotor. This condition isnormal. DO NOT scrape residue from the rotor blade.When installing a replacement rotor, apply a thin coat0.75-3.0 mm (0.03-0.12”) of silicone dielectric compoundto the tip of the rotor blade.

4.2L IN-LINE 6 (IGNITION SYSTEM) 329IGNITION SYSTEM TIMINGA graduated timing degree scale located on the timing casecover is used for reference when timing the ignition system.A milled index notch on the vibration damper is used toalign the No. 1 cylinder ignition position of the crankshaftwith the correct timing degree mark on the graduated scale.Magnetic Timing ProbeA magnetic timing probe socket is provided and is integralwith the timing degree scale for use with a special magnetictiming probe. This special probe detects the milled notch onthe vibration damper. The probe is inserted through theprobe socket until it contacts the vibration damper.Ignition timing can then be obtained from a meter or computerprintout, depending on the type of equipment being used.The probe socket is located at 9.5" ATDC, and theequipment is calibrated to compensate for this location.DO NOT use the timing probe socket as a reference to checkthe ignition timing when using a conventional timing light.Ignition Timing ProcedureThe ignition timing can be adjusted according to thefollowing primary timing procedure.1. Set the parking brake. Shift automatic transmissions toPARK and manual transmissions to the NEUTRALposition.2.3.4.Start the engine and allow it to attain normal operatingtemperature. Ensure that the A/C is turned OFF, ifequipped.With the ignition switch OFF, connect an ignitiontiming light and a tachometer. (If the timing light hasan adjustable advance control feature, turn the controlto the OFF position.)Disconnect the 4" and IO" Hg (CEC System) vacuumswitch assembly wire connectors (located at the top ofthe cylinder head cover).5. Disconnect and plug the distributor vacuum advance hose.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or the fan. DONOT wear loose clothing.6. Start the engine.7. Increase the engine speed to 1,600 rpm and checkignition timing. If necessary, adjust the timing to thespecifications listed on the Emission Control Informationlabel. Also, refer to the ignition advance curveillustrations found in your vehicle's service manual.8.Tighten the distributor hold-down clamp and verifythat the ignition timing is correct.9. Turn the engine OFF and remove the timing light andtachometer.10. Connect the No. 1 spark plug wire, if disconnected.Connect the hose to the distributor vacuum advancemechanism. Connect the wire connector to the vacuumswitch assembly.Note: Ignition timing can also be adjusted according to thefollowing alternate procedure.Alternate Timing ProcedureThis alternate timing procedure does not require enginespeed be increased to 1,600 rpm.1.2.3.4.5.6.7.8.9.Set the parking brake.Shift automatic transmissions to PARK and manualtransmissions to the NEUTRAL position.Start the engine and allow it to attain normal operatingtemperature. Ensure that the A/C is turned OFF, ifequipped.With the ignition switch OFF, connect an ignitiontiming light and a tachometer. (If the timing light hasan adjustable advance control feature, turn the controlto the OFF position.)Disconnect the 4" Hg vacuum switch hose (located atthe top of the cylinder head cover) and plug the hoseopening. (The 4" Hg vacuum switch has black and redwires connected to it.)Disconnect the distributor vacuum advance hose andconnect the hose to the 4" Hg vacuum switch.Disconnect the knock sensor wire connector andconnect the wire connector to the cylinder block(GROUND) with a jumper wire.Grounding the knock sensor wire connector preventselectromagnetic interference (EMI) from causingerroneous reactions by the fuel feedback system microcomputerunit (MCU).Start the engine.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan.,DO NOT put your hands near the pulleys, belts or thefan. DO NOT wear loose clothing.With the engine at idle speed, check the timing. Ifnecessary, adjust the timing one degree higher than thespecifications listed on the Emission ControlInformation label. Also, refer to the ignition advancecurve illustrations.Note: With the alternate timing procedure, the basic timingmust be one degree higher than the specification listed onthe Emission Control Information label. For example, if thetiming specification is listed as 6" (+2") at 1,600 rpm, thealternate procedure requires 7" (+2") at idle speed.

~330 MOPAR PERFORMANCE PARTSSPARK PLUG SPECIFICATIONSSPARK PLUG ELECTRODE TIGHTENINGENGINE TYPE __ GAPTORQUE4.2L RFN- 14LY (0.035 in.) 37 Nom (27 ft-lbs)Mopar Performance Parts Spark PlugsNEW! These spark plugs are specifically designed for the optimum performance of your Moparengine. Each package contains 4 spark plugs.P4876939P4876940P487694 1P4876942P4876943P4 8 7 6944Race & Tuning Application Plugs (J-Strap Type)Pack P/N I Cross Reference IC 63C 1 AII except ‘B-RB’ enginesC 61C to C 59Cc 57c to c 55cc 53c to c 51cC s1cC 61C to C 59CApplicationAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesP4876945 c 57c to c 55c 1 ~ 1except 1 ‘B-RB’ enginesPack PINP4876928P4876929Cross ReferenceC 61C to C 59Cc 57c to c 55’CApplicationAll Race ApplicationsAll Race ApplicationsP4876930 1 C 53C to C SIC 1 All Race ApplicationsP487693 1P48 7 69 3 2S 61C to S 59Cs 57c to s 57cS 53C to S 51CAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsNote:C type plugs have 3/4 inch reach with flat seat and crush gasket.S type plugs have 3/4 inch reach with tapered seat.

4.2L IN-LINE 6 (IGNITION SYSTEM) 331SSI DISTRIBUTOR AND IGNITION COIL SPECIFICAT1C)NSDISTRIBUTOR PICKUP COILRESISTANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .400 to 800 OHMS @ 24°C (75°F)IGNITION COILPRIMARY RESISTANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.13 to 1.23 OHMS @ 24°C (75°F)1.5 OHMS @ 93°C (200°F)SECONDARY RESISTANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7700 to 9300 OHMS 0 24°C (75°F)12,000 OHMS @ 93°C (200°F)MINIMUM OPEN CIRCUIT OUTPUTAT1,OOO RPM ...............................................................24KVSPARK PLUGSREQUIRED VOLTAGE AT 100 RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 TO 16KVMAXIMUM VARIATION BETWEEN CYLINDERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 TO 5KV

332 MOPAR PERFORMANCE PARTSMOPAR PERFORMANCE PARTS ELECTRONICIGNITION COMPONENTSHigh Performance Electronic Control UnitsFor a hotter spark and more rpm capability, use one of MoparPerformance Parts' high performance ECUs. For generalhigh performance and usage up through 6,000 rpm, use theOrange Box ECU. For higher rpm output requirements upthrough 8,OOO, select the Chrome Box ECU.P4 120505P4120534Orange Box ECU.Chrome Box ECU.~Super Gold Electronic Control UnitThe Super Gold Electronic Control Unit is the culminationof eight years of high performance ignition systemsdevelopment. Designed to out perform any ignition unitpreviously offered to Mopar racers, it will handle the highcurrent demand by the P3690560 (Accel) high performancecoil, while keeping dwell variation to less than 1" from1,000 to 10,000 rpm. Dwell is set for maximum sparkoutput at low and high engine speeds. The Super Gold ECUprovides outstanding performance from idle to 12,000 rpm.P4 I20600Super Gold ECU- race only.Ballast Resistor- Electronic DistributorP244464 1P5206436Use with mechanical advance distributorusing P3690560 coil. 1/4 Ohm.Use with electronic ignition systemsusing P4 120505 Orange Box ECU andproduction coil, or with P4 I20889 coil.1 Ohm.Ignition CoilsP4 120889P.3690560Accel Super Coil for all 12-voltapplications. Not recommended forengine speeds over 6,500 rpm. (Use withballast resistor P5206436.)Accel Race Coil specifically designed tobe used with race electronic ignitionkits. Designed for racing applicationsonly. Not recommended for continuedoperation at speeds below 3,000 rpm formore than 30 minute periods. (Use withballast resistor P2444641.)Control Wiring Harness Kit for ElectronicIgnitionsKit used to convert to a new electronic ignition system.F'3690152Control wiring harness kit for electronicignitions.~~~ ~Chrome Ignition Coil BracketAnother underhood piece to dress-up your enginecompartment. Includes special clamp screw.~4286728 Chrome ignition coil bracket.~~Tach AdapterDesigned for applications when high capacitive dischargecoils interfere with tachometer or fuel injection signals.This device provides a clear 12 volt square wave signal(output with a 30% duty cycle.P487673 8Tach adapter...

~ ~~~Engine Assembly4.2L IN-LINE 6 (ENGINE ASSEMBLY) 333Note: For engine assembly information, performance modifications and tips, refer to 'Engine Assembly' section of Chapter4,4.0L Power Tech In-Line 6.1981, 4.2L ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1!381 Jeep Sewice Manual.Type ...................(USA)1nCh.rUnlaOthnvviuSp.cifid(METRIC)MillimetersUnlasOtherwise-ifidIn Line, OHV, Six-CylinderBore ................... 3.7595.25Stroke258. ................. 3.895 98.93Displacement258. .................258 cubic inches 4.2 litersCompression Ratio ...........8.0: 1Compression Pressure258.. ................ 1M150pl 827-1034kPaMaximum Variation BetweenCy I i nden............... 30 psi 206 kPaFiring Order. ..............1-5-3-6-24Taxable Horsepower .......... 33.75 Bhp 25.2 kW...................Fuel.CamshaftFuel Pump Eccentric Diameter ....Tappet Clearance ............End Play. ................Bearing Clearance. ...........Bearing Journal DiameterNo. 1. ................No.2 .................No.3 .................No. 4. ................Base Circle Runout. ..........Cam Lobe Lift. .............Intake Valve TimingOpens. ................Closes. ................Exhaust Valve TimingOpens. ................Closes. ................Valve Overlap ..............Intake Duration. ............Exhaust Duration. ...........unleaded1.615-1.625 41.0241.28Zero Lash (Hydraulic tappets)Zero (engine operating)0.001-0.003 0.025-0.0762.029-2.030 51.54-51.562.01 9-2.020 51.28-51.312.009-2.010 51.03-51.051.999.2.000 50.78-50.800.001 (max) 0.03 (maxl0.253 8.4390 BTDC73O ABDC57' BBDC25' ATDC340262026PConnecting RodsTotal Weight (less bearings)(USA)InchesUnlessOtherwiseSpecified258 . ................. 695-703 grams(METRIC)MillimetersUnlessOtherwiseSpecifiedTotal Length (center-tocenter)258. ................. 5.873-5.877 149.17-140.28Connecting Rod Bore (less bearings) . 2.2085-2.2080 56.09-56.08Bearing Clearance. ........... 0.001-0.0025 0.03-0.06(0.0015-0.002 (0.044preferred) preferred)Side Clearance. ............. .01 G.019 .25-.48Maximum Twist. ............ 0,001 per inch 0.025 per25.4 mmMaximum Bend. ............ 0.0005 0.01 27 perper inch 25.4 mmcr8nluhdtEnd Play. ................ 0.00150.0065Main Bearing Journal Diameter .... 2.4986-2.5001Main Bearing Journal WidthNo. 1. ................ 1.0861.098No.3. ................ 1.271-1.273No. 24-567 ............ 1.182-1.188Main Bearing ClearanceNo. 1 Main. ............. .OOO5 to .0026Loo1 5preferred)No. 2,3,4,5. & 6 Mains. ..... .0005 to .003(DO17preferred)No. 7 Main. ............. .0011 to .0035( DO23preferred)Connecting Rod Journal Diameter . . 2.0934-2.0955Connecting Rod Journal Width .... 1.070-1.0760.038-0.16563.464-63.50227.58-27.8932.28-32.3330.02-30.18.013 to .066( .04preferred).013 to .076( .045preferredl.028 to .OW( .058preferred)53.17-53.2327.18-27.3360263ArT r-r

T - i 7334 MOPAR PERFORMANCE PARTS(USA)InchasUnlaOtherwiseSpecifid(METRIC)MillinwtersUnlarOtherwiseSpocifidMaximum Out-of-Round(All Journals1 ............ 0.0005 0.01 3Maximum Taper (All Journals) .... 0.0005 0.013Cylinder BlockDeck Height ............... 9.487-9.493 240.97-241.12Deck Clearance ............. 0.0148 0.376(below block) (below block)Cylinder Bore (standard]. ....... 3.7501-3.7533 95.253-95.334Maximum Cylinder Taper ..... 0.005 0.13Maximum Cylinder(Out-of-Round) ......... 0.003 0.08Tappet Bore Diameter ......... 0.90550.9065 23.0-23.025Cylinder Block Flatness ........ 0.001 /I -0.002E 0.03/25-(305/152(maxl 0.20 (maxlCylinder HeadCombustion Chamber Volume .... 67.84-70.84~~Valve Arrangement ........... El-IE-IE-El-El-IEValve Guide ID (Integral1 ....... 0.3735-0.3745 9.487-9.512Valve Stem-to-Guide Clearance .... 0.001-0.003 0.03-0.08Intake Valve Seat Angle ........300Exhaust Valve Seat Angle .......44.50Valve Seat Width ............ 0.040-0.060 1.02-1.52Valve Seat Runout ........... 0.0025 0.064Cylinder Head Flatness. ........(3001/1-0.002E0.03/25-0.05/1520.008 (max) 0.20 (maxlLubrication SystemEngine Oil Capacity. .......... 4 quarts 3.8 liters(Add 1 quart (Add 0.9with filter liter with filterNormal Operating Pressure. ......change) change)13psi at 89.6 kPa at600 rpm; 600 rpm;psi 37-75 255.1-517.1(maxl at kPa Imax) at1600t rpm 160W rpmOil Pressure Relief ........... 75 psi (maxl 517.1 kPa (maxlGear-to-Body Clearance Radial .... .002-.004 .051-.lo2(.002 preferred) LO51 preferred)Gear End Clearance, Plastigage .... 0.0020.006 Q.0510.152(0.002 (0.0508Gear End Clearance, Feeler Gauge. .preferred] preferred)0.004-0.00810.0070.10160.2032(0.1778preferred) preferred)PistonsWeight (less pin) . ...........Piston Pin Bore Centerline-to-Piston498-502 gramsTOP ................. 1.651-1.655 41.9442.04Piston-to-Bore Clearance ....... 0.0009-0.0017 0.023-0.043(0.0012-0.0013 (0.030-0.033preferredl prefarredlPiston Ring Gap Clearance -Compression (both1 . ....... 0.010-0.020 0.25-0.51Piston Ring Gap Clearance -Oil Control Steel Rails ....Piston Ring Side ClearanceNo. 1 Compression ......No. 2 ComDression .........Oil Control . .............Piston Ring Groove HeightCompression (both) .........Oil Control .............Piston Ring Groove DiameterNo. 1 and No. 2 . ..........Oil Control . .............Piston Pin Bore Diameter. .......Piston Pin Diameter . ..........Piston Pin-to-Clearance ........Piston Pin-toConnecting Rod ...Rocker Arms, Puh Rods and TappetsRocker Arm Ratio ...........(USA)lnchaUnhOthemirSpHif id0.010-0.0250.0017-.0032(0.0017preferred)0.0017-.0032(0.0017preferred)0.001-0.008(0.003preferred 10.0795-0.08050.1 884.1 8953.3243.3293.329-3.3390.9308-0.93130.9304-0.93090.0003-0.0005loose(0.0005preferred)2000 Ibfpress-f i t(METRIC)MillimotorsUnlar0th-h.SpHif id1.6:l0.25-0.640.043-0.081(0.043preferred)0.043-0.081(0.043preferred)0.03-0.20(0.08preferred)2.01 9-2.0454.784.8084.43-84.6684.56848123.642-23.65623.632-23.6450.008-0.01 3loose(0.013preferred)8.900 kNpress-fitPush Rod Length ............ 9.640-9.660 244.856-245364Push Rod Diameter. .......... 312-.315 7.928.00Hydraulic Tappet Diameter ...... 0.904-0.9045 22.96-22.97Tappet-to-Bore Clearance ....... 0.0010.0025 0.030.05Valv€mValve Length(Tipto-Gauge Dim. Line) ..... 4.78954.8045 121.653-122.034Vakve Stem Diameter. ......... 0.3715-0.3725 9.436-9.462Stem-to-Guide Clearance. ....... 0.001-0.003 0.03-0.08Intake Valve Head Diameter. ..... 1.782-1.792 45.26-45.52Intake Valve Face Angle. .......290Exlhaust Valve Head Diameter. .... 1.401-1.4 1 35.59-35.84Exhaust Valve Face Angle. ......440Maximum Allowable Removed forTip Refinishing . .......... 0.010 0.25Valve Springl, ExhaustValve Open ............... 80-88 at 1.625Valve Closed. .............. 210-226 at 1.1881.C). ....................1 .OOO-1.020 in.Valve Springs, tntakeFree Length . .............. 1.99 approx.Spring TensionSix-Cylinder EngineFiring Order50.55 approx.Valve Closed. ............ 64-72 Ibf 285320 Nat 1.786 at 46.24Valve Open ............. 188-202 Ibf 836-898 Nat 1.41 1 at 3S.84Inside Diameter ............. 0.948-0.968 24.08-24.59602638

4.2L IN-LINE 6 (ENGINE ASSEMBLY) 3351981,4.2L ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1981 Jeep Service Manual .Torque SpecificationsSrvice Sot-To Torqua should be mod whon assambling componmtr . Sorvia IrrUso Rrheck Toqurr should be used for checking a pre-torqued item ...............................................................Air Injection Tube-toManifold 20Air Pump Adjusting Strap.toPump 20Air Pump Brackets-to-Engine (A/C Compressor or Pedestals) ............... 25Air Pump-to-Bracket ...................................... 20Alternator Adjusting Bolt ................................... 18Alternator Mounting Bracket-to-Engine ........................... 28Altarnator Pivot Bolt or Nut .................................. 28Alternator Pivot Mounting Bolt-to-Head ........................... 33Block Heater Nut ........................................Camshaft Sprocket Screw ................................... 50Carburetor Hold-Down Nuts .................................. 14USA (ft-lbdMetric (NmJServiceServiaservice In-Urn service In-lJwSt-To Rachack S.t-To R.ch.dcTorque Torque Torqw Torqw20 in-lbsClutch Housing Spacer to Block Screws ........................... 12Clutch Housing-to-Block Screws (bottom) .......................... 43Clutch Housing-to-Block Screws (top) ............................ 27Coil Bracket-tocylinder Head ................................. 14Connecting Rod Bolt Nuts ................................... 33Crankshaft Pulley-to-Damper Bolts ..............................20Cylinder Heed Capscrews ................................... 85Cylinder Head Cover Nuts ................................... 28 in-lbs13Distributor Clamp Bracket Screw ...............................EGRVal Ve ............................................ 13Exhaust Manifold Bolts .................................... 23Exhaust Pipe-toManifold ................................... 20Fan and Hub Assembly Bolts .................................18Drive Plate-toconverter Screw ................................ 22EGR Tube Nuts ......................................... 30Flywhwl or Drive Plate-tocrankshaft ............................ 105Front Support Bracket-to-Block Screw ........................... 35Front Support Cushion-to-Bracket .............................. 33Front Support Cushion-to-Bracket-to-Frame ........................ 37Fuel Pump Screws 16.......................................Idler Arm Bracket.to.Sill .................................... 50Idler Pulley Bracket-to-Front Cover Nut ...........................7Idler Pulley Bearing Shaft-to-Breckat Nut .......................... 33Intake Manifold Coolant Fittings ............................... 20Intake Manifold Heater Screws ................................ 7Intake Manifold Screws .................................... 23Main Bearing Capscrews .................................... 80Oil Filter Adapter ........................................ 48Oil Pan Drain Plug ....................................... 30Oil Pan Screws-114 inch-20 .................................7Oil Pan Screws-5/16 inch-16 ................................ 11Oil Pump Attaching Screws (Long) .............................. 17Oil Pump Attaching Screws (Short)..............................10Oil Pump Cover Screws .....................................Oxygen Sensor ......................................... 35Powr Steering Pump Adapter Screw .............................23Power Steering Pump Bracket Screw ............................. 43Power Steering Pump Mounting Screw ............................ 28Power Steering Pump Pressure Line Nut ........................... 38Power Steering Pump Pulley Nut ............................... 58Rear Crossmember-toaide Sill Nut .............................. 3070 in-lbsRear Support Bracket-to-Transmission ............................ 33Rear Support Cushion.to.Bracket ............................... 48Rear Support Cushion-toCrossmember ........................... 18Rocker Arm Assembly-toCylinder Head ........................... 19Sparkplug ............................................ 11Starter to Converter Housing Bolt .............................. 18Thermostat Housing Screw .................................. 13Timing Case Cover-to-Block Screws .............................. 5Timing Case Cover-to-Block Studs .............................. 16Vibration Damper Screw. Lubricated ............................. 80Water Pump Screws ....................................... 13All Torque valua given in foot-pounds and nmton-mmtws with dry fii unlmm 0th~~b. rp.cifid.15-2015-2218-2815-2215-2023-3020-3530-3517-25 in-I bs45-5512-209-1 5374722-3010-1 8303515-2580-902531 in-lbs10-1 89-1 818-2815-2512-2520-25253595115254027-36304513-1935604-926-3815-255-918-28758542-5525355-99-1 312-208-1 360-80 in-lbs32-3818-28374725-353045406520-3527-3840-5512-2516-267-1 513-2510-1 84813-1970-909-16272734272438384526819165837194527115321818312724304114247455022689452793110865419152314848315838527941456524261524187221081820-2720-3024-3820-3020-273141274741472-361-7516-2712-2050.64304114-24414720-34108-1222.8-3.514-2412-2424-3820-3416-3427-343447129-15634-5436-52416118-2647-815-1236-5220-347-1224-38101-11557-7534477-1212-1816-2711-187-943-5224-3850643447416154-88274737-5254-75163422-3510-2016-3414-245-1118-2695-12212-24Refer to the Standard Torque Spocifiationr and Copscrew Markin- Chert in Chaptor A of this man 8uel for any torqua I spocificstions not lktd .bow.602648r - T T T.

336 MOPAR PERFORMANCE PARTS1990,4.2L ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1990 Jeep Wrangler Service Manual.CamshaftTappet ClearanceEnd PlayBearing ClearanceBearing Journal DiameterNo. 1No. 2No. 3No. 4Base Circle RunoutCam Lobe liftValve LifeIntake Valve TimingOpensClosesExhaust Valve TimingOpensClosesValve OverlapIntake DurationExhaust DurationConnecting Rodszero lash (hyd.) tappetszero (engine operation)0.025-0.076 mm51.54-51.56 mm51.28-51.31 mm51.03-51.05 mm50.78-50.80 mm0.03 mm max.6.43 mm10.29 mm9 O BTDC73O ABDC57O BBDC25O ATDC340262O262O0.001-0.003 in.2.029-2.030 in.2.019-2.020 in.2.009-2.010 in.1.999-2.000 in.0.001 in. max.0.253 in.0.405 in.-Total Weight (less bearings)Total length (center-to-center)Piston Pin Bore DiameterConnecting Rod Bore (less bearings)Bearing ClearancePreferredSide ClearanceMaximum TwistMaximum Bend695-703 groms149.17-149.28 mm23.59-23.62 mm56.08-56.09 mm0.03-0.08 mm0.044-.050 mm0.25-0.48 mm0.025 per 25.4 mm0.0127 per 25.4 mm24.5-24.9 OZ.5.873-5.877 in.0.9288-0.9298 in.2.2080-2.2085 in.0.001-0.0025 in.0.0015-0.0020 in.0.010-0.019 in.0.001 per in.0.005 per in.CrankshaftsEnd PlayMain Bearing Journal DiameterMain Bearing Journal WidthNo. 1No. 2No. 3-4-5-6-7Main Bearing ClearancePreferredConnecting Rod Journal DiameterConnecting Rod Journal WidthMaximum Out-of-Round (All Journals)Maximum Taper (All Journals)0.038-0.165 mm63.489-63.502 rnm27.58-27.89 mm32.28-32.33 mm30.02-30.18 mm0.03-0.06 mm0.051 mm53.17-53.23 mm27.18-27.33 mm0.013 mm0.013 mm0.0015-0.0065 in.2.4996-2.5001 in.1.086-1.098 in.1.271-1.273 in.1.182-1.188 in.0.001-0.0025 in.0.002 in.2.0934-2.0955 in.1.070-1.076 in.0.0005 in.0.0005 in.J8909-172

4.2L IN-LINE 6 (ENGINE ASSEMBLY) 337Cylinder BlockDeck HeightDeck Clearance (below deck)Cylinder Bore Diameter (standard)Maximum TaperMaximum Out-of-RoundTappet Bore DiameterCylinder Block FlatnessMain Bearing Bore Diameter240.97-241.12 mm 9.487-9.493 in.0.376 mni 0.0148 in.95.253-95.334 mm 3.7501-3.7533 in.0.025 mni0.001 in.0.025 mni 0.001 in.23.000-23.025 mm 0.9055-0.9065 in..03 per 25 mm.001 per 1 in..05 per 152 mm.002 per 6 in.68.35-68.38 mm 2.691-2.692 in.Cylinder HoodCombustion Chamber VolumeValve ArrangementValve Guide ID (Integral)Valve Stem-to-Guide ClearanceIntake Valve Seat AngleExhaust Valve Seat AngleValve Seat WidthValve Seat RunoutCylinder Head Flatness64.45-67.45 ccEl-IE-IE-El-El-IE9.487-9.512 mm0.03-0.08 mm30°44O30’1.02-1.52 mm0.064 mm.03 per 25 mm.05 per lti2 mm0.3735-0.3745 in..001-.003 in..040-.060 in..0025 in..001 per 1 in..002 per 6 in.Oil PressureAt Idle Speed (600 rpm) .....................At 1600 + rpm .............................Oil Pressure Relief ...........................90 kPa255-517kPa,517 kPo13 psi37-75 psi75 psiOil PumpGear-to-Body Clearance (radial). ................0.051-0.102 mmPreferred ................................ .0.051 mmGear End Clearance - Plastigauge ............. .0.051-0.152 mmPreferred ................................ .0.051 mmGear End Clearance - Feeler Gauge. ............0.1016-0.2032 mmPreferred ................................ .0.1778 mni0.002-0.004 in.0.002 in.0.002-0.006 in.0.002 in.0.004-0.008 in.0.007 in.Rocker Arms. Push Rods and TaDDdsRocker Arm RatioPush Rod lengthPush Rod DiameterHydraulic Tappet DiameterTappet-to-Bare Clearance1.6:1244.856-245.364 mm7.92-8.00 mm22.962-22.974 mm0.03-0.05 mm9.640-9.660 in.0.312-0.315 in.0.904-0.9045 in.0.001-0.0025 in.J8909-173

338 MOPAR PERFORMANCE PARTSPistons__Weight (less pin)Piston Pin BoreCenterline-to-Piston TopPiston-to-Bore ClearancePreferredPiston Ring Gap Clearonce -Compression (both)Piston Ring Gap Clearance -Oil Control Steel RailsPiston Ring Side ClearanceNo. 1 and No. 2 CompressionPreferredOil ControlPreferredPiston Ring Groove HeightCopmression (both)Oil ControlPiston Ring Groove DiameterNo. 1 and No. 2Oil ControlPiston Pin Bore DiameterPiston Pin DiameterPiston-to-Pin ClearancePreferredPiston Pin-to-Connecting Rod510-514 grams41.94-42.04 mm0.023-0.043 mm0.030-0.033 mm18-18.1 02.1.651-1.655 in.0.0009-0.001 7 in.0.0012-0.0013 in.0.25-0.51 rnm 0.010-0.020 in.0.25-0.64 mm 0.010-0.025 in.0.030-0.081 mm0.043 mm0.03-0.20 mm0.08 mm2.019-2.045 mm4.78-4.80 mrn84.43-84.56 mrn84.56-84.81 mm23.624-23.655 mrri23.632-23.645 mm0.01 0-0.01 5 mmLoose 0.015 mm8.9 kN Press-fit0.0012-0.0032 in.0.0017 in.0.0080 in.0.003 in.0.0795-0.0805 in.0.188-0.1895 in.3.324-3.329 in.3.329-3.339 in.0.9308-0.9313 in.0.9304-0.9309 in.0.0004-0.0006 in.Loose 0.0006 in.2000 Ibs.4 Press-fitValves-Valve Length(Tip-to-Gauge Dim. Line) IntakeValve Etem DiameterStem-to-Guide ClearanceIntake Valve Head DiameterIntake Valve Face AngleExhaust Valve Head DiameterExhaust Valve Face AngleMaximum Allowable Removed forTip RefinishingValve Springs Free LengthValve Spring Tension ClosedValve Spring Tension Open121.653-122.034 rnm9.436-9.462 rnm0.03-0.08 mm45.26-45.52 mrn29O35.59-35.84 mm4400.25 mm50.55 mm285-320 N @ 45.4 mm836-898 N @ 35.84 mm4.7895-4.8045 in.0.3715-0.3725 in..001-,003 in.1.782-1.792 in.1.401-1.411 in.0.010 in.1.99 in.64.72 Ibs @ 1.786 in.188-202 Ibs @ 1.411 in.J9009-76..r --T -1

4.2L IN-LINE 6 (ENGINE ASSEMBLY) 339r --T ri

340 MOPAR PERFORMANCE PARTS1990,4.2L ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1990 Jeep Wrungler Service Manunl.ComponentTorqueA/C Compressor Bracket-to-Engine BoltsA/C Low Pressure Service Valve NutAlternator Adjusting BoltAlternator Pivot Bolt/NutCamshaft Sprocket BoltConnecting Rod Bolt NutsCrankshoft Main Bearing BoltsCylinder Head BoltsCylinder Head Cover BoltsCylinder Head Cover Retaining BoltsDamper Pulley Retaining BoltsExhaust Manifold-to-Downpipe NutsFlywheel/Converter Housing BoltsFuel Pump BoltsOil Pan Bolts - 1 /4-20- 5116-18Oil Pan Drain PlugOil Pan-to-Timing Case Cover Boltsoil Pump Attaching Bolts (Short)Oil Pump Attaching Bolts (Long)Oil Pump Cover BoltsPower Steering Pump Pressure Hose HutRocker Arm Assembly-to-Cylinder HeadSpark PlugsStarting Motor-to-Cylinder Block BoltsTiming Case Cover-to-Block BoltsVibration DomDer Bolt [Lubricatedl34 N-m38 N-m24 N-m38 Nvn108 Nvn45 N-rn108 N-m115 Nom8 N-m6 N-m27 N-m27 N*m38 N-m22 Nom9 Nom15 Nom41 Nom13 Nvn14 Nom23 N-rn8 Nvn52 N*m26 N-m38 N-m45 Nom7 N.m108 N-m(25 ft-lbs)(28 ft-lbs)(18 ft-lbs)(28 ft-lbs)(80 ft-lbs)(33 ft-lbs)(80 ft-lbs)(85 ft-lbs)(70 in-lbs)(55 in-lbs)(20 ft-lbs)(20 ft-lbs)(28 ft-lbs)(16 ft-lbs)(7 ft-lbs)(1 1 ft-lbs)(30 ft-lbs)(1 1 ft-lbs)(10 ft-lbs)(1 7 ft-lbs)(70 in-lbs)(38 ft-lbs)(19 ft-lbs)(28 ft-lbs)(33 ft-lbs)(62 in-lbs)(80 ft-lbs)J9009-77T - T l

Chapter 64.7L Power Tech V-8

342 MOPAR PERFORMANCE PARTSIntroduction ....................................................... .................. 343Block ........ .... .................................................344Crankshaft ............................................................................. 344TimingDriveSystem ....................................................... ... ..... 344Piston and Connecting Rod Assembly ........................................................ 345Cylinder Heads ......................................................................... 346Camshaft and Valve Gear .................................................................. 346Oiling System .......................................................................... 348Cooling System ......................................................................... 350Starting System ......................................................................... 355Charging System ........................................................................ 357IntakeManifold ......................................................................... 358FuelDelivery System ..................................................................... 358Powertrain Control Module (PCM) .......................................................... 361Positive Crankcase Ventilation (PCV) System ..........................................Exhaust System .................................................................Ignitionsystem ................................................... .............. 365Troubleshooting ......................................................................... 3661999,4.7L Engine Specifications ............................................................ 3701999,4.7L Engine Torque Specifications ...................................................... 372....T .. T '7

-In4.7L POWER TECH V-8 343Note: Due to the limited number of performance parts currently available for 4.7L Power Tech V-8 engine, only a briefdiscussion and general specifications will be covered in this chapter. All other procedures, techniques, and modificationtips which are generic to all Jeep performance engines can be found in Chapter 4,4.0L Power Tech In-Line 6. It is highlyrecommended that 4.7L Power Tech V-8 engine owners read both this chapter and Chapter 4 in their entireties.For additional information, refer to the proper service manual.INTRODUCTIONGeneral SpecificationsType. ........... .90" SOHC V-8Displacement ...... 4.71, (287 CID)Bore. ............ 93.0 mm (3.66")Stroke. ........... 86.5 mm (3.40")Compression Ratio . . 9.0: 1Horsepower ....... 230 bhp @ 4,600 rpmTorque ........... 300 Ib-ft @ 3,200 rpmLead Cylinder. ..... #I Left BankCylinder Block. .... Cast IronCylinder Head ..... AluminumConnecting Rod .... Powdered Metal with Cracked CapPiston ............ Aluminum (Press-Fit Wrist Pin)Lubrication. ....... Pressure Feed-Full Flow Filtration(Direct Crankshaft Driven Pump)Cooling System .... Liquid Cooled-Forced CirculationEngine Firing OrderINJECTOR INJ. INJ. INJ.#2 #4 #6COIL #2 Coli #4 COIL #6 Coil #86I FIRING ORDER 11-8-4-3-6-5-7-2

344 MOPAR PERFORMANCE PARTSEngine IdentificationThe 4.7L engine is stamped with the vehicles identificationnumber (VnU). This area is located at the right front side ofthe engine block. The engine build date code is included in theyellow bar code sticker on the oil fill housing. (Figure 6- 1).BLOCKThe cylinder block is made of cast iron. The block is aclosed deck design with the left bank forward. To providehigh rigidity and improved NVH, an enhanced compactedgraphite bedplate is bolted to the block. The block designallows coolant flow between the cylinders bores, and aninternal coolant bypass to a dual poppet inlet thermostat isincluded in the cast aluminum front cover.Structural Dust CoverThe structural dust cover is made of die cast aluminum andjoins the lower half of the transmission bellhousing to theengine bedplate. The structural cover provides additionalpowertrain stiffness and reduces noise and vibration.CRANKSHAFTFuel RequirementsFigure 6 - 7The 4.7L engine is designed to meet all emissionsregulations and provide excellent fuel economy andperformance when using high quality unleaded gasolinehaving an octane rating of 87. The use of premium gasolineis not recommended. The use of premium gasoline willprovide no benefit over high quality regular gasoline, and insome circumstances may result in poorer performance.Light spark knock at low engine speeds is not harmful toyour engine. However, continued heavy spark knock at highspeeds can cause damage and immediate service is required.Engine damage resulting from operation with a heavy sparkknock may not be covered by the new vehicle warranty.Poor quality gasoline can cause problems such as hardstarting, stalling and hesitations. If you experience thesesymptoms, try another brand of gasoline before consideringservice for the vehicle.The American Automobile Manufacturers Association(AAMA) has issued gasoline specifications to define theminimum fuel properties necessary to deliver enhancedperformance and durability for your vehicle.DaimlerChrysler recommends the use of gasoline that meetthe AAMA specifications if they are available.The crankshaft is constructed of nodular cast iron. Thecrankshaft is a cross-shaped four throw design with eightcounterweights for balancing purposes. The crankshaft issupported by five select main bearings with the No. 3serving as the thrust washer location. The main journals ofthe crankshaft are cross drilled to improve rod bearinglub'rication. The No. 8 counterweight has provisions forcrankshaft position sensor target wheel mounting.Thle select fit main bearing markings are located on the rearside of the target wheel. The crankshaft oil seals are onepiece design. The front oil seal is retained in the timingchain cover, and the rear seal is pressed in to a bore formedby the cylinder block and the bedplate assembly.TIMING DRIVE SYSTEMThe timing drive system (Figure 6-2) has been designed toprovide quiet performance and reliability to support a nonfreewheeling engine. Specifically, the intake valves arenon-free wheeling and can be easily damaged with forcefulengine rotation if camshaft-to-crankshaft timing isincorrect. The timing drive system consists of a primarychain and two secondary timing chain drives.The primary timing chain is a single inverted tooth type.The primary chain drives the large 50 tooth idler sprocketdirectly from a 25 tooth crankshaft sprocket. Primary chainmotion is controlled by a pivoting leaf spring tensioner armand a fixed guide. The arm and the guide both use nylonplastic wear faces for low friction and long wear. Theprimary chain receives oil splash lubrication from thesecondary chain drive and oil pump leakage. The idlersprocket assembly connects the primary and secondarychain drives. The idler sprocket assembly consists of twointegral 30 tooth sprockets and a 50 tooth sprocket that issplined to the assembly. The spline joint is a press-fit, antirattletype. A spiral ring is installed on the outboard side ofthe 50 tooth sprocket to prevent spline disengagement. Theidler sprocket assembly spins on a stationary idler shaft...

4.7L POWER TECH V-8 345SECONDARYSECONDARY SECONDARY LEFTCAMSHAFTSPROCKETANDSECONDARYCHAINCHAIN GUIDETENSIONER ARMTWO PLATEDLINKS ON RIGHTAMSHAFT CHAINTWO PLATEDLINKS ON LEFTCAMSHAFT CHAINPRIMARY CHAINIDLER SPROCKETPRIMARY CHAINCRANKSHAFTTENSIONER SPROCKET 8ob3c710Figure 6 - 2The idler shaft is press fit into the cylinder block. A largewasher on the idler shaft bolt and the rear flange of the idlershaft are used to control sprocket thrust movement.Pressurized oil is routed through the center of the idler shaftto provide lubrication for the two bushings used in the idlersprocket assembly.There are two secondary drive chains, both are invertedtooth-type, one to drive the camshaft in each SOHCcylinder head. There are no shaft speed changes in thesecondary chain drive system. Each secondary chain drivesa 30 tooth cam sprocket directly from the a 30 toothsprocket on the idler sprocket assembly. A fixed chainguide and a hydraulic oil damped tensioner are used tomaintain tightness in each secondary chain system. Thehydraulic tensioners for the secondary chain systems arefed pressurized oil from oil reservoir pockets in the block.Each tensioner also has a mechanical ratchet system thatlimits chain slack if the tensioner piston bleeds down afterengine shut down. The tensioner arms and guides alsoutilize nylon wear faces for low friction and long wear. Thesecondary timing chains receive lubrication from a smallorifice in the tensioners. This orifice is protected fromclogging by a fine mesh screen which is located on the backof the hydraulic tensioners.PISTON AND CONNECTING ROD ASSEMBLY(Refer to Figure 6-3.)The pistons are made of a high strength aluminum alloywith an anodized top ring groove and crown. Piston skirtsare coated with a solid lubricant (Molykote) to reducefriction and provide scuff resistance. The connecting rodsare made of powdered metal, with a “fractured cap” design.A press-fit piston pin is used to attach the piston andconnecting rod.Note: DO NOT use a metal stamp to mark connecting rodsas damage may result; instead, use ink or a scratch awl.

l- --r 7346 MOPAR PERFORMANCE PARTSCylinder Head CoversCylinder head covers are made of die ca\t magnesium andare not interchangeable from side-to-side. It is imperativethat nothing rest on the cylinder head covers. Prolongedcontact with other items may wear a hole in the cylinderhead cover.Engine Gasket Surface PreparationIRIGHTSIDE OFENGINEFRONT VIEWOF ENGINELEFTSIDE OFENGINEmrn,To ensure engine gasket sealing, proper surface preparationmust be performed, especially with the use of aluminum enginecomponents and multi-layer steel cylinder head gaskets.NEVER use the following to clean gasket surfaces:a metal scraperFigure 6 - 3an abrasive pad or paper to clean cylinder block and heada high speed power tool or wire brush on any gasketsealing surfacePISTON DIAMETER92.975mm (3.665 in.)RING GROOVE WIDTHUpper Ring1.541 - 1.566mm(0.0607 - 0.0617 in.)Middle Ring1.53 - 1.55 mm(0.0603 - 0.0611 in.)Oil Rails3.031 - 3.055 mm(0.1194 - 0.1203 in.)PISTON PIN BOREDIAMETER24.026 - 24.032mm(0.946 - 0.9462 in.)RING GROOVEDIAMETERUpper Ring83.73 - 83.97mm(3.2965 - 3.3059 in.)Middle Ring82.833 - 83.033 mm(3.2612 - 3.2691 in.)Oil Rails83.88 - 84.08 mm(3.3024 - 3.3103 in.)Note: Multi-Layer Steel (MLS) head gaskets require ascratch free sealing surface.Onlly use the following for cleaning gasket surfaces:Mopar Brake and Parts Cleanera plastic or wood scraperCAMSHAFT AND VALVE GEARCamshafts consist of powdered metal steel lobes which aresinl-er-bonded to a steel tube. A steel post or nose piece isfriction welded to the camshaft steel tube. Five bearingjournals are machined into the camshaft, four on the steeltube and one on the steel nose piece. Camshaft end play iscontrolled by two thrust walls that border the nose piecejournal. Engine oil enters the hollow camshafts at the thirdjournal and lubricates every intake lobe rocker through adrilled passage in the intake lobe.CYLINDER HEADSCylinder heads are made of an aluminum alloy and featuretwo valves per cylinder with pressed-in, powdered metalvalve guides. The cylinder heads also provide enclosuresfor the timing chain drain, necessitating unique left andright cylinder heads.Valve GuidesValve guides are made of powdered metal and are pressedinto the cylinder head. The guides are not replaceable orserviceable. Valve guide reaming is NOT recommended. Ifthe guides are worn beyond acceptable limits, replace thecylinder heads.Rocker ArmsRocker arms are steel stampings with an integral rollerbearing. Rocker arms incorporate a 2.8 mm (0.1 I") oil holein the lash adjuster socket for roller and camshaft lubrication.ValvesValves are made of heat resistant steel and have chromeplated stems to prevent scuffing. Each valve is actuated bya roller rocker arm which pivots on a stationary lashadjuster. All valves use three bead lock keepers to retain thesprings and promote valve rotation (Figure 6-4).

- .PT-T4.7L POWER TECH V-8 347VALVELOCKS(3-BEAD)4VALVESPRING VALVEEVALVEX H A U S T dValve SpringsRETAINER0&sfSTEMOIL SEALFigure 6 - 4INTAKEVALVEBW89831Valve springs (Figure 6-4) are made from high strengthchrome silicon steel. The springs are common for intakeand exhaust applications. The valve spring seat is integralwith the valve stem seal, which is a positive type seal tocontrol lubrication.Hydraulic Lash AdjustersValve lash is controlled by hydraulic lash adjusters that arestationary mounted in the cylinder heads. The lash adjustershave a hole in the ball plunger that feeds oil through therocker arm squirt holes for rocker arm roller and camshaftlobe lubrication.Engine base timing can be verified by the followingprocedure:1.2.3.4.5.6.Remove the cylinder head covers. Refer to the properservice manual for the procedure.Using a mirror, locate the TDC arrow on the frontcover (Figure 6-5). Rotate the crankshaft until the markon the crankshaft damper is aligned with the TDCarrow on the front cover. The engine is now at TDC.Note the location of the V-8 mark stamped into thecamshaft drive gears (Figure 6-6). If the V-8 mark oneach camshaft drive gear is at the twelve o’clockposition, the engine is at TDC on the exhaust stroke. Ifthe V-8 mark on each gear is at the six o’clockposition, the engine is at TDC on the compressionstroke.If both of the camshaft drive gears are off in the sameor opposite directions, the primary chain or bothsecondary chains are at fault. Refer to Timing Chainand Sprockets procedure in the appropriate servicemanual.If only one camshaft drive gear is off and the other iscorrect, the problem is confined to one secondarychain. Refer to Single Camshaft Timing in theappropriate service manual.If both camshaft drive gear V-8 marks are at the twelveo’clock or the six o’clock position, the engine basetiming is correct. Reinstall the cylinder head covers.Valve Stem SealsValve stem seals (Figure 6-4) are made of rubber andincorporate an integral steel valve spring seat. The integralgarter spring maintains consistent lubrication control to thevalve stems.Engine Timing VerificationCaution: The 4.7L is a non free-wheeling design engine.Therefore, correct engine timing is critical.Note 1 : Components referred to as left hand or right handare as viewed from the driver’s position inside the vehicle.Note 2: The blue link plates on the chains and the dots onthe camshaft drive sprockets may not line up during thetiming verification procedure. The blue link plates are linedup with the sprocket dots only when re-timing the completetiming drive. Once the timing drive is rotated, blue link-todotalignment is no longer valid.Figure 6 - 5

~ ~~~~ ~ -~348 MOPAR PERFORMANCE PARTSENGINE LUBRICATION FLOW CHART-BLOCK: TABLE iFigure 6 - 6--FROMOil Pickup TubeOil PumpOil FilterBlock Main Oil GalleryCrankshaft Main JournalsCrankshaft Number OneMain Journal-Left Cylinder HeadRight Cylinder Head--TOOil PumpOil FilterBlock Main Oil Gallery1. Crankshaft MainJournal2. Left Cylinder Head*3. Right Cylinder Head*Crankshaft Rod Journals1. Front Timing ChainIdler Shaft2. Both Secondary ChainTensionersSee Table 2See Table 2ENGINE LUBRICATION FLOW CHART-CYLINDER HEADS: TABLE 2OILING SYSTEMThe lubrication system (Figure 6-7) is a full flow filtration,pressure feed-type. Oil from the oil pan is pumped by ageroter-type oil pump directly mounted to the crankshaftnose. Oil pressure is controlled by a relief valve mountedinside the oil pump housing. For lubrication flow refer toEngine Lubrication Flow Chart- Block: Table I, andEngine Lubrication Flow Chart- Cylinder Heuds: Table 2.The camshaft exhaust valve lobes and rocker arms arelubed through a small hole in the rocker arm. Oil flowsthrough the lash adjuster then through the rocker arm andonto the camshaft lobe. Due to the design of the rocker armconfiguration, the camshaft intake lobes are not lubed in thesame manner as the exhaust lobes. Intake lobes are lubedthrough internal passages in the camshaft. Oil flowsthrough a bore in the No. 3 camshaft bearing bore. As thecamshaft turns, a hole in the camshaft aligns with the holein the camshaft bore allowing engine oil to enter thecamshaft tube. Oil then exits through 1.6 mm (0.063") holesdrilled into the intake lobes. lubing the lobes and the rockerarms.1Cylinder Head Oil Port (in DiagonalCross Drilling tobolthole)Main Oil GalleryMain Oil Gallery (drilled 1. Base of Camshaftthrough head from rear to Towers-front)2. Lash Adjuster TowersBase of Camshaft Towers Vertical Drilling ThroughTower to Camshaft-Bearings'*,Lash Adjuster Towers Diagonal Drillings toHydraulic Lash AdjusterPockets** The number three camshaft bearing journal feeds(oil into the hollow camshaft tubes. Oil is routed tothe intake lobes, which have oil passages drilledinto them to lubricate the rocker arms.I- I.. T --T 7

4.7L POWER TECH V-8 349LEFTCYLINDERHEAD OILGALLERYFigure 6 - 7Engine OilAn SAE viscosity grade is used to specify the viscosity ofengine oil. Use only engine oils with multiple viscositysuch as SW-30 or 1OW-30. These are specified with a dualSAE viscosity grade which indicates the cold-to-hottemperature viscosity range. Select an engine oil that is bestsuited to your particular temperature range and variation(Figure 6-8). The 4.7L engine oil capacity (with filterchange) is S.7L (6.0 quarts).ENGINE OIL VISCOSITY GRADES"F -20'oc -290 -18" -120 -70 160 270 380IFigure 6 - 880b89880 IEngine Oil Level InspectionCaution: DO NOT overfill crankcase with engine oil;pressure loss or oil foaming can result.Inspect engine oil level approximately every 800lulometers (500 miles). Unless the engine has exhibited aloss of oil pressure, run the engine for about five minutesbefore checking oil level. Checking engine oil level on acold engine is not accurate.To ensure proper lubrication of an engine, engine oil mustbe maintained at an acceptable level. The acceptable levelsare indicated between the ADD and SAFE marks on theengine oil dipstick.1.2.Position vehicle on level surface.With engine OFF, allow approximately ten minutesfor oil to settle to bottom of crankcase, remove engineoil dipstick.3. Wipe dipstick clean.4.5.6.Install dipstick and verify it is seated in the tube.Remove dipstick, with handle held above the tip, takeoil level reading.Add oil only if level is below the ADD mark on dipstick.

T - T 7350 MOPAR PERFORMANCE PARTSEngine Oil ChangeChange engine oil at mileage and time intervals describedin Maintenance Schedules.Run engine until achieving normal operating temperature.1.2.3. Remove oil fill cap.4.5.6.7.Position the vehicle on a level surface and turn engine off.Hoist and support vehicle on safety stands.Place a suitable drain pan under crankcase drain.Remove drain plug from crankcase and allow oil todrain into pan. Inspect drain plug threads for stretchingor other damage. Replace drain plug if damaged.Install drain plug in crankcase.Lower vehicle and fill crankcase with specified typeand amount of engine oil described in this section.8. Install oil fill cap.9. Start engine and inspect for leaks.10. Stop engine and inspect oil level.Engine Oil Filter ChangeAll engines are equipped with a high quality, full-flow,disposable-type oil filter. DaimlerChrysler Corporationrecommends a Mopar or equivalent oil filter be used.1. Oil Filter Removala. Position a drain pan under the oil filter.b. Using a suitable oil filter wrench, loosen filter.c. Rotate the oil filter (Figure 6-9) counterclockwiseto remove it from the cylinder block oil filter boss.d. When filter separates from adapter nipple, tipgasket end upward to minimize oil spill. Removefilter from vehicle.e. With a wiping cloth, clean the gasket sealingsurface (Figure 4-39) of oil and grime.2. Oil Filter Installationa. Lightly lubricate oil filter gasket with engine oil.b.c.Thread filter onto adapter nipple. When gasket makescontact with sealing surface (Figure 4-39), handtighten filter one full tum. DO NOT over tighten.Add oil, verify crankcase oil level and start engine.Inspect for oil leaks.IOil PanFigure 6 - 9ac476t01The engine oil pan is made of laminated steel and has asingle plane sealing surface. The sandwich style oil pangasket has an integrated windage tray and steal carrier. Thesealing area of the gasket is molded with rubber and isdesigned to be reused as long as the gasket is not cut, tomor ripped.COOLING SYSTEM(Refer to Figure 6-10 and Figure 6- 1 1 .)Caution: Vehicle may be equipped with long life coolant.Extended life coolant is identified by an orange color.Nonnal coolant is identified by a greenish color. It isrecommended that the two types of coolant not be mixed.The cooling system regulates engine operating temperature.It allows the engine to reach normal operating temperatureas quickly as possible. It also maintains normal operatingtemperature and prevents overheating.The cooling system also provides a means of heating thepassenger compartment and cooling the automatictransmission fluid (if equipped). The cooling system ispressurized and uses a centrifugal water pump to circulatecoolant throughout the system.Vehicles equipped with the 4.7L engine receive a “max”cooling package which consists of a heavy duty radiator, alow disengaged fan viscous fan drive and an mechanicalcooling fan. This package will provide additional coolingcapacity for vehicles used under extreme conditions such astrailer towing in high ambient temperatures.

T - ~ r i4.7L POWER TECH V-8 351TORADIATORRH CY1HEADIFigure 6 - 10ICooling System Capacity4.7L 12.3 liters (13.0 quarts)** Includes 2.2 liters (2.3 quarts) for coolant recovery bottle.FANSHROUDFigure 6 - 11COOLING FANCONNECTOR80b8991eCooling System ComponentsThe cooling system consists of:000000000000RadiatorMechanical cooling fanThermal viscous fan drive-Low disengagedFan shroudRadiator pressure capThermostatCoolant reserve/oveflow systemTransmission oil cooler (if auto. trans. equipped)CoolantWater pumpHoses and hose clampsAccessory drive belt

352 MOPAR PERFORMANCE PARTSWater Pump Bypass(Refer to Figure 6- 12.)The 4.7L engine uses an internal water/coolant bypasssystem. The design uses galleries in the timing chain coverto circulate coolant during engine warm-up, preventingcoolant from flowing through the radiator. The thermostatuses a stub shaft located at the rear of the thermostat tocontrol flow through the bypass galley. When thethermostat is in the closed position, the bypass galley is notobstructed allowing 100% flow. When the thermostat is inthe open position, the stub shaft enters the bypass galleyobstructing bypass coolant flow by 50%. This designallows the coolant to reach operating temperature quicklywhen cold, while adding extra cooling during normaltemperature operati on.THERMOSTATSHOWN INTHE CLOSEDPOSITIONFigure 6 - 12FROMHEATERCoolant Reservoir/Overflow SystemThis system works along with the radiator pressure cap. Thisis done by using thermal expansion and contraction of thecoolant to keep the coolant free of trapped air. It provides:A volume for coolant expansion and contraction.A convenient and safe method for checkinghdjustingcoolant level at atmospheric pressure. This is donewithout removing the radiator pressure cap.Some reserve coolant to the radiator to cover minorleaks and evaporation or boiling losses.As the engine cools, a vacuum is formed in the coolingsystem of both the radiator and engine. Coolant will then bedrawn from the coolant tank and returned to a proper levelin the radiator.The coolant reservoir/overflow system has a radiatormounted pressurized cap, an overflow tube and a plasticcoolant reservoir/overflow tank.Accessory Drive Belt TensionCorrect drive belt tension is required to ensure optimumperformance of the belt driven engine accessories. Ifspecified tension is not maintained, belt slippage may causeengine overheating, lack of power steering assist, loss of airconditioning capacity, reduced generator output rate, and/orgreatly reduced belt life.It i:s not necessary to adjust belt tension on 4.7L engines.These engines are equipped with an automatic belttensioner. The tensioner maintains correct belt tension at alltimes. Due to use of this belt tensioner, DO NOT attempt touse a belt tension gauge on 4.7L engines.Thermostat(Refer to Figure 6-13.)A pellet-type thermostat controls the operating temperatureof the engine by controlling the amount of coolant flow tothe radiator (Figure 6-12). The thermostat is closed belowI95'"F (9OOC). Above this temperature, coolant is allowedto flow to the radiator. This provides quick engine warm upand overall temperature control. The thermostat is designedto block the flow of the coolant bypass journal by 50%instead of completely blocking the flow. This designcontrols coolant temperature more accurately.An arrow, plus the word UP is stamped on the front flangenext to the air bleed. The words TO RAD are stamped onone arm of the thermostat. They indicate the properinstalled position.The same thermostat is used for winter and summer seasons.An engine should not be operated without a thermostat,except for servicing or testing. Operating without athermostat causes other problems. These include longerengine warm-up time, unreliable warm-up performance,increased exhaust emissions, and crankcase condensation.Crankcase condensation can result in sludge formation.The most common type of thermostat failure, usually foundon high mileage vehicles, is a thermostat failed in the shutposition. The temperature gauge (if equipped) will give anindication of this condition. Depending upon length of timethat vehicle is operated, the pressure cap may vent. Thiswill expel steam and coolant to coolant reserve/overflowtank and surface (ground) below vehicle.

4.7L POWER TECH V-8 353Figure 6 - 13Coolant1. Routine CheckNote: DO NOT remove the radiator cap for routinecoolant level inspections. The coolant level can bechecked at the coolant reserve/overflow tank.The coolant reserve/overflow system provides a quickvisual method for determining coolant level withoutremoving radiator pressure cap. With engine idling andat normal operating temperature, observe coolant levelin reservehverflow tank. The coolant level should bebetween ADD and FULL marks.2. Adding AdditionalDO NOT remove the radiator cap to add coolant tosystem. When adding coolant to maintain correct level,do so at coolant reserve/overflow tank. Removeradiator cap only for testing or when refilling systemafter service. Removing cap unnecessarily can causeloss of coolant and allow air to enter system, whichproduces corrosion. Refer to the owner’s manual forrecommended coolant type to use.Radiator Pressure CapAll radiators are equipped with a pressure cap. This capreleases pressure at some point within a range of 124-145kPa (18-21 psi). The pressure relief point (in pounds) isengraved on top of the cap.The cooling system will operate at pressures slightly aboveatmospheric pressure. This results in a higher coolantboiling point allowing increased radiator cooling capacity.The cap contains a spring-loaded pressure relief valve. Thisvalve opens when system pressure reaches the release rangeof 124- 145 kPa (1 8-21 psi).A vent valve in the center of the cap allows a small coolantflow through the cap when coolant is below boilingtemperature. The valve is completely close when boilingpoint is reached. As the coolant cools, it contracts and createsa vacuum in cooling system This causes the vacuum valve toopen and coolant in reserve/overflow ..Ink to be drawnthrough connecting hose into radiator. If the vacuum valve isstuck shut, radiator hoses will collapse on cool-down.A rubber gasket seals the radiator filler neck. This is doneto maintain vacuum during coolant cool-down and toprevent leakage when system is under pressure.Water Pump(Refer to Figure 6-14.)A centrifugal water pump circulates coolant through thewater jackets, passages, intake manifold radiator core,cooling system hoses and heater core. The pump is drivenfrom the engine crankshaft by a single serpentine drive belt.The water pump impeller is pressed onto the rear of a shaftthat rotates in bearings pressed into the housing. Thehousing has two small holes to allow seepage to escape.The water pump seals are lubricated by the antifreeze in thecoolant mixture. No additional lubrication is necessary.A quick test to determine if the pump is working is to checkif the heater warms properly. A defective water pump willnot be able to circulate heated coolant through the longheater hose to the heater core.Both heater hoses are connected to fittings on the timingchain front cover. The water pump is also mounted directlyto the timing chain cover and is equipped with a nonserviceable integral pulley.Replace water pump assembly if it has any of thefollowing conditions:The body is cracked or damagedWater leaks from shaft seal (evident by traces ofcoolant below vent hole)Loose or rough turning bearing (also inspect viscousfan drive)Impeller rubs either the pump body or timing chaincasekover

T --T 1354 MOPAR PERFORMANCE PARTSIINTEGRAL WATERpump PULLEYTHERMOSTATHOUSING 80089884Cooling System HosesFigure 6 - 14Warning! Constant tension hose clamps are used on mostcooling system hoses when removing or installing, use onlytools designed for servicing this type of clamp. Snap-Onclamp tool (number hpc-20) may be used for larger clamps.Always wear safety glasses when servicing constanttension clamps.Caution: A number or letter is stamped into the tongue ofconstant tension clamps. If replacement is necessary, use onlyan original equipment clamp with matching number or letter.Rubber hoses route coolant to and from the radiator, intakemanifold and heater core. The lower radiator hose is springreinforcedto prevent collapse from water pump suction atmoderate and high engine speeds.Inspect hoses at regular intervals. Replace hoses that arecracked, feel brittle when squeezed, or swell excessivelywhen the system is pressurized.In areas where specific routing clamps are not provided, besure that hoses are positioned with sufficient clearance. Checkclearance from exhaust manifolds and pipe, fan blades, drivebelts and sway bars. Improperly positioned hoses can bedamaged, resulting in coolant loss and engine overheating.When performing a hose inspection, inspect the radiator lowerhose for proper position and condition of the internal spring.An electrical cooling fan located in the fan shroud aids inlow speed cooling. It is designed to augment the viscousfan; however, it does not replace the viscous fan.A thiermostatic bimetallic spring coil is located on the frontface of the viscous fan drive unit (Figure 4-46). This springcoil reacts to the temperature of the radiator discharge air. Itengages the viscous fan drive for higher fan speed if the airtemperature from the radiator rises above a certain point.Until additional engine cooling is necessary, the fan willremain at a reduced rpm regardless of engine speed.Only when sufficient heat is present, will the viscous fandrive engage. This is when the air flowing through theradiator core causes a reaction to the bimetallic coil. It thenincreases fan speed to provide the necessary additionalengine cooling.Once the engine has cooled, the radiator dischargetemperature will drop. The bimetallic coil again reacts andthe fan speed is reduced to the previous disengaged speed.Caution: Engines equipped with serpentine drive beltshave reverse rotating fans and viscous fan drives. They aremarked with the word REVERSE to designate their usage.Installation of the wrong fan or viscous fan drive can resultin engine overheating.If the viscous fan drive is replaced because of mechanicaldamage, the cooling fan blades should also be inspected.Inspect for fatigue cracks, loose blades, or loose rivets thatcould have resulted from excessive vibration. Replace fanblade assembly if any of these conditions are found. Alsoinspect water pump bearing and shaft assembly for anyrelated damage due to a viscous fan drive malfunction.Viscous Fan DriveThe thermal viscous fan drive (Figure 4-46) is a siliconefluid-filledcoupling used to connect the fan blades to thewater pump shaft. The coupling allows the fan to be drivenin a normal manner. This is done at low engine speedswhile limiting the top speed of the fan to a predeterminedmaximum level at higher engine speeds.

4.7L POWER TECH V-8 3551. NoiseNote: It is normal for fan noise to be louder(roaring) when:The under hood temperature is above theengagement point for the viscous drive coupling.This may occur when ambient (outside airtemperature) is very high.2. LeaksEngine loads and temperatures are high such aswhen towing a trailer.Cool silicone fluid within the fan drive unit isbeing redistributed back to its normal disengaged(warm) position. This can occur during the first 15seconds to one minute after engine start-up on acold engine.Viscous fan drive operation is not affected by small oilstains near the drive bearing. If leakage appearsexcessive, replace the fan drive unit.Serpentine Drive Belt DiagnosisWhen diagnosing serpentine drive belts, small cracks thatrun across ribbed surface of belt from rib to rib (Figure 4-42), are considered normal. These are not a reason toreplace belt. However, cracks running along a rib (notacross) are not normal. Any belt with cracks running alonga rib must be replaced (Figure 4-42). Also replace belt if ithas excessive wear, frayed cords or severe glazing.Refer to the Serpentine Drive Belt Diagnosis Chart,‘Cooling System’ section of Chapter 4, for further beltdiagnosis. For serpentine belt routing, refer to Figure 6- 15.Figure 6 - 15STARTING SYSTEMThe starting system consists of the following components:BatteryStarter relayStarter motor (including an integral starter solenoid)Ignition switchParldneutral position switchWire harnesses and connections (including thebattery cables).The starting system components form two separate circuits.A high-amperage feed circuit that feeds the starter motorbetween 150 and 350 amperes, and a low-amperage controlcircuit that operates on less than 20 amperes. The highamperagefeed circuit components include the battery, thebattery cables, the contact disc portion of the startersolenoid, and the starter motor. The low-amperage controlcircuit components include the ignition switch, theparkheutral position switch, the starter relay, theelectromagnetic windings of the starter solenoid, and theconnecting wire harness components.Battery voltage is supplied through the low-amperagecontrol circuit to the coil battery terminal of the starter relaywhen the ignition switch is turned to the momentary Startposition. The parkheutral position switch is installed inseries between the starter relay coil ground terminal andground. This normally open switch prevents the starterrelay from being energized and the starter motor fromoperating unless the automatic transmission gear selector isin the Neutral or Park positions.When the starter relay coil is energized, the normally open relaycontacts close. The relay contacts connect the relay commonfeed terminal to the relay normally open terminal. The closedrelay contacts energize the starter solenoid coil windings.The energized solenoid pull-in coil pulls in the solenoidplunger. The solenoid plunger pulls the shift lever in thestarter motor. This engages the starter overrunning clutchand pinion gear with the starter ring gear on the automatictransmission torque converter drive plate.As the solenoid plunger reaches the end of its travel, thesolenoid contact disc completes the high-amperage starterfeed circuit and energizes the solenoid plunger hold-in coil.Current now flows between the solenoid battery terminaland the starter motor, energizing the starter.Once the engine starts, the overrunning clutch protects thestarter motor from damage by allowing the starter piniongear to spin faster than the pinion shaft. When the driverreleases the ignition switch to the On position, the starterrelay coil is de-energized. This causes the relay contacts toopen. When the relay contacts open, the starter solenoidplunger hold-in coil is de-energized.

356 MOPAR PERFORMANCE PARTSWhen the solenoid plunger hold-in coil is de-energized, thesolenoid plunger return spring returns the plunger to itsrelaxed position. This causes the contact disc to open thestarter feed circuit, and the shift lever to disengage theoverrunning clutch and pinion gear from the starter ring gear.Starter MotorThe starter motor is mounted with two screws to theautomatic transmission torque converter housing and islocated on the right side of the engine.The starter motor incorporates several features to create areliable, efficient, compact, lightweight and powerful unit.The electric motor of the starter features four electromagneticfield coils wound around four pole shoes, and four brushescontact the motor commutator. The starter motor is rated at1.4 kilowatts (about 1.9 horsepower) output at 12 volts.The starter motor is equipped with a planetary gearreduction (intermediate transmission) system. Theplanetary gear reduction system consists of a gear that isintegral to the output end of the electric motor armatureshaft that is in continual engagement with a larger gear thatis splined to the input end of the starter pinion gear shaft.This feature makes it possible to reduce the dimensions ofthe starter. At the same time, it allows higher armaturerotational speed and delivers increased torque through thestarter pinion gear to the starter ring gear.The starter motor is activated by an integral heavy dutystarter solenoid switch mounted to the overrunning clutchhousing. This electromechanical switch connects anddisconnects the feed of battery voltage to the starter motorand actuates a shift fork that engages and disengages thestarter pinion gear with the starter ring gear.The starter motor uses an overrunning clutch and starterpinion gear unit to engage and drive a starter ring gear thatis integral to the torque converter drive plate mounted onthe rear crankshaft flange.The starter motor is serviced only as a unit with its startersolenoid and cannot be repaired. If either component isfaulty or damaged, the entire starter motor and startersolenoid unit must be replaced.ManufacturerEngine ApplicationPower RatingVoltageNumber of FieldsNumber ofBrushesDrive TypeFree Runnina Test VoltaaeMitsubishi4.0L, 4.7L1.4 Kilowatt (1.9 Horsepower)12 VoltsI Number of Poles I 4 IFree Running Test Maximum Amperage DrawFree Running Test Minimum SpeedSolenoid Closing Maximum Voltage Required*Cranking Amperage Draw Test*Test at operating temperature. Cold engine, tight (new) engine,44Planetary Gear Reduction11.2 Volts7.8 Volts

4.7L POWER TECH V-8 357Starter RelayThe starter relay is an electromechanical device thatswitches battery current to the pull-in coil of the startersolenoid when the ignition switch is turned to the Startposition. The starter relay is located in the PowerDistribution Center (PDC), in the engine compartment. Seethe fuse and relay layout label affixed to the inside surfaceof the PDC cover for starter relay identification and location.The starter relay consists of an electromagnetic coil, aresistor or diode. and three (two fixed and one movable)electrical contacts. The movable (common feed) relaycontact is held against one of the fixed contacts normallyclosed) by spring pressure. When the electromagnetic coilis energized, it draws the movable contact away from thenormally closed fixed contact, and holds it against the other(normally open) fixed contact.When the electromagnetic coil is de-energized, spring pressurereturns the movable contact to the formally closed position.The resistor or diode is connected in parallel with theelectromagnetic coil in the relay, and helps to dissipate voltagespikes that are produced when the coil is de-energized.The starter relay cannot be repaired or adjusted and, iffaulty or damaged, it must be replaced.CHARGING SYSTEMThe charging system consists ofGeneratorElectronic Voltage Regulator (EVR) circuitry withinthe Powertrain Control Module (PCM)Ignition SwitchBatteryBattery Temperature SensorGenerator Lamp (if equipped)Check Gauges Lamp (if equipped)VoltmeterWiring Harness and ConnectionsThe charging system is turned on and off with the ignitionswitch. The system is on when the engine is running and theauto shutdown (ASD) relay is energized. When the ASD relayis on, voltage is supplied to the ASD relay sense circuit at thePowertrain Control Module (PCM). This voltage is connectedthrough the PCM and supplied to one of the generator fieldterminals (Gen. Source +) at the back of the generator.The amount of direct current (DC) produced by thegenerator is controlled by the Electronic Voltage Regulator(EVR) (field control) circuitry contained within the PCM.This circuitry is connected in series with the second rotorfield terminal and ground.A battery temperature sensor, located in the battery trayhousing, is used to sense battery temperature. Thistemperature data, along with data from monitored linevoltage, is used by the PCM to vary the battery charging rate.This is done by cycling the ground path to control the strengthof the rotor magnetic field. The PCM then compensates andregulates generator current output accordingly.All vehicles are equipped with On-Board Diagnostics(OBD). All OBD-sensed systems, including EVR (fieldcontrol) circuitry, are monitored by the PCM. Eachmonitored circuit is assigned a Diagnostic Trouble Code(DTC). The PCM will store a DTC in electronic memoryfor certain failures it detects. Refer to the proper servicemanual for more DTC information.The Check Gauges Lamp (if equipped) monitors chargingsystem voltage, engine coolant temperature, and engine oilpressure. If an extreme condition is indicated, the lamp will beilluminated. This is done as reminder to check the three gauges.Refer to the proper service manual for additional information.GeneratorThe generator is belt-driven by the engine using aserpentine-type drive belt. It is serviced only as a completeassembly. If the generator fails for any reason, the entireassembly must be replaced.As the energized rotor begins to rotate within the generator,the spinning magnetic field induces a current into thewindings of the stator coil. Once the generator beginsproducing sufficient current, it also provides the currentneeded to energize the rotor.The Y type stator winding connections deliver the inducedAC current to 3 positive and 3 negative diodes forrectification. From the diodes, rectified DC current isdelivered to the vehicle electrical system through thegenerator battery terminal.Although the generators appear the same externally,different generators with different output ratings are usedon the Jeep Grand Cherokee. Be certain that thereplacement generator has the same output rating and partnumber as the original unit. Refer to the proper servicemanual for amperage ratings and part numbers.Noise emitting from the generator may be caused by: worn,loose or defective bearings; a loose or defective drivepulley; incorrect, worn, damaged or misadjusted fan drivebelt; loose mounting bolts; a misaligned drive pulley or adefective stator or diode.

358 MOPAR PERFORMANCE PARTSBattery Temperature SensorThe battery temperature sensor is attached to the batterytray located under the battery. It is used to determine thebattery temperature and control battery charging rate. Thistemperature data, along with data from monitored linevoltage, is used by the PCM to vary the battery chargingrate. System voltage will be higher at colder temperaturesand is gradually reduced at warmer temperatures.Electronic Voltage RegulatorThe Electronic Voltage Regulator (EVR) is not a separatecomponent. It is actually a voltage regulating circuit locatedwithin the Powertrain Control Module (PCM). The EVR isnot serviced separately. If replacement is necessary, thePCM must be replaced.The amount of DC current produced by the generator iscontrolled by EVR circuitry contained within the PCM.This circuitry is connected in series with the generatorssecond rotor field terminal and its ground.Voltage is regulated by cycling the ground path to controlthe strength of the rotor magnetic field. The EVR circuitrymonitors system line voltage and battery temperature. Itthen compensates and regulates generator current outputaccordingly. Refer to the proper service manual foradditional information.INTAKE MANIFOLDThe intake manifold is made of a composite material andfeatures long runners which maximize low end torque. Theintake manifold uses single plane sealing which consists ofeight individual press-in-place port gaskets to preventleaks. Eight studs and two bolts are used to fasten the intaketo the head.FUEL DELIVERY SYSTEMThe fuel delivery system consists ofThe fuel pump module containing the electric fuelpump, fuel gauge sending unit (fuel level sense and aseparate fuel filter located at bottom of pump module)A separate combination fuel filtedfuel pressureregulatorFuel tubes/lines/hosesQuick-connect fittingsFuel injector railFuel injectorsFuel tankFuel tank fillerhent tube assemblyFuel tank filler tube capAccelerator pedal'Throttle cableThe fuel tank assembly consists of the fuel tank, fuel tankshield, fuel tank straps, fuel pump module assembly, fuelpump module locknut/gasket, and roll over valve.A fuel fillerlvent tube assembly using a pressure/vacuumfuel filler cap is used. The fuel filler tube contains a springloadedflap (door) located below the fuel fill cap. The flapis used as a secondary way of sealing the fuel tank if thefuel fill cap has not been properly tightened.Also to be considered part of the fuel system is theEvaporative Control System. This is designed to reduce theemission of fuel vapors into the atmosphere. Thedescription and function of the Evaporative Control Systemcan be found in the appropriate service manual.Both fuel filters (at bottom of fuel pump module and withinfuel pressure regulator) are designed for extended service.They DO NOT require normal scheduled maintenance.Filters should only be replaced if a diagnostic procedureindicates to do so.Fuel Pump ModuleThe fuel pump module is installed in the top of the fueltank. The fuel pump module (Figure 6-16) contains thefollowing components:000A separate fuel pick-up filter (strainer)An electric fuel pumpA threaded locknut to retain module to tankA gasket between tank flange and moduleFuel gauge sending unit (fuel level sensor)Fuel supply tube (line) connection

4.7L POWER TECH V-8 359Fuel return tube (line) connectionThe fuel gauge sending unit and pick-up filter may beserviced separately. If the electrical fuel pump requiresservice, the entire fuel pump module must be replaced.Fuel PumpPIGTAILHARNESSIINLETFUELGAUGESENDING UNIT ~ ~ 2 2__uFigure 6 - 16The electric fuel pump is located inside of the fuelpump module.The fuel pump used in this system has a permanent magnetelectric motor. Fuel is drawn in through a filter at thebottom of the module and pushed through the electricmotor gear set to the pump outlet.The pump outlet contains a one-way check valve to preventfuel flow back into the tank and to maintain fuel supply linepressure (engine warm) when pump is not operational. It isalso used to keep the fuel supply line full of gasoline whenpump is not operational. After the vehicle has cooled down,fuel pressure may drop to 0 psi (cold fluid contracts), butliquid gasoline will remain in fuel supply line between thecheck valve and fuel injectors. Fuel pressure that hasdropped to 0 psi on a cooled down vehicle (engine off) is anormal condition.Voltage to operate the electric pump is supplied through thefuel pump relay.The filterhegulator is equipped with three different fuel lineconnections (Figure 6-17). They are used for: fuel pressure(from the fuel pump module to the filter/ regulator), fuelreturn (from the filterhegulator back to the fuel pumpmodule), and fuel supply (to the fuel rail and fuel injectors).The pressure regulator is a mechanical device that is notcontrolled by engine vacuum or the Powertrain ControlModule (PCM). The regulator is calibrated to maintain fuelsystem operating pressure of approximately 339 kPa f 34kPa (49.2 psi * 5 psi) at the fuel injectors. It contains adiaphragm, calibrated springs and a fuel return valve. Theinternal fuel filter is also part of the assembly.Fuel is supplied to the filterhegulator by the electric fuelpump. The regulator acts as a check valve to maintain somefuel pressure when the engine is not operating. This willhelp to start the engine. A second check valve is located atthe outlet end of the electric fuel pump.If fuel pressure at the pressure regulator exceedsapproximately 49 psi, an internal diaphragm closes. Excessfuel is then routed into a separate fuel return line and returnedto the fuel tank through the top of the fuel pump module.Both fuel filters (at bottom of fuel pump module and withinfuel pressure regulator) are designed for extended service.They DO NOT require normal scheduled maintenance.Filters should only be replaced if a diagnostic procedureindicates to do so.FUEL RETURNLIYEFUEL SUPPLY LINE(TO FU5L RAIL)Fuel Gauge Sending UnitThe fuel gauge sending unit (fuel level sensor) is attachedto the side of the fuel pump module. The sending unitconsists of a float, and arm and a variable resistor (track).Fuel Filter/Fuel Pressure RegulatorA combination fuel filter and fuel pressure regulator is usedon 4.7L engines. It is remotely mounted the body near thefront of the fuel tank (Figure 6-17). A separate framemounted fuel filter is not used with this engine.REAR;i/AXLE' 'Figure 6 - 17

~ ~~T -- T -1360 MOPAR PERFORMANCE PARTSFuel TankThe fuel tank is constructed of a plastic material. Its mainfunctions are for fuel storage and for placement of the fuelpump module.All models pass a full 360 degree rollover test without fuelleakage. To accomplish this, fuel and vapor flow controlsare required for all fuel tank connections.A rollover valve(s) is mounted into the top of the fuel tank(or pump module). Refer to the proper service manual forrollover valve information.An evaporation control system is connected to the rollovervalve(s) to reduce emission of fuel vapors to theatmosphere. When fuel evaporates from the fuel tank,vapors pass through vent hoses or tubes to a charcoalcanister where they are temporarily held. When the engineis running, the vapors are drawn into the intake manifold.Fuel Injector RailTOP (FUEL ENTRY)Figure 6 - 188Ob6M35Fuel Injectors(Refer to Figure 6-18.)The fuel injectors are electrical solenoids. The injectorcontains a pintle that closes off an orifice at the nozzle end.When electric current is supplied to the injector, thearmature and needle move a short distance against a spring,allowing fuel to flow out the orifice. Because the fuel isunder high pressure, a fine spray is developed in the shapeof a pencil stream. The spraying action atomizes the fuel,adding it to the air entering the combustion chamber. Aseparate fuel injector is used for each individual cylinder.The top (fuel entry) end of the injector is attached into anopening on the fuel rail. The nozzle (outlet) end of theinjector is positioned into an opening in the intake manifoldjust above the intake valve port of the cylinder head. Theengine wiring harness connector for each fuel injector isequipped with an attached numerical tag (INJ 1, INJ 2 etc.).This is used to identify each fuel injector.The injectors are electrically energized, individually and ina sequential order by the Powertrain Control Module(PCM). The PCM will adjust injector pulse width byswitching the ground path to each individual injector onand off. Injector pulse width js the period of time that theinjector is energized. The PCM will adjust injector pulsewidth based on various inputs it receives.During start up, battery voltage is supplied to the injectorsthrough the ASD relay. When the engine is operating,voltage is supplied by the charging system. The PCMdetermines injector pulse width based on various inputs.The metal fuel injector rail is used to mount the fuelinjectors to the engine. It is mounted to the intake manifold(Figure 6-19). The fuel rail is not repairable.High pressure fuel from the fuel pump is routed to the fuelrail. The fuel rail then supplies the necessary fuel to eachindividual fuel injector.A fiuel pressure test port is located on the fuel rail (Figure6-19). A quick-connect fitting with a safety latch is used toattach the fuel line to the fuel rail.Caution: The left and right sections of the fuel rail arejoined with a connector tube (Figure 6-19). DO NOTattempt to separate the rail halves at this tube. Due to thedesign of this connecting tube, it does not use any clamps.Never attempt to install a clamping device of any kind tothe tube. When removing the fuel rail assembly for anyreason, be careful not to bend or kink the connector tube.MOUNTINGQUICK-CONNECTLFigure 6 - 19

4.7L POWER TECH V-8 361Fuel Tank Filler Tube CapThe plastic fuel fill cap is threaded onto the end of the fuelfill tube.The loss of any fuel or vapor out of fuel filler tube isprevented by the use of a pressure-vacuum fuel fill cap.Relief valves inside the cap will release fuel tank pressureat predetermined pressures. Fuel tank vacuum will also bereleased at predetermined values. This cap must be replacedby a similar unit if replacement is necessary. This is in orderfor the system to remain effective.Caution: Remove fill cap before servicing any fuel systemcomponent. This is done to help relieve tank pressure. Ifequipped with a California emissions package and a LeakDetection Pump (LDP), the secondary seal below the fillcap must be pressed (opened) to relieve fuel tank pressure.POWERTRAIN CONTROL MODULE (PCM)The Powertrain Control Module (PCM), formerly referredto as the SBEC or engine controller, is a pre-programmed,triple microprocessor digital computer. It regulates ignitiontiming, air-fuel ratio, emission control devices, chargingsystem, certain transmission features, speed control, airconditioning compressor clutch engagement and idle speed.The PCM can adapt its programming to meet changingoperating conditions.The PCM receives input signals from various switches andsensors. Based on these inputs, the PCM regulates variousengine and vehicle operations through different systemcomponents. These components are referred to as PCMOutputs. The sensors and switches that provide inputs to thePCM are considered PCM Inputs.The PCM adjusts ignition timing based upon inputs itreceives from sensors that react to engine rpm, manifoldabsolute pressure, engine coolant temperature, throttleposition, transmission gear selection (automatictransmission), vehicle speed, and the brake switch.The PCM adjusts idle speed based on inputs it receivesfrom sensors that react to throttle position, vehicle speed,transmission gear selection, engine coolant temperature, airconditioning clutch switch, and brake switch.Based on inputs that it receives, the PCM adjusts ignitioncoil dwell. The PCM also adjusts the generator charge ratethrough control of the generator field and provides speedcontrol operation.Modes of OperationAs input signals to the PCM change, the PCM adjusts itsresponse to the output devices. For example, the PCM mustcalculate different injector pulse width and ignition timingfor idle than it does for wide open throttle.The PCM operates in two different modes: Open Loop andClosed Loop.During Open Loop modes, the PCM receives input signalsand responds only according to preset PCM programming.Input from the oxygen (0,) sensors is not monitored duringOpen Loop modes.During Closed Loop modes, the PCM will monitor theoxygen (0,) sensors input. This input indicates to the PCMwhether or not the calculated injector pulse width results inthe ideal air-fuel ratio. This ratio is 14.7 parts air-to-I partfuel. By monitoring the exhaust oxygen content through the0, sensor, the PCM can fine tune the injector pulse width.This is done to achieve optimum fuel economy combinedwith low emission engine performance.The fuel injection system has the following modes ofoperation:Ignition switch ONEngine start-up (crank)Engine warm-upIdleCruiseAccelerationDecelerationWide open throttleIgnition switch OFFThe ignition switch On, engine start-up (crank), engine warmup,acceleration, deceleration, and wide open throttle modesare Open Loop modes. The idle and cruise modes (with theengine at operating temperature) are Closed Loop modes.

362 MOPAR PERFORMANCE PARTSIgnition Switch (Key-On) ModeThis is an Open Loop mode. When the fuel system isactivated by the ignition switch, the following actionsoccur:The PCM pre-positions the idle air control (IAC) motor.The PCM determines atmospheric air pressure fromthe MAP sensor input to determine basic fuel strategy.The PCM monitors the engine coolant temperaturesensor input. The PCM modifies fuel strategy based onthis input.Intake manifold air temperature sensor input is monitored.Throttle position sensor (TPS) is monitored.The auto shutdown (ASD) relay is energized by thePCM for approximately three seconds.The fuel pump is energized through the fuel pumprelay by the PCM. The fuel pump will operate forapproximately three seconds unless the engine isoperating or the starter motor is engaged.The 0, sensor heater element is energized via the 0,relays, The 0, sensor input is not used by the PCM tocalibrate air-fuel ratio during this mode of operation.Engine Start-up ModeThis is an Open Loop mode. The following actions occurwhen the starter motor is engaged.The PCM receives inputs from:Battery voltageEngine coolant temperature sensorCrankshaft position sensorIntake manifold air temperature sensorManifold absolute pressure (MAP) sensorThrottle position sensor (TPS)0 Starter motor relayCamshaft position sensor signalThe PCM monitors the crankshaft position sensor. If thePCM does not receive a crankshaft position sensor signalwithin approximately 3 seconds of cranking the engine, itwill shut down the fuel injection system.The fuel pump is activated by the PCM through the fuelpump relay.Voltage is applied to the fuel injectors with the ASD relayvia the PCM. The PCM will then control the injectionsequence and injector pulse width by turning the groundcircuit to each individual injector on and off.The PCM determines the proper ignition timing accordingto input received from the crankshaft position sensor.Engine Warm-up ModeThis is an Open Loop mode. During engine warm-up, thePCM receives inputs from:Battery voltageCrankshaft position sensorEngine coolant temperature sensorIntake manifold air temperature sensorManifold absolute pressure (MAP) sensorThrottle position sensor (TPS)0 Camshaft position sensor signalParkheutral switch (gear indicator signal - automatictransmission only)Air conditioning select signal (if equipped)Air conditioning request signal (if equipped)Based on these inputs the following occurs:Voltage is applied to the fuel injectors with the ASDrelay via the PCM. The PCM will then control theinjection sequence and injector pulse width by turningthe ground circuit to each individual injector on andoff.The PCM adjusts engine idle speed through the idle aircontrol (IAC) motor and adjusts ignition timing.The PCM operates the A/C compressor clutch throughthe clutch relay. Thls is done if A/C has been selected bythe vehicle operator and requested by the A/C thermostat.When engine has reached operating temperature, thePCM will begin monitoring 0, sensor input. Thesystem will then leave the warm-up mode and go intoclosed loop operation.Idle ModeWhen the engine is at operating temperature, this is a ClosedLoop mode. At idle speed, the PCM receives inputs from:00Air conditioning select signal (if equipped)Air conditioning request signal (if equipped)0 Battery voltageCrankshaft position sensor0 Engine coolant temperature sensorIntake manifold air temperature sensorManifold absolute pressure (MAP) sensorThrottle position sensor (TPS)

4.7L POWER TECH V-8 363Camshaft position sensor signalBattery voltageParWneutral switch (gear indicator signal - automatictransmission only)0 Oxygen (0,) sensorsBased on these inputs, the following occurs:Voltage is applied to the fuel injectors with the ASDrelay via the PCM. The PCM will then controlinjection sequence and injector pulse width by turningthe ground circuit to each individual injector and offand on.The PCM monitors the 0, sensor input and adjusts airfuelratio by varying injector pulse width. It alsoadjusts engine idle speed through the idle air control(IAC) motor.The PCM adjusts ignition timing by increasing ordecreasing spark advance.The PCM operates the N C compressor clutch throughthe clutch relay. This happens if N C has been selected bythe vehicle operator and requested by the N C thermostat.Cruise ModeWhen the engine is at operating temperature, this is aClosed Loop mode. At cruising speed, the PCM receivesinputs from:Air conditioning select signal (if equipped)Air conditioning request signal (if equipped)Battery voltage0 Engine coolant temperature sensorCrankshaft position sensorIntake manifold air temperature sensorManifold absolute pressure (MAP) sensorThrottle position sensor (TPS)Camshaft position sensor signalParWneutral switch (gear indicator signal -automatictransmission only)Oxygen (0,) sensorsBased on these inputs, the following occurs:Voltage is applied to the fuel injectors with the ASDrelay via the PCM. The PCM will then adjust theinjector pulse width by turning the ground circuit toeach individual injector on and off.The PCM monitors the 0, sensor input and adjusts airfuelratio. It also adjusts engine idle speed through theidle air control (IAC) motor.The PCM adjusts ignition timing by turning the groundpath to the coil on and off.The PCM operates the A/C compressor clutch throughthe clutch relay. This happens if N C has been selected bythe vehicle operator and requested by the A/C thermostat.Acceleration ModeThis is an Open Loop mode. The PCM recognizes an abruptincrease in throttle position or MAP pressure as a demandfor increased engine output and vehicle acceleration. ThePCM increases injector pulse width in response toincreased throttle openingDeceleration ModeWhen the engine is at operating temperature, this is anOpen Loop mode. During hard deceleration, the PCMreceives the following inputs.0Air conditioning select signal (if equipped)Air conditioning request signal (if equipped)Battery voltage0 Engine coolant temperature sensorCrankshaft position sensorIntake manifold air temperature sensorManifold absolute pressure (MAP) sensorThrottle position sensor (TPS)Camshaft position sensor signalParkheutral switch (gear indicator signal - automatictransmission only)0 Vehicle speedIf the vehicle is under hard deceleration with the proper rpmand closed throttle conditions, the PCM will ignore theoxygen sensor input signal. The PCM will enter a fuel cut-offstrategy in which it will not supply a ground to the injectors.If a hard deceleration does not exist, the PCM will determinethe proper injector pulse width and continue injection.Based on the above inputs, the PCM will adjust engine idlespeed through the idle air control (IAC) motor.The PCM adjusts ignition timing by turning the groundpath to the coil on and off.Wide Open Throttle ModeThis is an Open Loop mode. During wide open throttleoperation, the PCM receives the following inputs.0 Battery voltageCrankshaft position sensorEngine coolant temperature sensor

364 MOPAR PERFORMANCE PARTS0Intake manifold air temperature sensorManifold absolute pressure (MAP) sensorThrottle position sensor (TPS)Camshaft position sensor signalDuring wide open throttle conditions, the following occurs:Voltage is applied to the fuel injectors with the ASDrelay via the PCM. The PCM will then control theinjection sequence and injector pulse width by turningthe ground circuit to each individual injector on andoff. The PCM ignores the oxygen sensor input signaland provides a predetermined amount of additionalfuel. This is done by adjusting injector pulse width.The PCM adjusts ignition timing by turning the groundpath to the coil on and off.During periods of high manifold vacuum, such as idle orcruising speeds, vacuum is sufficient to completelycompress the spring. It will then pull the plunger to the topof the valve. In this position there is minimal vapor flowthrough the valve.During periods of moderate manifold vacuum, the plungeris only pulled part way back from inlet. This results inmaximum vapor flow through the valve.O-RING\LOCATINGTABSIgnition Switch Off ModeWhen the ignition switch is turned to the OFF position, thePCM stops operating the injectors, ignition coil, ASD relayand fuel pump relay.POSITIVE CRANKCASE VENTILATION (PCV)SYSTEMThe 4.7L V-8 engine is equipped with a closed crankcaseventilation system and a Positive Crankcase Ventilation(PCV) valve.This system consists ofa PCV valve mounted to the oil filler housing (Figure6-20). The PCV valve is sealed to the oil filler housingwith an O-ring.0 the air cleaner housing.0 two interconnected breathers threaded into the rear ofeach cylinder head (Figure 6-21).0 tubes and hose to connect the system components.The PCV system operates by engine intake manifoldvacuum. Filtered air is routed into the crankcase through theair cleaner hose and crankcase breathers. The metered air,along with crankcase vapors, are drawn through the PCVvalve and into a passage in the intake manifold. The PCVsystem manages crankcase pressure and meters blow-bygases to the intake system, reducing engine sludge formation.The PCV valve contains a spring loaded plunger. Thisplunger meters the amount of crankcase vapors routed intothe combustion chamber based on intake manifold vacuum.When the engine is not operating, or during an engine popback,the spring forces the plunger back against the seat.This will prevent vapors from flowing through the valve.RUBBERHOSEFigure 6 - 20FRESH AIRFITTING1Figure 6 - 2 1LOCK-CRAN~KCASEBREATHERS (2)T '17

T - n r i4.7L POWER TECH V-8 365EXHAUST SYSTEMExhaust ManifoldsExhaust manifolds are log style with ii patcnted flowenhancing design to maximir.e pcrfornimce. The exhaustmanifolds are made of high silicon molybdenum cast iron. Aperforated core graphite cxhaust manifold gasket is used toimprove sealing to the cylinder liead. Exhaust iiianitolds arecovered by a three layer larninated heat shield for thermalprotection and noise reduction. Heat shields are fastened witha torque prevailing nut that is backed off slightly to allow forthe thermal expansion of exhaust manifolds.Oxygen SensorsThe exhaust system uses oxygen wnsors to detect exhaustgasses. These gasses arc sampled to determine whether thesystem is rich (to much fuel) or lean (not enough fuel). ThePowertrain Control Module (PCM) then makes theappropriate ad.justnient to the fuel system.Muffler and TailpipeThe 4.7L engine uses a galvanized steel muffler to controlexhaust noise levels and exhausl backprcssure.The tail pipe is also made of gnlvani/ccl steel and channelsthe exhaust out of the muffler and out lrom under thevehicle to control noise and prevent exhaust gas luiiies fromentering the passenger compartment.IGNITION SYSTEMThe 4.7L V-8 engine uses a dedicated and individually l‘iredcoil for each spark plug (8 total). Each coil is mounteddirectly to the top of each spark plug. A scparate electricalconnector is used for each coil.Because of coil design, spark plug cables (secondarycables) are not used. A distributor is also not used.The ignition system is controlled by the Powertrain ControlModule (PCM), and consists of:Spark PlugsIgnition CoilsPowertrain Control Module (PCM)Crankshaft Position SensorCamshaft Position SensorThe MAP, TPS, IAC and EC‘T also have ;in et‘l’ect onthe control of the ignition system.Spark PlugsThe 4.71, V-8 engine is equippcd with “fired-in suppressorseal,” resistor-type spark plugs using a copper core grounde I cc t rode. To pre ve n t pos s i b I e pre- i g ni t i on and/ormechanical engine damage, the correct type/heatrange/nuniber spark plug iniist be used.4.71, V-8 engine spark plugs have resistance values rangingfrom 6,000 to 20,000 ohms (when checked with at least a1,000 volt spark plug tester). DO NOT use an ohmmeter tocheck the resistance values of the spark plugs. Inaccuratereadings will result. Remove the spark plugs and examinethem tbr burned electrodes and fouled, cracked or brokenporcelain insulators. Keep plugs arranged in the order inwhich they were reniovcd from the engine. A single plugdisplaying an abnormal condition indicatcs that a problemexists in the corresponding cylinder. Replace spark plugs atthe intervals recommended in your owner’s manual.Spark plugs that have low rnileagc may be cleaned andreused if not otherwise defective, carbon or oil fouled.Caution: Never use a motorized wire wheel brush to cleanthc spark plugs. Metallic dcposits will remain on the sparkplug insulator and will cause plug misfire.Because of the use of aluminum cylinder heads on the 4.7Lengine, spark plug torque is very critical. Refer to theproper service manual for procedure and specifications.Ignition Coils'lie 4.7L V-8 engine uses a dedicated and individually firedcoil (Figure 6-22) for each spark plug (8 total). Each coil ismounted directly to the top of‘each spark plug.Battery voltage is supplied to the 8 ignition coils from theASD relay. The Powertrain Control Module (PCM) opensand closes each ignition coil ground circuit at a determinedtime foi- ignition coil operation.Base ignition timing is not adjustable. By controlling thecoil ground circuit, the PCM is ahle to set the base timingand aci,iiist the ignition timing advance. This is done to meetchanging engine operating conditions.Thc ignition coil is not oil filled. The windings areembedcicd in an epoxy compound. This provides heat andince that nllows the ignition coil to beinounted on the engine.I3ccausc of coil design, spark plug cables (secondarycahles) are not uwd.

T - r 7366 MOPAR PERFORMANCE PARTSO-RINGIGNITIONCOILELECTRICALCONNECTORFigure 6 - 2280676fe6TROUBLESHOOTINGCylinder Compression Pressure TestThe results of a cylinder compression pressure test can beutilized to diagnose several engine malfunctions.Ensure the battery is completely charged and the enginestarter motor is in good operating condition. Otherwise, theindicated compression pressures may not be valid fordiagnosis purposes.

- --I ri4.7L POWER TECH V-8 367ICYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHARTCONDITIONAIR ESCAPES THROUGHTHROTTLE BODYAIR ESCAPES THROUGHTAILPIPEAIR ESCAPES THROUGHRADIATORMORE THAN 50% LEAKAGEFROM ADJACENT CYLINDERSMORE THAN 25% LEAKAGE ANDAIR ESCAPES THROUGH OILFILLER CAP OPENING ONLYPOSSIBLE CAUSEIntake valve bent, burnt, or notseated DroDerlvExhaust valve bent, burnt, or notseated properlyHead gasket leaking or crackedcylinder head or blockHead gasket leaking or crack incylinder head or block betweenadjacent cylindersStuck or broken piston rings;cracked piston; worn rings and/orcylinder wallCORRECTIONInspect valve and valve seat.Reface or replace, as necessaryInspect valve and valve seat.Reface or replace, as necessaryRemove cylinder head and inspect.Replace defective partRemove cylinder head and inspect.Replace gasket, head, or block asnecessaryInspect for broken rings or piston.Measure ring gap and cylinderdiameter, taper and out-of-round.Replace defective part as necessaryI1. Disconnect the ignition coil tower electrical connectorsand remove ignition coil towers.2. Remove the spark plugs.3.4.5.6.7.Clean the spark plug recesses with compressed air.Secure the throttle in the wide-open positionDisable the fuel system. (Refer to the proper servicemanual for the correct procedure)Insert a compression pressure gauge and rotate the enginewith the engine starter motor for three revolutions.Record the compression pressure on the 3rd revolution.Continue the test for the remaining cylinders.Refer to 4.7L Engine Specifications, in this chapter, for thecorrect engine compression pressures.Engine Cylinder Head Gasket Failure DiagnosisA leaking engine cylinder head gasket usually results inloss of power, and/or coolant and engine misfiring. Anengine cylinder head gasket leak can be located betweenadjacent cylinders or between a cylinder and the adjacentwater jacket.An engine cylinder head gasket leaking betweenadjacent cylinders is indicated by a loss of powerand/or engine misfire.Cylinder-to-Cylinder Leakage TestTo determine if an engine cylinder head gasket is leakingbetween adjacent cylinders, follow the procedures outlinedin Cylinder Compression Pressure Test. An engine cylinderhead gasket leaking between adjacent cylinders will result inapproximately a 50-70% reduction in compression pressure.Cylinder-to-Water Jacket Leakage TestWarning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or the fan. DONOT wear loose clothing.Remove the radiator cap.Start the engine and allow it to warm up until the enginethermostat opens.If a large combustiodcompression pressure leak exists,bubbles will be visible in the coolant.If bubbles are not visible, install a radiator pressure testerand pressurize the coolant system.If a cylinder is leaking combustion pressure into the waterjacket, the tester pointer will pulsate with every combustionstroke of the cylinder.An engine cylinder head gasket leaking between acylinder and an adjacent water jacket is indicated bycoolant foaming or overheating and loss of coolant.

368 MOPAR PERFORMANCE PARTSCylinder Combustion Pressure Leakage TestThe combustion pressure leakage test provides an accuratemeans for determining engine condition.Combustion pressure leakage testing will detect:Exhaust and intake valve leaks (improper seating).Leaks between ad-jacent cylinders or into water jacket.Any causes for combustionkompression pressure loss.The procedure is as follows:I.2.3.4.5.6.7.8.9.Check the coolant level and fill as required. DO NOTinstall the radiator cap.Start and operate the engine until it attains normaloperating temperature, then turn the engine OFF.Disconnect ignition coil tower electrical connectors.Remove ignition coil towers.Remove the spark plugs.Remove the oil filler cap.Remove the air cleaner.Calibrate the tester according to the manufacturer’sinstructions. The shop air source for testing shouldmaintain 483 kPa (70 psi) minimum, 1,379 kPa (200psi) inaxirnuni, and 552 kPa (80 psi) recommended.Perform the test procedures on each cylinder accordingto the tester manufacturer’s instructions. While testing,listen for pressurized air escaping through the throttlebody, tailpipe and oil filler cap opening. Check forbubbles in the radiator coolant.All gauge pressure indications should be equal, with nomore than 25% leakage.Example: At 552 kPa (80 psi) input pressure, a minimumof 414 kPa (60 psi) should be maintained in the cylinder.Refer to the Cylinder Combustion Pressure LeakqgeDiagnosis Cliurt.3. Using a black light, inspect the entire engine forfluorescent dye, particularly at the suspected area of oilleak. If the oil leak is found and identified, repair perservice manual instructions.4.5.If dye is not observed, drive the vehicle at variousspeeds for approximately 24 km (IS miles), andrepeat inspection.If the oil leak source is not positively identified at thistime, proceed with the Air Leak Detection Test Method.Air Leak Detection Test Method1. Disconnect the breather cap to air cleaner hose at thebreather cap end. Cap or plug breather cap nipple.2.3.Remove the PCV valve from the cylinder head cover.Cap or plug the PCV valve grommet.Attach an air hose with pressure gauge and rcgulator tothe dipstick tube.Caution: DO NOT subject the engine assembly to morethan 20.6 kPa (3 psi) of test pressure.4. Gradually apply air pressure from 1 psi to 2.5 psimaximum while applying soapy water at the suspectedsource. Adjust the regulator to the suitable test pressurethat provide the best bubbles which will pinpoint theleak source. If the oil leak is detected and identified,repair per service manual procedures.5.6.7.If the leakage occurs at the rear oil seal area, refer toIn.spction ,fi)v Reur Seal Area Leaks.If no leaks are detected, turn off the air supply andremove the air hose and all plugs and caps. Install thePCV valve and breather cap hose.Clean the oil off the suspect oil leak area using asuitable solvent. Drive the vehicle at various speedsapproximately 24 km (15 miles). Inspect the engine forsigns of an oil leak by using a black light.Engine Oil Leak InspectionBegin with a thorough visual inspection of the engine,particularly at the area of the suspected leak. If an oil leaksource is not readily identifiable, the following steps shouldbe followed:1. DO NOT clean or degrease the engine at this timebecause some solvents may cause rubber to swell,temporarily stopping the leak.2. Add an oil soluble dye (use as recommended bymanufacturer). Start the engine and let idle forapproximately 15 minutes. Check the oil dipstick tomake sure the dye is thoroughly mixed as indicatedwith a bright yellow color under a black light...T --T 7

T -114.7L POWER TECH V-8 369Inspection for Rear Seal Area LeaksSince it is sometimes difficult to determine the source of anoil leak in the rear seal area of the engine, a more involvedinspection is necessary. The following steps should befollowed to help pinpoint the source of the leak.If the leakage occurs at the crankshaft rear oil seal area:1. Disconnect the battery.2. Raise the vehicle.3. Remove torque converter or clutch housing cover andinspect rear of block for evidence of oil. Use a blacklight to check for the oil leak:a. Circular spray pattern generally indicates sealleakage or crankshaft damage.b. Where leakage tends to run straight down, possiblecauses are a porous block, camshaft bore cup plugs,oil galley pipe plugs, oil filter runoff, and mainbearing cap-to-cylinder block mating surfaces.4. If no leaks are detected, pressurize the crankcase asoutlined in the Air Leak Detection Test Method.Caution: DO NOT exceed 20.6 kPa (3 psi) of test pressure.5. If the leak is not detected, very slowly turn thecrankshaft and watch for leakage. If a leak is detectedbetween the crankshaft and seal while slowly turningthe crankshaft, it is possible the crankshaft seal surfaceis damaged. The seal area on the crankshaft could haveminor nicks or scratches that can be polished out withemery cloth.Caution: Use extreme caution when crankshaft polishingis necessary to remove minor nicks and scratches. Thecrankshaft seal tlange is specially machined to complementthe function of the rear oil seal.6. For bubbles that remain steady with shaft rotation,no further inspection can be done until the engineis disassembled.

370 MOPAR PERFORMANCE PARTS1999,4.7L ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1999 Jeep Grand Cherokee Service Manual.DESCRIPTIONSPECIFICATIONGeneral SpecificationType. ................ 90" SOHC V-8 16-ValveDisplacement .............. 4.7 Liters 4701 cc(287 Cubic Inches)Bore & Stroke ............ 93.0 mm x 86.5 nun'(3.66 in. x 3.40 in.)1Compression Ratio ....................9.0:Lead Cylinder .................#1 Left Bank:Finhg Order .................. 1,8,4,3,6,5,7,2'Cylinder Block ..................... Cast IronCylinder Head ..................... Aluminum'Cylinder BlockCylinder Bore Diameter .... 93.010 t .0075 111111.(3.6619 2 0.0003 in.)DESCRIPTIONSPECIFICATIONOut of Round (Max) ...... 0.076 mm (0.003 in.)Taper (Max) ............ 0.05 1 mm (0.002 in.)PistonsType Material ............... Aluminum alloy 'Piston diameter ........ 92.975 mm (3.6605 in.)Clearance at Size Location .. 0.0198 - 0.0501 mmPiston WeightPiston Ring Groove Diameter(0.0008 - 0.0020 in.).................... 367.5 grams ( 12.96 02.1NO. 1 ...... 83.73 - 83.97 mm (3.296 - 3.269 in.)NO. 2 .... 82.833 - 83.033 mm(3.261 - 3.310 in.)NO. 3 ...... 83.88 - 84.08 mm (3.302 - 3.310 in.)Piston PinsType .......................... Pressed FitClearance In Piston ......... 0.018 - 0.019 mm(0.0008 in.)Diameter, ............... 24.008 - 24.013 mm(0.9452- 0.9454 in.)Piston RingsRing Gap Top CompressionRing. ..... 0.37 - 0.63 mm (0.0146- 0.0249 in.)Ring Gap 2nd CompressionRing. ..... 0.37 - 0.63 mm (0.0146- 0.0249 in.)Ring Gap Oil Control(Steel Rails) . . 0.25 - 1.27 mm (0.0099- 0.05 in.)Ring Side Clearance'Ibp Compression Ring. ........ .051- .lo4 mm(0.0020- 0.0041 in.)Second Compression Ring. .... 0.040 - 0.080 mm(0.0016- 0.0032 in.)Oil Ring (SteelRails). ..... .019- .229 mm LO007 - .0091 in.)Ring WidthTop Compression Ring ....... 1.472 - 1.490 mm(0.057- 0.058h.)2nd Compression Ring ....... 1.472 - 1.490 mm(0.057 - 0.058in.)Oil Ring (Steel Rails). ....... 0.445 - 0.470 mm( 0.017 - 0.018 in.)Connecting RodsBearing Clearance .......... 0.010 - 0.048 mm(0.0004- 0,0019 in.)Side Clearance .............. 0.10 - 0.35 mm(0.004- 0.0138 in.)Piston Pin BoreDiameter ....... Interference fit .022- .045 mm(0.0009 - 0.0018 in.)Bearing Bore Out of bund(Max. Allowable) ............. 0.004 mm ( in.)Total Weight (Less Bearing) ......... 578 grams(20.388 ounces)Crankshaft Main Bearing JournalsDiameter. ............... 63.488 - 63.512 mm(2.4996 - 2.5005 in.)Bearing Clearance .......... 0.004 - 0.032 mm(0.0002 - 0.0013 in.)Out of Round (Max.) ...... 0.005 mm (0.0002 in.)Taper (Max.) ............ 0.008 mm (0.0004 in.)End Play. ................. 0.052 - 0.282 mm(0.0021 - 0.0112 in.)End Play (Max. Allowable) .......... 0.282 mmConnecting Rod Journals(0.0112 in.)Diameter. ............... 50.992 - 51.008 mm(2.0076 - 2.0082 in.)Bearing Clearance .......... 0.010 - 0.048 mm(0.0004 - 0.0019 in.)Out Of Round (Max.)..... 0.005 mm (0.0002 in.)Taper (Max.) ............ 0.008 mm (0.0004 in.)CamshaftBore Diameter ............. 26.02 - 26.04111113(1.0245- 1.0252 in.)Bearing Journal Diameter .. 25.975 - 25.995 mm(1.0227- 1.0235 in.)Bearing Clearance .......... 0.025 - 0.065 mm(0.001- 0.0026 in.)Bearing Clearance (Max. Allowable) ... 0.065 mm(0.0026 in.)End Play ........................ mm (in.)Valve Timing Intake ValveOpens (ATDC) ........................ 3.5"Closes (ATDC) ........................ 247"Duration ........................... 243.5"..T - T T

4.7L POWER TECH V-8 371DESCRIPTIONValve Timing Exhaust ValveSPECIFICATIONOpens (BBDC) ...................... 232.5'Closes (ATDC) ...................... 21.25"Duration .......................... 253.75'Valve Overlap ....................... 17.75"Cylinder HeadGasket Thickness (Compressed) .. .7 mm (0.0276in.)Valve Seat Angle ................ 44.5" - 45.0"Valve Seat Runout (Max) ... 0.051 mm (0.002 in.)Intake Valve Seat Width ....... 1..75 - 2.36 mm(0.0698 - 0.0928 in.)Exhaust Valve Seat Width ...... 1.71 - 2.32 mm(0.0673 - 0.0911 in.)Guide Bore Diameter (Std.) .... 6.975 - 7.00 mm(0.2747- 0.2756 in.)Cylinder Head Warpage (Flatness) ... 0.0508 mm(0.002 in.)ValvesFace Angle .................... 45.0" - 45.5"Head Diameter Intake ....... 47.87 - 48.13 mm(1.8846 1.8949 in.)(1.0227- 1.0235 in.)Bearing Clearance .......... 0.025 - 0.065 mm(0.001- 0.0026 in.)Bearing Clearance (Max. Allowable) ... 0.065 mm(0.0026 in.)End Play ........................ mm (in.)Head Diameter Exhaust ...... 36.87 - 37.13 mm(1.4516- 1.4618 in.)Length-Intake (Overall) ... 113.13 - 113.89 mm(4.4539 - 4.4839 in.)Length-Exhaust (Overall) . . 114.92 - 115.68 mm(4.5244 - 4.5543 in.)Stem Diameter-Intake ...... 6.931 - 6.957 mm(0.2729 - 0.2739 in.)Stem Diameter-Exhaust ..... 6.902 - 6.928 mm(0.2717 - 0.2728 in.)Stem-to-Guide Clearance Intake(New) ..... .026 - .043 mm (0.0011 - 0.0017 in.)Stem-to-Guide ClearanceExhaust(New) ............ .072 - .073 mm (0.0029 in.)Max. Allowable (Rocking Method&Intake ................ 0.069 mm (0.0028 in.)Max. Allowable (Rocking Method&Exhaust ............... 0.098 mm (0.0039 in.)Valve Lift (Zero LashbIntake ....... 11.25 mm(0.443 in.)Valve Lift (Zero LashbExhaust ...... 10.90 mm(0.4292 in.)DESCRIPTIONSPECIFICATIONValve SpringFree Length (Approx.)Intake & Exhaust. ......... 47.5 mm (1.870 in)Spring Force (Valve Closed)Intake & Exhaust ... 285.2-320.8 N @ 40.69 mm(64.0-72.0 lbs. Q 1.6020 in.)Spring Force (Valve Open)Intake ........... 775.3-846.7 N @ 29.29 mm(176.2-192.4 lbs. @ 1.1532 in.)Spring Force (Valve Open)Exhaust ........... 775.3-846.7 N @ 29.29 mm(176.2-192.4 Ibs. @ 1.1532 in.)Number of Coils-Intake & Exhaust ........ 6.6Wire DiameterIntake & Exhaust. ........ 4.2799 - 4.3561 mm(0.1685 - 0.1715 in.)Installed HeightIntake(Spring Seat to Bottom of Retainer) ... 40.97 mm(1.613 in.)Installed HeightExhaust(Spring Seat to Bottom of Retainer) ... 40.81 mmOil Pump(1.606 in.)Clearance Over Rotors (Max.) ... .035 - .095 mm(0.0014 - 0.0038 in.)Cover Out-of-Flat (Max.) .... .025 mm (0.001 in.)Inner and Outer Rotor Thickness .... 12.08 mm(0.4756 in.)Outer Rotor Clearance (Max.) ........ 85.96 mm(3.3843 in.)Outer Rotor Diameter (Min.) ........ 85.925 mm(0.400 in.)Tip Clearance Between Rotors (Max.) ... .150 mmOil Pressure(0.006 in.)At Curb Idle Speed * ... 25 kPa (4 psi) minimumAt 3000 rpm .................. 170 - 550 Wa(25 - 80 psi)*CAUTION: If pressure is zero at curb idle, DO NOTrun engine at 3000 rpm.

372 MOPAR PERFORMANCE PARTS1999,4.7L ENGINE TORQUE SPECIFICATIONSNote: The following information has been repsinted from the 1999 Jeep Grrind Cherokee Service Munual.DESCRIPTIONCamshaft SprocketTORQUEBolt .................... 122 N.m (90 ft. lbs.)Camshaft Bearing CapsBolt. ................... 11 N.m (100 in. lbs.)Timing Chain CoverBolt ..................... 54 N.m (40 ft. lbs.)Connecting Rod CapBolt ............ 20 N-m (15 ft. lbs.), Plus 110"'Crankshaft Main Bearing CapmedplateBolt ..................... Refer to ProcedureCrankshaft DamperBolt ................... 175 N-m (130 R. lbs.)Cylinder Head BoltsM11 Bolt ................. 81 N.m (60 R. lbs.)M8 Bolt ................ 28 N-m (250 in. lbs.)Cylinder Head CoverBolt ................... 12 Nam (105 in. lbs.)Exhaust ManifoldBolt.. ................... 25 N.m (18 ft. lbs.)Exhaust Manifold Heat ShieldNut. ........ 8 N-m (72 in. lbs.), then loosen 45"FlexplateBolts .................... 60 N.m (45 ft. lbs.)Engine Mount Bracket to Block-FrontBolts .................... 61 N-m (45 ft. lbs.)Engine MounCD-ar-to-TransmissionBolts .................... 46 N.m (34 ft. lbs.)Generator MountingM10 Bolts ................ 54 N.m (40 ft. lbs.)M8 Bolts. ............... 28 N-m (250 in. lbs.)Intake ManifoldBolts ... 12 N-m (105 in. 1bs.bRefer to procedurefor tightening sequence.Oil PanBolts ................... 15 N-m (130 in. lbs.)Oil Pan Drain PlugPlug .................... 34 N.m (25 R. lbs.)DESCRIPTIONTORQUEOil PumpBolts ................... 28 N.m (250 in. lbs,)Oil Pum.p CoverBolts. .................. 12 N.m (105 in. lbs.)Oil Pickup TubeBolts ................... 28 N-m (250 in. lbs.)Oil Dipstick TubeBolt ................... 28 N.m (250 in. lbs.)Oil Fill 'hbeBolts ................... 12 N.m (105 in. lbs.)Spark PlugsPlugs .................... 37 N.m (27 ft. lbs.)Starter MountingBolts .................... 45 N.m (33 ft. lbs.)Timing Chain GuideBolts ................... 28 N.m (250 in. lbs.)Timing Chain Tensioner ArmSpecial Pin Bolt .......... 17 N-m (150 in. lbs.)Secondary Timing Chain Hydraulic TensionerBolts ................... 28 N.m (250 in. lbs.)Timing Chain Primary TensionerBolts ................... 28 N.m (250 in. lbs.)Timing Drive Idler SprocketBolt. .................... 34 N-m (25 ft. lbs.)Thermostat HousingBolts ................... 12 N.m (105 in. lbs.)Torque Converter to FlexplateBolts .................... 38 N-m (28 ft, lbs.)Water PumpBolts .................... 54 N-m (40 R. lbs.)

Chapter 7

374 MOPAR PERFORMANCE PARTSIntroduction ............ ................................ ................. 375................. ......................... 377..................................... ......................... 380....................................... ......,388CylinderHeads .......................................................................... 394Camshaft and Valve Gear ........... .......................................397............................... ............................. 406Cooling System ............ ................................. ..........413Induction System ... .. ............................. ......................... 414FuelDelivery System ............................................................421Exhaust System ..................................... .............................Ignition System .............................. ................................ 425Engine Assembly ........................................................................ 435

360 AMC V-8 (INTRODUCTION) 375Note: The following procedures for the 360 AMC V-8 engine are intended to be performed in-vehicle, on a dynamometer,or as an individual change/modification.In addition to the information contained in this chapter, much of the information contained in Chapter 4, 4.0L Power Tech Zn-Line 6, is generic to all Jeep engines (including the 360 AMC V-8). Therefore, in addition to this chapter, we highlyrecommend that all 360 AMC V-8 engine owners read Chapter 4 in its entirety.For additional 360 AMC V-8 engine general service informal.ion, refer to the proper service manual.Note: The AMC-built 360 V-8 engine is NOT related toeither the DaimlerChrysler small block 360 'A' engine or5.2L Magnum engine. For complete information on theDaimlerChrysler 'A' engine family, refer to Small Block 'A 'Engines (P4876826). For complete information on theDaimlerChrysler Magnum engine family, refer to MagnumEngines (P4876668).The AMC-built 360 CID engine is a cast iron, 8 cylinder,90" V-block design that was in production from 1970-9 1. Ithas a standard bore and stroke of 103.63 x 87.38 mm (4.08x 3.44"), and an 8.25:l compression ratio.IntroductionAMC-built V-8 engines also came in the following CIDversions:Enaine CID [Year)Bore x Stroke290 (1966-69) 3.75 x 3.28"304 (1 972-80) 3.75 x 3.44"343 (1 967-69) 4.08 x 3.28"360 (1 970-9 1) 4.08 x 3.44"390 (1 968-70) 4.165 x 3.514"401 (1973-79) 4.17 x 3.68"Engine Description, CylinderIType ................................................Bore ond Stroke .........................................Displacement ...........................................Compression Ratio ........................................Torque ..............................................Firing Order.. .........................................lubrication ............................................Engine Oil Capacity. ......................................Cooling System. .........................................Cooling System Capacity ...................................Cylinder Block ..........................................Crankshaft ............................................Head ..........................................Camshaft ............................................Pistons .............................................Pistons Combustion Cavity ...................................Connecting Rods ........................................8 cylinder 9 P V-Block103.63 x 87.38 mm (4.08 x 3.44 in)5.9L (360 cu. inch)8.25:i379 N.m (280 ft-lbs) @ 1500 rpm1-8-4-3-6-5-7-2Pressure Feed-Full Flow Filtration4.7L (5 Quarts)Liquid Cooled-Forced Circulation13.2L (14 Quarts)Cast IronCast Nodular IronCast IronCast IronAluminum Alloy (with Struts)Open ChamberCast IronJ8909-40 3

376 MOPAR PERFORMANCE PARTSI

~~ ~~ ~T -7 T lINTRODUCTIONThe 360 AMC V-8 engine block cylinders are numbered 1 - 8from front to rear. Cylinders 1, 3, 5 and 7 are on the leftbank and cylinders 2,4,6 and 8 are on the right bank. Thefiring order is 1-8-4-3-6-5-7-2.For more information, refer to 360 AMC V-8 EngineSpecifications, 'Engine Assembly' section of this chapter.Cylinder Block Hardware PackageThis cylinder block hardware package comes completewith cam bearings, various freezekore plugs and locatingpins. For use when block is tankedstress relieved andmachined. For 360 AMC V-8 only.P4529639Engine Teardown Gasket SetCylinder block hardware package.Designed for bearing check, bore check, or cylinder headmodifications/teardown only. Gaskets include: cylinderheads, oil pan, intake manifold, exhaust manifolds andfront cover gaskets. For 360 AMC V-8 only.P4529634Engine teardown gasket set.Flywheel Attaching PackageThis Mopar Performance Parts flywheel attaching packagecomes complete with all the bolts required to attach theflywheel and clutch to your engine assembly. Includes six(6) flywheel bolts, six (6) clutch bolts, and pilot bearing.For 360 AMC V-8 only.P4529636Short Block Disassembly1.2.3.4.5.6.7.8.Drain the engine oil.Flywheel attaching package.Remove the engine assembly from the vehicle. Referto the proper service manual for the procedure.Use an engine stand to support the engine assembly.Remove the distributor.Remove the cylinder head covers and gaskets.Remove the bridge and pivot assemblies and rockerarms. Alternately loosen the capscrews one turn at atime to avoid damaging the bridge.Remove the pushrods. Retain the bridges, pivots,rocker arms, pushrods and tappets in the same order tofacilitate installation in their original locations.Remove the intake manifold assembly.Block360 AMC V-8 (BLOCK) 3779. Remove the valve tappets.10. Remove the cylinder heads and gaskets.11. Position the pistons, one at a time, near the bottom ofthe stroke. Use a ridge reamer to remove the ridge, ifany, from the top end of the cylinder walls.12. Loosen all drive belts. Remove the power steering pump,air pump and air conditioner compressor, if equipped.13. Scribe a mark on the torque converter and drive plateprior to crankshaft removal. Install in the same positionduring assembly.14. Remove the damper pulley and vibration damper.15. Remove the timing case cover.16. Remove the oil pan.17. Remove the camshaft.18. Remove the connecting rod bearing caps and inserts.Retain in the same order as removed. The connectingrods and caps are stamped with the number of theassociated cylinder.19. Remove the connecting rod and piston assembliesthrough the top of the cylinder bores. Ensure that theconnecting rod bolts DO NOT scratch the connectingrod journals or cylinder walls. Short pieces of rubberhose slipped over the rod bolts will provide protectionduring removal.20. Remove the oil pickup tube and screen assembly.21. Scribe a mark on the torque converter and drive plateprior to crankshaft removal. Install in the same positionduring assembly.22. Remove the main bearing caps and inserts.23. Remove the crankshaft.Cylinder Bore MeasurementUse a bore gauge to measure the cylinder bores. If a boregauge is not available, use an inside micrometer.Measure the cylinder bore crosswise to the block near thetop of the bore. Repeat the measurement at the bottom ofthe bore. Determine cylinder bore taper by subtracting thesmaller dimension from the larger dimension.Turn the measuring device 120" and repeat the procedure.Then turn another 120" and repeat the measurements.Determine out-of-roundness by comparing the differencebetween the measurements taken 120" apart.

378 MOPAR PERFORMANCE PARTSIf cylinder bore taper does not exceed 0.127 mm (0.005”)and out-of-roundness does not exceed 0.076 mm (0.003”),true the cylinder bore by honing. If cylinder bore taper orout-of-round condition exceeds these limits, bore and thenhone the cylinder for an oversize piston.Cylinder Bore ReconditioningCaution: DO NOT use rigid type hones to removecylinder glaze. A slight amount of taper always exists incylinder walls after the engine has been in service for aperiod of time.Use an expanding hone to true the cylinder bore and toremove glaze for faster ring seating. Move the hone up anddown at sufficient speed to produce a uniform 60” anglecrosshatch pattern on the cylinder walls. DO NOT use morethan ten (10) strokes per cylinder. A stroke is one downand-upmotion.Caution: Protect the engine bearings and lubricationsystem from abrasives.Scrub the cylinder bores clean with a solution of hot waterand detergent. Wipe with a clean, lint-free cloth.Note: If the crankshaft is not removed from the block,cover the connecting rod journals with a clean cloth duringthe cleaning operation.Short Block Assembly1.2.3.4.5.6.7.8.Install and lubricate the upper main bearing inserts andrear main upper seal half. Lubricate the seal lip.Install the crankshaft.Install the main bearing caps and inserts. Ifreplacement bearings are installed, measure eachbearing clearance with Plastigauge (P4286819).Install a replacement oil pickup tube and screenassembly. DO NOT attempt to install the originalpickup tube. Ensure the plastic button is inserted in thebottom of the replacement screen.Install the camshaft.Position the piston rings on the pistons. Refer to PistonRing Fitting, ‘Piston and Connecting Rod Assembly’section for the procedure.Lubricate the piston and ring surfaces with cleanengine oil.Use a piston ring compressor tool to install theconnecting rod and piston assemblies through the topof the cylinder bores. Ensure that the connecting rodbolts DO NOT scratch the connecting rod journals orcylinder walls. Short lengths of rubber hose slippedover the connecting rod bolts will provide protectionduring installation.9. Install the connecting rod bearing caps and inserts inthe same location as removed. Tighten the nuts to 45Nom (33 ft-lbs) torque.10. Install the camshaft and crankshaft sprockets andtiming chain as an assembly.11. Install the timing case cover and gaskets. Refer toTiming Case Cover Installation, ‘Crankshaft’ sectionfor the procedure.12. Install the engine oil pan using replacement gasketsand seals. Tighten the drain plug securely.13. Install the vibration damper and pulley.14. Install the cylinder heads with replacement gaskets.15. Install the valve tappets.16. Install the intake manifold with a replacement gasket.17. Install the pushrods.18. Install the rocker arms and bridge and pivotassemblies. Loosely install the capscrews through eachbridge and then alternately tighten the capscrews, oneturn at a time, to avoid damaging the bridge. Tightenthe capscrews 26 Nom (19 ft-lbs) torque.19. Turn the crankshaft to position the No. 1 piston at TDCon the compression stroke.20. Reseal and install the cylinder head covers.21. Install the power steering pump, air pump and airconditioner compressor.22. Install the distributor.23. Point the rotor at the No. 1 spark plug firing position.24. ‘Turn the oil pump drive shaft with a long screwdriverto engage it with the distributor shaft.25. With the rotor pointing at the No. 1 spark plug firingposition, rotate the distributor housing counterclockwiseuntil the leading edge of the trigger wheel segment isaligned with the center of the sensor. Tighten thedistributor hold down clamp. When the engine isinstalled and operating, check the ignition timing.26. Remove the engine from the stand.27. Install the engine assembly. Refer to the proper servicemanual for the procedure.

-r -TTT360 AMC V-8 (BLOCK) 379PlastigaugeWhen reassembling your engine you'll need a variety 01.Plastigauge to measure bearing clearances. This popularassortment includes one blue strip for ,004" - ,009"tolerances, two red strips for .002" - ,006" tolcranccs, andtwo green strips for .OO I I' - ,003" tolermces. Each strip is12" long.P42868 19Plastigauge assortment.Renioval or rcplaccnient of any cushion may beaccomplichcd hy supporting the weight of the engine ortransmission in (he ;iru of' the cushion.ENGINE MOUNTSResilient rubber mounting cushions support the engine andtransmission at three points. A cushion is located at eachside on the centerline of the engine (Figure 7- 1 ). The rear issupported by a cushion between the transmission extensionhousing and the rear support crossnieiiiber.[OR PLATESJ8909-37Figure 7 - 1

380 MOPAR PERFORMANCE PARTSCRANKSHAFTThe 360 AMC V-8 engine uses a cast nodular ironcrankshaft that rotates within five (5) main bearings and hasa standard bore and stroke of 103.63 x 87.38 mm (4.08 x3.44"). Crankshaft rotation is clockwise, when viewed fromthe front of the engine.The crankshaft has main bearing journal diameters of (Nos.1, 2, 3 and 4) 69.784-69.822 mm (2.7474-2.7489"), a rearmain bearing journal diameter of 69.759-69.797 mm(2.7464-2.7479"), and main bearing journal widths of (No.1) 32.093-32.250 mm (1.2635-1.2695"), (No. 2) 31.650-3 1.700 mm (1.2460- 1.2480"), (No. 3) 32.330-32.390 mm(1.2730-1.2750"), (No. 4) 3 1.650-3 1.700 mm (1.2460-1.2480"), and (No. 5) 30.860-30.910 mm (1.2150-1.2170").The crankshaft has a connecting rod journal diameter of53.172-53.266 mm (2.0934-2.0955"), and a connecting rodjournal width of 50.750-50.900 mm (1.998-2.004").Other Jeep V-8 bore and stroke measurements are:Crankshaft4. Remove the upper insert by loosening all the otherbearing caps and inserting a tool fabricated from a cotterpin approximately 14 mm (1/2") into the crankshaft oilhole. Fabricate a cotter pin as in Figure 7-2.5. With the cotter pin in place, rotate the crankshaft sothat the upper bearing insert is rotated in the directionof its locking tab.6. Remove the remaining bearings in the same manner.r nCOTTER PINJ8909-47Enaine CID (Year)Bore x Stroke290 (1966-69) 3.75 x 3.28"304 (I 972-80)3.75 x 3.44"343 (1967-69) 4.08 x 3.28"390 (1 968-70)4.165 x 3.574"401 (1973-79) 4.17 x 3.68"For more crankshaft specifications, refer to 360 AMC V-8Engine Specifications, 'Engine Assembly' section of thischapter.CRANKSHAFT MAIN BEARINGSReplace crankshafts that are damaged or worn beyondfeasible reconditioning. Use the procedures outlined inShort Block Disassembly, 'Block' section of this chapter, toremove and install a crankshaft.RemovalThe following procedure can be used when the engine isinstalled in the vehicle.1.2.3.Drain the engine oil and remove the oil pan.Remove the main bearing cap and lower insert.Remove the lower insert from the bearing cap.IInspectionFigure 7 - 21. Wipe the inserts clean and inspect for abnormal wearpatterns and for metal or other foreign materialimbedded in the lining.2.3.4.5.If any of the crankshaft journals are scored, remove theengine for crankshaft repair.Inspect the back of the inserts for fractures, scrapingsor irregular wear patterns.FittingInspect the upper insert locking tabs for damage.Replace all damaged or worn bearing inserts.The main bearing caps are numbered 1 through 5, front torear, with an arrow to indicate the forward position. Theupper main bearing insert surfaces are grooved. The lowerinsert surfaces are smooth.Each bearing insert pair is selectively fit to its respectivejournal to obtain the desired operating oil clearance. Inproduction, the select fit is obtained by using various-sizedcolor-coded main bearing inserts as listed in the MainBearing Fitting Chart (Figure 7-3). The bearing color codeappears on the edge of the insert. The bearing size is notstamped on production inserts.T -T7

T - 1 1360 AMC V-8 (CRANKSHAFT) 381Crankshaft Main Bearing JournalColor Code and DiameterUpperlnrert SizeBearing Color CodeILower Insert SizeYellow - 69.8220-69.8093 mm(2.7489-2.7484 in.)(Standard)IYellow - StandardIYellow - StandardtOrange - 69.8093-69.7966 mm(2.7484-2.7479 in.)(0.0005 Undersize)Black - 69.7966-69.7839 mm(2.7479-2.7474 in.)(0.001 Undersize)IIYellow - StandardBlack - 0.025 mm Undersize(0.00'1 in.)IBlack - 0.025 mm Undersize(0.001 in.)Black - 0.025 mm Undersize(0.001 in.)Green - 69.7839-69.771 2 mm(2.7474-2.7469 in.)(0.001 5 Undersize)Black - 0.025 mmUndersizeGreen - 0.051 mm Undersize(0.001 iin.) (0.002 in.)Red - 69.5680-69.5553 mm(2.7389-2.7384 in.)(0.01 0 Undersize)Red - 0.254 mm UndersizeRed - 0.254 mm Undersize(0.010 in.) (0.010 in.)J8909-34Figure 7 - 3The main bearing journal diameter is identified inproduction by a color-coded paint mark on the adjacentcheek toward the flanged (rear) end of the crankshaft, exceptfor the rear main journal. The paint mark that identifies therear main journal diameter is on the crankshaft rear flange.Refer to Main Bearing Fitting Chart (Figure 7-3) to selectthe proper bearing inserts to obtain the specified bearingclearance. Refer to 360 AMC V-8 Engine Specifications,'Engine Assembly' section of this chapter, for the correctmain bearing clearances.When required, use different size upper and lower bearinginserts as a pair. Use a standard size upper insert incombination with a 0.025 mm (0.001") undersize lowerinsert to reduce the clearance by 0.013 mm (0.0005").Never use bearing inserts in combination with greater than0.025 mm (0.001") difference in size.Example: When installing upper and lower inserts ofdifferent sizes, install the undersize inserts either all on thetop (upper) or all on the bottom (lower).Main Bearing-to-Journal Clearance- CrankshaftInstalled1. Support the weight of the crankshaft with a jack placedunder the counterweight adjacent to the journal beingmeasured.2.3.4.Note: Measure the clearance of one bearing at a time.ALL other bearing caps must remain tightened.Remove the main bearing cap and lower insert.Wipe the insert and the exposed portion of thecrankshaft journal clean.Place a stripe of Plastigauge across the full width of thebearing insert. The Plastigauge must not crumble. If itis brittle, obtain fresh stock.Caution: DO NOT rotate the crankshaft. The Plastigaugewill shift, resulting in an inaccurate indication.5.6.Install the bearing cap and tighten the retaining bolts to136 Nom (100 ft-lbs) torque.Remove the bearing cap and determine the amount ofclearance by measuring the width of the compressedPlastigauge with the scale on the Plastigauge envelope.Refer to 360 AMC V-8 Engine Specifications, 'EngineAssembly' section of this chapter, for the correctclearance.

382 MOPAR PERFORMANCE PARTSThe compressed Plastigauge should maintain the same sizeacross the entire width of the insert. If the size varies, thismay indicate either a tapered journal or foreign materialtrapped behind the insert.If the correct clearance is indicated, bearing replacement isnot necessary. Remove the Plastigauge from the crankshaftand insert. Proceed to crankshaft Installation. Small piecesof Plastigauge may remain on the insert or journal surfaces.It will dissolve in the hot engine oil when the engine isoperated.If the oil clearance exceeds the specification, install a pairof 0.025 mm (0.001") undersize bearing inserts andmeasure the clearance as described earlier.The clearance measured with 0.025 mm (0.001") undersizeinserts installed will determine if a pair of 0.025 mm(0.001") undersize inserts or some other size combinationwill provide the correct clearance.Example: If the clearance was 0.089 mm (0.0035")originally, a pair of 0.025 mm (0.00ll') undersize insertswill reduce the clearance by 0.025 mm (0.001"). The oilclearance will be 0.064 mm (0.0025") and within thespecification. The combination of a 0.051 mm (0.002")undersize insert and 0.025 mm (0.001") undersize insertwill reduce this clearance by an additional 0.013 mm(0.0005") and the oil clearance will be 0.05 1 mm (0.0021').Caution: Never use a combination of inserts that have adifference of more than one bearing size. For example, DONOT use a standard upper and 0.051 mm (0.002")undersize lower insert.If the oil clearance exceeds the specification with a pair of0.051 mm (0.002") undersize inserts, measure thecrankshaft journal diameter with a micrometer. If thejournal diameter is correct, the crankshaft bore in thecylinder block may be misaligned, which requires cylinderblock replacement. If the journal diameter is incorrect,replace or grind the crankshaft to the standard undersize.Main Bearing Journal Diameter - CrankshaftRemovedWipe the main bearing journals clean.Measure each journal diameter with a micrometer. Note thedifference between the maximum and minimum diametersof each journal. (Refer to 360 AMC V-8 EngineSpecifications, 'Engine Assembly' section of this chapter,for the maximum allowable taper and out-of-roundness.)Compare the largest journal diameter you measured withthe journal diameter listed in the Main Bearing FittingChart (Figure 7-3).Select the insert pairs that will provide the specifiedbearing clearance. Refer to 360 AMC V-8 EngineSpecifications, 'Engine Assembly' section of this chapter,for the correct clearance.Installation1. Lubricate the journal contact surface of each insertwith clean engine oil.2. Loosen all main bearing caps.3. Install the main bearing upper insert(s).4. Install the main bearing cap(s) and lower insert(s).Tighten the retaining bolts evenly to 136 Nom (100 ftlbs)torque in steps of 41,81,122 and 136 N*m (30,60,90 and 100 ft-lbs) torque. Rotate the crankshaft aftereach tightening step to determine if it rotates freely. Ifit does not rotate freely, examine the inserts for properinstallation and size.5. Install the oil pan using replacement gaskets and seals.Tighten the drain plug securely.6. Fill the crankcase to the specified level with cleanengine oil.Crankshaft End PlayCrankshaft end play is controlled by the No. 3 mainbearing, which is flanged for this purpose.1. Attach a dial indicator to the crankcase adjacent to theNo. 3 main bearing.2. Set the dial indicator stem on the face of the adjacentcounterweight (Figure 7-4).3. Pry the crankshaft fore and aft (Figure 7-4).4. Note the dial indicator readings. End play is thedifference between the high and low measurements.The proper crankshaft end play is 0.08-0.20 mm(0.003-0.0081).5. If the end play is not within the specification, inspectthe crankshaft thrust faces for wear. If no wear isapparent, replace the No. 3 (thrust) main bearinginserts and measure the end play. If the end play is notwithin specification, replace the crankshaft.Note: When installing the No. 3 (thrust) main bearinginserts, pry the crankshaft fore and aft to align the thrustfaces of the bearing inserts before final tightening.

360 AMC V-8 (CRANKSHAFT) 3836. Remove the damper retaining bolt and washer andloosely install the bolt to prevent damage to the boltthreads when the removal tool is used.7.Use a vibration damper removal tool to remove thedamper from the crankshaft (Figure 7-5).VIBRATION DAMPERFigure 7 - 4The vibration damper is balanced independently and thenrebalanced as part of the complete crankshaft assembly.DO NOT attempt to duplicate the original vibration damperbalance holes when installing a service replacement damper.The vibration damper is not repairable and is serviced onlyas a complete assembly.Vibration DamperProduction replacement vibration damper compatible withproduction crank and piston rod weight. For 360 AMC V-8 without serpentine belt drive (only).P52495 36Vibration damper.Vibration Damper Attaching PackageAttaching bolt package necessary to attach damper tocrankshaft. For 360 AMC V-8 only.P4529678Removal1.2.3.4.5.Vibration damper attaching package.Loosen the damper retaining screw.Loosen the alternator drive belt.Loosen the air conditioner compressor drive belt andmove it aside.Loosen the power steering pump drive belt and move itaside.Remove the damper pulley retaining bolts. Remove thedamper pulley from the damper.Installation1.2.3.4.5.6.7.8.v J8909-29Figure 7 - 5Polish the damper hub with crocus cloth to preventseal damage.Apply a light film of engine oil to the seal contactsurface area of the damper.Align the key slot in the damper hub with thecrankshaft keyway.Position the damper on the end of the crankshaft.Lubricate the bolt threads and washer with engine oil.Install the damper retaining bolt and washer andtighten to 122 Nom (90 ft-lbs) torque. If the crankshaftturns before the specified torque is attained, proceedwith the drive belt installation (refer to the properservice manual for the procedure). With the beltsinstalled, tighten the damper retaining bolt to 122 Nom(90 ft-lbs) torque.Install the damper pulley retaining bolts. Tighten thebolts to 41 N*m (30 ft-lbs) torque.Install the drive belts and adjust to the specified tension.Refer to the proper service manual for the procedure.

384 MOPAR PERFORMANCE PARTSTIMING CASE COVERThe timing case cover is die-cast aluminum (Figure 7-6). Acrankshaft oil seal is used to prevent oil leakage at thevibration damper hub. The oil seal may be installed fromeither side of the timing case cover. It is not necessary toremove the cover whenever oil seal replacement is required.TIMING CASECOVER GASKET)IL :LINGER / TIMING,CASE COVERRemovalb-e-4"" \TIMING CASECOVER OIL SEALFigure 7 - 6VIBRATION DAMPERJ9009-82Warning! If the engine has been recently operated, use careto prevent scalding by hot coolant. The system is pressurized.1.2.3.4.5.6.7.8.9.10. Remove the distributor.11.12.Drain the radiator and cylinder block. If the coolant isreusable, drain it into a clean container.Disconnect the radiator hoses and bypass hose.Remove all drive belts.Remove the fan and hub assembly.Remove the A/C compressor and bracket assemblyfrom the engine and move aside. DO NOT disconnectthe air conditioner hoses.Remove the alternator, alternator mounting bracket andback idler pulley.Disconnect the heater hose at the water pump.Remove the power steering pump and bracketassembly. Remove the air pump and mounting bracketas an assembly. DO NOT disconnect the powersteering pump hoses.Remove the distributor cap. Note the rotor andhousing position.Remove the fuel pump.Remove the vibration damper pulley.13. Remove the vibration damper.14. Remove the two front oil pan bolts.15. Remove the bolts that secure the timing case cover to theengine block. The cover retaining bolts are various lengthsand must be installed in the same location as removed.16. Remove the cover by pulling it forward until it is clearof the locating dowel pins.17. Clean the gasket contact surface of the cover.18. Remove the oil seal. Always replace the oil sealwhenever the timing case cover is removed. Refer toOil Seal Replacement, in this section, for the procedure.Oil Seal Replacement1.2.3.4.5.6.7.8.9.Loosen all the drive belts.Remove the vibration damper pulley.Remove the vibration damper bolt and washer.Install the damper bolt in the crankshaft to preventthe damper puller from damaging the bolt threads inthe crankshaft.Remove the vibration damper. Remove the damper bolt.Remove the oil seal (Figure 7-7).Wipe the crankshaft sealing area clean.Apply Permatex No. 2, or equivalent, to the outer metalsurface of the replacement seal.Install the seal using installer tool (Figure 7-8).10. Apply a light coating of engine oil to the seal contactsurface of the damper.11. Install the damper, flat washer and bolt. Tighten thedamper bolt to 122 Nom (90 ft-lbs) torque.12. Install the pulley and belts. Adjust belts tospecification. Refer to the proper service manual forthe procedure.IFigure 7 - 7-- ..r --r I

360 AMC V-8 (CRANKSHAFT) 385InstallationFigure 7 - 8Remove the lower locating dowel pin from the engineblock. The dowel pin is required for correct coveralignment. The dowel must be installed after the coveris in position.Use a sharp knife or razor blade to cut both sides of theoil pan gasket flush with the engine block.Apply Permatex No. 2, or equivalent, to both sides ofthe replacement timing case cover gasket. Install thegasket on the timing case cover.Install a replacement front oil pan seal to the bottom ofthe timing case cover. There are two methods ofsealing the timing case cover to the oil pan where theoil pan gaskets were cut off. If replacement oil pangaskets are used, perform step a. If room temperaturevulcanizing (RTV) silicone is used, perform step b.a. Using Oil Pan Gasketsi. Using original gasket pieces as a guide, trimthe replacement gaskets to correspond to theamount cut off in the procedure above.ii. Align the tongues of the replacement oil pangasket pieces with the oil pan seal and cementthem into place on the cover.iii. Apply Permatex No. 2, or equivalent, to thecut off edges of the original oil pan gaskets.iv. Place the timing case cover in position andinstall the front oil pan bolts.v.Tighten the bolts slowly and evenly until thecover aligns with the upper locating dowel.vi. Insert the lower dowel through the cover anddrive it into the corresponding hole in theengine block.vii. Install the remaining cover retaining bolts inthe same location as removed. Tighten allbolts to 34 N*m (25 ft-lbs) torque.b. Using RTVi. Apply a coating of RTV silicone 3.175 mm(1/8") thick on the timing case cover flanges.Use Mopar Gasket-In-A-Tube, or equivalent.The flanges must be clean and dry.ii.Place the cover in position. Align it with thetop dowel.iii. Loosely install the front cover retaining boltsin the same location as removed.iv. Insert the lower dowel through the cover anddrive it into the corresponding hole in theengine block.v. Install the remaining cover retaining bolts andtighten all bolts to 34 N*m (25 ft-lbs) torque.vi. Apply a small bead of RTV to the jointbetween the pan and the cover and force itinto place with a finger.vii. Apply a drop of Loctite, or equivalent, to theoil pan bolts and tighten until snug. DO NOTover-tighten because the oil pan will distort.5. Once the timing case cover is sealed to the oil pan,install the vibration damper. Tighten the retaining boltto 122 Nem (90 ft-lbs) torque.6.Install the damper pulley. Tighten the retaining bolts to41 Nom (30 ft-lbs) torque.7. Install the fuel pump.8. Install the distributor with the rotor and housing in thesame position as removed.9. Install the distributor cap and connect the heater hose.10. Install the power steering pump, air pump andmounting bracket, if removed.11. Install the alternator, alternator mounting bracket andback idler pulley assembly.12. Install the air conditioner compressor and bracketassembly, if removed.13. Install the fan and hub assembly.14. Install all drive belts and adjust to the specified tension.15. Connect the radiator hoses and bypass hose.16, Fill the cooling system to the specified level.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put hands near pulleys, belts or the fan. DO NOTwear loose clothing.17. Start the engine and inspect for oil and coolant leaks.18. Adjust the initial ignition timing.

~386 MOPAR PERFORMANCE PARTSTIMING CHAIN AND SPROCKETS~~~~ ~ ~ ~Timing Chain and Sprockets SetThis kit is the ideal service replacement package for 360AMC V-8 engines. The package includes single rollertiming chain and sprockets.P4529820Timing chain and sprockets set.Timing Chain Wear Measurement1.2.3.4.5.6.7.8.9.Remove the timing case cover.Rotate the camshaft or crankshaft sprocket until allslack is removed from the right side of the chain.Determine a reference point for the deflectionmeasurement (Figure 7-9). Measure up from the dowelon the right side of the engine 19 mm (3/4") and markthe location.Position a straightedge across the timing chain from thepoint at the lowest tooth (X) on the camshaft sprocketto the point marked (Z) previously (Figure 7-9).Grasp the chain where the straightedge dissects thechain and use it as a reference.Move the chain in toward the centerline of the engineand mark the engine block at the point of maximuminward chain deflection (D - Figure 7-9).Move the chain out from the centerline of the engineand mark the engine block at the point of maximumoutward chain deflection (E - Figure 7-9).Measure the distance between the two marks todetermine the total deflection (F - Figure 7-9).Replace the chain assembly if the deflection (wear)exceeds 22 mm (7/8").10 . Install the timing case cover.Removal1. Remove the vibration damper pulley, damper, timingcase cover and gasket.2.3.4.5.6.Remove the crankshaft oil slinger.Remove the camshaft sprocket retaining bolt and washer.Remove the distributor drive gear and fuel pump eccentric.Rotate the crankshaft until the zero timing mark on thecrankshaft sprocket is closest to and on centerline with thezero timing mark on the camshaft sprocket (Figure 7-10).Remove the crankshaft sprocket, camshaft sprocketand timing chain as an assembly.InstallationFigure 7 - 10Assemble the timing chain, crankshaft sprocket andcamshaft sprocket with the timing marks positioned on thesame centerline.1. Install the chain and sprocket assembly on thecrankshaft and camshaft.2.3.4.Install the fuel pump eccentric and the distributor drivegear. Install the fuel pump eccentric with the stampedword REAR facing the camshaft sprocket.Install the camshaft washer and retaining bolt. Tightenthe bolt to 41 Nom (30 ft-lbs) torque.To verify the correct installation of the timing chain:a. Rotate the crankshaft until the timing mark on thecamshaft sprocket is on a horizontal line at the 3o'clock position.IFigure 7 - 9- --I 1

360 AMC V-8 (CRANKSHAFT) 3875.6.7.8.9.b. Beginning with the pin directly adjacent to thecamshaft sprocket timing mark, count the numberof pins down to the timing mark on the crankshaftsprocket.c.There must be 20 pins between these two points;the crankshaft sprocket timing mark must bebetween pins 20 and 21 (Figure 7-11).Install the crankshaft oil slinger.Remove the original oil seal from the timing case cover.Install a replacement oil seal in the timing case cover.Install the timing case cover using a replacement gasket.Tighten the retaining bolts to 34 N*m (25 ft-lbs) torque.Install the vibration damper and pulley.REAR MAIN OIL SEALfigure 7 - 77The rear main bearing oil seal consists of a two-pieceneoprene single lip seal. Correct installation of the seal isrequired for leak-free engine operation.Removal9. Clean the main bearing cap thoroughly to remove allsealer.10. Loosen all remaining main bearing capscrews.11. Use a brass drift and hammer to tap the upper seal halfuntil a sufficient portion of the seal is protruding topermit pulling the seal out completely.Installation1.2.3.4.5.6.7.Wipe the crankshaft seal surface area clean and apply alight film of oil.Coat the block contact surface area of the replacementupper seal half with soap and the lip of the seal withclean engine oil.Insert the upper seal half into the engine block. The lipof the seal must face the front of the engine.Coat both sides of the replacement lower seal half endtabs with Mopar Gasket-In-A-Tube, or equivalent. DONOT apply sealer to the lip of the seal.Coat the outer curved surface of the lower seal halfwith soap and the lip of the seal with clean engine oil.Insert the seal into the cap recess and seat firmly(Figure 7-12).Apply Mopar Gasket-In-A-Tube, or equivalent, to bothchamfered edges of the rear main bearing cap.Caution: DO NOT apply sealer to the cylinder blockmating surface of the rear main cap because bearingclearance could be affected.8. Tighten all main bearing bolts to 136 N*m (100 ft-lbs)torque.9. Install the oil pan using replacement gaskets and seals.Tighten the drain plug securely.10. Install the starter motor.11. Fill the crankcase to the specified level with cleanengine lubrication oil.1.Drain the engine oil.2.Remove the starter motor.3.Remove the oil pan.4.Remove the oil pan front and rear neoprene oil seals.5.Remove the oil pan side gaskets.6.Thoroughly clean the gasket mating surfaces of the oilpan and engine block. Remove all sludge and residuefrom the oil pan sump.7.Remove the rear main bearing cap.8.Remove and discard the lower seal.Note: To ensure leak-free operation, always replacethe upper and lower seal halves as a pair.LFigure 7 - 72J8909-55

- --T 7388 MOPAR PERFORMANCE PARTSPiston and Connecting Rod AssemblyPart Number Bore Stroke Rod CR DomeP.5249907 4.110" 3.44" 5.875" 9.0: 1 FlatRingsP4876959Standard Size Connecting Rod BearingThis Mopar Performance Parts connecting rod bearing isthe same as production bearing. For 360 AMC V-8 only.(Sold individually.)P4529607Standard size connecting rod bearing.Undersize Connecting Rod BearingsThese Mopar Performance Parts undersize connecting rodbearings are of same high quality as standard productionbearings. For 360 AMC V-8 only. (Sold individually.)P4529608P4529609Connecting rod bearing, .OO 1 'I undersize.Connecting rod bearing, .002" undersize.PISTONSThe 360 AMC V-8 uses aluminum alloy pistons (withstruts) that weigh 601-605 grams (21.20-21.34 oz.) each.The piston combustion cavity is an open chamber design.For more piston (and piston ring) specifications, refer to360 AMC V-8 Engine Specifications, 'Engine Assembly'section of this chapter.CONNECTING RODS AND BEARINGSThe 360 AMC V-8's connecting rods are made of cast ironwith a total weight (less the bearings) of 681-689 grams(24.0-24.3 oz.), and a total length (center-to-center) of149.17-149.28 mm (5.873-5.877").Connecting rod journal diameter is 53.172-53.266 mm(2.0934-2.0955"). Connecting rod journal width is 50.750-50.900 mm (1.998-2.004").For more connecting rod specifications, refer to 360 AMCV-8 Engine Specifications, 'Engine Assembly' section ofthis chapter.Connecting RodThis heavy duty forging is shot-peened and Magna-fluxed.Includes high strength bolts. Can be used as heavy dutystock replacement. Center-to-center distance of 5.875".For 360 AMC V-8 only. (Sold individually.)P4529611Connecting rod.Rod RatioFor all-out modified race engines, it is recommended thata rod ratio (length of the rod divided by the stroke) of 1.75to 1.85 be maintained (if possible) for best performance.(The stock 360 AMC V-8 has a rod ratio of 1.7 1 -this isconsidered short.) Side clearance should be 0.25-0.48 mm(0.010-0.0191).Basic Preparation1.2.3.4.5.Rods should be checked for alignment; bores should beparallel. Check big and small ends for size. Use only aSunnen rod reconditioner for this purpose.Using a small file, deburr rods, paying particularattention to the mating surfaces and the tab groove. Youneed the clamping effect of a 60 micro bore. The sidesshould be polished by hand on a flat plate using #600paper.In an engine that is to used in a high rpm situation, therods and rod bolts should be Magna-Glo checked forcracks or forging flaws.A race engine should always use heavy duty rod boltsand nuts.The rod bearing clearances should be 0.03-0.06 mm(0.001 -0.0025").

360 AMC V-E) (PISTON AND CONNECTING ROD ASSEMBLY) 3896. The rod bolt head should be seated against the flat,machined surface in the rod.7.8.9.For a race engine, the big end rod should be sized tothe minimum diameter to get the maximum crush fromthe bearing.Shot-peening the rods is recommended if they haven'tbeen already.Clean all parts before proceeding.Inspectiona. Connecting Rod BearingsIClean the inserts.Inspect the linings and backs of the inserts for anirregular wear pattern. Note any scraping, stress cracksor distortion. If the bearing has spun in the rod, replacethe bearing and connecting rod and inspect thecrankshaft journal for scoring.The wear pattern is always greater on the upper bearinginsert. Grooves can be caused by the rod boltsscratching the journal during installation.Inspect for material imbedded in the linings that mayindicate abnormal piston, timing gear, distributor gearor oil pump gear wear (Figure 7-13).Inspect the fit of the insert locking tab in the rod cap.If the inspection indicates that the insert tab may havebeen pinched between the rod and rod cap, replace theupper and lower bearing inserts.Inspect the contact area of the locking tab. Abnormal wearindicates bent tabs or improper installation of the inserts.Replace bearing inserts that are damaged or worn.b. Connecting RodsMisaligned or bent connecting rods can causeabnormal wear on pistons, piston rings, cylinder walls,connecting rod bearings and crankshaft connecting rodjournals. If wear patterns or damage to any of thesecomponents indicates the probability of a misalignedconnecting rod, inspect it for correct rod alignment.Replace misaligned, bent or twisted connecting rods.Connecting Rod Bearing FittingConnecting rod bearing inserts are selectively fit to theirrespective journals to obtain the desired operatingclearance. In production, the select fit is obtained by usingvarious sized, color coded bearing inserts. The bearingcolor code appears on the edge of the insert.Note: Bearing size is not stamped on production inserts.The rod journal size is identified in production by a colorcoded paint mark on the adjacent cheek or counterweighttoward the flanged (rear) end of the crankshaft. Refer tothe color codes listed on the Connecting Rod BearingFitting Chart (in your service manual) to identify thejournal size and select the correct bearing inserts to obtainthe correct clearances.Caution: Never use a pair of bearing inserts that aregreater than 0.025 mm (0.001") difference in size.When required, different sized upper and lower bearinginserts may be used as a pair. A standard size insert issometimes used in combination with a 0.025 mm (0.001")undersize insert to reduce clearance by 0.013 mm(o.ooost~).Service replacement bearing inserts are available in pairs inthe following sizes:Standard0.025 mm (0.001") undersize0 0.051 mm (0.002") undersize0.254 mm (0.010") undersizeThe size is stamped on the back of the service replacementinserts. The 0.051 mm (0.0021') undersize inserts were notused for production engine assembly.Measuring Bearing-to-Journal ClearanceJ8909-381. Plastigauge Methoda. Wipe the bearing inserts and rod journal clean.b. Lubricate the upper insert and install it in the rod.c. Place a strip of Plastigauge across the full width ofthe lower insert at the center of the bearing cap.The lower insert must be dry.Figure 7 - 13-.T - 1 1

390 MOPAR PERFORMANCE PARTSd. Install the bearing cap on the connecting rod andtighten the retaining nuts to 45 Nom (33 ft-lbs)torque. DO NOT rotate the crankshaft. ThePlastigauge will shift, resulting in an inaccurateindication. The Plastigauge must not crumble. Ifbrittle, obtain fresh stock.e. Remove the bearing cap and determine the amountof clearance by measuring the width of thecompressed Plastigauge with the scale on thePlastigauge envelope.If the correct clearance is indicated, bearing fitting isnot necessary. Remove the Plastigauge. Traces ofPlastigauge left on the bearing surfaces will dissolve inhot engine oil after the engine is operating.If the oil clearance exceeds the specification, install0.025 mm (0.001") undersize bearing inserts andmeasure the clearance as described earlier.The measured clearance with 0.025 mm (0.001")undersize bearing inserts installed will determine if a pairof 0.025 mm (0.001") undersize inserts or some othercombination is needed to provide the correct clearance.Example: If the initial clearance was 0.076 mm(0.003"), 0.025 mm (0.001") undersize inserts willreduce the clearance by 0.025 mm (0.00l"). The oilclearance will be 0.051 mm (0.002") and withinspecification. A combination of a 0.051 mm (0.0021')undersize insert and a 0.025 mm (0.001") undersizeinsert will reduce the clearance an additional 0.013 mm(0.0005"). The oil clearance will then be 0.038 mm(0.00 15").Caution: Never use a combination of inserts thatdiffer more than one bearing size as a pair. Forexample, DO NOT use a standard upper and a 0.051mm (0.002'') undersize lower insert.If the oil clearance exceeds the specification when0.05 1 mm (0.002") undersize inserts are installed,measure the diameter of the connecting rod journalwith a micrometer. If the journal diameter is correct,the inside diameter of the connecting rod is incorrectand the rod must be replaced.2. Micrometer MethodIf the journal diameter does not conform to thespecification, if may have been ground 0.254 mm(0.010") or more undersize.If the journal diameter is incorrect, replace thecrankshaft or grind the journal to accept theappropriate undersized bearing insert pair.Wipe the connecting rod journal cleanUse a micrometer to measure the journal diameter attwo locations 90" apart at each end of the journal.Note the difference between the maximum andminimum diameters.Refer to 360 AMC V-8 Engine Specqications, 'EngineAssembly' section of this chapter, for the maximumallowable taper and out-of-roundness. If any rod journaldimension is not within the specifications, replace thecrankshaft or recondition the crankshaft journals and fitwith the appropriate undersize bearing inserts.Compare the largest diameter measurement with thejournal diameters listed on the Connecting RodBearing Fitting Chart found in your service manual.Select the bearing insert pair required to provide thespecified bearing clearance.Always measure clearances with Plastigauge afterinstalling replacement bearing inserts. Also, measurethe clearance of each journal after installing acrankshaft kit (crankshaft supplied with bearings).Measuring Side Clearance1. Rotate the crankshaft to the position where theconnecting rod journal is at the bottom of the stroke.2. Insert a snug fitting feeler gauge between theconnecting rods (Figure 7- 14).3. Compare the feeler gauge measurement to thespecified clearance. Replace rods that are not withinthe specifications.Figure 7 - 14

360 AMC V-8 (PISTON AND CONNECTING ROD ASSEMBLY) 391PISTON PINRemovalPiston pins are press-fit into the connecting rods and DONOT require a locking device.1. Position the piston and connecting rod assembly on anarbor press.2. Apply force to a piloted driver and press the pincompletely out of the connecting rod and pistonassembly. Note position of the pin through the gaugewindow of removal support tool.InspectionInspect the piston and connecting rod bores for nicks andburrs. Replace the rod and piston, if necessary.Caution: Never reuse a piston pin after it has been pressedin and out of a connecting rod.With the pin removed from the piston and connecting rod,clean and dry the piston pin bores.Position the piston so that the pin bore is in a verticalposition. Insert a replacement pin in the bore. At roomtemperature, the replacement pin should slide completelythrough the piston bore without force.Replace the piston if the pin jams in the bore.Installation1. Position the piston and connecting rod so that the pistonnotches will face forward and the rod squirt hole willface in when the assembly is installed in the engine.2. Place a pilot tool through the piston and connecting rodpin bores.3.Place the pin pilot, piston and connecting rod on asupport tool.4. Insert the piston pin into the piston pin bore and intothe connecting rod pin bore.5. Insert a driver tool into the piston pin.6. Use an arbor press to press the piston pin through theconnecting rod and piston bores until the pin pilotindexes with the mark on the support. The piston pinrequires 8900 N (2,000 lbs) force for installation. Ifinsufficient force is required to press the piston pin intothe connecting rod, or if the rod slides along the pin,replace the connecting rod.7.Remove the piston and connecting rod assembly fromthe press. The pin should be centered in the rod k0.787mm (*1/32").PISTON AND CONNECTING ROD ASSEMBLYRemovalUse the following procedures to service connecting rodsand pistons with the engine installed in the vehicle.1. Remove the cylinder head cover(s).2. Alternately loosen the bridge and pivot assemblycapscrews one turn at a time to avoid damaging thebridges. Remove the bridges, pivots and rocker arms.3.4.5.6.Remove the pushrods. Retain the bridges, pivots, rockerarms and pushrods in the same order as removed tofacilitate installation in their original locations.Remove the intake manifold assembly.Remove the exhaust manifold(s). It is not necessary todisconnect the exhaust pipe from the manifold.Remove the cylinder head(s) and gasket(s).7. Position the pistons, one at a time, near the bottom ofthe stroke. Use a ridge reamer to remove any ridgefrom the top end of the cylinder walls.8. Drain the engine oil.9. Remove the oil pan.10. At any journal, loosen all four (4) connecting rod nutsat the same time. Remove the connecting rod bearingcaps and inserts. Retain in the same order as removedto facilitate installation in their original locations. Thenumber stamped onto the removable bearing cap andonto the adjacent machined surface of the rodcorresponds to the associated cylinder.11. Remove the connecting rod and piston assembliesthrough the top of the cylinder bores. Ensure that theconnecting rod bolts DO NOT scratch the connectingrod journals or the cylinder walls. Short pieces ofrubber hose slipped onto the rod bolts will provideprotection during removal.Piston Fitting1. Micrometer Methoda. Use an inside micrometer to measure the cylinderbore inside diameter at a location 59 mm (2-5/16")below the top of the bore and crosswise to theblock.b. Measure outside diameter of piston. Pistons arecam ground and must be measured at a right angle(90") to the piston pin at the centerline of the pin(Figure 7- 15).C. The difference between the cylinder bore diameter andthe piston diameter is the piston-to-bore clearance.Refer to 360 AMC V-8 Engine Specifications,'Engine Assembly' section of this chapter.

-- T -7392 MOPAR PERFORMANCE PARTS@0GROOVE HEIGHT@ 2.0447-2.01 93 mm (0.0805-0.0795 in.)@ 4.81 33-4.7752 mm (0.1 895-0.1 880 in.)GROOVE DIAMETER@-@ 92.1 766-92.0496 mm (3.629-3.624 in.)@ 93.477-93.21 8 mm (3.680-3.670 in.]2. Feeler Gauge MethodFigure 7 - 15MEASURE PISTONAT THIS AREAJ8909-31(Not recommended for racing.)a. Remove the rings from the piston.b. Insert a long 0.013 mm (0.0005") feeler gauge intothe cylinder bore.C. Insert the piston (top first) into the cylinder borealong side the feeler gauge. With the entire pistoninserted in the cylinder bore, the piston should notbind against the feeler gauge.d. Repeat the above procedure with a long 0.051 mm(0.002") feeler gauge. The piston should bind.e. If the piston binds on the 0.013 mm (0.0005")feeler gauge, either the piston is too large or thecylinder bore is too small. If the piston does notbind on the 0.051 mm (0.002") feeler gauge, thepiston may be enlarged by hurling or shotpenning.Replace any piston that is 0.102 mm(0.004") or more undersize.Piston Ring FittingCaution: DO NOT remove metal from the grooves orlands. Doing so will change the ring groove clearances andwill destroy the ring-to-land seating.1. Carefully clean carbon deposits from all the ringgrooves. Ensure the oil drain openings in the oil ringgrooves and pin boss are open.2.3.4.5.6.7.Measure the ring side clearance with the correct sizefeeler gauge that fits snugly between the ring land andring (Figure 7-16). Slide the ring around the groove. Itmust slide freely around the circumference of thegroove. Refer to 360 AMC V-8 Engine Specifications,'Engine Assembly' section of this chapter, for thecorrect ring side clearance.Place the ring in the cylinder bore. Use an invertedpiston to push the ring down near the lower end of thering travel area. Measure the ring gap (clearance) witha feeler gauge fitting snugly in the ring opening. Referto 360 AMC V-8 Engine Specifcutions, 'EngineAssembly' section of this chapter, for the correct ringgap (clearance).Install the oil control rings according to the instructionsin the package. Roll the upper and lower rails intoplace without the use of a tool (Figure 7-17).Install the bottom compression ring using the ringinstaller to expand the ring around the piston. Installthe top compression ring using the ring installer toexpand the ring around the piston.Ensure the top and bottom compression rings areinstalled properly. Ideally, the ring gaps should bespaced 180" from each other.Ensure the top and bottom compression rings areinstalled with the top side up.Figure 7 - 16J8909-41

T --ll T7360 AMC V-8 (PISTON AND CONNECTING ROD ASSEMBLY) 3939. Install the rocker arms and bridge and pivotassemblies. Loosely install the capscrews through eachbridge and alternately tighten, one turn at a time, toavoid damaging the bridge.10. Install the intake manifold gasket and manifoldassembly.11. Install the exhaust manifold(s).12. Reseal and install the cylinder head cover(s).13. Fill the crankcase with clean oil to the specified level.Warning! Use extreme caution when operating engine.DO NOT stand in direct line with the fan. DO NOT puthands near pulleys, belts or fan. DO NOT wear looseclothing.14. Start the engine and inspect for leaks.Figure 7 - 17Installation1. Thoroughly clean the cylinder bores. Apply a light film ofclean engine oil to the bores with a clean, lint-free cloth.2.3.Arrange the spacing of the piston ring gaps. Refer toPiston Ring Fitting, in this section, for the procedure.Lubricate the piston and ring surfaces with cleanengine oil.Caution: Ensure that the connecting rod bolts DO NOTscratch the connecting rod journals or cylinder walls. Shortlengths of rubber hose slipped over the connecting rod boltswill provide protection during installation.4.5.6.7.8.Use a piston ring compressor tool to install theconnecting rod and piston assemblies through the topof the cylinder bores. To ensure correct installation ofthe pistons in the bore, two notches are cast in the topperimeter of the pistons.Note: The notches must face forward when installed(Figure 7-1 8). The squirt holes in the connecting rods mustface inward. The rod and cylinder numbers face outward.Install the connecting rod bearing caps and inserts intheir original positions. Tighten the retaining nuts to 45N*m (33 ft-lbs) torque.Install the engine oil pan using replacement gasketsand seals.Install the cylinder head(s) and replacement gasket(s).Install the pushrods.5. ‘L J8909-42Figure 7 - 18

~~~394 MOPAR PERFORMANCE PARTSIntroductionCylinderHeadsCleaning and InspectionThe 360 AMC V-8 uses two cast iron cylinder heads (rightand left banks) with combustion chamber volumes of58.62-61.62 cc (3.58-3.76 cu. in.) each. In(ake and cxhau\tvalve lengths are 12 I .hS3- 122.034 mm (4.7805-4.8045").For more cylinder head specifications, refer to 360 AMCV-8 Engine SpecIfkcilion.~, 'Engine Assembly' section ofthis chapter.Cylinder Head Gasket SetThis heavy duty head gasket set ciin be used ;I\replacement. Factory approved and cngineered l'orperformance applications. For 360 AMC V-8 onlyP4.529630 Cylinder hcad gasket \et.RemovalThe following procedure can be performed with the enginein or out of the vehicle.1.2.3.4.5.6.Disconnect the battery negative cable.Drain the cooling system and cylinder block. If thecoolant is reusable, drain it into ;I clean container.Remove the ignition uircs and spark plugs.Remove the cylinder head cover and gasket.Remove the capscrews, bridge and pivot assembliesand rocker arms. Alternatcly loosen the capscrews. oneturn at a time, to avoid damaging the bridge.Remove the pushrods. Retain thc rocker iirnis, bridges,pivots and pushrods in the same order a\ rc~noved tofacilitate installation in the original locations.7. Remove the intake manilold.8. Disconnect the exhaust manifold from the hcad. It isnot necessary to remove the exhaust do\vn pipe I'romthe manifold.9. Loosen all drive belts.10. On the right side, remo\.c the A/C compressormounting bracket and battei-y negative cable from thecylinder head.11. On the right side. disconnect the alternator supportbrace from the cylinder head.12. On the left side, disconnect the ail pump and powersteering mount bracket from the cylinder head.13. Remove the cylinder head retaining bolts.14. Remove the cylinder head and gasket.Thoroughly clean the gasket surfaccs of the cylinder headand block to remove all foreign material and gasket cement.Remove carbon deposits from the combustion chambersand the top of each piston.Use a straightedge and feeler gauge to determine thetlatncss of the cylinder head and block mating surfaces.Refer to 360 AMC V-K Engine Specifications, 'EngineAssembly' section of this chapter, for the proper tolerances.If the cylinder hcad is to be replaced and the original valvesreused. remove the valves and measure the stem diameters.Service replacement heads have standard-size valve guidebores. If valves with oversire stems from the original headarc: to be installed in a replacement head, ream the valveguide bores to the appropriate oversize diameter.If the original valvcs are used, remove all carbon depositsan'd rcface the valves. Install the valves in the cylinder headus] ng rcplacement valve stem oil deflectors. If valves withoversiie stems are used, oversize deflectors are alsorequircd. Transfer all the components from the originalhe,d chat are not included with the replacement head.Wire brush the threads of the cylinder head bolts prior toinstallation. Unclean threads will affect the tightening torque.Blow coolant from the bolt holes to prevent trapping coolant.InstallationI.2.3.4.5.Apply an even coat of non-hardening sealingcompound to both sides of the replacement headgasket.Caution: DO NOT apply sealing compound to thehead and block surfaces. DO NOT allow sealer to enterthe cylinder bores.Position the gasket tlush on the block with the stampedword TOP facing up.Install the cylinder head over the zasket.Tighten the cylinder head bolts evenly with 108 Nom(80 ft-lbs) torque following the tightening sequence(Figure 7- 19). Then repeat the sequence and tighten thebolts to I40 Nom ( I IO ft-lbs) torque.Note: The 360 AMC V-8 engine uses an aluminumcoated, laminated steel and asbestos gasket. Retighteninghead bolts after the engine has been run isnot necessary.On the left side, connect the air pump mountingbracket and power steering pump (if removed) to thecylinder head.. ..- -7'1

~~360 AMC V-8 (CYLINDER HEADS) 3956. On the right side, connect the alternator supportbracket to the cylinder head.7. On the right side, install the air conditioner compressormounting bracket and the battery negative cable on thecylinder head.8.9.Adjust all drive belts to the specified tension. Refer tothe service manual for the proper tension and procedure.Install the exhaust manifold and tighten the two centerretaining bolts to 34 N*m (25 ft-lbs) torque. Tighten thefour outer bolts to 20 N*m (15 ft-lbs) torque. Install theother exhaust manifold.10. Install the intake manifold. Tighten the retaining boltsto 58 Nem (43 ft-lbs) torque.11. Install all the disconnected pipes, hoses, linkage andwires.12. Install the pushrods, rocker arms and bridge and pivotassemblies in their original positions. Loosely installthe capscrews through the bridges. Tighten thecapscrews alternately, one turn at a time, to avoiddamaging the bridges. Tighten the capscrews to 26N*m (19 ft-lbs) torque.13. Install the cylinder head cover.14. Install the spark plugs and connect the ignition wires.Tighten the plugs to 38 Nem (28 ft-lbs) torque.15. Fill the cooling system to the specified level.16. Connect the battery negative cable.I1 9 1CYLINDER HEAD SHIMSFigure 7 - 19J8909-10IWhy would you want to do this? Gasoline! The 100+octane fuel (leaded premium) that was readily available 20years ago is no longer available. High compression ratios(10.0: 1 and higher) require good gas. The best gas availabletoday from the pump is unleaded premium which has (atbest) 94 octane. This gas works best with 9 or 9.5:lcompression ratios. There is racing gas available in 55gallon drums, but this isn't a good solution for non-racers.You could back the spark down, but the performance dropsdrastically. Therefore, the solution is to lower thecompression ratio.The head shim looks like a head gasket except that it'sflat-no beads. The shim should be installed next to theblock, and the gasket should be installed on top of the shim.We recommend that gasket sealer be used on the shim.Don't forget that with the shim installed, the head has nowmoved up ,060" which means that multiple gaskets have tobe used on the intake manifold.The extra intake gasket thickness can be calculated thesame way you would calculate head millingspecifications - just in reverse. Be sure to allow some extrathickness for gasket compression.CYLINDER HEAD COVERSThe cylinder head covers are installed with a formed-inplaceRTV (room temperature vulcanizing) silicone gasket.Crankcase BreatherA universal high performance re-usable crankcasebreather (must have stand pipe on valve cover). Washesclean with P4529392 cleaning fluid for extra miles ofservice.P4529394Crankcase breather.Air Filter Cleaning FluidMopar Performance Parts long-life high performance airfilters are reusable. This cleaning fluid is designed toremove dirt to extend the life of the filter.P4529392RemovalAir filter cleaning fluid.The primary purpose of cylinder head shims is to lowercompression ratio, a primary concern of pre- 1972production engines. A shim that is .060" thick will drop anengine's actual compression ratio about one full point.Shims allow you to lower your compression ratio withoutrebuilding your engine. The other method of dropping thecompression ratio is replacing the pistons. This is moreexpensive and obviously requires the engine to be rebuilt,which is much more work. We look at the head shim as atemporary fix. It's a repair that allows you to go until youcan schedule (or afford) a complete engine rebuild.1.2.3.4.5.Remove the air cleaner assembly.Disconnect the air hose from the air injection manifold.On the left side, disconnect the power brake vacuumhose at the intake manifold.Disconnect the throttle stop solenoid wire on the left side.Remove the thermostatically controlled air cleaner(TAC) hot air hose on the right side.*.T - 7 T l

--n n396 MOPAR PERFORMANCE PARTS6. Disconnect the ignition wires and remove the plasticwire separator from the cylinder head cover bracket.7.Remove the retaining bolts and washers. Strike thecover with a rubber mallet to break it loose from thecylinder head. Remove the cover and gasket.Cleaning and InspectionInspect the cover for bends or cracks and repair or replaceas required.Thoroughly clean the cylinder head cover and cylinderhead gasket surface area.Installation1. Apply a bead of Mopar Gasket-In-A-Tube, orequivalent, to the cylinder head cover gasket surfacearea. Ensure the sealant is fresh (i.e., not stored forlonger than one year and storage area temperature isless than 27°C (80°F).2.3.4.5.6.7.8.9.Position the cylinder head cover on the engine.Install the retaining bolts and tighten to 6 Nom(50 in-lbs) torque.Connect the ignition wires and install the plastic wireseparator on the cylinder head cover bracket.Install the TAC hot air hose.On the left side, connect the power brake vacuum hoseat the intake manifold.Connect the throttle stop solenoid wire on the left side.Connect the air hose to the air injection manifold.Install the air cleaner assembly.

360 AMC V-8 (CAMSHAFT AND VALVE GEAR) 397Camshaft and Valve GearCAMSHAFTThe 360 AMC V-8 uses a cast iron camshaft with intakeand exhaust cam lobe lifts of 6.604-6.858 mm (0.260-0.270"), and intake and exhaust durations of 263.5'.To advance or retard camshaft centerline, the 360 AMC V-8 uses offset keys. For more information on centerlining,refer to the 'Camshaft and Valve Gear' section of Chapter4, 4.0L Power Tech In-Line 6.For more camshaft specifications, refer to 360 AMC V-8Engine Spec$cations, 'Engine Assembly' section of thischapter.Degree WheelDurable Mopar Performance Parts aluminum plate, 0"-90-180"-90-0" degree wheel for centerlining camshafts.Features step-by-step installation instructions printed onback side.P4452990Degree wheel.Cam Lobe Lift Measurement1.2.3.4.5.6.7.8.Remove the cylinder head cover and gasket.Remove the bridge and pivot assemblies and rockerarms. Alternately loosen the capscrews one turn at atime to avoid damaging the bridge.Remove the spark plugs.Use a piece of rubber tubing to secure the dial indicatoron the end of the pushrod (Figure 7-20).Rotate the crankshaft until the cam lobe base circle(pushrod down) is under the valve tappet.Set the dial indicator to zero.Rotate the crankshaft until the point of maximumpushrod upward movement occurs.Note the travel on the dial indicator. Correct lift is6.604-6.858 mm (0.260-0.270"). The rocker arm ratiois 1.6: 1. Multiply the cam lift by 1.6 to determine thevalve lift.RemovalFigure 7 - 20Warning! If the engine has been recently operated, use careto prevent scalding by hot coolant. The system is pressurized.1.2.3.4.5.6.7.8.9.Drain the radiator and cylinder block. If the coolant isreusable, drain it into a clean container.Remove the radiator assembly.Remove the air conditioning condenser and receiverassembly as a charged unit.Remove the cylinder head covers and gaskets.Remove the bridge and pivot assemblies and rockerarms. Alternately loosen the capscrews one turn at atime to avoid damaging the bridge.Remove the pushrods. Retain the pushrods, rockerarms, bridge and pivot assemblies and tappets in thesame order as removed.Remove the intake manifold assembly.Remove the tappets.Remove the drive belts.10. Remove the fan and hub assembly.1 1. Remove the distributor,12. Remove the damper pulley and vibration damper.13. Remove the timing case cover.14. Install the vibration damper bolt with two or more flatwashers to provide means of rotating the crankshaft.15. Rotate the crankshaft until the timing mark on thecrankshaft sprocket is closest to and on the centerlinewith the timing mark on the camshaft sprocket.

398 MOPAR PERFORMANCE PARTS16. Remove the retaining bolt from the camshaft (Figure7-21). Remove the retaining bolt from the crankshaft.17. Remove the distributor drive gear and fuel pumpeccentric from the camshaft (Figure 7-2 1 ).18. Remove the crankshaft sprocket, camshaft 5procketand timing chain a5 an assembly.19. Remove the hood latch support bracket, front bumperor grille as required and remove the camshaftCAMSHAFT SPROCKETInspection1. Inspect the camshaft bearing journals for an unevenwear pattern or rough finish. Replace the camshaft ifeither condition exists.2. Inspect the distributor drive gear for damage orexcessive wear.3.4.Inspect the fuel pump eccentric for excessive wear.Inspect each cam lobe and the associated hydraulicvalve tappet for wear. If the face of the tappet(s) isworn concave and the corresponding camshaft lobe(s)is also worn, replace both the camshaft and tappet(s).FUEL PUMPRETAININGBOLTJpoop-85Installation1. Lubricate the entire camshaft generously with MoparSuper Oil Conditioner, or equivalent.2.3.4.Carefully install the camshaft into the engine block.Assemble the timing chain, crankshaft sprocket andcamshaft sprocket with the timing marks aligned.Refer to Timing Chain and Sprockets, ‘Crankshaft’section of this chapter, for the procedure.Install the oil slinger on the crankshaft.Figure 7 - 21

360 AMC v-a (CAMSHAFT AND VALVE GEAR) 3995. Install the fuel pump eccentric and distributor drivegear on the camshaft. The fuel pump eccentric has theword REAR stamped on it to indicate the properinstalled position. The camshaft washer fits into therecess in the distributor drive gear. Tighten theretaining bolt to 41 N*m (30 ft-lbs) torque.6. Install a replacement timing case cover gasket.7. Install the timing case cover.8. Install a replacement oil seal. Apply a light film ofengine oil to the lips of the seal.9. Install the vibration damper.10. Install the damper pulley with the retaining bolts.Tighten the bolts to 41 Nm (30 ft-lbs) torque.11. Install the hydraulic valve tappets lubricated with MoparSuper Oil Conditioner, or equivalent. DO NOT drain theMopar Super Oil Conditioner from the engine for atleast 1,609 km (1,000 miles); However, it does not haveto be drained until the next scheduled oil change.12. Install the intake manifold assembly with areplacement gasket.13. Install the pushrods.14. Install the rocker arms and bridge and pivotassemblies. Tighten the capscrews alternately, one turnat a time, to avoid damaging the bridge. Tighten thecapscrews to 26 Nem (19 ft-lbs) torque.15. Reseal and install the cylinder head covers.16. Install the fuel pump.17. Rotate the crankshaft until the No. 1 piston is at theTDC position on the compression stroke. After the No.1 intake valve has closed, TDC can be attained byrotating the crankshaft clockwise as viewed from thefront until the timing mark on the vibration damperaligns with the TDC index on the timing degree scale.18. Install the distributor so that the rotor is aligned with theNo. 1 terminal of the cap when fully seated on the block.19. Install the distributor cap.20. Install the ignition wires.21. If removed, install the air conditioner condenser andreceiver assembly.Caution: Both service valves must be open before theair conditioning system is operated.22. Install the hood latch support bracket and the frontbumper grille, if removed.23. Install the radiator.24. Install the fan and hub assembly.25. Fill the cooling system to the specified level.26. Install and adjust the drive belts to the proper tension.BREAKING CAMSHAFTSUsually, the only reason you break a camshaft is because itgets hit by a connecting rod. You can fail a camshaft bywearing off a lobe, but typically they are still in one piece.However, there is another problem that can cause thecamshaft to break in two and it is not caused by theconnecting rods. One problem is related to valve springs.We have valve springs today that have almost 1,000 Ib. openload! This goes along with the camshaft (or lobes) higher liftwhich makes the base circle smaller. This can cause twopotential problems. The 360 AMC V-8 engine has fivecamshaft journals. There are four lobes between eachjournal. With 16 tappets each with a 1,000 Ib. spring, thetorsional load is extremely high. With the small diameterbase circle, the high torsional load will cause the camshaftto break after the first journal where the load is the highest.Another potential problem is related to the second or fourthjournal. These journals have four lobes on either side whichcould be 4,000 lbs. bending the camshaft across the journal.This causes a bending failure around the second or fourthjournal where the stress is the highest. You could also havea failure caused by a combination of these two situations.The real problem in these cases is the camshaft itself. Highload springs are used to keep down valve float. Valve floatis a problem because the camshafts are too aggressive andhave poor dynamics. On a naturally aspirated engine likePro Stock, these aggressive camshafts can be accepted ifyou can accept the basic parts failures and maintenance. Ina supercharged engine or an engine with nitrous, the falsemotionor camshaft failure will cause a much greater messwith the engine. In these case, a smoother camshaft profile(one that is less aggressive) is the better solution so theblowerhitrous can be used to its full advantage. This willactually make more power and be more reliable.CAMSHAFT BEARINGSThe camshaft is supported by five steel-shelled, Babbitlinedbearings that are pressed in the cylinder block andthen line reamed. The stepped bored camshaft journals arelarger at the front bearing than at the rear to permit easyremoval and installation of the camshaft. The camshaftbearings are pressure lubricated.It is not advisable to attempt to replace camshaft bearingsunless special removal and installation tools are available.Camshaft end play is maintained by the load placed on thecamshaft by the oil pump and distributor drive gear. Thehelical cut of the gear holds the camshaft sprocket thrustface against the cylinder block face. Camshaft end play iszero during engine operation. The rear camshaft bearingjournal has two holes drilled through it to relieve pressurethat could develop between the journal and camshaft plugand force the camshaft forward.

400 MOPAR PERFORMANCE PARTSVALVES AND VALVE SPRINGSPart NumberP4.5296 1 3P45296 14Location Diameter Length Material ModificationIntake Std. Std. Std. Back-cut 3/8" stemExhaust Std. Std. Std. Back-cut 3/8" stemI All AMC V-8 Engine Valve Spring Specifications Chart 11 I I I I I I 11 Part Number I Installed Ht. I Description 1 O.D. I Wire Diameter I Lift Range I Material IP4876063 1.78" Single w/damper 1.36" .200" .35 O/. 560 " Chrome-si1I360 AMC V-8 Engine Keepers (Locks) Specifications ChartI I I I I I II Part Number I Valve Stem Size I Angle I Hardened I Groove I Use With Retainers I SetsP45296S3 8 mm 8" Std. Single P4S296 16 16 Pieces360 AMC V-8 Engine Valve Spring Retainer Specifications ChartRetainer Material Valve Spring3.4.Remove the valve stem oil deflectors.Remove the valves individually and place them in arack in the same order as installed in the cylinder head.SPRING CgZPRESSORRemoval -Cylinder Head RemovedVALVESPRINGS1. Compress each valve spring with a C-clamp type springcompressor tool (Figure 7-22). Remove the valve locksand retainers. Release the compression tool.2.Remove the valve springs and retainers.Figure 7 - 22

360 AMC V-8 (CAMSHAFT AND VALVE GEAR) 401CleaningRemove all carbon deposits from the combustion chambers,valve ports, valve stems and heads.Remove all foreign material and gasket cement from thecylinder head gasket mating surface.InspectionInspect for cracks in the combustion chambers and valveports and in the gasket surface area at each coolant passage.Inspect for cracks on the exhaust seats.Inspect for burned or cracked valve heads and scuffed valvestems. Replace any valve that is bent, warped or scuffed.Installation -Cylinder Head Removed1.2.3.4.5.Thoroughly clean the valve stems and valve guide bores.Lightly lubricate the stem and install the valve in the samevalve guide bore from where it was originally removed.Install the replacement valve stem oil deflector on thevalve stem.Position the valve spring and retainer on the cylinderhead and compress the valve spring with the compressortool. Install the valve locks and release the tool.Tap the valve spring from side to side with a lighthammer to seat the spring properly on the cylinder head.VALVE STEM OIL DEFLECTORNylon valve stem oil deflectors are installed on each valvestem to prevent lubricating oil from entering thecombustion chamber through the valve guide bores.Caution: Ensure that the valve stem is free of burrs orsharp edges before replacing the oil deflectors.Replace the oil deflectors whenever valve service isperformed or if the oil deflectors have deteriorated.Oil deflector replacement requires removal of the valve springs.Viton Valve Stem Oil Seal SetViton heavy duty umbrella seals are specially designed towithstand high temperatures. Helps prevent oil seepagedown valve guides. Good for dual purpose highperformance engines. Includes 8 intake and 8 exhaustseals. Not recommended for dual valve springs. Fits 360AMC V-8 engine valves with 3/8" stems only.P4.529629 Viton valve stem oil seal set.Race Valve Stem Oil Seal SetsPerfect Circle valve stem oil seals for use with dual valvesprings in race applications. Set of 16 seals. Includesinstallation tool.P3690963P4876099P4876 100Race valve stem oil seal set, 3/8" insidediameter.Race valve stem oil seal set, 11/32"inside diameter.Race valve stem oil seal set, 5/16"inside diameter.Removal -Cylinder Head NOT RemovedValve springs and oil deflectors can be removed withoutremoving the cylinder head.Each valve spring is held in place on the valve stem by aretainer and a set of valve locks. The locks can be removedonly by compressing the valve spring.1.2.3.4.5.6.7.8.9.10. Remove the valve locks (Figure 7-23).11.Remove the cylinder head cover.Remove the bridge and pivot assemblies and the rockerarms from the valves requiring valve spring or oildeflector removal.Remove the two capscrews at each bridge. Alternatelyloosen the capscrews one turn at a time to avoiddamaging the bridge.Remove the bridge, pivot and rocker arms.Remove the pushrods. Retain the rocker arms, bridge andpivot assemblies and pushrods in the same order asremoved to facilitate installation at their original locations.Remove the spark plug from the cylinder that requiresvalve spring or oil deflector removal.Install a 14 mm (thread size) air adapter in the sparkplug hole. An adapter can be constructed by welding anair hose connection to the body of a spark plug that hasthe porcelain removed.Connect the air hose to the adapter and maintain atleast 620 kPa (90 psi) pressure in the cylinder to holdthe valves against their seats.Use a valve spring removal/installation tool tocompress the valve spring (Figure 7-22).Remove the valve spring and retainer from the cylinderhead (Figure 7-23).12. Remove the oil deflector (Figure 7-23)... .. r -in

402 MOPAR PERFORMANCE PARTSValve Stem-to-Guide Clearance MeasurementValve stem-to-guide clearance can be measured by eitherone of two methods.EXHAUSTFigure 7 - 23OIL DEFLECTORSJ8909-17Installation - Cylinder Head NOT Removed1.2.3.4.Use an 11 mm (7/16") deep socket and a hammer togently tap the oil deflector onto the valve stem.Install the valve spring and retainer. A close-coil valvespring is used with all valves. The close-coiled endmust face the cylinder head when installed.Compress the valve spring with a valve springremoval/installation tool (Figure 7-22).insert the valve locks.1. Preferred Methoda. Remove the valve from the head and clean thevalve guide bore with solvent and a bristle brush.b. Insert a telescoping gauge into the valve stemguide bore approximately 9.525 mm (0.375") fromthe valve spring side of the head with the contactscrosswise to the head.C. Use a micrometer to measure the telescopinggauge contact width.d. Repeat the measurement with the contactslengthwise to the cylinder head.e. Compare the lengthwise and crosswisemeasurements to determine the out-of-roundcondition.f. If the measurements differ by more than 0.0635mm (0.0025"), ream the guide bore toaccommodate an oversize valve stem.g. Compare the valve guide bore diametermeasurement with the diameter listed in 360 AMCV-8 Engine Specifications, 'Engine Assembly'section of this chapter. If the measurement is largerby more than 0.076 mm (0.003"), ream the guidebore to accommodate an oversize valve stem.5.6.7.8.9.10Release the spring compression and remove the tool.Tap the valve spring from side to side with a hammer toensure the spring is seated properly on the cylinder head.Disconnect the air hose, remove the air adapter fromthe spark plug hole and install the spark plug. Tightenthe spark plug to 38 Nom (28 ft-lbs) torque.install the pushrods. Ensure that the bottom end of eachrod is centered in the plunger cap of the hydraulicvalve tappet.install the rocker arms and bridge and pivot assembly.At each bridge, tighten the capscrews alternately, oneturn at a time, to avoid damaging the bridge. Tightenthe capscrews to 26 N*m (19 ft-lbs) torque.2. Alternate Methoda. Use a dial indicator to measure the lateralmovement of the valve stem with the valveinstalled in its guide and barely off the valve seat(Figure 7-24).b. The correct clearance is 0.025-0.076 mm(0.001-0.003").11. Install the cylinder head cover.VALVE GUIDESThe valve guides are an integral part of the cylinder headand are not replaceable. When the stem-to-guide clearanceis excessive, ream the valve guide bores to the next highervalve stem size. Ream the valve guide bores in steps. Startwith the 0.076 mm (0.003") reamer and progress to the nextsize until the proper size is achieved.LFigure 7 - 24

360 AMC V-8 (CAMSHAFT AND VALVE GEAR) 403VALVE SEATSWith cast iron cylinder heads, all the valve seats aremachined into the head material. (Aluminum heads usevalve seat inserts.) One of the most important items in ahigh output engine is the valve job.Valve Seat RefacingInstall a pilot of the correct size in the valve guide andreface the valve seat to the specified angle with a dressingstone in good condition (Figure 7-25).Remove only enough metal to provide a smooth finish. Thisis especially important on exhaust valve seats. The seathardness varies in depth.Use tapered stones to obtain the specified seat widths whenrequired. Measure the seat runout with a dial indicator(Figure 7-26). Maximum seat runout is 0.064 mm (0.0025").VALVE TIMING1.2.3.4.5.6.7.8.9.10.Remove the spark plugs.Remove the cylinder head covers and gaskets.Remove the bridge and pivot assemblies and rockerarms from the No. 1 cylinder.Rotate the crankshaft until the No. 6 piston is at topdead center (TDC) on the compression stroke. Thispositions the No. 1 piston at TDC on the exhaust strokein the valve overlap position.Rotate the crankshaft counterclockwise 90" as viewedfrom the front.Install a dial indicator on the No. 1 intake valvepushrod end. Use rubber tubing to secure the stem onthe pushrod.Set the dial indicator at zero.Rotate the crankshaft slowly in the direction of normalrotation (clockwise, viewed from the front) until thedial indicator indicates 0.508 mm (0.020").This should align the milled timing mark on the vibrationdamper with the TDC mark on the timing degree scale. Ifa variation of more than 13 mm (1/2") exists in eitherdirection from the TDC mark, remove the timing casecover and inspect the timing chain installation.Inspect for an incorrect camshaft sprocket location.The sprocket keyway should align with the centerlineof the first lobe of the camshaft.ROCKER ARMSFigure 7 - 25The most important considerations in rocker arms arestrength and durability. Strength is required to minimizedeflections and transfer the cam motion to the valveaccurately. One important item in high performancehydraulic cams is that the higher valve spring loadsrequired by these cams put more load on the rocker arms,which causes the pushrods to have a tendency to pierce therocker arm. Thicker material in the pushrod ball or cup areais the only solution to this problem.Heavy Duty Rocker ArmHeavy duty stamped rocker arms for use with hydrauliccams (only). Right and left rockers are the same. Can beused to service stock engines. For 360 AMC V-8 engineonly. (Sold individually.)P45296 19Heavy duty rocker arm,Figure 7 - 26

T -- - --T~~~404 MOPAR PERFORMANCE PARTS3. Loosely install two capscrews through each bridge.Tighten the rocker arm capscrews alternately one turnat a time to avoid damaging the bridge. Tighten thecapscrews to 26 Nmm (19 ft-lbs) torque.4.Seal and install the cylinder head cover.PUSHRODSRemoval1. Remove the cylinder head cover. Refer to CylinderHead Cover Remnvul, ‘Cylinder Head’ section of thischapter for the procedure.2.3.4.5.Remove the two capscrews at each bridge. Alternatelyloosen the capscrews one turn at a time to avoiddamaging the bridge.Remove the bridge and pivot assemblies and placethem on the bench in the same order as removed.Remove the rocker arms and place them on the benchin the same order as removed.Remove the pushrods and place them on the bench inthe same order as removed.Cleaning and InspectionClean all the parts with cleaning solvent. Use compressed airto clean out the oil passages in the rocker arms and pushrods.Inspect the pivot contact surface of each rocker arm andpushrod. Replace any parts that are scuffed, pitted orexcessively worn. Inspect the valve stem contact surface ofeach rocker arm and replace the rocker arm if deeply pitted.Inspect each pushrod end for scuffing or excessive wear. Ifany pushrod is excessively worn from lack of oil, replacethe pushrod as well as the corresponding hydraulic valvetappet and rocker arm.It is not normal for a wear pattern to exist along the lengthof the pushrod. Inspect the cylinder head for obstruction ifthis condition exists.Length, strength and weight are the most critical items forpushrods, especially the first two. Length affects thegeometry and the valve gear oiling. Strength keeps thedeflections minimized and weight helps the engine speed,but a weight loss that causes a strength loss will result in aperformance loss.The valve train of the 360 AMC V-8 is oiled through thepushrods. Jeep engine pushrods (all Jeep engines) arehollow so that oil can pass through them to oil the valvetrain.Caution: Because the 360 AMC V-8 valve train is oiledthrough hollow pushrods, SOLID SHAFT PUSHRODSCANNOT BE USED.Pushrod SetThi.s Mopar Performance Parts pushrod set is of the samehigh quality as production pushrods. They are hollow toproqide valve train oiling (same as production pushrods).Cornes complete with sixteen (1 6) pushrods. For 360AMC V-8 engine only.P4529676Pushrod set.HYDRAULIC LIFTERS (TAPPETS)Hydraulic TappetFor use with general purpose, high performance hydrauliccamshafts. Can be used as a production replacement.(Solld individually.)P4529220Roller Tappet SetHydraulic tappet.Sold as a matched pair with guide bar. For 360 AMC V-8engine only.P4529856Roller tappet set.Installation1. Install the pushrods. Ensure that the bottom end of eachrod is centered in the plunger cap of the hydraulicvalve tappet.2.Install the bridge and pivot assembly and pair of rockerarms adjacent to the cylinder from where they wereoriginally removed.

360 AMC V-8 (CAMSHAFT AND VALVE GEAR) 405Removal-Cylinder Head NOT RemovedInstallation -Cylinder Head NOT Removed1. Remove the cylinder head cover (refer to Cylinder HeadCover Removal, ‘Cylinder Head’ section of this chapter).2.3.Remove the bridge and pivot assemblies and the rockerarms. Alternately loosen the capscrews, one turn at atime, to avoid damaging the bridge.Remove the pushrods. Retain the bridge and pivotassemblies, rocker arms and pushrods in the sameorder as removed.4. Remove the intake manifold. Refer to the servicemanual for the proper procedure.5. Remove the tappet from the guide bore in theengine block.Disassembly, Cleaning and Inspection1.2.3.4.5.Release the lock ring.Remove the plunger cap, metering disc, plungerassembly and plunger return spring from the tappetbody. Retain the tappets and all components in the sameorder as removed. DO NOT interchange components.Clean all tappet components in cleaning solvent toremove all varnish and gum deposits.Visually inspect each tappet assembly for evidence ofscuffing on the side and face of the tappet body. Inspectthe tappet face for wear using a straightedge across theface. If the tappet face is concave and thecorresponding lobe on the camshaft is worn, replacethe camshaft and tappets.Replace the entire assembly if any component is wornor damaged.Assembly1. Install the plunger return spring, check valveassembly, plunger, metering valve and plunger cap inthe tappet body.2.Use a pushrod on the plunger cap to compress theplunger assembly and install the lock ring.1.2.3.4.5.6.7.8.Coat each tappet assembly in Mopar Super OilConditioner, or equivalent.Note: DO NOT fill the tappets with oil as this maymake the engine difficult to start. The tappets willcharge themselves within three to eight minutes oncethe engine has been started.Install the tappet in the same bore from where it wasoriginally removed.Install the pushrods in the same position as removed.Install the rocker arm and bridge and pivot assembliesin the same position as removed. Tighten thecapscrews alternately one turn at a time to avoiddamaging the bridge. Tighten the capscrews to 26 Nom(1 9 ft-lbs) torque.Pour the remaining Mopar Super Oil Conditioner overthe entire valve train mechanism. DO NOT drain theMopar Super Oil Conditioner from the engine for atleast 1,609 km (1,000 miles); however, it does not haveto be drained until the next scheduled oil change.Reseal and install the cylinder head cover. Refer toCylinder Head Cover Installation, ‘Cylinder Head’section of this chapter.Install the intake manifold using a replacement gasketand end seals. Refer to the proper service manual forthe procedure.Install all pipes, hoses, linkage and wires disconnectedfrom the intake manifold.

406 MOPAR PERFORMANCE PARTSINTRODUCTIONOilingThe 360 AMC V-8 uses a pressure feed, full flow filtrationoiling system utilizing a positive displacement, gear-typeoil pump driven by the distributor shaft. The oiling systemhas a capacity of 4.7L (5 quarts). (For more oiling systemspecifications, refer to 360 AMC V-8 Engine Spec$icicutions,'Engine Assembly' section of this chapter.)OIL PANRemoval1.2.3. Drain the engine oil.4. Remove the starter motor.5.6.Disconnect the battery negative cableRaise and support the vehicle.Remove the oil pan attaching bolts. Remove the oil pan.Note: It may be necessary to raise the engine in orderto remove the oil pan.Remove the oil pan front and rear neoprene oil seals.Remove the oil pan bolts.CleaningThoroughly clean the gasket surfaces of the oil pan andengine block.Remove all sludge and residue from the oil pan sump.Installation1.2.3.4.5.6.Install a replacement oil pan front seal for the timingcase cover. Apply a generous amount of MoparGasket-In-A-Tube, or equivalent, to the end tabs.Coat the inside curved surface of the replacement oilpan rear seal with soap or Mopar Gasket-In-A-Tube, orequivalent. Apply a generous amount of MoparGasket-In-A-Tube, or equivalent, to the gasketcontacting surface of the seal end tabs.Install the seal in the recess of the rear main bearingcap, ensuring it is fully seated.Apply Mopar Gasket-In-A-Tube, or equivalent, to the oilpan contacting surface of the front and rear oil pan seals.Cement replacement oil pan side gaskets into positionon the engine block. Apply a generous amount of MoparGasket-In-A-Tube, or equivalent, to the gasket ends.Install the oil pan. Tighten the 1/4-20 oil pan bolts to 9Nom (80 in-lbs) torque and the 5/16-18 oil pan bolts to15 Nom (1 I ft-lbs) torque.System7.8.9.Lower and secure the engine, if it was raised.Tighten the drain plug securely.Install the starter motor and connect the cable.10. Lower the vehicle.1 I . Connect the battery negative cable.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or fan. DO NOTwear loose clothing.12. Fill the oil pan with engine oil to the specified level.Start the engine and inspect for leaks.Oil Pan Gasket SetThis Mopar Performance Parts oil pan gasket set comescomplete with front, rear and side gaskets. For 360 AMCV-8 engine only.P4S2963 3 Oil pan gasket set.Stock (Production) Oil Pan ModificationsThe standard pan can be helped by reworking the sump so itis 2" deeper. (See Figure 7-27.) A longer oil pick-up must alsobe installed at the same time. A deepened pan can also beused. With this pan the pick-up must also be lengthened, or astrainer and pipe assembly, which is designed for use with thedeepened pan, should be purchased. With any oil pan capacityor shape change, the dipstick should be carefully recalibrated.Be bure to fill the oil filter before calibrating!With either of these pans installed in the vehicle, the groundclearance will be reduced and the pan will no longer beprotected by the vehicle's frame. For added pan protection,a skid plate should be added and the vehicle should bedriven with increased care.In Ihe stock pan, especially the deepened pan, the rearacceleration baffle is very important. It keeps the oil fromrunning up into the #7 and #8 cylinders and slowing downthe last rod journal with increased drag. The baffle must besealed to the three walls (back and two sides) of the sumpor it becomes useless.

360 AMC V-8 (OILING SYSTEM) 407IFrontBottom ofWINDAGE TRAYPick-UpFigure 7 - 27BaffleNot To ScaleCUSTOM DRAG RACING OIL PAN FABRICATIONA Super Stockhigh performance bracket race oil panshould be designed similar to Figure 7-28. The first item tocheck before building a race pan is to determine the lowestpoint of the connecting rod travel and the relationship ofthis point to the pan rail. The dimensions given in Figure 7-28 are measured from the lowest point in the connecting rodtravel, not from the pan rail. This means that the pan mustbe made deeper than the number shown in Figure 7-28 bythe amount that the lowest point in the connecting rod travelis below the pan rail or bottom of the block.In-vehicle clearances should always be checked carefullybefore making the pan. Important items to watch for areheader clearance, steering linkage clearance, frame railclearance, and ground clearance.The steering centerlink will usually pass through the centerof the pan (Figure 7-28). This can be done by welding in atube through the pan. This tube should only be large enoughto allow the installation of the centerlink and to provideclearance during the lock-to-lock travel of the steeringlinkage. If the rules allow it, the engine can be removed andthe centerlink dropped or reshaped so that the tube throughthe pan is not required. Any reshaping or changing of thecenterlink should be done carefully so that the relationship ofthe end holes is not changed at all. If one of these points ismoved, it will change the toe pattern of the front suspensionwhich could be very dangerous in ii drag race vehicle.The two baffles shown in Figure 7-28 should be sealed onthe three sides next to the actual pan sides. No oil should beable to pass between the baffle and the side of the pan, orthe baffle loses its effectiveness.If you use a swinging pick-up, the oil sump should bedesigned such that the pick-up can swing from the rear ofthe sump on acceleration to the front of the sump ondeceleration. The pick-up should stop within 1/4" of theback and front walls of the sump. See Figure 7-28.The sump should be filled with six to ten quarts of oil, witheight quarts an absolute minimum for a modifiedproduction type, high speed engine.IMany newer drag race pans have a side-bucket. The oilpan's sump is extended on the right side (passenger side asinstalled in the vehicle). See Figure 7-29 and Figure 7-30.Just the sump is extended externally and the swinging pickupis extended internally. The major reason for this sidebucketdesign is to get more capacity from a shallow orlimited-depth pan. It puts some of the oil reservoir off to theside (i.e., not directly under the crankshaft), and the oil inletis to the side and has a longer swing travel. Refer to ProStock Pm, in this section, for more information.IPro Stock PanFrontPick-UpPositionFigure 7 - 28lRLlNKI Pick-Up IUB-RBPan, RailRearPick-UpPosRlonThere are two acceptable modifications to theaforcmentioned Super Stockhigh performance bracket raceoil pan design. One is to add a side-bucket (right-side first,double side-bucket also acceptable). This is done for addedcapacity. It makes the bottom of the pan actually wider thanthe bottom of the block. Header clearance should becarefully considered before this modification is performed.Another acceptable design is a low profile side-bucketintendcd primarily for Pro Stock. This design is discussed inDry Simp Oilirig Systrnz, later in this section, and can beused on a Super Stock vehicle if the centerlink tube is added.Pro Stock cars and similar race vehicles such as Gassers arebuilt very low to the ground. This means there usually isn'tenough room for a full 10" deep Super Stock pan, so somecompromise must be made. This means a shorter oil pan;but to keep the capacity up so that the pick-up stayscovered, the basic Super Stock pan design has to bechanged. A design similar to the following should be used.

~~ ~408 MOPAR PERFORMANCE PARTSIn Pro Stock cars having space for only a 7” deep oil pan,usually a rear half windage tray must be used. However, incases where a 9” to 9-112’’ deep pan can be used, spacepermitting, a pan can be constructed requiring no windagetray as shown in Figure 7-29 and Figure 7-30. Oil can bekept at least six inches below the pan rail for the front sixcylinders rather easily.When using a pan like this one, two areas of caution mustbe observed:1. Be sure to trap at least two quarts on deceleration.2. The huge “bucket” requires use of ten quarts drainableto keep the pick-up covered at 8,000 rpm with theclutch disengaged.IOil Pan Capacity and Swinging Pick-UpCheck-outIt is a good idea to install a rubber lip seal on your wet sumpswinging pick-up. In cases where a rubber oil seal has beeninslalled on the swinging pick-up, a simple check must bemade to determine whether or not the pick-up swings freelyenough. Simply incline the pan rail to a 20 degree angle(nose-down) with no oil fill and move the pick-up to therear-most position (acceleration); then release it (Figure 7-31). If it doesn’t swing forward and stop with a resoundingthump, the seal is too tight.In addition, the deceleration baffle should trap at least fourquarts when the pan is in the 20” position (Figure 7-31).The acceleration baffle can be similarly checked byinclining the pan to a 45 degree angle (nose-up). Theacceleration baffle in this position should trap at least fivequarts of oil.DecelBaffle“Bow” Out Slightly9” Big Bucket Wet PanUse NO Windage TrayrBFigure 7 - 29IForwardPL-C10 Quarts DrainableRec.Figure 7 - 30..1- -17

360 AMC V-8 (OILING SYSTEM) 409TestingFor DecelQuantity5Figure 7 - 31DRY SUMP OILING SYSTEMFor drag racing, a dry sump system should only beconsidered for vehicles that have almost no groundclearance. Dry sump oiling systems can be veryadvantageous in an oval track vehicle. Dry sumps providemore ground clearance so the vehicle can sit lower. This isbecause dry sump pans are very shallow. This allows thecenterline of the crankshaft to get closer to the ground whilemaintaining the same actual ground clearance. (Groundclearance is usually specified and enforced by thesanctioning body.)All production (stock) oil pans are wet sump designs. Witha dry sump, the oil that is being stored in preparation forbeing pumped back into the engine is stored outside theengine (or remotely), usually in a separate tank (withbaffles, etc.) located ahead of the engine. A race wet sumppan would have a large capacity rear sump located directlyunder the crankshaft.Production wet sumps are small and may be located in thecenter, front or rear. A race wet sump ideally designedwould be 9 to 10 inches deep. But many professionally-builtrace vehicles are built so low to the ground that there is noroom for this style pan. Enter the dry sump. However, aproperly designed dry sump system is expensive. Therefore,a racer who doesn't have his crankshaft dragging on theground doesn't need a dry sump because it's money spentfor no gain. Here, look closely at a race wet sump. There isperformance in a good wet sump system race pan.A dry sump oil system should be used whenever a deep oilpan cannot be used. There is approximately 40 hp lost to ashallow, wet sump pan.The dry sump system consists of an oil tank, scavengepump, and a pressure pump. The oil pump used is a multistage,external assembly with 2 or 3 stages for scavenge anda pressure stage. Drag race engines require 2 scavengestages, oval track engines require 3. The pump should berun at .5 to .6 engine speed. The drag racing pump has two1.45" wide scavenge stages and a 1.2" or 1.45" pressurestage; the oval track pump uses three 1.45" scavenge stagesand a 1.45" pressure stage.Figure 7-32, Figure 7-33, and Figure 7-34 show three viewsof a dry sump oil pan. Figure 7-32 shows that the sump isoffset to the right side. Figure 7-33 shows the locations ofthe dual pick-ups. Figure 7-34 shows the windage tray(baffle) inside the pan and how it had to be slightlymodified (dented) for installation of the dual pick-ups.Note: After removing the stock oil pump, remember toblock off the oil passage.The oil pans for drag racing and oval track racing aredifferent, mainly in pick-up location and baffles. (See Figure7-35.) The tank for drag racing use can be as small as 5 qts.,while an oval track racing tank should be 3 gallons.Now that we know all the parts, let's see how it works. Thepressure stage picks oil up from the tank, then sends it to anexternal oil filter, and then to the engine. The engine then getsoiled and dumps the oil back in the pan where the scavengestages pick up the oil and return it to the tank. The tank isvented to the valve cover to equalize pressures. ContactWeaver Brothers for further details and dry sump hardware.Weaver Brothers1980 Boeing WayCarson City, NV 89706If you're doing a lot of development on the engine, then acast pan is more durable than a stamped pan, unless a stockpan is being used; that is, an unmodified one-piecestamping. But that's not likely with a dry sump.In developing our cast pan we found there are some verysimple basics that you can't violate. Once the pan, tank andpump (we used a 4-stage Weaver Bros. - 3 scavenge and 1pressure) are selected, everyone feels everything is handled.This can easily be a 20 to 30 horsepower error. If you checkthe drawing for the oil lines in Figure 7-35, it shows #I 2 lineT --TIrl

41 0 MOPAR PERFORMANCE PARTSfrom the pick-ups all the way to the tank. Having three longoil lines running to the dry sump tank adds weight. So, if thedrawing is modified, we can have some problems. If youonly run one line from the pump to the tank then you mustuse a #16 line. In an arrangement such as this, each scavengesection of the pump feeds into a manifold that has three #12size inlets, and one #16 size outlet. For reference, a #I2 linehas a diameter of approximately 3/4" while a #16 line is 1inch. This allows our new lightweight system to make asmuch power as our earlier system.All Lines Shouk Ie%*lZlete Frmt ScavengeBall Plate TODrag 011 PanFlmr shouldbe angled backand lo the nghluilh car on lwelgroundVenlcal BalmUnder X3 Main CarFigure 7 - 35Figure 7 - 32Figure 7 - 33OIL PUMPThe positive-displacement, gear-type oil pump is driven bythe distributor shaft, which is driven by a gear on thecamshaft. The pump is integral with the timing case cover.A cavity in the cover forms the body of the pump. Apreissure relief valve regulates the maximum oil pressure.Oil pump removal or replacement will not affect thedistributor timing because the distributor drive gear willremain in mesh with the camshaft drive gear.Oil Pressure Relief ValveThe: oil pressure relief valve is not adjustable. The springtension is calibrated for 5 17 Wa (75 psi) maximum pressure.In the relief position, the valve permits oil to bypassthrough a passage in the pump cover to the inlet side of thepump (Figure 7-36).Figure 7 - 34

~~~360 AMC V-8 (OILING SYSTEM) 41 1Cleaning and InspectionClean the cover thoroughly. Test the operation of the reliefvalve by inserting the poppet valve and determining if itslides back and forth freely. If not, replace the pump coverand poppet valve.Gear End Clearance MeasurementRemovalFigure 7 - 361. Remove the retaining bolts and separate the oil pumpcover, gasket and oil filter as an assembly from thepump body (timing case cover) (Figure 7-37).2.3.Remove the drive gear assembly and idler gear bysliding them out of the body.Remove the oil pressure relief valve from the pump coverfor cleaning by removing the retaining cap and spring.This measurement determines the distance between the endof the pump gear and the pump cover. The ideal clearanceis as close as possible without binding the gears. The pumpcover gasket is 0.229-0.279 mm (0.009-0.01 1 ") thick.Symptoms of excessive pump clearance are fair to goodpressure when the oil is cold, and low or no pressure whenthe oil is hot.I. Preferred Methoda. Place a strip of Plastigauge across the full width ofeach gear (Figure 7-38).b.Install the pump cover and gasket. Tighten thebolts to 6 Nom (55 in-lbs) torque.c. Remove the pump cover and determine theamount of clearance by measuring the width of thecompressed Plastigauge with a scale on thePlastigauge envelope. The correct clearance bythis method is 0.05 1-0.203 mm (0.002-0.008"),with 0.05 1 mm (0.002") preferred.TIMING CASE COVER011 PRESSURERELEASE VALVEASSEMBLY+-I1 LI-OIL PUMPCOVEROIL FILTER J8909-16Figure 7 - 37Figure 7 - 382. Alternate Methoda. Place a straightedge across the gears and pumpbody.b. Select a feeler gauge that will fit snugly but freelybetween the straightedge and the top of the gear(Figure 7-39). The correct clearance by thismethod is 0.102-0.203 mm (0.004-O.00Stt) with0.203 mm (0.008") preferred.Note: Ensure the gears are up into the body as faras possible before the measurement is made... r - T T T

41 2 MOPAR PERFORMANCE PARTSIIf the gear end clearance is excessive, install athinner gasket. If the gear end clearance is stillexcessive, replace the gears and idler shaft.STMI?- ITEDGEInstallation1. Install the oil pressure relief valve in the pump coverwith the spring and retaining cap (Figure 7-36).2.3.Install the idler shaft, idler gear and drive gearassembly (Figure 7-37).Note: To ensure self-priming of the oil pump, fill thepump with petroleum jelly prior to the installation ofthe oil pump cover. DO NOT use grease of any type.Install the pump cover and oil filter assembly with areplacement gasket. Tighten the retaining bolts to 6Nom (55 in-lbs) torque.Oil Pressure RequirementsOil pressure requirements for the 360 AMC V-8 are asfollows:Figure 7 - 39Gear-to-Body Clearance MeasurementInsert a feeler gauge between the gear tooth and the pumpbody inner wall directly opposite the point of the gear mesh(Figure 7-40). Select a feeler gauge that fits snugly but canbe inserted freely.Rotate the gears and measure the clearance of each tooth andbody in this manner. The correct clearance is 0.013-0.064mm (0.0005-0.0025"), with 0.013 mm (0.0005") preferred.If the gear-to-body clearance is more than specified,measure the gear diameter with a micrometer. If the geardiameter is correct and the gear end clearance is correct andthe relief valve is functioning properly, replace the timingcase cover. If the gear diameter is incorrect, replace thegears and idler shaft.Note: If the oil pump shaft or distributor drive shaft isbroken, inspect for a loose oil pump gear-to-shaft fit orworn front cover. Oversize pump shafts are not available.At Idle Speed (600 rpm). ... 13 psi ..... .90 kPaAt 1,600+ rpm .......... .37-75 psi. ... 255-5 17 kPaOil Pressure Relief. ....... 75 psi ...... 517 WaOil Pump PrimingThe lubrication system should be checked to ensure that itis supplying pressure to the bearings before any attempt ismade to start the engine. If the engine is run without oilpressure for even for a few seconds, there will be extensivedamage done to the engine.After installing a mechanical oil pressure gauge (only if yourvehicle is not already equipped with an oil pressure gauge),remove all the spark plugs in order to relieve the compressionin the cylinders and to prevent the engine from starting. Theengine should be turned over with the starter motor until theoil pressure gauge shows a reading of over 10 psi.The pump can be manually primed instead of turning thewhole engine to get oil pressure and supply the bearings withoil before the engine is started. This method is preferred butrequires a special adapter (usually a modified intermediateshaft) to be made in order to drive the oil pump only.Once you have determined that the engine does have oilpressure, the spark plugs may be reinstalled and the enginemay be started. When the engine starts, the gauge shouldshow a minimum reading of 90 kPa (13 psi) at 600 rpm(idlle speed).IFigure 7 - 40...Til

INTRODUCTIONThe AMC 360 V-8 has a liquid cooled, forced circulationcooling system with a capacity of 13.2L (14 quarts).Not surprisingly. race engine cooling problems arise duringthe summer and tend to disappear in the fall. There arevarious ca~ises: Ilex-fans, watcr pumps, radiator size andfunctioning shrouds, grille openings, and fan bladediameter and number. The not so obvious areas areimproper spark advance and too lean I‘uel mixture.Now, what happens if a racer has fixed all of these problemsand he still overheats or runs too hot? Whal could thisproblem be? Some people feel this nienns there is somemysterious design problem with the engine. This is a witchhunt! Generally, engines don’t have an overheatingproblem. Big engines mukc more heat than small ones, butthis just requires a bigger radiator. Put simply, enginesmake heat; cooling systems get rid of heat. Nothing fancy!If your engine overheats, that means the balance betweenthese two functions has been lost somewhere.The best cooling systems to copy are late 1960s to early1970s Chrysler-Plymotlth-Dodge muscle cars. Kememberthe size and shape (vertical) of the grillc and the size of theradiator on those inuxle cars? They were very good coolingsystems. If yo~i’ve checked the fan. radiator. watcr pump,shroud, grille opening. ctc., and found no problems, youobviously shouldn’t overheat. However, if you still have 311overheating condition, what could possibly be wrong?Cooling System360 AMC V-8 (COOLING SYSTEM) 413Problems usually occur after an engine rebuild or partsswap that increased the engine’s output. This is not easy tosolve. Without scratching for “design” flaws or water pumpimpeller cracks, the best guess is gasoline. Althoughgasoline quality may be the cause, the real problem is toomuch compression ratio inside the engine. Having toomuch compression ratio is not easy to solve. You can’t getrid of compression ratio without rebuilding the engine. Thatseems like an extreme solution. The quickest solution is tolower the total spark advance. In a race vehicle, this maymake it go somewhat slower, but it also may solve theoverheating problem.A better solution is to use higher quality gas. It’s usuallycalled “race gas,” and it comes in various octane/pricelevels. Most race vehicles use race gas that’s somewhatmiddle of the road (cost $2-3 per gallon). Most race gascompanies have a premium brand with high octane thatsells for a higher price ($5-7 per gallon). Upgrading the gaswill answer the question-is your overheating caused by toomuch compression ratio?If you’ve been using regular race gas, be sure to drain itcompletely from your tank before you fill up with premiumultra high octane fuel. At the added gas price, this test maycost $50, but there is no other test that can be run for less,short of rebuilding the engine, and you certainly can‘t dothat for $50. If the premium ultra high octane fuel solvesyour overhcating problems, your best long term strategy isto rebuild the engine to lower the compression ratio.However, until you have time (and money) to attack thatmajor project, you will have solved the overheatingproblem and can continue to race without performance lossby simply continuing to use ultra high octane gas.

T - T T41 4 MOPAR PERFORMANCE PARTSINTRODUCTIONInduction SystemThe 360 AMC V-8 engine es Model 2 150, two venturicarburetor (Figure 7-4 I ). The carburetor is identified by acode number and build date code stamped on theidentification tag (Figure 7-42). Each carburetor buildmonth is coded alphabetically beginning with the letter Afor January and ending with the letter M for December (theletter I is not used). The tag is attached to the carburetor andmust remain with it for proper identification.l 9 8(CODEBUILD DATE1. VENDOR CHECK LETTER 7. DAY2. MODEL YEAR 8. MONTH3. ENGINE 9. YEAR4. TRANSMISSION5. VENTURI6. REVISION LETTERJ8914-246CARBURETION SYSTEMFigure 7 - 421. AIR HORN2. MAIN BODY3. ALTITUDE COMPENSATION CHOKE CIRCUIT4. CHOKE COVER5. CHOKE VACUUM DIAPHRAGM6. VACUUM SOURCE HQSE7. ADJUSTMENT SCREW8. ALTITUDE COMPENSATION ANEROIDFigure 7 - 4 1J8914-245A carbureted engine’s induction system consists of theintake manifold and the carburetor(s). It is very importantthat this induction system be matched to the compressionratiio and camshaft set-up used in your racing engine. Thesethrlee components make up the “3 C’s” of engine building(compression, carburetion. and camshaft), and all threemust be matched to work in perfect harmony before theengine can run at peak levels at all times. These decisionsmust be made before the engine building process is begun,so that none of your time will be wasted and none of yourmoney will be spent on the wrong parts. Without theseconsiderations, the addition of a large cfm carburetor (forexample) could actually result in no increase inperformance at all, or in some cases, a large decrease.Foir drag and oval track racing vehicles it is recommendedthat the heat (exhaust) cross-over in the intake manifold beblocked by either putting shims in the gasket, or by brazinga metal plate into both sides of the cross-over in the intakemanifold. (The best shim material is thin stainless steel.)With the heat crossover blocked, the choke will no longerfunction. The carburetor will usually have to be rejetted forracing. Blocking the heat cross-over usually causes thevehicle to run poorly when dead cold, which is why it isrecommended for racing vehicles only. It also should not beconsidered for cold weather use. (Not required on cylinderheads that have no heat cross-over.)

360 AMC V-8 (INDUCTION SYSTEM) 415For any racing application, the carburetor must be speciallyjetted for proper fuel distribution. Standard productionintake manifolds might be used with non-standardproduction carburetors, aftermarket manifolds installed, orintake manifold heat blocked, all of which require thecarburetor to be jetted differently for each application.Holley Universal Performance CarburetorsHollev P4781 - 850 cfm 4-Bbl.P4348232Hollev R1850 - 600 cfm 4-Bbl.P4349227Mechanical secondaries, doubleaccelerator pumps.Vacuum secondary.Hollev R3310 - 750 cfm 4-Bbl.P4349228Vacuum secondary.Hollev R3418 - 855 cfm 4-Bbl.P5249808Vacuum secondary.Holley Service Gasket SetsThese handy carburetor service gasket sets include therequired parts to service and performance tune yourHolley. Since every model is different, package contentswill include only the necessary parts for proper servicingof the following: primary bowl, primary metering block,secondary bowl, secondary metering blocklplate gaskets,required bowl screw O-rings and fuel transfer tube O-rings, as required.P4349302P4349304P434930SHolley Needle and Seat SetsFor Holley R 1 850 and R33 10 4-Bbls.For Holley R4412 and R7448 2-Bbls.For Holley R4777, R4779 and R47814-Bbls.Consists of two needle and seat assemblies.P4349329P434933 1P4349332All Holley carburetors except spreadbore, .I IO" orifice.Holley spread bore only, ,097" orifice.Holley spread bore only, .l 1 0" orifice.~Miscellaneous Plastic Plugs and Caps PackageAssorted pieces for blocking vacuum taps. For 2-Bbl. and4-Bbl. racing applications.P400790 1Miscellaneous plastic plugs andcaps package.Accelerator Pump Diaphragm SetsConsists of two diaphragms.P43493 14P43493 ISCarter Strip PackageFor Holley carburetors with 30 ccaccelerator pumps.For Holley carburetors with 50 ccaccelerator pumps.This package contains an assortment of primary andsecondary main jets, metering rods, needle\ and seats forfine tuning Carter carburetors. Fits all AFB models.P4 1 20238 Carter strip package.Carburetor AdaptersP4007522 Adapter to install spread bore carburetor(Thermo-Quad or Quadra-Jet) on squarebore manifold.P48765 12 Adapts large 1-1 1/16" Holley 2-Bbl. tostandard 2-Bbl. bore intake manifold.P4876S 13 Adapts 4-Bbl. carburetor to 2-Bbl.intake, or 2-Bbl. carburetor to4-Bbl. intake.Carburetor JetsTo get the most out of your performance engine, you haveto fine-tune the metering system. This translates intochanging the jets in your carburetor. For racing purposes,the Holley is the most common performance carburetor.Whether it's a big two barrel, small four barrel or giant fourbarrel, all Holley performance carburetors use the samebasic jets. Obviously the hole sizes change, but the jets areinterchangeable except for their effect upon the fuel-airratio in the engine. In the heat of the summer the jetstypically need to be changed, and racing in the cool fall airrequires them to be changed again. These jet changes aredone to enrich or "lean-out'' the engine for betterhorsepower and performance. To accomplish all thesechanges you need a spread of jet sizes. Holley jet packagescome with jet sizes from #64 to #99 (usually two of each).This should cover just about any application. However, ifyou race two vehicles or have two carburetors on yourengine, you may to get two packages...

41 6 MOPAR PERFORMANCE PARTSSPECIAL CARBURETOR CONSIDERATIONSHeaders vs. CarburetorsHeaders are one of the most common performancemodifications. Thirty years ago, the installation of headersnetted an instant performance gain. Today, thc installation ofheaders doesn’t always result in a gain except at theracetrack itself. The headers haven’t really changed-thecarburetors have.Pre- 1970 carburetors were richer in fuel-air ratio. Headersalways lean out the fuel-air ratio of an engine. With theextra fuel available in richer, older cngincs, the headersleaned out the mixture level to the point that the engine wasstill running well, and the lower backpressure availablewith headers resulted in an increase in horsepower.The emissions laws since 1Y70 forced productioncarburetors and inlet packages to have almost perfect fueldistribution, but with much leaner fuel mixtures. The bctterfuel distribution is a plus, but the leaner mixtures leave noroom for modification. The installation of headers on tothese “emissions” engines leans them out too far. Thismeans that the gain the engine got for the decrease in backpressure was canceled because of the engine output loss ducto the too lean fuel mixture.The solution is quite simple: enrich the carburetor. Thisusually requires richer jets to be installed. This allows thefuel-air ratio to be corrected. The headers with thc richercarburetor will then result in better output (horsepower).Carburetor cfmThere always seems to be a lot of questions relating tocarburetion, especially questions such LIS which carburetorto use or how much cfm the engine should have. Theproblem with answering these questions is that the answersvary with engine size and tuning rpm. A related problem isthat all carburetor manufacturers don’t use the same ratingsystem for their carburetors, and some don’t rate theircarburetors’ “cfm” at all. Cfm stands for cubic ,feet perminute, which is used for rating the air flow of a carburetor.OE manufacturers (such as DaimlerChrysler) don’t testcarburetors for air flow. Since the advent of emissions laws,OE engineers test carburetors for fuel flow because it relatesto the richness level in the engine which relates to emissions.Air flow relates better to horsepower, high rpmperformance, and inversely, driveability. To use it, first youhave to obtain air flow data. The only good sourcc isHolley, but don’t try to compare 2-Bbl. to 4-Bbl. data.Check and record the accelerator pump shooter size. Alsocheck the accelerator pump and adjust it for maximumtravel. Rod adjustment to the hole closest to the pivot isrecommended as the initial starting point. Bc sure themetering rods move up and down smoothly by pressinglightly in the center of the metering rod bar.The point at which the throttle opening opens the air dooris determined by the number of turns on the spring. Toadsjust the spring, two screwdrivers (or a special tool) arerequired. The adjustment is typically on the driver’s side.The outer slotted ring is the locking screw and must beloosened before the spring can be adjusted. Once loosened,the air door will hang vertically. Adjust the inner screws(which tensions the spring) until it just closes the air door.Thcn turn the screw and tension the spring an additional 1 -I/:: to 2 turns. Once set, always use the same technique forfuture adjustments. The fewer turns, the quicker the air dooropen- typically used on faster vehicles. The more turns,thc slower the door opens- typically used with automaticsand street tires.Thc amount that the air door opens can be adjusted at the trackwithout disassembling the carburetor, This adjustment canchange the amount of air flow that goes through the carburetorand also change the fuel-air ratio (richness level) of the mixturedeilivered to the engine. Before you make any adjustments youmust know how to accurately measure the amount of opening.(R’efer to the proper service manual for details.)Remember, the first thing to do is to measure your specificcarburctor and record its reading. Once the vehicle has beenba’selined at the track at this setting, adjustments can be made.Always measure the air door opening using exactly thesame technique. Adjust as follows: open up to increasepower and lean out the mixture; close down to enrich. If itdevelops a miss in high gear at high speed, you haveopened it up too far and it’s too lean. Close it back down forbest performance.If all else fails, keep in mind the golden rule of carburetorselection -don’t over carburete!Lean CarburetorOn any given performance engine, the odds are the engineis lean. Since every engine performance increase requiresmore fuel, the carburetor should be rejetted for everyperformance modification that we make. However, thisdoes not happen most of the time. Therefore, the enginetends to be lean (or close to it).One of the most common modifications to a performanceengine is to install a performance ignition system. Thesesystems typically include a performance distributor. Thesedistributors have a fast advance curve for betterperformance. (For more information, refer to ‘IgnitionSystems’ section of this chapter.). ..

360 AMC V-8 (INDUCTION SYSTEM) 417After installation, some people say that their engine runsbetter with the vacuum disconnected. This is most oftencaused by the engine being too lean to begin with. Then theengine rpm will “hunt” and “wander.” The idle enginespeed will surge up and down. The engine may stall whenyou put it in gear. If it’s an automatic transmission, the idlemay drop hundreds of rpm when you put it in gear. All ofthese are signs that the engine is too lean. It needs more idlefuel. This idle enrichment cannot be done by simplyopening the throttle screw adjustment. This approach willmake it worse. To solve, richen the idle djusting screws orinstall larger primary jets. On Carter carburetors you canalso swap in smaller metering rods.Lean Idle Fuel MixtureIn high performance cars and trucks, it is a very commonproblem to have a lean idle fuel mixture in the carburetorthat you are using. This can be more common in Cartercarburetors than in Holley carburetors.Why would a lean mixture problem be more common in aCarter carburetor than a Holley? Good question! Cartercarburetors were commonly used on production enginesand were not as popular in the aftermarket. Holley was verystrong in the aftermarket. So if you have a Carter carburetorchances are it was used on a production vehicle while aHolley carburetor was probably obtained in the aftermarket.The typical aftermarket carburetor was built with a richeridle circuit. The production carburetor was built with a leanidle circuit.Within the Carter carburetor family, the AFB will have theleast problems, and the AVS and Thermo-Quads will havethe most problems. The reason is similar to the Holleycarburetor. The AFB was built up through 1967 beforeengine emissions became a bigger concern than engineperformance. Therefore, the AFB tends to be richer at idle.Fuel economy in the early 1960s was not a big concern whichalso lead to using more fuel. The AVS and Thermo-Quadcarburetors are both emissions carburetors that were built totough standards. (Emissions engines actually had much betterfuel distribution than older engines. From a technologystandpoint, AVS and Thermo-Quad were better carburetors.)Today, only the AFB carburetor is still made. Since it isprimarily made for the aftermarket, it tends to have a richeridle. There were many more AVS and Thermo-Quadcarburetors built from 1968-78 than there were AFBs from1962-67. It’s all percentages, the law of averages! There aremany exceptions. Holley makes replacement carburetorsfor emissions engines. There are also Carter AFB versionsfor emissions engines.What’s the big deal? So production carburetors are lean.The lean fuel problem is trouble to racers because it isusually not diagnosed properly. A bigger camshaft isinstalled and the engine idles poorly. Blame the camshaft!Or the heads! Or the intake! The actual solution is usuallya carburetor adjustment. More idle fuel! On oldercarburetors and aftermarket carburetors you might actuallybe able to adjust the idle by turning the idle screwadjustment-usually two, a left and a right. Typically thisidle adjustment is not adequate-it was adjusted and itdidn’t solve the problem. Some people will then assumethat idle fuel level is not the problem. In most cases, youhave to change the primary jets to larger ones. Usually oneor two steps will solve the problem.Primary jets for Holley and Carter AFB carburetors arereadily available. Jets for Carter AVS and Thermo-Quadcarburetors are not as easily found. If you only have one setof jets, then we DO NOT recommend you make anychanges. With no spare pieces or jet kits, it may be a betterchoice to swap carburetors to a Holley. If you can find a setof jets, even if they are the same size as the ones youalready have, you can drill them out (very carefully). Firstyou need a numbered drill set. (Most machine shops havecomplete sets.) Then you measure the jet size with thenumbered drills. You can also find this information in theservice manual for your engine. Measure it to be sure! Ifyou have a slight problem, go up one step. If you have a badproblem, go up two steps. A step is one number drill size.Be careful to drill the hole straight through the jet. Removeany burrs from the drill surface by hand. Save the stock jetsthat are in the carburetor so that you can go back to them ata future date. (You may not always want to race.)Carter carburetors have metering rods that are used for theidle mixture. To put a jet in you have to take the carburetorapart. You can change metering rods very easily withouttaking the carburetor apart. The problem is that it is noteasy to find richer metering rods and it is not easy to makethem if you don’t have a jet kit. For the Carter AFBcarburetor these jet kits should be readily available. If youcan find it, this is a very quick and easy way to change theidle mixture.STANDARD PRODUCTION 2150 CARBURETORADJUSTMENTS/OVERHAULA complete disassembly is not necessary when performingroutine service adjustments. In most instances, serviceadjustments of individual circuits may be accomplishedwithout removing the carburetor from the engine.A complete carburetor overhaul includes disassembly,thorough cleaning, inspection and replacement of allgaskets and any damaged or worn parts. When using anoverhaul kit, use all the parts included with the kit.Flooding, hesitation on acceleration, and other performanceproblems are in many instances caused by the presence ofdebris, water, or other foreign matter in the carburetor. Toaid in diagnosing the cause of the problem, carefullyremove the carburetor from the engine without removingthe fuel from the bowl. Examine the contents of the bowlfor contamination as the carburetor is disassembled.Refer to the proper service manual for detailed adjustmentand overhaul procedures.. ..

41 8 MOPAR PERFORMANCE PARTSTroubleshootingA thorough road test and check of minor carburetoradjustments should always precede major carburetorservice. Specifications for some adjustments are listed onthe Vehicle Emission Control Information label found ineach engine compartment.Many performance complaints are directed at thecarburetor. Some of these are a result of loose, misadjustedor malfunctioning engine or electrical components. Othersdevelop when vacuum hoses become disconnected or areimproperly routed. The proper approach to analyzingcarburetor complaints should include a routine check ofsuch areas.1. Inspect all vacuum hoses and actuators for leaks.2. Tighten intake manifold bolts, carburetor mountingnuts, and isolator mounting bolts to specifications.3.4.5.6.7.8.9.10.11.12Perform cylinder compression test.Clean or replace spark plugs as necessary.Test resistance of spark plug cables. Refer to IgnitionSystem Secondary Circuit Inspection, ‘ElectricalSection’ of the service manual for complete procedure.Inspect ignition primary wire. Test coil output voltage,primary and secondary resistance. Replace parts asnecessary. Refer to ‘Ignition System’ section of theservice manual for complete procedure, and makenecessary adjustment.Reset ignition timing.Check carburetor idle mixture and speed adjustment.Test fuel pump.Remove air cleaner filter element and blow out dirtgently with an air hose. Install a new air filter elementif necessary.Inspect crankcase ventilation system.Road test vehicle as a final test.CleaningThere are many commercial carburetor cleaning solventsavailable which can be used with good results.The choke diaphragm, choke housing assembly, and someplastic parts of the carburetor can be damaged by solvents.Avoid placing these parts in any liquid. Clean the externalsurfaces of these parts with a clean cloth or a soft brush.Shake dirt or other foreign material from the stem (plunger)side of the diaphragm. Compressed air can be used toremove loose dirt but should not be connected to thevacuum diaphragm fitting.If the commercial solvent or cleaner recommends the use ofwater as a rinse, “HOT” water will produce better results.After rinsing, all traces of water must be blown from thepassages with air pressure. Never clean jets with a wire, drill,or other mechanical means, because the orifices may becomeenlarged, making the mixture too rich for proper performance.When checking parts removed from the carburetor, it is attirnes difficult to be sure they are satisfactory for furtherservice. It is therefore recommended that in such cases, newparts be installed.Caution: The practice of priming an engine by pouringgasoline into the carburetor air horn for starting afterservicing the fuel system should be strictly avoided.Cranking the engine, and then priming by depressing theaccelerator pedal several times should be adequate.Diagnosing carburetor complaints may require that theengine be started and run with the air cleaner removed.Warning! While running the engine with the air cleaner itis possible that the engine could backfire. A backfiringsiluation is likely to occur if the carburetor ismalfunctioning. DO NOT place your hands or face on,over, or near the carburetor while the engine is being startedor running. Severe personal injury may occur.INTAKE MANIFOLDOnce carburetion and engine applications are known, thebest intake manifold can be selected. For drag and ovaltrack racing vehicles it is recommended that the heat(exhaust) cross-over in the intake manifold be blocked byeither putting shims in the gasket, or by brazing a metalplate into both sides of the cross-over in the intakemanifold. (The best shim material is thin stainless steel.)With the heat cross-over blocked, the choke will no longerfunction. The carburetor will usually have to be rejetted forracing. Blocking the heat cross-over usually causes thevehicle to run poorly when dead cold, which is why it isrecommended for racing vehicles only. It also should not beconsidered for cold weather use. Not required on cylinderheads that have no heat cross-over.Intake Manifold GasketTlhis intake manifold gasket can be used with productioncast iron or aftermarket aluminum intake manifolds.DaimlerChrysler engineered and approved. For 360 AMCV-8 engine only.Pi452963 1 Intake manifold gasket.

360 AMC V-8 (INDUCTION SYSTEM) 419~Intake and Exhaust Manifold Attaching PackagePackage of factory original nuts and bolts to attach intakemanifold and exhaust manifolds. Includes 24 bolts, 24washers, 4 studs and 6 plugs. For 360 AMC V-8 engineonly.P452968 1Vacuum LeaksIntake and exhaust manifold attachingpackage.All engines need an intake manifold of some kind, andusually they are made of cast iron or aluminum. Althoughcommon on standard production vehicles, using a cast ironintake manifold in racing is fairly rare. Aluminummanifolds are typically used in both drag and oval trackracing. Despite these different applications, cast iron andaluminum intake manifolds do share one commonproblem - vacuum leaks.Vacuum leaks are perhaps the most common type of intakemanifold problem. Once solved, vacuum leaks aren’t likelyto return, but when you first install that new intakemanifold, they can be very troublesome.The most common locations for vacuum leaks are theintake flanges next to the heads. The second most commonare the various ‘‘taps’’ that are screwed into the intake (oneor more). On a race manifold these taps may not exist. Inthis case, the holes are typically plugged. However, a leakmay exist around the plug.Typically, an aluminum intake manifold is an aftermarketpiece. This means it is not a production intake manifold.There are a couple exceptions to this, but we’ll assume thatyou’re using an aftermarket intake. These manifoldsgenerally have a “dual” mounting pad for the 4-Bbl.carburetor. This allows all the popular carburetors to bebolted to the same intake manifold. This is easily observedby looking at the carburetor mounting flange with thecarburetor removed and counting the holes machined andtapped. A dual mounting pad will have eight holes.The trick here is related to the way single plane intakemanifolds are made-one of the carburetor mounting holesmay be machined into (or “leak” into) the top of the “runner”or “plenum.” This is possible even in production manifolds.However, the production manifold typically only has fourholes and any potential vacuum leak would be plugged oncethe carburetor is installed. This can be further ensured byusing sealer on the carburetor attaching bolt threads.With the eight hole flange and the carburetor installednormally, four holes are left unfilled. To ensure againstvacuum leaks, you should plug the threaded bolt holes thatare not going to be used. Why mention anything thissimple? It is easy to overlook, and once you’ve assembledthe carburetor on to the manifold, it can be almostimpossible to find and can cause you a great deal of trouble... T -17

T - i l l420 MOPAR PERFORMANCE PARTSVacuum Leak DiagnosisAn intake manifold leak is characterized by lower thannormal manifold vacuum. Also, one or more cylinders maynot be functioning.1.Start the engine and allow it to warm up.2. Inspect for disconnected vacuum hoses or hardened orcracked vacuum lines.3. With a spray bottle, spray a small stream of water onthe suspect area. If there is a change in rpm's, thesuspected leak has been found.4. Repair as required.AIR CLEANERSCast Air Cleaner PackageThis complete air cleaner package features a castaluminum lid with Mopar Performance logo to match thestyle of the cast aluminum Mopar Performance valvecovers. 14-inch element. Universal for all 5-1/8" insidediameter carburetor mounts. (If needed, K & N makes anadapter for small 2-Bbl. carburetor mount.)P5249807Cast air cleaner package.Lowered Air Cleaner BasesFor use with typical 14" outside diameter elements.Lowers air cleaner over carburetor for added hoodclearance.P4876755P4876756AIR FILTERSLowered air cleaner base, 13/16" drop.Lowered air cleaner base, 1-1/4" drop.High Performance Air Filter ElementSpecial reusable filter element for high performance.Increases air flow versus stock filters which increasesengine output. Fits all 197 1-84 Jeep V-8 engines.P5249606High performance air filter element.Air Filter Cleaning FluidMopar Performance Parts long-life high performance airfilters are reusable. This cleaning fluid is designed toremove dirt to extend the life of the filter.P4529392 Air filter cleaning fluid.Air Filter OilLong life, high performance air filters trap dirt with aspecial oil on the filter. After cleaning air filters, re-oilthem with this special fluid.P4529393Air filter oil.

T -1[-7FUEL PUMPSThe fuel pumps of carbureted and fuel injected vehicles aredifferent. Carbureted vehicles have a mcchanical fuel pumpdriven by an eccentric lobe of the engine camshaft. Fuelinjected engines have a gearhtor type pump driven by apermanent, magnetic electric motor. The mechanical pump ismounted to the engine block while electric fuel pumps aresuspended in the fuel tank and immersed in fuel. The electricfuel pumps used with Throttle Body Injection and Multi-PointInjection systems are different and cannot be interchanged.Carter Electric Fuel PumpIn Stock Eliminator, one pump is sufficient. In fastercategories, two pumps can be used in parallel. Provides 72gph @ 7.0 psi.P4007038Carter electric fuel pump.Holley Electric Fuel PumpHigh capacity, high pressure. Can be used in parallelwithout mechanical pump for multiple carburetorapplications. Regulator included. Provides 70 gph at 9.0 psi.P4 120227Holley electric fuel pump.Fuel Delivery System360 AMC V-8 (FUEL DELIVERY SYSTEM) 421Holley Fuel Pressure RegulatorTo service Holley fuel pump P4120227.P4 120228Holley fuel pressure regulator.High Capacity Electric Fuel PumpsHigh capacity, high pressure electric fuel pump can beused singularly or in parallel with mechanical pump.Designed for drag race applications.~524978 1 I10 gph.PS249782P5249783140 gph.250 gph.Chrome Fuel Pump Block-Off PlateThis good looking chrome plate covers the hole left whenremoving the mechanical fuel pump for replacement withan electric pump. Gasket included.P4529404Chrome fuel pump block-off plate.

l- - 7 . 7422 MOPAR PERFORMANCE PARTS360 AMC V-8 Mechanical Fuel PumpAll 360 AMC V-8s have a single action, mechanical fuelpump. The fuel pump is comprised of an actuating lever, adiaphragm and spring, an inlet valve, and an outlet valve.An eccentric lobe on the engine camshaft operates the fuelpump lever, which is linked to the pump diaphragm. Thelever pulls the diaphragm to its extended position to pumpfuel into the inlet valve. When the carburetor float needlevalve closes, fuel pump output is limited to the amount thatreturns to the fuel tank through the fuel return tube. Thefuel accumulated in the fuel pump chamber prevents thediaphragm from relaxing. The actuating lever continues tomove up and down, but is prevented from operating thediaphragm, which is held in its extended position by fuelpressure. Fuel flow from the pump remains halted untilexcess pressure is released through the fuel return tube oruntil the carburetor tloat needle moves off its seat. Thisprocedure continues as long as the engine is running.Mechanical fuel pumps cannot be overhauled. Replace anymechanical fuel pump that fails either a pressure, capacity(volume) or vacuum test.Mechanical Fuel PumpStock replacement mechanical fuel pump for use withcarbureted systems. Factory original equipment comeswith pump and gasket. For 360 AMC V-8 engine only.P4S2964 1Mechanical fuel pump.High Capacity Mechanical Fuel PumpSpecial high capacity mechanical fuel pump. Provideshigh flow rate. Ideal for race applications. For 360 AMCV-8 engine only.P4.529594 High capacity mechanical fuel pump.FUEL FILTERThe carburetor is protected from dirt and other foreignmatter by a replaceable, 15 micron, pleated paper filter. Thefuel filter is located in the fuel supply tube between the fuelpump and carburetor and is secured in place with hoses andclamps. The filter has an extra nipple for the fuel return tube.The filter must be installed with the return nipple pointingupward to ensure correct operation of the Fuel ReturnSystem. Replace the fuel filter at the intervals outlined in theMaintenance Schedule in the service manual.FUEL HOSES AND CLAMPSWhen installing hoses, ensure that they are routed awayfrom contact with other vehicle components that could rubagainst them and cause failure.FlJELGasolineTwenty to thirty years ago, pump gasoline could be obtainedthat would support a high output, high performance enginewith a moderately high compression ratio. All highperformance engines had at least 10 or 10.5: 1 compressionratios up to 1972. Then, everything dropped to 8 or 8.5:l.Today, these early engines will not perform adequately onpump gasoline. Using the inferior pump gasoline that’savailable today in these high performance engines can causefailure, especially in pistons and rings. Therefore, to racehigh compression engines, special high octane gasolinemust be obtained. This is easier said than done.Today, the best pump gas (highest octane) is unleadedpnemium. To use this fuel in older high compressionengines, the racer has to back down on his ignition’s sparkadvance. This cuts performance but at least the engine lives.The best solution, time and money allowing, is to lower thecompression ratio to 9.0:1 or less. A compression ratio of9.5: 1 could be used with “blends” (octane booster, etc.), butwould only be recommended for engines that are racedexclusively. Blending is troublesome and offers manyopportunities for error. The 9.5: 1 engine will also “carbonup’’to an actual 10.0: I or 10.5: 1 in a few thousand miles.Now you’re in trouble and there isn’t a good solution, except1e:js spark advance, and that’s not good for performance.These comments are directed at the engine builder.Obviously, once the engine is built, it’s too late. Thecompression ratio can’t be adjusted at this point. Worse yet,it gets higher as deposits build up. Also keep in mind thatthe solution isn’t to use high compression and just add morepower parts (Le., potential). Now you’ve got an engine with400 hp potential (for example) that makes maybe 260-270hp (and cost thousands more). Another problem of highcompression engines running on bad gas is that they don’trespond. The camshaft that normally might make 20horsepower may gain 5 hp, no gain, or even a loss in somecases. All of this caused by detonation problems resultingfrom the use of inferior gas.In summary, high compression ratio engines on race gasmake more horsepower than low compression ratioengines, but without the racing gas the lower compressionratio engine wins.Inspect all hoseklamp connections for completeness andensure that no leaks are present. Hoses that are cracked,scuffed, swollen, have rubbed against other vehiclecomponents or show any other signs of wear that could leadto failure must be replaced.

360 AMC V-8 (FUEL DELIVERY SYSTEM) 423Now, let’s look at the octane boosters themselves. Basically,there are three kinds - alcohol, aromatic hydrocarbon, andmetallic. Examples of each are as follows:Alcohol: MethanolGasoline AdditivesWarning! Gasoline additives are poisonous! Use with caution!Gasoline additives do help current pump gas for racingapplications. The two most common substances used areToluene and Aniline oil. Aniline is the more effective.Gasoline additives work better on regular gasoline than theydo on premium. The gasoline additive added to an 89 octaneregular would result in a 4-5 point increase in octane rating.However, the same additive and a 94 octane premium fuelonly results in a .5 to 1 point increase in octane rating.Therefore, engines with an 11 .O: 1 or greater compressionratio must have some percentage of special premium(“race”) gasoline to perform at their maximum outputs.Octane Booster EffectivenessIn this day of lower octane ratings and unleaded fuel, octaneboosters/gasoline additives are more common than everbefore. Simply stated, octane boosters are gasoline additivesthat are supposed to increase the octane of the fuel to whichthey are added. Because most of us don’t really know whatour octane requirement is, these octane boosters look like agreat idea. Unfortunately, for most of us, they aren’t!First of all, octane is key to engine performance. We canonly make as much power as the octane allows us to.However, octane itself doesn’t make performance. Puttingexpensive race gas in a 360 2-Bbl. isn’t going to make morepower. On the other hand, running unleaded regular in a426 Hemi 4-Bbl. isn’t going to allow the engine to performup to its rated output.This is extremely important in older, pre- 1972 engines.These engines tend to have higher compression ratios.Higher compression ratios require (demand) higher octanefrom the gas to perform properly. Therein lies theproblem-less octane, or at least a fixed octane level(around 92-94), for the last few years. This means that if wecan’t get more octane we can’t have higher compressionratios. Octane boosters to the rescue!Aromatic Hydrocarbon: TolueneMetallic: Lead or ManganeseThe metallics are usually found within a complexcompound; for example, tetraethyl lead. But you can findthe “metal” part in the name that gives you the clue. Theproblem is that most manufacturers don’t publish this data.In general, we’ve always lumped all the octane boosterstogether and stated that they increase premium unleadedgas (best pump gas available) about one octane number.This isn’t quite fair. The metallics are slightly better whilethe other two types are slightly below this average number.Specifically, aromatic hydrocarbons increase the octaneapproximately .75 octane point. Alcohol “blends” vary a lotin effectiveness, depending on the brand, but still rangefrom .3 to .75. On the top of the chart are the metallics,which range from 1.5 to 2.0, or slightly over twice aseffective as the others. On the flip side is cost! Themetallics cost around $7.00 (or more) per can.Before you jump at this stuff, keep in mind that even twooctane numbers translate into only a 1/2 point ofcompression ratio-max! So don’t start building high ratioengines. The big advantage of octane boosters is on enginesthat have already been built. The high ratio was built into ityears ago and now you’ve got it and somehow have to livewith it. If an engine rebuild costs $1,000 (bearings, rings,pistons, machine work, head work, etc.), then you’d have todrive 20,000 to 40,000 miles before the rebuild wouldbalance off the cost of the octane booster. At this point, theoctane booster is a quick and dirty fix for having too muchcompression ratio. It looks even better when you realizethat you really can’t rebuild your engine for $1,000. Itmight pay for the parts, but not the labor.The biggest problem with knowing all this about octaneboosters is that you tend to think that they solve all octaneproblems. For a used 9.5: 1 high performance engineoriginally built in the late 1960s or early 1970s, they maybe just what you need to solve your problem, but the I I .O: 1or 12.O:l engine is in trouble. Even the octane boosterwon’t help.A related problem is that most of us may not find this outuntil it’s too late! Detonation ruins the engine. How do yousolve this problem‘? If you are building the engine, measureits exact compression ratio as assembled. If you’ve boughtan engine built by someone else, do your best to measure itsexact cornpression ratio before you do anything seriouswith your new project. It’s not worth the gamble.

424 MOPAR PERFORMANCE PARTSExhaustThe basic exhaust system on all vehicles consists of anexhaust manifold(s), front exhaust pipe, catalytic converter,heat shield(s), muffler and tailpipe.Vehicles with the 360 AMC V-8 use a single muffler exhaustsystem with a single, monolithic-type catalytic converter.The exhaust system must be properly aligned to preventstress, leakage, and body contact. If the system contacts anybody panel, it may amplify objectionable noises originatingfrom the engine or body.When inspecting an exhaust system, critical items toinspect for are cracked or loose joints, stripped screw orbolt threads, corrosion damage, and worn, cracked orbroken hangers. Replace all components that are badlycorroded or damaged. DO NOT attempt to repair. Whenreplacement is required, use original equipment parts (ortheir equivalent). This will assure proper alignment andprovide acceptable exhaust noise levels.All exhaust systems should be checked for leaks. A leak inthe exhaust system is unsafe and will cost you power.SystemCaution: Avoid application of rust prevention compoundsor undercoating materials to exhaust system floor pan heatshields. Light overspray near the edges is permitted.Application of coating will result in cxcessive floor panternperatures and objcctionablc fumes.Intake and Exhaust Manifold Attaching PackagePackage of factory original nuts and bolts to attach intakemanifold and exhaust manifolds. Includes 24 bolts, 24washers, 4 studs and 6 plugs. For 360 AMC V-8 engine only.P4S2968 1Exhaust Manifold Gasket SetIntake and exhaust manifold attachingpackage.This exhaust manifold gasket set can be uscd with castiron manifolds or headers. For 360 AMC V-8 engine only.P4.529632 Exhaust in ani fo I d gasket set .- .. ..

~Ignition System360 AMC V-8 (IGNITION SYSTEM) 425INTRODUCTIONIgnition systems and components have been changingrapidly in the last few years. Further development isexpected in the future to provide the DaimlerChryslercustomer with the best high performance ignition systemsavailable for his race vehicle. Older ignition systems, suchas the breaker point-type, will not be covered in any detailbecause we no longer produce or recommend these piecesfor high performance race vehicles.Spark AdvanceSpark advance is vital to an engine’s overall performance.This is true whether it’s a drag, oval track, or dual purposevehicle. It even affects the engine’s fuel economy, if thevehicle is used in the dual purpose mode.Something that affects performance this extensively mustbe set very carefully. Unfortunately, we tend to do this verycasually and our understanding of the “how-it-works’’aspect is somewhat limited. We’ll try to improve both ofthese “problems.”Spark advance is also referred to as “timing” or “ignitiontiming.” In standard electronic ignitions (as well as breakerpoint-type systems), the spark advance is determined by thedistributor. However, spark advance is not related directlyto the type of triggering mechanism; that is, points or pickupand reluctor. Spark advance is something that’s commonto both styles of ignitions/distributors.There are 3 phases to spark advance: initial advance,primary advance, and secondary advance (see Figure 7-43).Vacuum advance is an add-on or supplemental functionwhich we’ll discuss later. (For the time being we’ll assumethat it’s zero.)Initial advance is what we set with a timing light while theengine is idling. The sum of the primary advance and thesecondary advance is commonly called the centrifugaladvance. The sum of the initial advance and the centrifugaladvance is called the total advance. Total advance is whatis used in racing to “set the timing” rather than initialadvance, because of accuracy. If the spark advance is“plotted’ against engine rpm, the result is called the sparkadvance curve (see Figure 7-44 for a typical advancecurve). This all sounds pretty easy.Three Phases of Spark Advance\ Initial AdvanceENGINE RPMFigure 7 - 43.Secondary AdvanceNow, let’s do some performance modifications. Let’sassume that our distributor has 18 degrees of centrifugaladvance built into it. If we set 12 degrees initial advancewith this distributor, then our total advance is 30 degrees(12 + 18). If we increase the initial advance to 17 degrees,then the total advance is increased to 35 degrees (17 + 18 =35). This is not considered recurving the distributor. To dothat we have to disassemble the distributor itself. Changingthe initial setting just moves the whole curve up (or down).Let’s assume that we have a production distributor and wewant to have it recurved for improved performance. To do thiswe have to disassemble the distributor. We can do it ourselvesor take it to a distributor shop. The trick is what to do!The first step in recurving a distributor is to run it on adistributor machine and find out what it actually has. Thefirst question is how many degrees does the distributor have“built-in”? If we used the distributor from our example, theanswer would be 18 degrees. The second question is what doesthe advance curve look like? A typical production distributor’sadvance curve is shown in Figure 7-44. If we recurve thisdistributor, the desired “performance CLING” is also shown inFigure 7-44. It is important to look closely at this performancecurve for a moment and analyze some of its characteristics.First, the centrifugal advance is the same- 18 degrees. Therecurving of the distributor hasn’t changed this overallnumber. It can be changed by machining, but this isexpensive and generally not recommended. Second, note thatthe secondary advance is zero with the performance curve.Next, with the performance curve, it is fully advanced by2,000 rpm. This is a very desirable characteristic formaximum performance and lowest E.T. at the drag strip.Note that at 2,000 rpm the production curve hasapproximately 11 degrees where the performance curve has18. That’s a 65% increase in spark advance at this specificpoint. The engine obviously should respond!

I.426 MOPAR PERFORMANCE PARTSTypical Distributor Advance CurvesTypical Performance CurveTypical Production Curve0 1ooommm5ooomENGINE RPMFigure 7 - 44It is important to understand that the difference betweenadvance curves (production vs. performance) within thesame distributor is accomplished by changing one or twoadvance springs inside the distributor. A distributor musthave one spring. There are positions in the advancemechanism for two springs. The second spring is somewhatoptional, depending upon the desired advance curve.Changing these springs (first, second, or both) is whatactually changes the curve.In Figure 7-44, note that the “zero” point for the two curvesis not the same. In truth, this point floats a lot. In aperformance distributor we want it to start advancing before1,200 rpm. Actually, the range is 750 to 1,200. A productiondistributor typically starts advancing before 900 rpm and hasa range of 500-900. The “zero” point is controlled bytolerances in the parts, friction in the bushing, clearances,viscosity of the grease, etc. For performance applications,the “zero” point is not important. However, it does have atremendous effect, especially if we aren’t careful!To better explain “zero” point we need to look at the lowspeed part of the curve in greater detail. To do this we’vecreated Figure 7-4.5. We’ve used 750 rpm as the typicalinitial (“zero”) point. We used only one point for ourstarting location since we’ve assumed that we have onlyone distributor that we’re working with.ntnKTypical Distributor Advance CurvesZ 6$ 5n2 430 3zY2W0= Is9(Enlarged View)0 200 400 600 800 loo0 1200ENGINE RPMFigure 7 - 45We’ve shown two spark advance curves for reference only.The slow curve is typical of a production advance curvewhile the fast curve is typical of a performance curve (orafter recurving). Now let’s analyze Figure 7-45 and seewhat it tells us.Wle’ll assume that we have a performance/race vehiclewhich has a high performance engine in it. These enginestypically idle at 1,000 to 1,200 rpm. We’ll assume that ourexample idles at 1,000 rpm. On Figure 7-45 we’ve drawn adashed line at 1,000 rpm. Notice that the distributor has“advanced’ 2-3 degrees (depending on curve) at this point.Does this have any effect on the engine’s performance? Theanswer is absolutely YES!Let’s assume that we want to set 12 degrees initial advanceand we have an 18 degree centrifugal advance distributor.Using the example in Figure 7-45, we’ll set 12 degreesinitial advance on the damper at idle (1,000 rpm). Question:Have we set 30 degrees advance for our desiredperformance number? Those of you who said “yes” arewrong! We’ve only set 27 or 28 degrees. Now let’s explainwhy this happened and how to solve it.When we set 12 degrees at 1,000 rpm, the advance curveshown in Figure 7-45 says that the distributor has alreadyadlvanced 2 or 3 degrees. This means there are only 1.5 or 16degrees left in the distributor. So, when going from 1,000 to5,000+ rpm we gain an additional 15 or 16 degrees.Therefore, the total advance is 27 or 28 degrees (12 + 15 or16). Obviously, the engine isn’t going to make as muchpower at 27 degrees as it would at 30. Notice that if the idlewas 1,200 rpm we could lose as much as 5 degrees. Thefaster the curve, the worse this condition becomes. How dowe solve this problem?1- -7-7

360 AMC V-8 (IGNITION SYSTEM) 427The solution is quite simple. The problem occurs in varyingdegrees in all performance applications. The way to getaround this problem is you set totul advance. This meansyou set the “30 degree” number for total advance instead ofthe 12 degree initial number. Initial advance is set at idle(1,000 rpm or so); however, total advance is set at the pointwhere the centrifugal advance reaches its maximum (theadvance curve goes horizontal). With a performance curve(see Figure 7-44) this means around 2,000 rpm. With aproduction curve, this rpm would be around 5,000. So witha production curve in the distributor, stay with the initialsetting method. (The maximum power, total advancenumber varies from engine to engine.)For our performance and racing applications, we now knowhow to set our timing correctly and why. The next questionthat comes up pertains to the vacuum advance system. Inour initial discussion we assumed that the vacuum advancewas zero. Now we’ll add it into our analysis.The first item and most important thing to realize is thatvacuum advance does not affect the previous discussion.Vacuum advance is an add-on device designed primarily toincrease fuel economy. Race distributors don’t even usevacuum advance. However, most people have a distributor withvacuum advance, so we’ll cover this to remove the mystery.The basic operation of the vacuum advance is quite simple.Vacuum advance increases the amount of spark advance inhigh vacuum conditions. Realize that we race at W.O.T.(wide open throttle) which means zero vacuum. So vacuumadvance doesn’t affect our performance at W.O.T. Figure 7-46 shows a typical vacuum advance curve. Note that in ahigh vacuum (12 inches of Mercury) the advance isapproximately 16 degrees. This means that in a highvacuum condition (cruising, coasting, etc.) we can have 46degrees of advance (30 + 16). As we open the throttle the16 number drops until at low vacuum (approaching W.O.T.)it goes to zero.Typical Vacuum Advance Curves2” To 9.2” @ 7.7”14” To 20” @ 10.5”Vacuum advance units vary greatly from year to year andengine to engine. On some electronic distributors, theamount of vacuum can be adjusted. By inserting a smallAllen wrench into the vacuum tube and rotating it, theamount of vacuum can be dialed-out. In other words, the 16degrees built into the vacuum unit can’t be increased, but youcan adjust it to any lower number desired. You can adjust itto be zero which would mean it didn’t work. Generally, wewouldn’t recommend this approach. If you don’t want it towork, just disconnect the vacuum hose. When setting yourtiming, if you have a vacuum unit on your distributor alwayspull the vacuum hose off and plug it (usually with a handybolt). At this point it doesn’t work (zero add-in advance) andwon’t affect the total advance setting.Now you should completely understand spark advance.However, recurving distributors usually requires adistributor machine. Spending time assembling anddisassembling distributors and running them on adistributor machine gets expensive. The easiest, and inmost cases, least expensive way to get the same result is toget a distributor which is already recurved. It will have aperformance curve similar to the one shown in Figure 7-44.This gives you the performance curve, adjustable advance,and electronic triggering all built-in.Race (only) distributors have an even faster advance curve(see Figure 7-47). These distributors have 20 degrees builtin(typically) and are fully advanced by 1,000-1,400 rpm.This is much too quick for a dual purpose vehicle.However, the idle of a race engine is typically above 1,200-1,400. This means these race distributors give race enginesa flat advance curve which is desired for racing. Pick thedistributor specifically for your race application, but alwaysremember to set totul udvunce!Typical Advance Curve for Race_.Dist ri but0 rst2 -248 ” -2::0 16 -I; 14 y 1210 -9 a :m 6IVACUUM - INCHES OF MERCURYFigure 7 - 461 1 1 1 l l l lno 1 2 3 4 5 6 7 8ENGINE RPM x 1000Figure 7 - 47. ..l- -1-7

l- - 7 1428 MOPAR PERFORMANCE PARTSLean-Burn IgnitionThe lean-burn ignition system was introduced in the mid-1970s on production cars. It was a specialized version ofthe breaker point-type ignition system.For high performance applications, this ignition system istoo complicated and worrisome, and it can’t be utilizedwith a high output electronic ignition system, which is thesystem Mopar Performance Parts recommends.MagnetosA magneto is a completely different ignition system fromany other detailed in this section. A properly set up and tunedmagneto will fire a very high output race engine. However,magnetos have more spark scatter than race electronicdistributors and have a large amount of spark retard withspeed. The spark retard can be as high as 1 degree perthousand rpm. Another problem with magnetos is that theywill “go away” in a short period of time and slow the vehicledown. And because they don’t “miss” like other ignitionsystems, racers can’t easily tell if the ignition is not doing itsjob, a problem that can be almost impossible to find.SOLID STATE IGNITION (SSI) IGNITION SYSTEMA Solid State Ignition (SSI) system is used on the 360AMC V-8 engine. The SST system consists of thefollowing components:Ignition moduleIgnition coilResistance wireDistributor0 Knock sensorCap and rotorSpark plugs and wiresThe central tower on the distributor cap is connecteddirectly to the high voltage at the coil. The current flowsthrough the spring-loaded contact on the rotor to the carbonbutton in the cap. The rotor tip aligns with a contact in thecap that corresponds to the cylinder to be ignited just as theignition coil output high voltage is applied to the rotor. Inthis way, each spark plug is “fired” in turn.SSI IGNITION COMPONENTSIgnition ModuleThe electronic Ignition Module is located in the enginecompartment on the left wheel well. It is a permanentlysealed, solid state module that is not repairable and must bereplaced as a unit if service is required.The ignition module processes the ignition signals itrecseives from the distributor and then interrupts the primarycircuit to the ignition coil causing spark to occur. Dwell isadjusted automatically.When disconnecting SSI system connectors, pull themapart with a firm, straight pull. DO NOT attempt to prythem apart with a screwdriver. When connecting them,press together firmly to overcome hydraulic pressurecaused by the silicone dielectric compound.If the connector locking tabs weaken or break off, DO NOTreplace the associated component. Bind the connectorstogether with tape or a harness tie strap to assure goodelectrical connection.Distributor360 AMC V-8 distributors are equipped with centrifugaland vacuum assisted advance to advance the engine timingthe correct number of degrees during engine operation.The distributor consists of three groups of components:pickup coil and trigger wheel, ignition advancemechanisms, cap and rotor. The distributor driver gear isinstalled on the distributor shaft and meshes with a spiralcut gear that is installed on the nose (front) of the camshaft.The end of the distributor shaft is flattened and fits into aslot in the top of the oil pump and provides the force todrive the oil pump.~ ~ ~ ~~ ~Electronic Ignition DistributorThds Mopar Performance Parts electronic ignitiondistributor is the same as the production distributor andcan be used as a replacement. Comes complete with capand rotor. For 360 AMC V-8 engine only.P4529684 Electronic ignition distributor.Distributor Cap and Rotor SetReplacement cap and rotor set. For 360 AMC V-8 engineonlly.P4.529687 Distributor cap and rotor set.1. Ignition AdwinceCentrifugal (mechanical) advance is controlled byengine speed. Flyweights connected to the distributorshaft are thrown outward by centrifugal force. Higherengine rpm throws the weights further out. Calibratedrate springs are used to control this movement. Theoutward motion of the flyweights causes the rotor andtrigger wheel to be advanced on the distributor shaftseveral degrees in the direction of normal rotation.This is referred to as centrifugal ignition advance.

360 AMC V-8 (IGNITION SYSTEM) 4292.When the engine is operating under light load, thecarburetor throttle plates restrict airflow, causing arelatively lean mixture to enter the combustionchambers. Ignition must occur earlier because the leanmixture requires a longer time to burn. The vacuumignition advance mechanism is used for this purpose.When carburetor ported or manifold vacuum is high,the vacuum advance mechanism moves the pickup coilassembly several degrees opposite to the direction thedistributor is rotating. This causes the pickup coil toreact to the presence of the trigger wheel teeth earlier.This is referred to as vacuum ignition advance. Withlow vacuum operating conditions, such as wide openthrottle acceleration, a spring in the vacuum advancesmechanism pushes the pickup coil back to a position ofzero advance.Pickup Coil and Trigger WheelThe ignition coil primary circuit is opened and closedelectronically by the ignition module. The distributorpickup coil and trigger wheel provide the input signalfor the ignition module.The trigger wheel, which is installed on the distributorshaft, has one tooth for each engine cylinder. Thewheel is mounted so that the teeth rotate past thepickup coil one at a time.The pickup coil has a magnetic field that is intensifiedby the presence of ferrous metal (contains iron - can bepicked up with an ordinary magnet). The pickup coilreacts to the trigger wheel teeth as they pass. As atrigger wheel tooth approaches and passes the polepiece of the pickup coil, it reduces the reluctance(compared to air) to the magnetic field and increasesfield strength. Field strength decreases as the toothmoves away from the pole piece. This increase anddecrease of field strength induces an alternating current(pulse) into the pickup coil, which triggers the ignitionmodule. The ignition module opens and closes the coilprimary circuit according to the position of the triggerwheel teeth.There is no contact between the trigger wheel andpickup coil assembly. Because there is no wear, thedwell angle does not require adjustment. The dwellangle is determined electronically by the control unitand is not adjustable. When the ignition coil primarycircuit is switched open, the internal electronic timer inthe ignition module keeps the coil primary only longenough for the electromagnetic field within the coil tocollapse and the voltage to discharge. The ignitionmodule then automatically closes the coil primarycircuit. The period of time the circuit is closed isreferred to as dwell.3. Distributor CupThe central tower on the distributor cap is connecteddirectly to the high voltage at the coil. The currentflows through the spring-loaded contact on the rotor tothe carbon button in the cap. The rotor tip aligns witha contact in the cap that corresponds to the cylinder tobe ignited just as the ignition coil output high voltageis applied to the rotor. In this way, each spark plug is“fired” in turn.Remove the distributor cap and wipe it clean with adry, lint free cloth. Visually inspect the cap for cracks,carbon paths, broken towers, white deposits on theinside (caused by condensation entering the vehiclethrough cracks), and damaged rotor button. Replaceany cap that displays charred or eroded terminals. Themachined surface of a terminal end (faces towardrotor) will indicate some evidence of erosion fromnormal operation. Examine the terminal ends forevidence of mechanical interference with the rotor tip.If replacement of the distributor cap is necessary,transfer spark plug wires from the original cap to thenew cap one at a time. Ensure that each wire isinstalled into the tower of the new cap that correspondsto its tower position in the original cap. Fully seat thewires into the towers.4. Distributor RotorA unique feature of the SSI is the silicone applied tothe distributor rotor blade. Radio interference is greatlyreduced by the presence of a small quantity of siliconedielectric compound on the rotor blade. After a fewthousand miles, this compound becomes charred by thehigh voltage current flowing through the rotor. Thiscondition is normal. DO NOT scrape residue from therotor blade.When installing a replacement rotor, apply a thin coat0.75-3.0 mm (0.03-0.12”) of silicone dielectriccompound to the tip of the rotor blade.Visually inspect the rotor for cracks, evidence ofcorrosion and the effects of arcing on the metal tip, andevidence of mechanical interference with the cap.Some charring is normal on the end of the metal tip.The silicone dielectric compound applied to the rotortip for radio interference noise suppression (six-andeight-cylinder engines) will appear charred. This isnormal.DO NOT remove the charred compound. Test thespring for insufficient tension. Replace a rotor thatdisplays any of the adverse conditions. Coat the tip ofa replacement rotor with Mopar Silicone DielectricCompound or equivalent.

430 MOPAR PERFORMANCE PARTSIgnition SwitchThe ignition switch is mounted on the lower section of thesteering column and is connected to the key lock assemblyby a remote lock rod.In race vehicles, the production ignition switch issometimes replaced by a toggle switch. This can causeproblems if a high-amp rated switch (I 8-20 amp) isn’t used.Most readily available switches are 14-16 amp rated. Thelower rating causes more resistance in the ignition circuit,which cuts down on the voltage available to the ignition’scontrol unit. The lower voltage can cause the ignitionsystem to perform poorly or develop a miss which can bevery difficult to analyze.There are 2 special switches that are helpful in wiring a racevehicle: “On-Off’ Micro Switch Assembly (P3690282);and, Push Button Starter Switch Assembly (P3690823).The “On-Off’ Micro Switch Assembly is the mostimportant. Other “econo” switches aren’t rated as high onamperage and therefore put resistance between the batteryand the ignition and can cause misfiring.Ignition SwitchesP3690282P3690823Ignition Wires“On-Off’ micro switch assembly (20 amp).Push button starter switch assembly.If you don’t have top quality ignition wires you aren’tconducting maximum spark.Production spark plug wire is 7 mm. For racing purposeswe recommend an 8 mm, 19-strand, copper, siliconejacketedwire. The added insulation of the larger diameterwire helps control today’s high energy ignition systems.Nine millimeter plug wires are not recommended becauseof the mismatch of the terminals in coils and caps. If moreinsulation is required, neoprene hose of the proper insidediameter is recommended.Usually, once the wire is installed, pulling on the wire toremove the boot from the plug is the most common causeof failure. This is especially true of stock or cheap wires.Using the Mopar Performance Parts Plug Wire Boot Puller(P5249718) will help plug wire removal without damagingthe connector. The boot puller will probably double plugwire life, malung it one of the best deals in the ignition area.The Mopar Performance Parts plug wires have straight endsat the spark plug, which is the most common style. Havingbeen in racing for many years, we know that the straightend is not best for all applications, especially with headers.In an effort to solve this problem, we have introduced VariAngle Plug Adapters (P4286742), which adjust easily fromstraight to right angles.Our Ignition Wire Separator Package (P4007667) keeps thewires separated from the cap to the plug. This helpsperformance by preventing cross firing and makes theengine compartment look much more organized.Spark Plug Wire Boot PullerHere’s the tool you need for easy removal of spark plugwires without pulling the wire out of the terminal end andboot. Saves on knuckles, too.P5 249718Spark plug wire boot puller.Vari-Angle Plug AdaptersHere’s a convenient way to steer spark plug wires aroundheaders, brackets, and other tight areas, in any directionyou want. Vari-angle plug adapters have a built-in swiveldevice which maintains the position you bend them in. Ahandy set-up for any racer. Sold two per set.P4286742 Vari-angle plug adapters.Ignition Wire Separator SetIgnition wire separators. 8 pieces per set.P4.007667 Ignition wire separator set.Ignition Coil ConnectorThe ignition coil terminals and connector are of uniquedesign. The connector is removed from the coil by graspingboth sides and pulling away from the coil.When a tachometer is required for engine testing or tuneup,connect it using an alligator jaw type connector.Resistance WireA wire with 1.35 ohms resistance is provided in the ignitionwiring to supply less than full battery voltage to the ignitioncoil after the starter motor solenoid is de energized. Duringengine starting, the resistance wire is bypassed and fullbattery voltage is applied to the ignition coil. The bypass isaccomplished at the I-terminal on the starter motor solenoid.

360 AMC V-8 (IGNITION SYSTEM) 431Vacuum Advance Control SystemManifold vacuum and carburetor ported vacuum are bothused for the ignition vacuum spark advance mechanism onthe 360 AMC V-8. A coolant temperature override (CTO)valve determines the appropriate vacuum source,depending upon coolant temperature. The CTO valve isscrewed into the thermostat housing. A thermal sensor atthe CTO valve tip is in contact with engine coolant.Depending on the coolant temperature, the CTO valvepermits either manifold vacuum or carburetor portedvacuum to control the distributor vacuum advance. Whencoolant temperature is below 104°C (220"F), carburetorported vacuum is supplied to the distributor vacuumadvance mechanism. Above 104°C (220"F), manifoldvacuum is supplied.Spark Plugs1. RemovalRemove the ignition wire by grasping it at the sparkplug boot, and then turn (1/2 turn) and pull it straightback in one steady motion.a. Prior to removing the spark plug, spraycompressed air around the spark plug hole and thearea around the spark plug.b. Remove the spark plug using a quality socket witha rubber or foam insert.c.2. InspectionInspect the spark plug. Refer to step 2 -Inspection.Faulty and fouled plugs may perform well at idlespeed, but at higher engine speeds they frequently fail.Faulty plugs can be identified in a number of ways:poor fuel economy, power loss, decrease in enginespeed, hard starting and, in general, poor engineperformance. Spark plugs also malfunction because ofcarbon fouling, excessive air gap, or a broken insulator.Examine the spark plugs for burned electrodes andfouled, cracked or broken porcelain insulators. Keepplugs arranged in the order in which they wereremoved from the engine. An isolated plug displayingan abnormal condition indicates that a problem existsin the corresponding cylinder. Replace spark plugs atthe intervals recommended on the Maintenance Chartin the service manual.Spark plugs that have low mileage may be cleaned andreused if not otherwise defective. After cleaning, filethe center electrode flat with a small point file orjewelers file. Adjust the gap between the electrodes tospecification.3. SpecificationsSpark Plug Electrode TighteningEngine GaD Torque360 AMC V-8 RN 12YC 0.825 mm 37 Nam(0.033") (27 ft-lbs)4. Gup AdjustmentCheck the spark plug with a gap (feeler) gauge. If thegap is not correct, adjust it by bending the groundelectrode. The gap for 360 AMC V-8s is 0.825 mm(0.033").5. Installationa. Start the spark plug into the cylinder head by handto avoid cross threading.b. Tighten the spark plug to 35 Nom (27 ft-lbs)torque.c. Install ignition wires over spark plugs.Always torque spark plugs to specification. Overtightening can cause distortion resulting in a change inthe spark plug gap.When replacing ignition wires, route the wirescorrectly and secure them in the proper retainers.Failure to route the wires properly can cause ignitionnoise radio reproduction, cross ignition of the sparkplugs or short-circuit the wires to ground.BatteryIt is very important that the battery be fully charged inracing applications with electronic ignitions. A voltmetershould be used to check the battery voltage before thevehicle is raced. The voltage should not be allowed to dropbelow 12.0 volts. Lower voltage will cause poor ignitionperformance such as misfires and result in slowing thevehicle down. It may also cut down on the electric fuelpump's efficiency.

T -7‘7432 MOPAR PERFORMANCE PARTSMopar Performance Parts Spark PlugsNEW! These spark plugs are specifically designed for the optimum performance of your Moparengine. Each package contains 4 spark plugs.Race & Tuning Application Plugs (J-Strap Type)Pack PIN I Cross Reference I ApplicationC 61C to C 59Cc 57c to c 55cAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ’B-RB’ enginesP4876942 C 53C to C 51C All except ’B-RB’ enginesC 61C to C 59Cc 57c to c 55cProfessional Race PlugsAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesAll except ‘B-RB’ enginesP4 876928P4876929C 61C to C 59Cc 57c to c 55cc 53c to c SICAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsAll Race ApplicationsP4876932 S 61C to S 59C All Race Applicationss 57c to s 57cAll Race ApplicationsS 53C to S 51CAll Race ApplicationsAll Race ApplicationsNote:C type plugs have 314 inch reach with flat seat and crush gasket.S type plugs have 314 inch reach with tapered seat.

360 AMC V-8 (IGNITION SYSTEM) 433VOLTAGE REGULATORSFor standard or dual purpose use, the original voltageregulator should work fine. However, if your engine is arace-only piece, a constant output voltage regulator shouldbe used.Caution: Using a constant output voltage regulator on avehicle intended for standard or dual purpose applicationcan overcharge the battery and cause an electrical failure.IGNITION SYSTEM TIMINGA graduated timing degree scale located on the timing casecover is used for reference when timing the ignition system.A milled index notch in the vibration damper is used toalign the No. 1 cylinder ignition position of the crankshaftwith the correct timing degree mark on the graduated scale.Magnetic Timing ProbeWith both engines, a magnetic timing probe socket isprovided integral with the timing degree scale for use witha special magnetic timing probe.This special probe detects the milled notch on the vibrationdamper. The probe is inserted through the probe socketuntil it contacts the vibration damper. Ignition timing canthen be obtained from a meter or computer printout,depending on the type of equipment being used.The probe socket is located at 9.5" after TDC, and theequipment is calibrated to compensate for this location.DO NOT use the timing probe socket as a reference to checkthe ignition timing when using a conventional timing light.Ignition Timing ProcedureThe ignition timing can be adjusted according to thefollowing primary timing procedure.1. Set parking brake. Shift transmission to PARK.2. Run engine until it reaches normal operating temperature.3.Ensure that AIC is turned OFF, if equipped.4. With the ignition switch OFF, connect an ignition timinglight and a calibrated, expanded scale tachometer.5. Disconnect and plug the distributor vacuum advance hose.6. Loosen distributor hold down bolt to allow adjustment.Warning! Use extreme caution when the engine isoperating. DO NOT stand in a direct line with the fan. DONOT put your hands near the pulleys, belts or fan. DO NOTwear loose clothing.7. Start the engine.8. With the engine at idle speed, check and adjust (ifnecessary) the timing according to the specificationlisted on the Emission Control lnformation labellocated in the engine compartment.9. Tighten the distributor hold-down clamp and verifythat the ignition timing is correct.10. Turn the engine OFF and remove the timing lightand tachometer.11. Connect the hose to the distributor vacuumadvance mechanism.MOPAR PERFORMANCE PARTS ELECTRONICIGNITION COMPONENTS~~ ~High Performance Electronic Control UnitsFor a hotter spark and more rpm capability, use one of Mop=Performance Parts' high performance ECUs. For generalhigh performance and usage up through 6,000 rpm, use theOrange Box ECU. For higher rpm output requirements upthrough 8,000, select the Chrome Box ECU.P4 120505 Orange Box ECU.P4120534Chrome Box ECU.Super Gold Electronic Control UnitThe Super Gold Electronic Control Unit is the culminationof eight years of high performance ignition systemsdevelopment. Designed to out perform any ignition unitpreviously offered to Mopar racers, it will handle the highcurrent demand by the P3690560 (Accel) highperformance coil, while keeping dwell variation to lessthan 1" from 1,000 to 10,000 rpm. Dwell is set formaximum spark output at low and high engine speeds.The Super Gold ECU provides outstanding performancefrom idle to 12,000 rpm.P4 120600Super Gold ECU -race only.Ballast Resistor - Electronic DistributorP2444641 Use with mechanical advance distributorusing P3690560 coil. 1/4 Ohm.P5206436 Use with electronic ignition systemsusing P4120505 Orange Box ECU andproduction coil, or with P4120889 coil.1 Ohm.l- -'T 1

434 MOPAR PERFORMANCE PARTSIgnition CoilsP4120889P3690560Accel Super Coil for all 12-voltapplications. Not recommended forengine speeds over 6,500 rpm. (Use withballast resistor PS206436.)Accel Race Coil specifically designed tobe used with race electronic ignitionkits. Designed for racing applicationsonly. Not recommended for continuedoperation at speeds below 3,000 rpm formore than 30 minute periods. (Use withballast resistor P2444641.)Chrome ignition Coil BracketAnother underhood piece to dress-up your enginecompartment. Includes special clamp screw.P4286728Tach AdapterChrome ignition coil bracket.Designed for applications when high capacitive dischargecoils interfere with tachometer or fuel injection signals.Thiis device provides a clear 12 volt square wave signaloutput with a 30% duty cycle.P4876738Tach adapter.Control Wiring Harness Kit for ElectronicIgnitionsKit used to convert to a new electronic ignition system.P3690152Control wiring harness kit for electronicignitions.. ..

T - T IENGINE ASSEMBLY360 AMC V-8 (ENGINE ASSEMBLY) 435Note: For engine assembly information, performance modifications and tips, refer to 'Engine Assembly' section ofChapter 4, 4.0L Power Tech In-Line 6.1971, 304-360 AMC V-8 ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1971 Jeep Service MLrnunl.-V-8 ENGINE SPECIFICATIONS304 CID 360 UDTvpeBoreStrokeFiring OrderDisplacementCompression RatioNet Brake HorsepowerNet TorqueTaxable HorsepowerFuelCylinder Head and Block Flatness90" V-8 OHV3.7502'"-3.7534"3 .w1-8-4-3-6-5-7-20048.4: 1150 @ 4200 RPM245 @ 2500 RPM4:5.00Regular- .008 Max. Full Length,90" V-8 OHV4.0799"-4.0831''3.44"1-8-4-3-6-5-7-23608.5:l175 @ 4000 RPM285 @ 2400 RPM53.27Regular.002" in 6", .001" in 1"-

436 MOPAR PERFORMANCE PARTSV-8 ENGINE304-360 Cubic Inch DisplacementVALVESValve Arrangement(Front to Rear - 1 Bank)Valve Stem DiameterValve LengthValve Guide I.D. (Integral)Stem to Guide ClearanceIntake Valve Face AngleIntake Valve Seat AngleIntake Valve Seat WidthExhaust Valve Face AngleExhaust Valve Seat AngleExhaust Valve Seat WidthValve Seat Run-OutVALVE SPRING TENSION (LBS.)ClosedOpenINTAKE VALVE TIMINGOpensClosesEXHAUST VALVE TIMINGOpens (California)Opens (Nationwide]Closes (California)Closes (Nationwide)Valve Opening Overlap(California)Valve Opening Overlap(Nationwide)304 CID 360 CIDc - CI IC c, IC -LI-IC-KI-IC-L -.3715"-.3725" c- 4.7895"-4.8045"3735"-3745"- -.oo 1 "-.oo3"c29'44--~ --tJI .040"-.060" *+ .0025" Max.- - 80 Lb.-88 Lb. @ 1 1*/16" -:210 Lb.-226 Lb. @ 1**/6/ *- 14.75' BTDC c- -60.75' ABDC *-4- -- 56.77' BBDC* - 56.75' BBDC56.75' ATDC- 26.75" ATDC-- -471.49' L+ 41 So *CAMSHAFTCam Lobe LiftEnd PlayBearing ClearanceIntake DurationExhaust Duration (California)Exhaust Duration (Nationwide)Base Circle Run-OutTappet Clearance-.2w4 .oOO" Engine Operating- -.WI -.Vu0263.5'263.5'I .001" Max. -4 Zero Lash (Hydraulic lifters) -5PISTONS AND RINGSPiston to Bore Clearance @Center Line of Piston PinPiston Ring GapTop and CenterBottom (Steel Rail)Piston Ring Side Clearance#1 Compression#2 CompressionOil ControlPiston Pin to Connecting RodPiston to Pin ClearanceCRANKSHAFT AND BEARINGSMain Bearing Journal Diameter(Rear Main Only).OO 1 "-.OO 18" .0012"-.002"-.010"-.020"-.o 10"-.02Y .015"-.045".0015"-.OO35".OO15"-.003".0015"-.oo3" .0015"-.0035".0011"-.008" .000"-.007"-PressI. -Fit 2000 Lbs..0003"-.0OO5"z - 2.7489"-2.7474" z- . - 2.7479"-2.7464" 9-

l- -17360 AMC V-8 (ENGINE ASSEMBLY) 437V-8 ENGINE304-360 Cubic lnlch DisplacementCRANKSHAFT AND BEARINGSMain Bearing Journal WidthMain Bearing Clearance(Rear Main Only)Crankshaft End PlayConnecting Rod Journal DiameterConnecting Rod Journal WidthConnecting Rod Bearing ClearanceConnecting Rod Side ClearanceOIL PUMP AND LUBRICATING SYSTEMOil Pump TypeNormal Operating Pressure@ 600 RPM@ 1600 RPM or HigherOil Pressure Relief MaximumGear to Body ClearanceGear End Clearance (Cover andGasket Removed)FilterEngine Oil Capacity304 CID 360 CID# 1 - 1.2665" # 1 - 1.2665"#2 - 2.247" #2- 1.247"#3 - 1.274" #3 - 1.274"#4 - 1.247" #4 - 1.247"#5- 1.216" #5 - 1.216"/ .001"-.002"- .002"-.003".003"-.008" -2.0955"-2.0934" 2.0955"-2.0934"2.001 " 2.00 1 'II .001"-.002" -d .006-.018 cc Gear c-* 13 PSI c37 PSI Min.-75 PSI Max. 4 75 PSI c .0005"-.0025"(Each Tooth) * .002"-.006"- -Full Flowc 4 Quarts c(One (1) Additional Quart With Filter Change)

438 MOPAR PERFORMANCE PARTS1971,304-360 AMC V-8 ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1971 Jeep Service Manual.V-8 ENGINE304-360 Cubic Inch DisplacementFootTORQUE SPECIFICATIONS304 CID Pounds360 CIDAlternator to Mounting Bracket Nuts 30-35 LAlternator Bracket to Lower Support Nuts 18-25 cAlternator Support Bracket to Cylinder Head Bolts -= 25-30 +Alternator Adjusting Strap to Alternator Bolts - 18-25 -Camshaft Front Lock Bolt 25-35 LCarburetor Adapter to Manifold Screws - 42V 18-25 L.Carburetor Hold-Down Nuts12-15 *Coil Mounting Bracket Bolts - 30-35 Connecting Rod NutsI 26-30 -Cylinder Head Boltst w - I IUCrankshaft Pulley Attachment Bolts - 18-25-Clutch Housing Spacer to Block Screws .I 10-13 cClutch or Converter Housing to Block25-28 *Distributor Clamp Screws10-15Drive Plate to Converter * 21-23 cFan Spacer to Water Pump BoltFlywheel or Drive Plate to Crankshaft Bolts - 100-110 cFront Engine Cover to Block Bolts I 20-30 -Fuel Pump Screws30-35Main Bearing Cap Screws - 95- 105 cManifold:Air Injection Tube to ManifoldAir Pump Bracket to Cylinder HeadAir Pump to Mounting Bracket NutAir Pump Pulley BoltAir Pump Reinforcement Nut-c 35-40 -40-45 --Air Pump Reinforcement Bolt to Water Pump Nut-25-35By-Pass Valve Bracket to Stud Nut 18-25 -Choke Heater Tube Bolt d 10-12 LDiverter Bracket to Valve Bolt 5-8 c. .. 1- ' T - l

360 AMC V-8 (ENGINE ASSEMBLY) 439V-8 ENGINE304-360 Cubic Inch DisplacementFootTORQUE SPECIFICATIONS304 CID Pounds 360 CIDExhaust Manifold to Cylinder Head Bolt30-35 -Exhaust Pipe to Manifold Nut c 20-25 cIntake Manifold to Cylinder Head Bolt - 40-45 cMounting and Connecting PartsEngine Mounting Bracket to Engine Bolt - 25-30Engine Mounting Bracket to Frame Bolt * 30-35*-Cushion to Support &to Frame Bracket Nut = 30-35 cInsulator Assembly to Crossmember Locknut- 25-30 Mounting to Adapter Bolt -25-30 Adapter to Transmission Bolt 1 15-20 tInsulator and Bracket to Transmission Bolt 25-30 -Insulator to Crossmember Locknut 25-30Insulator to Transfer Case Locknut 15-20 =-Insulator to Transfer Case Screw - 20-30 *Torque Reaction Bracket to Transfer Case Bolt - 25-30 cOil Pump Cover Bolts -48-60 In. Lbs.cOil Pan Screws%"-20 1 5-8 c'/I."- 18I 10-12 Rocker Arm Screws * 20-30 In. Lbs. *Rocker Arm Cover Screws -20-30 In. Lbs.Rocker Arm Retainer Studs * 65-70 -Rocker Arm Retainer Stud Nuts - 20-25 cSpark Plugs * 25-30 cStarter to Engine Bolts 1 30-35 +Thermostat Housing Bolts 1 18-25 -Vibration Damper Retainer Bolt * 50-60 cWater Pump to Block Bolts 1 40-45 *Water Pump to Front Cover Bolts4-50 In. Lbs. *-." 7- - 7 - 7

440 MOPAR PERFORMANCE PARTS1981,304-360 AMC V-8 ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1981 Jeep Service Manual.(USA)InchesUnlessOtherwiseSpacif ied(METRIC)MillimetersUnlessOtherwiseSpecified(USA)InchesUnlessOthorwimSpmafied(METRIC)MillimetersUnlrrOthmiseSpecifiedBore304 .................. 3.75 95.25.......... 4.08 103.63Stroke304 .................. 3.44 87.38360 .................. 3.44 87.38Displacement304 .................. 304 cu .in. 5 liter360 ..... ... .... 360cu.in. 6 llterCompression Ratio304 .................. 8.40: 1360 ............... 8.25:lCompression Prsssure304 ................. ,120 - 140 psi (min) 823.1034 kPa360.. .... . ,120- 140 psi (min) 827-1034 kPaMaximum Variation BetweenCylinders ............. 30 psi 206 kPaTaxable Horsepower304.. .... ......... 45.00 33.56 kW360 .................. 53.27 39.72 kWFuel ................unleadedCamsheftFuel Pump Eccentric Diameter. .... 2.182-2.192 55.423-55.677Tappet Clearance ............ Zero lash (hydraulic tappets)End Play .................Zero (engine operating)0.001 -0.003 0.0254-0.0762(0.0017-0.0620 (0.0432-0.0508preferred) preferred)Bearing Journal DiameterNO. 1 ................. 2.1 195-2.1205 53.835-53.861NO. 2 ................. 2.0895-2.0905 53.073-53.099NO. 3 ................. 2.0595-2.0605 52.311-52.337NO. 4 ................. 2.0295-2.0305 51.549-51.575NO. 5 ................. 1.9995-2.0005 50.787-50.813Maximum Base Circle Runout ..... 0.001 0.0254Cam Lobe Lift304/360 ............... 0.266 6.7564Intake Valve limingOpens 304/360. ...........Closer 304/360. ...........14.750 BTDC68.750 BTDCExhaust Valva TimingOpens 304/360. ........... 56.750 BBDCCloses 304/360. .... 26.750 ATDCValw Overlap304/360 ............... 41.500Intake Duration304/360 ......... 263.500Exhaust Duration304/360 ............... 263.500Connecting RodsTotal Weight (Leu Bearings)304/360 ...............Total Lengtb (Center-to-Center)304/360 ...............Bearing Clearance ............Side Clearance . .............Maximum Twist . ............Maxiinum Bend .............5.873-5.8770.001-0.003(0.0020-0.0025preferred)0.006-0.01 80.0005per inch0.001per inch681 -689 grams149.1 7-149.280.03-0.08(0.051-0.064preferred)0.15-0.460.01 3per 25.4 mm0.03par 25.4 rnmCrankshaftEndplay ................. 0.003-0.008 0.06-0.20Main Bearing Journal DiameterNO. 1.2,3,4. ............ 2.7474-2.7489 69.784-69.822Rear Main .............. 2.7464-2.7479 69.759-69.797Main baring Journal Width3041380NO. 1 ............... 1.2635-1.2695 32.093-32.25NO. 2 ............... 1.246-1.248 31.65-31.70NO. 3 ............... 1.273-1.275 32.33-32.39NO. 4 ............... 1.246-1.248 31.65-31.70NO. 5 ............... 1.215-1.217 30.86-30.91Main bring ClwranoNo.1,2,3,4 ............ 0.001-0.003 0.03-0.08(0.0017-0.0020 (0.04-0.05prefer red) prefer redRMr MainNo.5 .................. 0.002-0.004 0.05-0.10(0.0025-0.003 (0.06-0.08preferred) preferred)Connecting Rod Journal Diameter304/360 ............... 2.0934-2.0955 53.172-53.266Connecting Rod Journal Width304/360 ............... 1.998-2.004 50.75-50.90Connecting Rod heringClearance .............. 0.001-0.003 0.03-0.08(0.0020-0.0025 (0.051-0.064preferred) preferred)Maximum Taper (AH Journals) .... 0.0005 0.013Maximum Outaf-Round(All Journals). ............ 0.0005 0.013Cylinder BlockDeck Height ............... 9.205-9.21 1 233.81-233.96Deck Clurana3041360 ............... 0.0145 0.368(below block) (below block)6027 1 A...T - 7 1

T- - 7 . 7360 AMC V-8 (ENGINE ASSEMBLY) 441(USA)InchesUnlessOtherwirSpecifid(METRIC)MillimetersUnlessOthwwirSpecified(USA)InchesUnlessOtherwiseSpecif ied(METRIC)MillimetersUnlessOtherwiseSpecifiedMaximum Cylinder Taper . . . . . . 0.005 0.13Maximum Cylinder Out-of-Round. . 0.003 0.08Tappet Bore Diameter . . . . . . . . . 0.9055-0.9065 22.999-23.025Cylinder Block Flatness . . . . . . . .Cylinder HeadCombustion Chamber Volume304 ..................360 . . . . . . . . . . . . . . . . . .Valve Arrangement . . . . . . . . . . .Valve Guide ID (Integral) . . . . . . .Valve Stem-to-Guide Clearance . . . .Intake Valve Seat Angle . . . . . . . .Exhaust Valve Seat Angle . . . . . . .Valve Seat Width . . . . . . . . . . . .Valve Seat Runout . . . . . . . . . . .Cylinder Head Flatness . . . . . . . . .Lubrication SystemEngine Oil Capacity . . . . . . . . . .Normal Operating Pressure. . . . . .Oil Pressure Relief . . . . . , . . . ,Gear-to-Body Clearance. . . . . . . .Gear End Clearance, Feeler Gauge .Gear End Clearance, Plestigage . . .PistonsWeight (Less Pin)304..................360 ..................Piston Pin Bore CL-to Piston Top3041360 . . . . . . . . . . . . . . .Piston-to-Bore Clearance304 ..................360 . . . . . . . .Piston Ring Gap ClearanceNo. 1 and No. 2 . . . . . . . . . . .Oil Control Steel Rail304 ..................360 . . . . . . . . . . . . . . . . . .Piston Ring Side Clearance340No. 1 . . . . . . . . . . . . .0.00111. 0.03125-0.00216 0.0511520.008 (maxl 0.20 (mad57.42-60.42 cc58.62-61.62 ccEl-IE-El-IE0.3735-0.3745 9.487-9.5120.001-0.003 0.03-0.0830044.500.040-0.060 1.02-1.520.0025 (maxl 0.064 (max)0.00111- 0.03125-0.00216 0.0511520.008 (maxl 0.20 (maxl4 quarts(add 1 quartwith filterchange)13 psi at600 rpm37-75 psiat 1600+ rpm75 psi (maxl0.0005-0.0025(0.0005preferred)0.004-0.008(0.008preferred)0.002-0.008(0.002preferred)3.8 liters(add 0.9 literswith filterchange190 kPa at600 rpm255-517 kPaat 1600+ rpm517 kPa (pax10.013-0.064(0.013preferred)0.010-0.2(0.10preferred)1.1 -1.1 2 Ibs 506510 arams1.32-1.33 ~bs 601805 ;rams1.599-1.603 40.6240.720.0010-0.0018 0.025-0.46(0.0014 10.035preferred) preferred)0.0012-0.0020 0.030-0.051(0.0016 (0.041preferred) preferred)0.010-0.020 0.25-0.51(0.010-0.012 10.25-0.305preferredl preferred)0.010-0.025 0.25-0.640.015-0.045 0.38-1.14(0.010-0.020 (0.25-0.51preferred 1 preferred I0.0015-0.0036 0.038-0.089(0.0015 (0.038preferred) preferred)No.2 . . . . . . . . . . . . . . . 0.0015-0.003(0.0015preferred)Oil Control . . . . . . . . . . . 0.001 1 -0.008360NO. 1 . . . . . . . . . . . . . . . 0.0015-0.003(0.0015preferredlNO. 2 . . . . . . . . . . . . . . . 0.0015-0.0035(0.0015preferredlOil Control . . . . . . . . . . . 0.000-0.007Piston Ring Groove HeightNo. 1 and No. 2 . . . . . . . . . . . 0.0795-0.0805oil Control . . . . . . . . . . . . . 0.1880-0.1895Piston Ring Groove Diameter304No. 1 and No. 2 . . . . . . . . 3.328-3.333Oil Control . . . . . . . . . . . 3.329-3.339360No. 1 and No. 2 . . . . . . . . . 3.624-3.629Oil Control . . . . . . . . . . . 3.624-3.635Piston Pin Diameter3041360 . . . . . . . . . . . . . . . 0.9308-0.9313Piston Pin Bore D iamr3041360 . . . . . . . . . . . . . . . 0.9288-0.9298Piston-to-Pin Clearance . . . . . . . . . 0.0003-0.0005(0.005preferred 1loosePiston Pin-toGonnecting Rod Fit. . .Rocker Arms, Push Rods, and TappetsRocker Arm Ratio . . . . . . . . . . .Push Rod Length . . . . . . . . . . . .Push Rod Diameter . . . . . . . . . . ,HydraulicTappet Diameter . . . . . .Tappet-to-Bore Clearance . . . . . . .ValvesValve Length(Tip-to-Gauge Dim. Line) . . . . . .Valve Stem Diameter . . . . . . . . . .Stem-to-Guide Clearance . . . . . . . .Intake Valve Head Diameter304 . . . . . . . . . . . . . . . . , ,360..................Intake Valve Face Angle . . . . . . . .2000 IbfPress-FitExhaust Valve Head Diameter304 .................. 1.401 -1.41 1 35.59-35.84360.................. 1.675-1.685 42.55-42.80440Exhaust Valve Face Angle . . . . . . .Valve SpringsFree Length . . . . . . . . . . . . . .Spring TensionValveClosed . .Valve Open . . . . . . . . . . . .Inside Diameter (All1 . . . . . . . . . .0.038-0.076(0.038preferred)0.028 -0.2030.038-0.076(0.038preferred I0.038-0.089(0.038preferred)0.000-0.182.019-2.0454.7754.81384.53-84.6684.56-84.8 192.05-92.1 892.05-92.3323 649-2 3.65523.592-23.61 70.008-0.013(0.013preferred)loose8900 NPress-Fit1.6:17.790-7.810 197.87-198.370.312-0.315 7.938.000.9040-0.9045 22.962-22.9740.001 -0.0025 0.025-0.0644.78954.8045 121.653-122.0340.3715-0.3725 9.436-9.4620.001-0.003 0.03-0.081.782-1.792 45.26-45.522.020-2.030 51.31-51.562901.99 50.5564-72 Ibf 282-317 Nat 1.786 at 45.36202-220 Ibf 889-968 Nat 1.358 at 34.440.9484.968 24.08-24.69602718

442 MOPAR PERFORMANCE PARTS1981. 304-360 AMC V-8 ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1981 Jet:p Service Manual .Torquo SpecificationsSmrvia Set-To Torques should be used when assembling components . Service In-UPr Rwhsdc Torqur hould b. uud for W i n g a' pn-torqud itwn .Air Injection Tube-to-Manifold ................................Air Pump-to-Bracket Pivot Screw ...............................Air Pump Brackets-to-Engine-AC Compressor or Pedestals . ...............Air Pump Adjusting Strap-to-Pump ..............................Alternator Pivot Bolt or Nut .................................Alternator Adjusting Bolt ...................................Alternator Mounting Bracket Bolt-to-Engine ........................Alternator Pivot Mounting Bolt-to-Head . ..........................Block Heater Nut. T-Screw Type ...............................Camshaft Gear Retainer Screw ................................Carburetor Adapter-to-Manifold Screws-2V ........................Carburetor Holddown Nuts ..................................Connecting Rod Bolt Nuts . ..................................Crankshaft Pulley-to-Damper .................................Cylinder Head Capscrews ...................................Cylinder Head Cover Screws ..................................Distributor Clamp Screw ...................................Drive Plate-to-Converter Screw ................................EGR Valve-to-Manifold .....................................Exhaust Manifold ScrewsCenter (2) ..........................................Outer(4) ...........................................Exhaust Pipe-to-Manifold Nuts ................................Fan and Hub Assembly Bolts .................................Flywheel or Drive Plate-to-Crankshaft ............................Front Support Cushion Bracket-to-Block Screw ......................Front Support Cushion.to.Bracket.to.frame .........................Fuel Pump Screws .......................................Idler Pulley Bearing Shaft-to-Bracket Nut ..........................Idler Pulley Bracket-to-Front Cover Nut ...........................Intake Manifold Screws . ....................................Main Bearing Capscrews . ....................................Oil Pump Cover Screws . ....................................Oil Pan Screws1/4inch-20 .........................................5/16 inch . 18 ........................................Oil Relief Valve Cap ......................................Power Steering Pump Adapter Screw .............................Power Steering Pump Bracket Screw .............................Power Steering Pump Mounting Screw ...........................Rear Crossmember-to-Side Sill Nut ..............................Rear Insulator Bracket.to.Trans . ScrewRear Support Insulator-to-Bracket Nut ...........................Rear Support Cushion-to-Crossmember Screw Nut.................................................Rocker Arm Capscrew .....................................Spark Plugs ...........................................Starter Motor to Converter Housing Screws .........................Thermostat Housing Screw ..................................Throttle Valve Rod Adjusting Screw .............................Timing Case Cover-to-Block ..................................Vibration Damper Screw (Lubricated) ............................Water Pump Screws .......................................ServiceSet-ToTorqueUSA (ft-lbdServiceIn-UseRecheckTorque38 30-4520 15-2225 18-2820 15-2228 20-3518 15-2028 23-3033 30-3520 in-lbs 17-25 in-lbs30 25-3514 12-1514 12-1533 30-3523 18-28110 100-12050 in-lbs 42-58 in-lbs20 18-2422 20-2513 9-1825 20-3015 12-1620 15-2518 12-25105 95-11535 254037 304516 13-1933 28-387 4 -943 3747100 90-10555 in-lbs 45-65 in-lbs71128234328303348181928181340 in-lbs259048 in-lbs5-99-1322-3518-28374725-3520-3527-3840-5512-2516-2622-3313-2510-1830-50 in-lbs18-3380-10040-55 in-lbsMetric (Nm)Serviceservice In-Useset-To RecheckTorque Torque5227342738243845241191945311 49618301841 -6120-3024-3820-30274720-27314141472-3344716-2016-20414724-38136-1635-714-2427-3412-2434 274120 16-2427 20-3424 16-34142 129-15647 34-5450 416122 18-2645 38-529 5-1258 50-64136 122.1 426 5-791538315838414565242638241853412257-1212-18304724-3850-643447274737-5254-7516-3422-35304518-3414-243-62445108-1 365-6All Torque values given in foot-pounds and newton-metars with dry fits unless otherwisa specified .Refer to the Standard Torque Specifications and Capscraw Markings Chart in Chapter A of this manual for any torque Specifications not listed above .60272

360 AMC V-8 (ENGINE ASSEMBLY) 443

444 MOPAR PERFORMANCE PARTS1990,360 AMC V-8 ENGINE SPECIFICATIONSNote: The following information has been reprinted from the 1990 Jeep Service Manual.Type. ................................................No. of Cylinders ............................................Bore. .......................................................90" V-BlockB103.63 mm 4.08 in.Stroke .......................................................Displacement .................................................Compression Ratio ............................................Compression Pressure (Minimum) ................................Maximum Variation Between Cylinders. ........................ComshaftFuel Pump Eccentric Diameter.. ...............................Tappet Clearance ...........................................End Play.. .................................................Bearing Clearonce ..........................................Preferred. ................................................Crankshaft Bearing Journal DiometerNo. 1.. .......No. 2.. ................ ...........................No. 3.. ............................ ................No. 4.. ...... ............................No. 5.. ................... .........................Maximum Base Circle Runout.. ..............87.:38 mm5.9 liter8.25:l827-1 034 kPa206 kPa55.423-55.677 mmZero lash (hydraulic tappets)Zero (engine operating)0.0254-0.0762 mm0.01432-0.0508 mm53.835-53.861 mm53.073-53.099 mm52.31 1-52.337 mm51.549-51.575 mm50.787-50.81 3 mm0.0254 mm3.44 in.360 cu. in.120-1 40 psi30 psi2.1 82-2.1 92 in.0.001 -0.003 in.0.001 7-0.002 in.2.1 195-2.1 205 in.2.0895-2.0905 in.2.0595-2.0605 in.2.0295-2.0305 in.1.9995-2.0005 in.0.001 in.Corn Lobe Lift.. ...........................................Intake Valve TimingOpens ...................................................Closes ...................................................Exhaust Valve TimingOpens .....................................................Closes .....................................................Valve Overlap.. ..............................................lntoke Duration ...............................................Exhaust Duration. .............................................6.7564 mm 0.266 in.14.75" BTDC68.75" BTDC56.75" BBDC261.75" ATDC41.5"263.5"263.5"Connecting RodsTotal Weight (Less Bearings). ..........................Total Length (Center-to-Center).... ..................Bearing Clearance ..............................Preferred. ......................... ................Side Clearance ........................ ............Maximum Twist (per in.). ...... ................Maximum Bend (per in.). .................... ..........681 -689 grams149.1 7-1 49.28 mm0.03-0.08 mm0.051 -0.064 mm0.1 5-0.46 mm0.01 3 mm0.03 mm24.0-24.3 02.5,873-5.877 in.0.001 -0.003 in.0.002-0.0025 in.0.006-0.01 8 in.0.0005 in.0.001 in.J8909-4t

7- - 7 1360 AMC V-8 (ENGINE ASSEMBLY) 445CrankshaftEnd Ploy.. .................................................Main Bearing Jaurnol DiometerNos. 1, 2, 3, and 4.. ......................................Rear Main ................................................0.08-0.20 mm69.784-69.822 mm69.759-69.797 mm0.003-0.008 in.2.7474-2.7489 in.2.7464-2.7479 in.Main Bearing Journal WdthNo. 1.. ............... ...............................................................................No. 3.. ............ ..............................No. 4.. ......................No. 5.. ................................32.093-32.250 mm31.650-31.700 mm32.330-32.390 mm31.650-31.700 mm30.860-30.91 0 mm1.2635-1.2695 in.1.2460-1.2480 in.1.2730-1.2750 in.1.2460-1.2480 in.1.21 50-1.21 70 in.Main Bearing ClearanceNos. 1, 2, 3, and 4.. ........................................Preferred. ................................................No. 5 (Rear Main). ..........................................Preferred. ................................................0.03-0.08 mm0.04-0.05 mm0.05-0.1 0 mm0.06-0.08 mm0.001 -0.003 in.0.001 7-0.002 in.0.002-0.004 in.0.0025-0.003 in.Connecting Rod JournalDiometer ...................................................Width. .....................................................53.1 72-53.266 mm50.750-50.900 mm2.0934-2.0955 in.1.998-2.004 in.Connecting Rod BearingClearance. .................................................Preferred. ................................................Maximum Taper (All Journals). ................................Maximum Out-of-Round (All Journals). .........................0.03-0.08 mm0.051 -0.064 mm0.01 3 mm0.01 3 mm0.001 -0.003 in.0.002-0.0025 in.0.0005 in.0.0005 in.Cylinder BlockDeck Height.. .........Deck Clearance (Below Block) ................Maximum Cylinder Taper ................Maximum Cylinder Out-of-Round. ............Taper Bore Diameter ........................................Flatness (per 25 mmhn.). ........... ..............(per 152 mm/6 in.). .............................. ..(Maximum) ........................233.81 -233.96 mm0.368 mm0.1 3 mm0.08 mm22.999-23.025 rnm0.03 mm0.05 mm0.20 mm9.205-9.21 1 in.0.01 45 in.0.005 in.0.003 in.0.9055-0.9065 in.0.001 in.0.002 in.0.008 in.Cylinder HeadCombustion Chamber Volume. ................................Valve Arrangement.. ........................................Valve Guide ID (Integral). ......... ...............Valve Stem-to-Guide Clearance. ..................... ...Intake Valve Seat Angle., .....................................................Valve Seat Wdth ...........................Valve Seat Runout (Maximum) .........................58.62-61.62 ccEl-IE-El-IE9.487-9.51 2 mm0.03-0.08 mm30"44.5"1.02-1 52 mm0.064 mm0.030 mm0.050 mm0.200 mm3.58-3.76 cu. in.0.3735-0.3745 in.0.001 -0.003 in.0.040-0.060 in.0.0025 in.0.001 0 in.0.0020 in.0.0080 in.J8909-49

446 MOPAR PERFORMANCE PARTSLubricotion SystemOil Capacity (with Oil Filter) ..................................Normal Operoting Pressure@ 600 rpm ................................................................Oil Pressure Relief .................................Geor-to-Body Clearance .....................................Preferred. .........................Oil Pump Gear End ClearanceFeeler Gauge Method .......................................Preferred. ................................................Plastigage Method ..........................................Preferred. ................................................Pistons weight). ..............................................Piston Pin Bore CL-to-Piston Top.. ...............................Piston-to-Bore Clearance. ......................................Preferred. ..................................................4.7 liters90 kPa255-51 7 kPa51 7 kPa0.01 3-0.064 mm0.01 3 mm0.1 02-0.203 mm0.203 mm0.051 -0.203 mm0.051 mm601 -605 groms4O.ti2-40.72 mm0.0:10-0.051 mm0.041 mm5.0 quarts13 psi37-75 psi75 psi0.0005-0.0025 in.0.0005 in.0.004-0.008 in.0.008 in.0.002-0.008 in.0.002 in.21.20-21.34 02.1 S99-1.603 in.0.001 2-0.002 in.0.001 6 in.Piston Ring Gap CleoranceNos. 1 and 2.. .............................................Preferred. ................................................Oil Control Steel Rail ..........................................Preferred. ..................................................Piston Ring Side ClearanceNo. 1. .....................................................Preferred. ................................................No. 2.. ....................................................Preferred. ................................................Oil Control.. ...............................................0.2J-0.51 mm0.25-0.305 mm0.38-1.1 4 mm0.2!5-0.51 mm0.038-0.076 mm0.038 mm0.0:38-0.089 mm0.038 mm0.0(~-0.180 mm0.01 0-0.020 in.0.01 0-0.01 2 in.0.01 5-0.045 in.0.01 0-0.020 in.0.001 5-0.0035 in.0.001 5 in.0.0015-0.0035 in.0.001 5 in.O.oo00-0.0070 in.Piston Ring GrooveHeightNos. 1 and 2 .............................................Oil Control.. .............................................DiometerNos. 1 and 2 .............................................Oil Control.. .............................................Piston Pin Diameter.. ..........................................Piston Pin BoreDiameter. ..................................................Clearance. .................................................Preferred (Loose). .........................................Piston Pin-to-Connecting Rod Fit. ................................(Press Fit)2.01 9-2.045 mm4.775-4.81 3 mm92.05-92.1 8 mm92.05-92.33 mm231649-23.655 mm23.592-23.61 7 mm0.008-0.01 3 mm0.01 3 mm8900 N0.0795-0.0805 in.0.1 880-0.1 895 in.3.624-3.629 in.3.624-3.635 in.0.9308-0.931 3 in.0.9288-0.9298 in.0.0003-0.0005 in.0.0005 in.2000 IbfJ8909-50

360 AMC V-8 (ENGINE ASSEMBLY) 447Rocker Arms, Push Rods and TappetsRocker Arm Ratio ...........................................Push Rod Length.. ..........................................Push Rod Diameter.. ........................................Hydraulic Tappet Diameter.. .................................Tappet-to-Bore Clearance ....................................ValvesLength (Tip-to-Gauge Dim. Line). ..............................Stem Diameter.. ............................................Stem-to-Guide Clearance ....................................Intake ValveHead Diameter .............................................Face Angle.. ...............................................Exhaust ValveHead Diameter .................................Face Angle.. .................. ......Valve SpringsFree Length ................................................Spring Tension - Valve Closed. ...............................(@45.36 mmA.786 in.)Spring Tension - Valve Open.. .....................(@34.44 mrnA.356 in.)Inside Diameter (All Springs). .................................1.6:l197.87-1 98.37 mm7.93-8.00 mm22.962-22.974 rnm0.025-0.064 rnm121.653-1 22.034 rnrn9.436-9.462 mm0.03-0.08 mm51.31-51.56 mm29"42.55-42.80 mm44"50.55 mm282-31 7 N889-968 N24.08-24.59 mm7.790-7.81 0 in.0.31 2-0.31 5 in.0.9040-0.9045 in.0.001 -0.0025 in.4.7895-4.8045 in.0.371 5-0.3725 in.0.001 -0.003 in.2.020-2.030 in.1.675-1.685 in1.99 in.64-72 Ibf202-220 Ibf0.948-0.968 in.J8909-51..

448 MOPAR PERFORMANCE PARTS1990, 360 AMC V-8 ENGINE TORQUE SPECIFICATIONSNote: The following information has been reprinted from the 1990 Jeep Service Munuul.ComponentTorqueA/C Compressor Bracket-to-Engine BoltsAlternator Adjusting BoltAlternator Pivot Bolt/NutCamshaft Gear Retaining BoltConnecting Rod Bolt NutsCrankshaft Main Bearing BoltsCylinder Head BoltsCylinder Head Cover Retaining BoltsDrive Plate-to-Converter BoltsExhaust Manifold Bolts - Center (2)Exhaust Manifold Bolts - Outer (4)Exhaust Manifold-to-Downpipe NutsFan and Hub Assembly BoltsFront Support Cushion Retaining NutsFuel Pump BoltsIntake Manifold BoltsOil Pan Bolts - 1/4-20- 5/16-18Oil Pump Cover BoltsRocker Arm Assembly-to-Cylinder HeadSpark PlugsStarting Motor-to-Converter HousingTiming Case Cover-to-Block BoltsVibration Damper Bolt (Lubricated)Vibration Damper Retaining Bolts34 N-m24 N*m38 N-m41 N-m45 Nvn136 N-m149 N-m6 N-m30 N-m34 N-m20 Nm27 N-m24 N-m45 N-m22 N-m58 N-m9 N-m15 N-m6 N-m26 N-m37 N-m24 N-m34 N-m122 Nvn41 N-m(25 ft-lbs)(18 ft-lbs)(28 ft-lbs)(30 ft-lbs)(33 ft-lbs)(100ft-lbs)(110ft-lbs)(55 in-lbs)(22 ft-lbs)(25 ft-lbs)(15 ft-lbs)(20 ft-lbs)(18 ft-lbs)(33 ft-lbs)(16 ft-lbs)(43 ft-lbs)(7 ft-lbs)(1 1 ft-lbs)(55 in-lbs)(19 ft-lbs)(27 ft-lbs)(18 ft-lbs)(25 ft-lbs)(90 ft-lbs)(30 ft-lbs)Jpoo9-91

Chapter 8Off- Roading and Racing

450 MOPAR PERFORMANCE PARTSOff-RoadDriving .................................................................. 45 1TREAD Lightly! ....... ......................... 453JeepJamborees ......................................................................... 45sCamp Jeep .......... ......................... 460Getting Started in Racing ......................................................... 464Contingency ............................................................................ 468Safety and the Performance Advantage ..........Personal Safety ..... ................... 471Body and Chassis Safety .........................................Engine and Drivetrain Safety .............................................................. .474Safety Checklist .............................................. .. .... 476Drag Racing ............................................................................ 477Building Your Performance Vehicle in Stages ................................................. .482Mopar Performance Parts Engine Package Recommendations ..................................... ,482Suspension Upgrades .........................................................Tires ......................................................................Mopar Performance Parts Information and Sources ................................. 487Additional Sources .............................................. .... ....... . .491

OFF-ROAD DRIVINGOff-Roading and RacingWe pride ourselves on the off-road capability of our Jeeps.The explosion of the Sport Utility Vehicle market (and oftrucks in general) has afforded us many opportunities thatdidn’t exist in the past. It has also presented us with manychallenges we have never had to face before. Thesevehicles are no longer strictly “workhorses.”Our biggest challenge is satisfying both the on-road andoff-road needs of our customers without sacrificingperformance in either area. The fact that only 20% of Jeepowners (estimated) actually take their vehicles off-roaddoes not mean that we can abandon them. The off-roadcapability of Jeeps is critical to brand identity, and is whatthe customer is buying. That is why we continue to make allof our Jeep products Rubicon Trail-capable.The Rubicon Trail is considered the benchmark that allproduction Jeeps must negotiate. It is located in the Sierra-Nevada mountains of east central California, southwest ofReno, Nevada. It is a rugged, rocky terrain that most of ourcompetitors cannot negotiate. There is a short Rubicon-liketrail at Chrysler’s Chelsea (Michigan) Proving Grounds.Jeep products are more suitable than trucks to off-roaddriving due in part to their shorter wheelbase, shorter bodyoverhangs, greater ground clearance and suspension travel.OFF-ROADING AND RACING 4510 You may need to lower the tire pressure, depending onthe terrain you are negotiating. This will soften the tiresand expand the footprint for greater flotation, whichresults in more traction when driving over rocks or insand. It will also cushion your ride. In loose sand, youmay want to lower the pressure down to 20 lbs. If youget stuck in sand, snow, or ice, you may want to lowerit even further, down to 10 Ibs. On trails like theRubicon, you will want pressures of 22 to 25 Ibs. Toolittle pressure can result in the tire being pushed off therim, causing it to go flat.Note: Don’t forget to restore your tire pressure tomanufacturer’s recommendations once you return tosurfaced roads. It is critical to the life of your tires!PreparationBefore you go off-road, there is some preparation that youmust do. The following items should be adhered to everytime you plan on going off-road.Oil and other fluid levels must be checked and toppedoff, if necessary. The battery must be inspected,making sure that it is good and is secured.Be careful of sharp rocks or limbs that could puncturea sidewall, and ulwuys carry a full-sized spare tire.Make sure that tow hooks are installed on your vehicleand bring tow straps and/or a vehicle with a winch. Ifit is not possible to install tow hooks, know where youcan attach a strap safely. Be certain that there are atleast two vehicles that can assist each other.Take a cellular phone or CB radio in case ofemergencies. Bring boots and shovels.0 Dress appropriately. Assume all of your clothing willget dirty!General AdviceBe sure to memorize the trail in front of you! Get out ofyour vehicle and look in all directions on the trail ahead.This is critical since you cannot always see what is directlyin front of you (especially when going over the top of ahill). There may be turns you need to make or obstacles youneed to avoid. Visualize the route you will take, where youwant to be, where to make turns, etc.. ..T --ll 1 --

452 MOPAR PERFORMANCE PARTSTk slower thc better. Thc commercials you see of off-roadvehiclcs racing over rocky terrain are not every day reality.More often than not, those vehicles end up in the scrapheap. Let the vehicle idle over more difficult areas, usingthe accelerator pedal only as needed. Conversely, it isimportant to maintain an adequate speed, or you may nothave enough power to make it over an obstacle. Keepmoving once you are committed, but not too fast! You don’twant to be going too fast as you reach the other side. Andremember, if the going gets too tough, don’t be afraid tostop and back up.Drive with your thumbs up and out of the steering wheel. Ifyour tire hits a large rock, it will cause the steering wheel tospin out of your hands. If your thumbs are in the steeringwheel, the spokes can in.jure or even break them.You should always drive with a partner (if possible). Mostimportantly, always wwir your secit belt!Manual Trunsmission ~Low RangeKeep your foot off of the clutch! With the transfer caseshifted into Low range, start the vehicle in gear withoutdepressing the clutch (unless it has clutch interlock),using the throttle a little as needed. Start and stop withyour key. Don’t spin your wheels. Give a little throttleas needed when going uphill or over obstacles.Warning! A vehicle should only be started in gear ifthe transfer case is shifted into the Low range. NEVERstart a vehicle in gear shifted into High range, or thevehicle may get away from you.Automatic TransmissionUse Low range and your lowest driving gear whennavigating very rough terrain. A helpful hint is to use atwo-footed driving method: left foot on the brake andright foot on the throttle. Operate both with a light foot.Speed and power are not necessary. Go slow!Trm.sj?>r CaseIn rugged terrain or in deep mud, sand, or snow, selectLow range 4WD with the 4WD transfer case selector.Off -Road TechniquesNote: Always remember to respect nature and privateproperty. Stay on established trails and obey anyordinances. Tread Lightly!L1. Rocks (Rock Picking)Do not straddle rocks! Know your clearance. Youcannot make it over a twelve inch rock with an eightinch clearance. Put your tire on top of the rock andcrawl over it slowly at 1-3 miles per hour. Use thethrottle only to maintain “crawling” momentum.2. Hills (Break-Over Angle)Never approach a hill on an angle-go straight up.Keep your wheels on the ground, and know what is onthe other side of the hill before you go over the top. Donot try to turn on a hill. Know your vehicle’slimitations and center of gravity. Do not go over thehigh center of a hill or mound of dirt. You may need ajack to get your vehicle off if it is in a position whereit is balanced on its underbody and none of the wheelshave a firm grip on the terrain.When going downhill, use your brakes to keep yourspeed low. If you start to slip or slide, turn in thedirection of the slide, as on snow or ice.When going down a steep hill in a vehicle with a manualtransmission, use your lowest gear. NEVER ride(disengage) your clutch, or it will begin to spin at anextremely high rate (1 5,000 rpm) and disintegrate. Withan automatic transmission, use your lowest drive setting.3. DitchesKnow your approach angle and departure angle.Vehicle size will affect angles of entry and departure.. .. ..T -1-1

OFF-ROADING AND RACING 4534. Traction5.If you lose traction or get stuck, one way of regainingtraction is to turn your steering wheel back and forthrapidly. Often this will transfer power to the wheelswhere it is needed. You can also place your floor matsin front of the tires, or dig out your wheels and placesmall logs or rocks underneath for traction.If you get stuck in sand, you can wet the sand in frontof the wheels to provide a firmer base, and rock backand forth. Lowering the tire pressure to eight or tenpounds can also help.Crossing a Log or a TreeKnow your clearance! If the log is too big, placesmaller logs on either side to create a ramp. Crossing atan angle is often easier than crossing head-on.6. SandIn addition to the tips already discussed, always have aflag on your antenna, or a mast when driving on sanddunes, to make yourself as visible as possible.Remember that sand can vary from firmly packed toloose, affecting the way you drive and the preparationsyou have to make.7. Mud HolesMud holes can be deceiving. They may be a lot deeperthan they appear, and they may have hidden obstacles.Use a stick to check depth and probe for obstacles.Analyze carefully before entering. If there are no tiretracks exiting out the other side, think carefully beforegoing into the hole.Keep moving even if you are only crawling. Turningthe wheels rapidly back and forth can often give thema new grip. If you get stuck and can’t go forward, trybacking up and going forward again. If you still can’tget across, back up and out and try to find a routearound the mud hole.If you get stuck, don’t spin your tires, they will just digyou deeper. Dig out under the wheels and place smallrocks or logs underneath for traction.8. RutsIf you are in deep ruts in mud or snow and can’t getout, dig two small trenches at a 45 degree angle andplace the materials removed into the ruts. If you driveahead slowly, the vehicle should drive out of the ruts.If you must enter a large rut, drive slowly and straddlewhere possible. If the rut gets too wide, ease into therut while keeping the vehicle level and ride on the tireedge, or even the sidewall. Remember to keep centeredin the rut and keep the vehicle as level as possible.9. DustWhen driving through a dusty area, close yourwindows and turn on the air conditioner or fan, makingsure the vent is closed. This will pressurize the cab andkeep the dust out. In an open Jeep, lower thewindshield. Dust will circulate behind the windshield,but with the windshield down, it will blow by.Additional InformationFor more information on off-roading techniques, refer to MarkA. Smith’s Guide to Saje, Common Sense Ojf-Road Driving.TREAD LIGHTLY!Tread Lightly! originated in 1985 when a task force wascreated by the U.S. Forest Service to look into the increaseof visitors to public lands for recreational purposes. Thegroup concluded that a long-term informative program wasneeded to increase public awareness and that special care ofthe land must be exercised by recreationists if opportunitieswere to continue. Accordingly, the Tread Lightly! programwas developed. It’s based on the same premise as theSmokey Bear and Woodsy Owl programs, where SmokeyBear and Woodsy Owl focus on fire and litter, respectively.Tread Lightly! emphasizes low-impact principles,applicable to all forms of recreational activities.Soon after the development of Tread Lightly! by the ForestService, the Bureau of Land Management adopted theprogram. Corporate America joined forces with the federalgovernment’s efforts by promoting Tread Lightly! like theyhad championed the “Don’t Drink and Drive” and “BuckleUp” safety programs.Given the popularity of the program, the federalgovernment determined, in order to optimize the program’soperational and promotional potential, it was logical totransfer the management of Tread Lightly! from thegovernment to the private sector. In October 1990,approximately SO companies and organizations founded thenonprofit organization, Tread Lightly!, Inc.

454 MOPAR PERFORMANCE PARTSJeep is a founding member of Tread Lightly!, Inc., and wasthe first brand of 4x4 to win a Tread Lightly! award for itsadherence to the Tread Lightly! mission in its marketingcommunications. Our message is simple: Use commonsense and stay off unmarked trails.MissionTread Lightly! is dedicated to increasing awareness on howto properly enjoy public and private lands. Tread Lightly!emphasizes responsible use of sport-utility vehicles (SUVs)and low-impact principles that apply to all outdoorrecreational activities. Tread Lightly! unites federal andstate land management agencies with manufacturers,publishers, environmental and user groups, and individualswho share a basic commitment to care for our valuablenatural resources. We achieve our goals in three ways:developing and distributing educational materials toteachers, youngsters, and outdoor recreationists;coordinating media coverage that helps get the TreadLightly! message out to the public; and working with bothindustry and public service agencies to help promoteadvertising that demonstrates responsible use of SUVs andother forms of backcountry travel. But Tread Lightly! canonly accomplish this with your help!The main points of the Tread Lightly! program can beeasily summarized and remembered.T Travel only where motorized vehicles are permitted.Never blaze your own trail.READRespect the rights of hikers, skiers, campers, andothers to enjoy their activities undisturbed.Educate yourself by obtaining travel maps andregulations from public agencies, complying withsigns and barriers, and asking owner’s permission tocross private property.Avoid streams, meadows, wildlife, etc. Stay off soft,wet roads. Stay out of wilderness areas. Cross streamsonly at designated crossings.Drive responsibly to protect the environment andpreserve opportunities to enjoy your vehicle in ourwild lands.Off-Highway Vehicle (OHV) Trip PreparationConsider the following as you prepare for an enjoyable,safie trip:1.2.3.4.5.6.7.8.Prepare your provisions checklist: food, first aid,water, fuel, etc.Plan well in advance. 30 days prior to a trip is not too early.Where are you going? Get a travel map and determinewhich areas are open for OHV use. Check to see ifthere are any special rules or regulations for OHV use.Find a destination point and mark it on the map.Determine how you will get there.How will the weather affect your destination during theseason you travel’? If roads are often wet and muddy or stillsnow covered, should you consider another area to visit?How difficult are the roads and trails in the area you havechosen? What are the skill levels of each of your drivers?Are wildlife species in the area especially sensitive toOHVs? How can you avoid disturbing them‘? Shouldyou choose another area?Know state laws for operating an OHV. Do you needany special equipment or a license for the driver orvehicle? Do you need to be safety certified?Keep your vehicle well maintained and tuned. Excessiveemissions, leaking fuel, and dripping oil are expensiveproblems. They also pollute the environment.Things to Remember1.2.3.4.5.6.Do not chase or intentionally disturb wildlife.Don’t gun the engine-save money, fuel, and your vehicle.Be courteous to others! Remember many people are notfond of OHVs. Don’t be a nuisance by creating excessivenoise and dust. (Wildlife doesn’t enjoy it either.)Many other people may also enjoy your special place.Don’t ruin their experience. STAY ON THE ROADSAND TRAILS.Visual scarring can destroy scenery and habitat whilestarting an erosion problem. Don’t shortcutswitchbacks or create unnecessary trails.Pack it in. Pack it out. Don’t leave any litter, includinghuman waste.7. Respect private property and closed areas. Don’t makea new trail to get around locked gates.8.9.Be courteous on the trail. Yield to horses, slow downfor hikers, maintain a cheerful attitude.Today’s degraded trail or road is tomorrow’s “closed” area. IStay off wet roads and trails, wetlands, and meadows.

OFF-ROADING AND RACING 45510. Wilderness arear are closed to all types of motorizedand mechani~ed equipment.1 1. Don’t run over young tree\ and shrubs.12. Be prepared for vehicle breakdowns. Travel withsomeone, pack emergency kits, let others know yourtravel routes in and out of all areas. Stick with your plan.13. Be safe, protect the environment, and have fun theTread Lightly! way.Reading Travel MapsTravel maps are available from land managers to explainwhich roads, areas and trails are open, closed or restrictedseasonally or year-round. The following is a brief overviewof the designations and the reasons for them.Open most ofthe timeMain roads, unless wet and soft. Most of the damagedone on backcountry roads and trails occur during thewet fall and spring seasons.Unused logging uad other high-clearance roads when dryThese roads, when designated open, offer challengessought by off-highway vehicles (OHVs).Trails outside wildernessSome are open only to foot or horse traffic. Others areopen to OHVs.Closed part-timeWildlife rearing areas. Specific areas may be closed inspring when disturbances can drive animals fromimportant h a b’ itat.Wet, soft trails or roadsSometimes fall snowstorms and spring thaws will bethe reason to close some routes to vehicles to preventdamage and costly repair. When roads and trails dry,they will be reopened.Wildlife winter habitatLate in the season, food is scarce. OHVs may disturbweakened animals, forcing them to use limited energy toescape the intruders. To protect a healthy herd of game,stay away from wildlife winter habitats. Winter habitatsare usually found in foothills and lowlands below snowlevel where game seek easier travel and food.Resource roadsLogging, mining and oil drilling roads are often closedto the public where collisions could occur with heavytrucks. Some primitive roads, requiring high-clearancevehicles, may be open to OHVs. Refer to your travelmap and current road status.Closed year-roundWilderness. Law forbids motorized or mechanizedvehicles from entering wilderness. Foot or horsebacktravel affords a frontier experience.Meadows, newj,forest, steep hillsides, stream banks andlakeshoresSensitive land areas may be closed to protect delicate,fragile meadow plants and young trees, grasses andshrubs and to prevent soil erosion, scars and waterpollution. These areas may be opened when snow isdeep enough to allow for oversnow use.Roads and trails no longer openjor useAn area may be closed to the public to preventdisturbance and help endangered or threatened species.Vehicles may disturb these unique creatures and hindertheir survival.JEEP JAMBOREESPerformance vehicles are great-as long as you keep themon the streets, highways, or otherwise paved areas. Butevery once in a while, it’s nice to have a change. To trysomething new. Not any less exciting, but different. Everysummer, Jeep Jamborees offer a great chance to do just that.Away from the fast and furious action at the strip or cruisingthe town, Jeep Jamborees offer a different kind ofexcitement. Instead of the heat and hassle of summer in thecity, YOU can snake your way up the side of a ruggedmountain, through narrow passes and along sheer offs. Oryou can tackle the most challenging off-road courses forboth driver and vehicle around. All with the expertise ofsome of the nation’s best off-roaders...

456 MOPAR PERFORMANCE PARTSSince 1953, when Mark Smith began the first Jeep Jamboreethrough the legendary Rubicon trail in California, theJamborees have been gaining in popularity. And number.Jamborees are now scattered all across the U.S. from coastto coast. Weekend excursions offer Jeep owners a chance tocheck out the capabilities of their vehicles, polish up theiroff-roading skills, and enjoy the wildlife. Basic off-roaddriving tips are offered for both first-timers and experiencedoff-road drivers. Jeep Jamborees are great because they offerpeople a chance to enjoy the outdoors and learn a little abouttheir vehicles without having to stick to a rigid schedule.You can pretty much go at your own pace.Each trail is different. Some of them are fairlystraightforward, more for a relaxing vacation than for hairraisingexperiences. Others are extremely difficult andsome can even be dangerous. In order to help you pick theright trail for you, they are rated by difficulty. A trail with adifficulty level of 10 would be a real test of skill, whereas atrail rated 1 would be purely for fun.But Jeep Jamborees are not just driving fun. Meals, permits,evening activities and accommodations are also provided.Some people enjoy the outdoors so much they bring theircamping gear along instead. For a great view of America atits finest, Jcep Jamborees are definitely the ticket. You caneven learn a little history along the way.All Jeep Jamborees participate in the Tread Lightly!program, which is sponsored by the Jeep and the U.S.Forestry Service and Bureau of Land Management. JeepJamboree tour guides are committed to preserving ournation’s wildlife for future enjoyment and responsibleoff-roading.A Typical Jeep Jamboree WeekendJeep Jamborees are family-oriented, four-wheel-driveadventures that feature the best trails and scenic beauty inAmerica. Jamborees are designed for all skill levels and arenot competitive events.For two full days (Friday and Saturday), you, your familyand your Jeep will venture into America’s backcountry - toplaces you would never see from the highway. To get there,you’ll follow unpaved trails and learn how to properly useyour Jeep in challenging off-highway situations. And best ofall, you’ll make lots of new friends who will help you alongthe way. The following is a sample itinerary.Note: Actual itineraries vary from trip to trip. Moreconiprehensive information will be sent to you uponregistration.Thursday Evening Registration (5-8 p.m.)Upon arrival at the Jamboree’s headquarters, attendeeshave the opportunity to register at the Jamboree desk,select trails, and informally meet with other attendees.Friday Morning Breakfast (6:30-8 a.m.)A country breakfast will be served for all Jamboreeparticipants. It’s just one more chance to get acquaintedwith fellow adventurers before hitting the trail.Drivers ’ Meeting (8:30 a.m. )A brief orientation meeting for all Jamboree driverscovers the various dos and don’ts of four-wheeling, JeepJamboree guidelines, and details of the day’s activities.Depart for Trails (9 a.m.)After getting final instructions, all drivers assembletheir vehicles for an orderly departure into thebackcountry. It’s time to hit the off-highway trails.Friday Noon Lunch Along the TrailA few hours into the wilderness and it’s time toregroup for lunch. The site chosen is usually one witha spectacular vista or breathtaking views ofsurrounding countryside.Friday Afternoon Trail Ride ContinuesParticipants press on throughout the afternoon, pushingfarther into the wilderness, crossing streams, traversingboulders, conquering grades - all under the watchfuleyes of veteran Jamboree guides.Friday Evening Dinner (6-7:30 p.m.)As the afternoon draws to a close, all vehicles will returnto a predetermined site where dinner will be served andparticipants will be able to discuss the day’s adventures.Saturday Mornings Breakfast (6:30-8 a.m.)The day starts with breakfast. Conversation aboutyesterday’s events continues while participants beginto speculate about the day’s adventures..“T -1‘1

OFF-ROADING AND RACING 457Sunday Morning Breakfast (7-9 a.m.)Participants enjoy a relaxed continental breakfast. Afterfinal farewells, all participants have the rest of the day totake in local sights and activities before heading for home.Frequently Asked Questions1. Who can I bring? How do I make u reservation?You can bring whomever you want-even the entirefamily, but you can only have as many people as thereare functional seat belts in the vehicle (for example,Wrangler maximum is 4 [with rear seat], Cherokee andGrand Cherokee maximum is 5). Bringing pets,however, is strongly discouraged. If, for some reason,your pet must attend, be sure to contact the JeepJamboree USA office for specific requirements.It’s best to register early since most Jamborees have a100 vehicle limit. The official host is Jeep JamboreeUSA, a division of Mark A. Smith Off-Roading, Inc.To make reservations, contact:Drivers’ Meeting (8:30 a.m.)Jamboree officials confer with all drivers to reviewyesterday’s happenings and to present a brief previewof the day’s itinerary. Four-wheeling tips andguidelines are reviewed once more.Depart for Trails (9 a.m.)It’s time to once again hit the trail.Saturday Noon Lunch Along the TrailsAs on Friday, the Jamboree entourage stops for a welldeservedlunch break in the midst of nature’s splendor.Saturday Afternoon Trail Ride ContinuesOne last drive through the backcountry, one last chanceto appreciate both the area’s natural beauty and eachJeep vehicle’s remarkable off-highway capabilities,and it’s time to return to “civilization.”Saturday Evening Dinner, Prize Drawing (6-7:30 p.m.)In the evening, everyone gathers for dinner. It’s timefor recounting the weekend’s adventures. A specialdrawing is held after dinner with several Jeep relateditems given away to attendees.2.Jeep Jamboree USAP.O. Box 16012776 Sourdough FlatGeorgetown, California 9.56341-530-333-4777If you have a credit card, you can send yourregistration by fax 1-530-333-2844 or via the Internetat http://JeepJamboreeUSA.com.Upon receipt of your completed registration form,drivers will receive a confirmation packet, a scheduleof events and meeting times and places,accommodations, and any other necessary information.Office hours are between 9 a.m. and 5 p.m. (PacificStandard Time), Monday-Friday.How much does it cost?Individual trip fees vary. Please refer to the JeepJamboree website for registration fees. There is nocharge for children under 3. VISA, Mastercard,personal checks, and money orders are welcome.Credit cards accepted by phone, mail, fax, or on-line.Please be aware that phone and on-line registrations needto be backed up by a mailed or faxed copy of theregistratiodwaiver form. All fees must be pdid in advance.Refund checks will be made payable to the driver only.There will be a $35 charge for returned checks... T - 7 - 7

458 MOPAR PERFORMANCE PARTS3. What does the,fee cover?Included in your fee are: experienced guides for theentire trip; all necessary permits; three meals on Friday,three on Saturday, and a continental breakfast onSunday; and access to some of the finest trails inAmerica, several of which are only available throughJeep Jamborees. A Jeep Jamboree event tee-shirt willalso be included in the registration fee. Each Jamboreealso features a giveaway, where you’ll have a chance towin some great prizes.Note: Meals vary. Unfortunately, no accommodationscan be made for special diets.)4. Where do we sleep?5.6.Although lodging is not covered in your fee, you willbe sent a list of motels and campgrounds in the generalarea of the Jamboree you select. This list will be mailedto you as soon as we receive your registration form.Please remember that rates may be subject to tax andmay change without notice. Be sure to mention thatyou are attending a Jeep Jamboree when you makeyour reservation.Will I be the only rookie?No. There will be both first-timers and veterans whomight be on their 5th or 10th Jamboree. No matter whatyour experience level, you’ll find plenty of peoplehappy to help you along.Can I bring my Grand Cherokee?Of course you can! All Jeep vehicles are tested ondemanding 4x4 trails before earning the Jeep name, soevery Wrangler, Cherokee, and Grand Cherokee isready to tackle any Jamboree (However, Cherokeesand Grand Cherokees are not recommended for theRubicon Trail Jeep Jamboree.) All we require is thatyour vehicle be a four-wheel-drive Jeep vehicle and ingood condition, with good tires, seat belts, and brakes.7.8.9.We do, however, require prior approval for larger Jeepmodels, such as older Grand Wagoneers and J-SeriesPickups. Jeep Jamboree USA reserves the right torefuse participation to any applicant whose vehicleexceeds size restrictions.Could my vehicle be damaged?Every effort is made by Jeep Jamboree USA to makethe trails as safe as possible and to provide the propertraining for four-wheeling off-highway. Participantsare advised to closely follow the instructions given bytrail guides, spotters, and Jeep Jamboree USA.However, there is the possibility of damage to yourvehicle when traveling over rough terrain. Any damageis the owner’s responsibility.Is there more than one trail at a given destination?This varies by destination, but there is usually morethan one trail. Most Jamborees feature multiple trails.What do the Jeep Jamboree Trail Numbers mean?Every Jamboree trail is rated from 1 (the easiest) to 10(the most difficult). These ratings are based on the trailoverall, not just on one or two tough spots. Rain canincrease ratings by one or two points. Also rememberthat these numerical ratings may vary from Jamboreeto Jamboree due to terrain, weather conditions, andother factors. Please remember, all vehicles are subjectto inspection prior to trail departure. Trails rated 1 to 2are quite mild and may not even require the use offour-wheel-drive (4WD), 3 to 4 are moderate trails inwhich 4WD is required, 5 to 6 mean that you couldencounter mud holes, climb over rocks, and generallyexperience more difficult four-wheeling conditions.Trails rated 7 to 9 present the possibility of gettingstuck. Mud holes here will be deep and extreme, andthe rock climbing will be arduous. 10 is reserved foronly one trail - the Rubicon. Past participants knowthat this rating is justly deserved. You’ll do things onthis trail that you never thought possible in your Jeep.The Rubicon is not recommended for Cherokee orGrand Cherokee models.Regardless of the rating and the experience level,you’ll get plenty of help to meet the challenge ofparticipating in a Jeep Jamboree. First, when youregister, you’ll receive a copy of Mark Smith’s Guideto Safe, Common Sense Off-Road Driving. Thiscomprehensive booklet, filled with off-highwaydriving tips, will arrive in the mail with your tripinformation. When you reach your Jamboreedestination, you’ll get on-site instruction beforehand,detailing how best to handle the terrain and localconditions you’ll encounter on the trail. Although trailswith higher ratings are obviously more difficult, youwill get help and expert advice from your guides allalong the way.

OFF-ROADING AND RACING 45910. Can my,friend who owns a Ford or Chevy purticipate?Only if he rides in your Jeep vehicle. Jeep Jamboreesare strictly for Jeep vehicles. There are no exceptions.1 1. Does my Jeep need special equipment to take part.?Although four-wheel-drive Jeep vehicles come fromthe factory ready for strenuous off-highway driving,the following equipment is STRONGLYRECOMMENDED for Jamboree vehicles:Front and rear tow-hooks should be properlymounted with high-test bolts. Draw bars orreceiver hitches are acceptable as an alternative torear tow-hooks. On some trails, tow-hooks aremandatory. If you do not have tow-hooks, you willbe limited in trail selections. Please see individualtrip descriptions for details.A full-size spare tire. In case of puncture, a spacesaver(or “donut”) spare just doesn’t cut it on thetrail.Skid plates covering the gas tank and transfer case.Rock rails for Jeep Cherokee and Grand Cherokeevehicles. (Please contact the Jamboree office foradditional information.)Heavy-duty, 20 foot long nylon tow straps (20,000pound minimum) with looped ends (no hooks).No body lifts or suspension lifts over three inchescombined are allowed. Running boards andsnowplow frames are also not allowed.14. What should I bring with me besides my Jeep?Here’s what we recommend you pack for yourJamboree adventure:A CB radio. Although not required, it’s highlyrecommended as a great way to communicate withnewfound friends on the trail.An ice chest filled with your favorite NON-ALCOHOLIC beverage. A frozen jug or two oficed tea or lemonade makes a great refresher, butalcohol and off-highway driving don’t mix.NO ALCOHOLIC BEVERAGES AREALLOWED ON ANY TRAIL RIDE forconsumption by Jeep Jamboree participants.Violation of this rule will result in the removal ofvehicle and occupants from the Jamboree. Theirmoney will not be refunded, and they will bebanned from future Jamborees.SnacksA tent, if camping outdoors.Warm clothes. It may be warm when you arrive,but temperatures can plummet overnight.Insect repellent. Sometimes the mosquitoes are astough as the trails.A camera and lots of film or videotape so that youcan capture the great time you had for family andfriends.One or two flashlights and fresh batteries.15. Where can I get more information?Jeep Jamboree USA1-530-333-477712. Can I add pussengers ut the lust minute .?Passengers may be added until three weeks prior to thetrip date. Be sure to have any new passengers sign thewaiver and note “adding passengers only” on theregistration form.13. What if the weather ,fi)recust calls for .snow or heavyrain? Should I still conie .?Absolutely! We’re talking about Jeep vehicles here.And, like the postman, neither rain, nor sleet, nor snowwill halt a Jeep Jamboree.Monday-Friday, 9 a.m.-5 p.m. PSTPO Box 16012776 Sourdough FlatGeorgetown, CA 95634E-mail: jeepjam@jeepjam.comWeb site (including on-line registration):http://JeepJamboreeUSA.comFor a copy of the 1998 Jeep Jamboree USAGuidebook, please call 1 -800-925-JEEP.Note: Due to unforeseen circumstances, trips andevents are subject to change and possible cancellation...

460 MOPAR PERFORMANCE PARTSCAMP JEEPJeep owners, like Mopar fans, are a breed unto themselves.They love the outdoors and demand optimum performancefrom their vehicles under the variety of circumstances theymay encounter while traversing the uncharted territories ofthe off-road experience. At the fifth annual Camp Jeep athistoric Oak Ridge Estate in Virginia’s Blue RidgeMountains (Aug. 6-7, 1999), over 7,500 Jeep aficionadosconverged on the spectacular 4,800 acre site for a weekendof education, entertainment and environmental awareness.The itinerary included outdoor adventures as well aslearning to respect and protect the environment. Jeepowners could choose family-friendly activities such asoutdoor concerts, fly fishing and Frisbee golf, or test theircourage with white-water rafting and all-terrain mountainboarding. And of course, what would Camp Jeep bewithout driving and discussing the famous four-wheelers,checking out the Mopar Performance parts available tomaximize the off-road experience, and looking over thenewest ways to dress the icon of off-road jaunts? Plenty ofMopar staffers were on hand to give and receive input abouthow to create the ultimate Jeep to fit every individual’sstyle.On top of the valuable training and exciting“extracurricular” activities, Jeep owners were able toreceive information on the latest Jeep product engineeringand accessories. Owners also had the opportunity to learnmore about their vehicles’ potential through Jeep 101training courses. Jeep 101 was designed to teach Jeepowners the basics of off-road driving and the four-wheeldrivecapabilities of their vehicles. Training began withowners working with experienced guides on trainingcourses, and allowed drivers to “graduate” to solo runs onsurrounding trails which were rated according to difficulty.There was also an opportunity for the youngest of the Jeepcontingent to get involved, with a mini-Jeep 101 trainingcourse designed exclusively for kids.Campers were educated on maintaining the natural beautyof the roads and trails they travel through Tread Lightly!, anon-profit organization funded by major outdoor recreationcompanies and vehicle manufacturers, including Jeep, thatpromotes off-road ethics and responsibility.Camp Jeep participants were also able to visit the on-siteJeep Store, an awesome collection of displays where onecould get fully decked out with all kinds of Jeep accessoriesand sportswear. The large tent housed the latest and greatestin Jeep parts and clothing, and everything could be orderedor purchased on the spot. The Mopar presence wasappreciated by the thousands in attendance who were ableto dress up their Jeeps, and themselves, with the manyaccessory and sportswear products offered.Judging from the record numbers who gathered to educateand entertain themselves at Camp Jeep 1999, it seems manyJeep owners would be quick to second that emotion.Events and ActivitiesThe following information highlights activities that tookplace at the 1999 Camp Jeep event in Virginia. Forinformation on future Camp Jeep events (and theiritineraries), refer to the Camp Jeep website(h ttp://www.jeepunpaved.com/campjeep/frameset_campjeep.html), or call the Camp Jeep hotline at 1 -800-798-JEEP.. ..T -IT7

.. .OFF-ROADING AND RACING 4611. Off-Road Activitiesa. Jeep 101 Driving CoursesParticipants learned off-road driving basics on oneof two safe courses. Courses featured a series ofchallenging off-road obstacles, and were ideal forboth new and veteran Jeep owners to hone theirskills before heading out on the trails. We providedthe vehicles; participants selected the one theywanted to drive. An experienced guideaccompanied each driver and provided driving tips.b. 4x4 Trail RidesParticipants tested the capabilities of their Jeepvehicle and explored some stunning terrain alongthe way, traveling in a group led by guides whowere familiar with the trail. Participants couldselect a half-day ride (about four hours) or a fulldayride (about six hours).c. Winching DemonstrationsThese 15 minute demonstrations taught participantshow to use a winch properly. Winch manufacturerswere present to provide demonstrations.d. Jeer, Agility ChallengeThe Jeep Agility Challenge included the followingthree driving exercises:- Wrangler balance platform: Participantsdrove a Wrangler onto a special platform totry and balance it. This was a timed activity.--Cherokee reverse steering course: A pyloncourse was setup to reverse steer a Cherokeethrough. This was a timed activity and timewas added for every pylon hit and every timethe driver had to back up.Grand Cherokee blind backup: All windowswere darkened with the exception of thewindshield and driver and passenger sidewindows. Participants had to back up througha pylon course using only the mirrors andparallel park at the end. This was a timedactivity and time was added for every pylon hitand every time the driver had to drive forward.2. Exhibitsa. Vehicle DisplaysCamp Jeep offered participants the opportunity tocheck out legendary Jeep vehicles from WorldWar I1 to the present along with Jeep memorabilia,samples of advertising, licensed productinformation, and a documentary on Jeep vehicles.Also present were concept vehicles that willcontinue to make the Jeep brand a leader in fourwheel-drivetechnology.b. Tech Center and ArenaMany of the Components that make Jeep vehiclesunique from their competitors were on displayalong with experts to help answer questions anddemonstrate how components work. Participantshad plenty of time to wander through the exhibitsand plenty of opportunities to talk with productexperts, handle parts, and ask questions.Participants also saw Jeep vehicles performagainst their competitors in challenging off-roadsituations and experienced why Jeep continues tobe the leader in four-wheel-drive technology.c. Engineering RoundtablesThis was an opportunity to talk with Jeepengineers about how you use your vehicle in thesevery popular and friendly 1-1/2 hour roundtables.Separate sessions were conducted for JeepWrangler, Cherokee, and Grand Cherokee owners.

462 MOPAR PERFORMANCE PARTSd. Engineering Technologv TentParticipants visited automotive supplier exhibitsand examined the components that go into Jeepvehicles. They also sat in on “Tech Talks” givenby Jeep engineers who discussed specific vehiclesystems (for example, braking, powertrain,suspension) and addressed specific questions.e. Jeep StoresThere were two stores on-site: one for Moparproducts and accessories for Jeep vehicles and onefor selling officially licensed Jeep products. BothJeep and Camp Jeep wearables and products wereavailable at both stores.3. Trail Activitiesa. Guided HikesParticipants explored area trails on their own orjoined others on a guided hike. A variety of themehikes was offered, including:- Backpacking HikeA moderate hike designed to teach theprinciples of backpacking.- Wilderness Survival Skills HikeA hike designed to demonstrate the followingsurvival skills: fire starting, emergencyshelter, food and hydration management.b. Mountain Biking and BMXParticipants were given the opportunity to join agroup or set out on their own. All sizes of Jeepmountain bikes were available, or folks couldbring their own.Also available was a BMX track. Bikes, helmetsand equipment were provided.c. Nature Explorations and PresentationsParticipants learned about the natural history ofthe region and got some exercise at the same time.- How the Blue Ridge Mountains were formedand how it came to be what we see today on aridgeline hike with spectacular views.---Walk deep into the local mountain wildernessand learn about the evolution of our forestsand the importance of good stewardshipLearn about the region’s native inhabitantsand discover how to locate an Indiancampsite.Attend nature workshops. Camp Jeep 1999included workshops on Woodland Mammals:Their Habits and Habitats; Epicurean Delight:Mushroom Cooking; and, Wildflowers of theVirginia Blue Ridge.Global Positioning System (GPS) LandNavigation Learning Center and HikesParticipants got hands-on training on the latestnavigational equipment, then took it to the trailsand participated in moderate hikes designed toprovide field training on the principles of landnavigation and the use of GPS.National Geographic Photo TalksA National Geographic photographer conductedseminars on endangered species and “how to takegood photographs.” The seminar overviewedsome of the different species and looked at thefuture of endangered species preservation.Outdoor Survival ClinicThis was a class for adults on the essential skillsneeded for outdoor adventures. Participantslearned one of the oldest friction techniques tostart a fire and the edible, constructive, medicinaluses of various plant families.Former Green Beret and educator Mitch Utterbackconducted classes that entire families participatedin. They learned to plan and pack for a trip in theoutdoors; experienced outdoor gear from theStone Age to the Space Age, and were taught howto think rationally and act as a team in an outdoorcrisis. Utterback also conducted presentations onadventure racing such as the Eco-Challenge.

OFF-ROADING AND RACING 4634. Water Activitiesa. Flv-Castinpb.Proper casting techniques were taught byinstructors from Sage@- a leading fly-fishingmanufacturer. Fly tying instructions were alsoprovided by premier fly-fishing magazinesAmerican Angler and Fly Tyer.Tubine Down the James RiverParticipants floated leisurely down the beautifulJames River on inner tubes that we supplied. Timeon the river lasted from 2-4 hours. Transportationwas provided to and from the river.c. Kavaking.Participants headed to a nearby lake and learn thebasics of this growing sport. All equipment wasprovided.d. Climbing Tower and ZiplineParticipants reached for the sky while ascending a50-foot climbing tower (age limit was 10 years oldand up).6. Children’s Activitiesa. Mini Jeep 101 CourseYoungsters drove in their own mini Jeep vehicles!5. Additional Family Activitiesa. ArcheryParticipants received a thorough introduction tothis challenging sport from Hoyt USA, a leadingarchery manufacturer. Proper archery techniqueswere learned and practiced at a target range. Allequipment was provided, and qualified instructorswere available.b.Participants learned the techniques of this fastgrowingsport in a safe, controlled environment.Two rock-climbing walls were available, and allequipment was provided.c. Golf Driving RanFeOur golf driving range provided an excellent placeto practice before playing one of the world-classcourses at Wintergreen Resort. Nets were set upon-site so participants could work on their swing.b. Jeep FactoryYoung builders used pre-cut wooden pieces tobuild play Jeep vehicles “just like mom anddad’s.’’ Following simple instructions, theyassemble their vehicle, added wheels that reallyturned, headlights, a bumper, and more. Then theytook their Jeeps to the Customizing Center to paintand add details that made each Jeep one of a kind.Afterward, they test drove their Jeeps by racingthem down a ramp at “full speed.”c. Fresh Produce 500Teams/families competed to build the fastest, mostedible Jeep this side of the Mississippi! Jeeps weremade of fruits and vegetables and competed in arace on Sunday.d. Computer Workshops

464 MOPAR PERFORMANCE PARTSe.f.%.h.1.j.k.1.m.n.0.Crafts- Children made Jeep hats, friendship beads,bearclaw necklaces and foam puzzle pictureframes-Tattoo Time and Nametag Button Make ’nTake- Face Painting- Paint a Shirt- Puppet Making- Zome SystemsMathematically elegant ball and stick designtoy.Obstacle CourseMarvelous Marble GamesRemote Control JeepsBirds of Prey PresentationChildren observed a hawk and an owl at closerange.Juggling WorkshopsCats Cradle WorkshopWatercolors WorkshopYO-YO WorkshopMusic and Movement Workshor,Children played instruments and danced in thisfun workshop.Tom ChapinPopular children’s entertainer Tom Chapin &Friends was present and gave two very specialperformances.7. Activities.for Teensa. Big Cats PresentationThis program focused on preservation andconservation and included a cougar, bobcat andCanadian lynx. The bobcat actually painted andthe paintings were on display at Camp Jeep.b. Health and Fitness Ex~oInteractive games and activities like a Velcro Wall,baseball fast pitch, and Bungee run.C. Soccer ClinicTeens got a kick out of this soccer clinic taught byU.S. Olympic Gold Medallist Julie Foudy.d. Paint BallParticipants took aim at stationary targets as theymoved through various stations. Markers and paintballs were provided.e. Explored rustic trails on Jeep Mountain Bikes.f. Discovered historic Oak Ridge Estate on foot.g. Raced through an obstacle course.8. Activities jor Adultsa. Sunset Magazine Craft CenterSunset Muguzine offered hands-on craft projectsthroughout the event. Participants made a uniquekeepsake of their visit to Camp Jeepb. Southern LivingParticipants were able to whet their appetites andlearn to make delicious southern dishes.c. Civil War CampParticipants witnessed an authentic Civil Warcamp at the Virginia Village, which includedperiod artisans and craftspeople.GETTING STARTED IN RACINGRacing is not all engineering and cold, hard facts. There aremany aspects of racing that are not quite so cut-and-dry.There isn’t just one answer or approach to follow, onlysuggestions for the racer to consider. In this section we’llcover various aspects of racing and provide suggestionswhich should help the amateur racer be more successful.Eacing today is at an all-time economic high, and it doesn’tlook like that will be changing anytime soon. Sponsorstloday are spending more money on racing than ever beforeand come from every type of business imaginable. Soapcompanies! Cereal companies! Television networks!Twenty-five to thirty years ago, the only sponsors other thanauto companies and parts suppliers were successful businesspeople who used their own money to sponsor themselves.But today, with the record number of sponsors available, notonly the rich can get sponsors, but just about anyone.

OFF-ROADING AND RACING 465As far as where to spend your money, think of it in terms ofpe$orrnance per dollars spent. That means putting the bestparts together for the least amount of money to go thefastest. These days, this approach seems a little datedbecause many racers have a lot of money and are willing tospend “whatever it takes” to go fast. The days of doingeverything yourself are disappearing in this age of “puredrivers”; that is, drivers that do nothing with (and possiblyknow nothing about) their engines or chassis. Drivers thatdon’t get their hands dirty. “Pure drivers” don’t talk abouttorque or horsepower, they talk about shift points, theperfect line through a turn, where to brake, where to go flatout,etc. So the first decision you must make is, do you wantto race cars or be a race car builder? Driver or crew chief?Or both?Recognize Your LimitationsThe typical racer doesn’t have a complete understanding ofautomotive engineering; that is, engine, transmission,chassis, suspension, etc. He or she will usually haveexpertise in only one or two specific areas, such as engineand/or drivetrain (or possibly suspension). However, mostracers can’t construct a decent, safe, and reliable tube framechassis or roll cage. For example, a chassis builder is anexpert in front end geometry, something that most racershave never heard of. And chassis builders talk to dozens ofracers every weekend about what’s working, what isn’tworking, and why. Racers usually don’t talk to anybodyother than their own team members (they’re afraid to giveany secrets away).Also, the average racer has passenger car knowledge,which is completely different from race car theory. A lot ofrace cars may look like passenger cars, but they aren’t evenclose. For example, an oval track car can’t drive through atwo inch puddle of water without stalling out, and a SuperStock drag race car can’t sit still and idle for long periodsof time, both things a passenger car must be able to do.Recognizing up front what you can do and what you mustrely on a professional to do for you will go a long way inmaking your race program a success.Where Do I Start?Everyone has to start somewhere. Racing is no different. Asmentioned earlier, the first choice you must make is whatrole you’re going to play. In racing, there are severaldifferent challenging and exciting roles to choose from.Consider the following:DriverThis is the glory function-the “quarterback’ of racing.To get started in racing as a driver, you need to havesomeone first explain the rule book. Second, attend alot of races as a spectator and ask a lot of questions.Third, decide whether or not you’re willing to spend alot of your hard earned money to get started (this isusually the step most people stop at).MechanicThe mechanic makes the vehicle go fast (hopefully)and fixes it when it doesn’t. The first step to being agreat mechanic is to get good basic training.Crew ChiefA racing crew chief must be an experienced mechanicfirst before he or she can be effective as a crew chief.Experience is the main ingredient. A crew chief mustbe an expert mechanic with engines, transmissions,axles, roll cages, suspensions, etc. This is arguably themost demanding position in racing.Racing EngineerThis is the most difficult racing position to obtainbecause there are very few jobs available. Many racersare very good engineers, but they don’t have the rightcollege degree. A racing engineer must have a lot ofracing experience (especially as a mechanic), and acollege degree (usually in mechanical or electricalengineering). Usually, working for an auto companysuch as DaimlerChrysler is good experience and alogical intermediate step. A racing engineer can neverknow too much about an automobile...T -1T1

466 MOPAR PERFORMANCE PARTS5. ApprenticeshipA common (and excellent) way of getting involved inracing is volunteering to work as an apprentice orhelper for someone who is already racing. The mostimportant characteristic of a good apprentice isreliability. The racer must know that if the apprenticewas told to do something, he or she did it exactly asexpected. Improperly torqued wheels could cause acrash! The wrong amount of oil in the engine couldcause it to fail! Simple things can cause expensivefailures in highly stressed racing vehicles.A good driver and a good mechanic are required to win atracing. Once the driver-mechanic team is formed, selectingthe class in which to compete becomes important. Initially,Super Stock racing (for example) might look good to you.However, this type of racing requires a lot of money and avery good driver and mechanic to consistently win (or evenbe competitive). Until you have your team formed,sponsorship secured, and have raced steadily for one or twoseasons, it would probably be best to race in a lesscompetitive (and less expensive) bracket racing class.Bracket racing classes still require a very good mechanic,but the pressure on the driver isn’t as high. However, everyclass isn’t for everyone, so the choice is up to you.Regardless of which racing class you start in, you mustunderstand that ir will take time before you’ll becomecompetitive on a regular basis. You must get out to the trackseveral times a season, qualify, race, and finish well to getyourself known and recognized. Once you are recognized, itwill become easier to get sponsors. When you win it will geteven easier, and you’ll also start to receive contingencypayouts in addition to prize money. With this extra money(and maybe even some factory support), you can do moretesting and make the vehicle faster, which will make youmore likely to win. Winning also gives you publicity, helpingto get newspaper and magazine articles written about youand your vehicle. Mention your sponsors! Make sure theirdecals are easy to see and read on your vehicle! This is their“payout” for sponsoring you, and your obligation to them forbeing your sponsor. There’s no doubt about it - successfulracers are also successful business people.Obtaining PublicityObtaining publicity for you and your race vehicle can be aneluijive goal. Being fast, winning, or having a show-stopper isnot always enough by itself. A nice vehicle, clean inside andout, is a good beginning. One common mistake is making thepaint job and lettering too complicated or cluttered.It is always easier to obtain publicity if the driver and/or creware unique. For example, a family race team, a teacher and hisstudents, or a crew made up of neighborhood orunderprivileged kids are more “publicity worthy” than average.A unique vehicle and/or engine package is also helpful ingaining publicity. Jeeps and AMCs have a definiteadvantage here. There are fewer Jeeps and AMCscompeting, which makes them more unique by definition.For newspapers and magazines, black and white photos arebest. It’s also helpful to have good photos of your vehicleand crew available for distribution to interested writers.One of the aspects of using black and white film is that a‘‘blue’’ vehicle looks the same as a “red” vehicle. Thisemphasizes the need for an uncluttered, uncomplicatedpaint job with easy-to-read lettering.

OFF-ROADING AND RACING 4671. Maga,.’ 71nes2.Articles in magazines are one of the best ways to getpublicity. Keep in mind that drag racing magazinesaren’t interested in off-road vehicles, and off-roadmagazines don’t want articles on drag racers. Beingsomething special (unique) is important to magazinesbecause they have the whole country from which topick their featured vehicles.Hometown Newspupers and Racing NewspapersRacing newspapers usually concentrate on reportingrace results - who won and how fast they went. Theyare difficult to get coverage in until you start to win.Hometown newspapers, on the other hand, are muchmore interested in the “local angle.” However, theirsportswriters usually understand football orbaseball (for example), but not racing. This meansyou have to help educate them. Explain your sportand your vehicle. Perhaps take the writer to anevent. Get them excited about racing, and inparticular, your race program. Keep them up-to-dateon your accomplishments (especially yourvictories) throughout the season.The responsibility for getting publicity always lies with you,the racer. If you don’t do something to promote yourvehicle, then someone else will get the publicity, even iftheir vehicle isn’t as nice or as fast as yours. Magazines havea lot of vehicles to pick from, so you must bring your vehicleto their attention. Newspapers have many different sports topick from; you not only have to convince them that you havesomething special (newsworthy) to offer, but you must helpthem with background material on the sport itself.Governing Body ProblemsIf you’ve ever raced in any organized (sanctioned)competition, most likely you had complaints and/orproblems with the governing body. In most cases this is dueto a lack of communication and/or failure to read the rulebook. Safety violations are the most common, yet they arethe easiest to avoid. You should always pay close attentionto governing body rules concerning safety; after all, they’retrying to save your life.Other than safety issues, most problems with governingbodies fall into two categories: classification and legalities.1. Cluss(ficationA majority of complaints concern classification. Thegoverning body tries to put various vehicles, engines,etc., into appropriate classes to make everyonecompetitive. Problems arise concerning horsepowerfactors, weight, engine restrictions, etc. Your ideas,suggestions, and opinions should be directed to the localand/or national representatives of the governing body.2. LegalitiesMost legal problems concern the engine. The rulebooks allow certain changes. These rules must befollowed to be legal and competitive. Cutting a rule tooclose is a gamble which is usually not worth it. Forexample, if the minimum allowable cylinder headvolume is 7 I .O cc and you mill your head to 71 .O cc,you’re gambling that the tech inspector in the tech area,under less than ideal conditions and with differentequipment than your own, won’t measure it at 70.5. 1/2cc is not worth the gamble.

T468 MOPAR PERFORMANCE PARTSMost engine inspections are based on numbers; forexample, bore, stroke, head casting number, orcarburetor part number. Be sure that the parts youare using agree with what the governing body saysthey should be. If you get a specific concession froma governing body official, try to get it in writing toavoid future problems, questions, or rejections fromother officials. For best results, have yourpaperwork up-to-date before the race and be sure toalways have it with you.CONTINGENCYThere is a difference between professional racing andamateur racing. Many amateur racers are not sponsored.They may or may not use contingency money. Mostprofessionals are sponsored, but they still use contingencymoney! Not all manufacturers post contingency money.What is contingency money? Very simply, it’s money paidby a manufacturer to a racer for winning and running themanufacturer’s decal. At an NHRA national event such asthe Mopar Mile-High Nationals, there may be as many as100 contingency postings. Postings can range from “oil” to“vehicle body.” At a local NHRA or IHRA event, thesepostings tend to drop to 50 or less (approximately).Compare this to a local circle track which may have onlyfive or 10 contingency postings. (This also varies bycategory - faster classes tend to have mpre postings.)How do you find out what is posted? At the local level, thetrack will usually print a sheet with all the contingencypostings on it. At a bigger race, the sanctioning body wouldpublish the posting. For the NHRA, these are publishedbefore each national event in National DRAGSTER. For theIHRA, refer to DRAG Review. Almost all types ofmotorsports have contingency sponsors, but the NHRA andIHRA programs are probably the largest and most wellorganizedfor the amateur!Now that you know what contingency is and how to findwhere it is posted, how do you get the money? First, youmust put the sponsor’s decal on your race vehicle. Mostcontingency programs are left to the racer to apply. At alarger event, the sanctioning body will handle some of this,but you have to fill out an information sheet and they willchleck for decals and product. (Many manufacturers ask thesanctioning bodies to check the race vehicle to verify it hasthe product claimed by the decal.)Contingency programs tend to be very specific. A postingcan be for only one event or for only one product. Forexample, Edelbrock may post for intake manifolds, but notall of the other products that they make. Goodyear may postfor the championship, but not all the local events that leadup to it.At the local level, contingency postings are more likely tobe product, not money. For example, you can win a case ofoil. This is helpful because you are going to need it to race!Another form of sponsorship is sometimes called a “partsdeal.” This usually means you get free parts to maintainyour vehicle.The hard part of contingency programs is the OEM aspect.The vehicle and/or engine must be a certain brand. There arebasically three OEMs - DaimlerChrysler, Ford, and GM.(Even a dragster or sprint car has some brand of engine.)

OFF-ROADING AND RACING 469Mopar has the biggest and best amateur contingencyprogram available. We post for ignition, intake manifolds,rocker arms, valve covers, etc. Our fellow OEMs tend topost only for the body (if they post at all). We also post forthe body when they do. So why is there an engine assemblyposting? Because it is the highest payout in the contingencyprogram. In addition to Chrysler-Plymouth-Dodge, we alsopay for AMCs, Jeeps, and DeSotos! The reason we do thisis to reward our racers for racing a DaimlerChrysler/Moparproduct. Other racers with different brands can’t get it.Another reason -let’s assume there are five JeepComanches in the same class. We can’t sponsor all of thembecause there isn’t enough money. If we sponsor one, theother four get mad! Contingency solves this problem. Thatis how DaimlerChryslerhIopar got into the contingencyprogram in the first place. We used it to replacesponsorships in the mid- 1970s. It has worked very well inhelping reward our racers over the past twenty-five years.Mopar Performance Parts Contingency ProgramContingency programs are offered by automotivemanufacturers for the use of their products. Theseautomotive manufacturers may produce assembledvehicles, such as DaimlerChrysler, or aftermarket parts,such as Holley and Crane. Most aftermarket partsmanufacturers are members of SEMA (SpecialtyEquipment Marketing Association), as Mopar PerformanceParts is. In 1999, Mopar posted over $I million dollars incontingency money to drag racers alone!How does it work? Easy! Run one or more of the eligibleMopar Performance parts in your race vehicle and have theappropriate Mopar Performance Parts decal on yourvehicle. If you’re a winner or runner-up in your class, thesanctioning body will inspect your vehicle and forward theappropriate information to the Mopar Performance PartsContingency Payout Center. A check will be in your handsless than 30 days after the event. Parts eligible forcontingency payout are available through the MoparPerformance Parts Racer Store (on site at every nationalevent), participating Chrysler-Plymouth-Dodge-Jeepdealerships, your local speed shop, as well as the MoprPerfbrmance Parts Catalog.Note: For the latest DaimlerChrysler contingency programinformation, check the latest issues of Mopar PerfbrmanceNews, or write to:Mopar Performance Parts Contingency Program20770 Westwood RoadStrongsville, Ohio 441 36SAFETY AND THE PERFORMANCE ADVANTAGERacing at an entry level usually involves taking a retiredproduction vehicle, putting a seat belt in it, some sort of rollbar, making some modifications (very minimal), and goingout to a track. And for those who race these old vehicles,depending on the vehicle’s history, everything probablyisn’t in the best shape (things such as wheel bearings,brakes, etc.). So ask yourself before you buy a vehicle,“Has it been maintained well enough to go racing?” Maybeit was originally, but how about now? And mostimportantly, will it he sufe.?.. r -7-1

l- -7-7470 MOPAR PERFORMANCE PARTSYou need to ask yourself these questions because no oneelse will. There are some entry level safety precautions, butthese are usually only the bare minimum and in no way dothey make your vehicle as safe as it should be. The theorythat track owners, promoters, etc., use when asked whyracers aren’t required to use proper safety equipment is that“they don’t go very fast.” This is simply not true. Theyforget that these racers are driving at 60, SO, or even 100+miles per hour. Can you imagine driving your vehicle downthe highway and hitting a bridge abutment‘? Well, that’s thesame as hitting a wall at the track, and you can get just asseriously injured.Most racers put a lot of emphasis on their engines and nottheir chassis. This completely ignores safety. It doesn’tmatter if you’re ahead in the point standings or not, if youcrash you’re just as injured. What good does all that workto the engine do if you are unable to survive a crash?Also, too many racers have the attitude, “I’m a good driverand therefore I won’t have a crash.” But the fact is therewill be a point when the other guy will crash or your vehiclewill break, and you will be involved whether you wanted tobe or not. You won’t have a choice. You could be the bestdriver in the world and it wouldn’t matter. At one time oranother, you will be involved in a crash.There are several things you can do to make your race vehicleas safe as possible, and many of them don’t cost a dime. Also,many of them have a hidden performance advuntuge,allowing you to perform better at the track as well as makingyou as safe as possible. These items will be coveredindividually following this introduction, but first, it isimportant to recognize several critical area3 involving safety.One of the most important is driver compartment roll overprotection; in other words, you’d like to have, in the case ofa bad crash, pieces of the race vehicle everywhere on thetrack, but the driver completely untouched in a little“cocoon.” It takes a lot of time and energy to make thatdriver’s compartment safe. Some people will tell you tosimply put the driver in what would amount to as a cast iron“survival cell,” and then build the vehicle around that. Thistheory just isn’t true. If the driver was sitting in a little castiron pod, he would get injured, and more than likelyseverely. What you need to do is use controlled crush toabsorb or “manage” the energy; that is, let the vehicleexpend all it’s kinetic energy bending itself up to the pointwhere it just reaches the driver and then stops. Other areasof concern include keeping the driver in the driver’scompartment, and the danger of flying debris within thedriver’s compartment. This takes a lot of engineering and alot of expertise, and is one of the reasons we suggest thatyou have your roll cage constructed by a reputable,professional chassis builder.On top of all this, the most critical area (and the biggestdanger) is fuel. You’ve got to manage the,fiiel-contain it andmanage it. For this there are fuel cells, which are steel enclosedrubber bladders that can deform in case of a crash andhopefully offer some puncture resistance. Even if the bladdersdo puncture, the fuel will drip out at a very slow, controllablerate, as opposed to engulfing the vehicle in raw fuel.Another safety area that is not immediately apparent tomost racers is to build a vehicle that handles properly soyou can uvoid an accident. Superior handling, that is,steering, suspension, and brakes, means that the vehiclewill do what you tell it to do-such as drive around anaccident. How many times has someone said, “Well, I hitthe brakes but nothing happened,” or “The steering gotloose on me”? If the vehicle is working correctly, that is, itslows down, goes fast, goes straight, goes left and goesright, you will avoid most accidents.The key to being safe is that you have to be single-purposeminded. You’ll see people at the race track who will have afancy trailer and a big expensive motor home-and sixmonth old tires on their race vehicle. But if they wereserious, really serious, they would get rid of thatmotorhome, get themselves an open trailer and a pickuptruck or van, and have Y L ~ W tires on their race vehicle everyweek. Most racers don’t understand this: they get theirpriorities confused. They’ll say, “Well, everyone else has amotorhome, and we don’t want to look like a second rateoperation.” But what do you think they’ll look like on thetrack’? If they’re out there losing races because their tires areold and worn, there’s only one way they will look-foolish.The only person that can make you safe is you. You have tomake the decision to racc as safely as you can so that incase of an accident, undyou will have un uccident, you willbe able to race again.Is it worth being competitive “at any cost” when that costmay be your own life‘? Only you can decide that-noarnount of rules or preaching can ever get you to “dosomething.” You alone have to rnake the choice.

OFF-ROADING AND RACING 471Always remember, safety is the key to having fun while yourace, and every professional driver will tell you safetyshould come first when you plan your race vehicle. Andisn’t having fun what racing is really all about?PERSONAL SAFETYClothingYour clothing should be loose fitting treatedcotton -NEVER anything synthetic (such as a nylotdplastic“racing” jacket). Synthetics are the worst possible thing youcan wear because in a fire they will melt and stick to yourskin, whereas cotton won’t-it burns and falls off. At leastwith treated cotton all you have to treat is the burn, asopposed to having to separate the melted synthetic from theskin and then treating what’s left. This may sound a bitgory, but it’s also very realistic and very true. Andunfortunately, very rarely considered.Also, the recovery time from a first or second degree burnthat you may suffer when wearing treated cotton issignificantly shorter than a third degree burn sustained ifyou were wearing a synthetic that melted. Synthetics willalso cause you to scar, and in many cases, quite severely.The next step up from treated cotton is a fire retardant suit,underwear, and gloves, but until you can get to that point,treated cotton gives you a good, reasonably safe place to start.HelmetsRacers are required to wear helmets, but should you buy a$50 helmet or a $300-$500 helmet’? Well, in racing there’sa saying that states “the helmet is worth the price of thehead.” For this reason, we recommend that you buy thevery best helmet you can afford. But remember, even withan expensive helmet you (uti still get injiiril>s. An expensivehelmet doesn’t guarantee that you won’t get injured, sodon’t start taking unnecessary chances on the track thinkingthat you “can’t get hurt.” However, when you are involvedin a wreck, and you will hP in one sootier or later; the moreexpensive helmet will lessen your chances of severe injuryand improve your chances of survivability.BODY AND CHASSIS SAFETYFireFire is the single biggest danger in racing. Fires willhappen, and all you can do about it is protect yourself asbest you can.To start with, make sure that you remove all plastic caps inthe firewall (bulkhead) and fill in all the holes, because thefirewall is the only thing that separates your body from apotential engine fire.Also make sure that the driver’s compartment is isolatedfrom the fuel system or fuel storage system, be it a stock gastank, a fuel cell, etc. Fuel lines should NEVER pass throughthe driver’s compartment at any point. Also, electric fuelpumps should never be used in oval track racing because ifthe fuel line breaks, raw fuel will keep pumping from theline, creating a major fire hazard. Mechanical pumpsshould always be used in an oval track race car.Another problem area, and one that is rarely even thought of(unless learned the hard way) is where the shifter goesthrough the floor. In case of a fire, when you’re going downthe track, that fire has to go somewhere, and that somewhereis the “path of least resistance.” If you DO NOT have thehole in the transmission tunnel plugged and the fire is beingforced under the vehicle (because of the hood and thefirewall), the transmission tunnel and, consequently, thehole where the shifter is mounted, becomes the path of leastresistance. What happens next is that you will be sitting nextto a virtual blowtorch.. .then what?A way to prevent this is using a fire retardant asbestos boot(available in the aftermarket) that you can tie around theshifter-then any fire that does come into the driver’scompartment is only that which can leak around the edgesof the asbestos boot. What you are looking for here is time.If you can gain 20 seconds before that boot gives way, it’sdone its job.Fire retardant means time. And time allows you to avoidmore serious injury.1. Fire Extinguishers2.Mopar Performance Parts recommends that a fireextinguisher be carried in all race vehicles. It should belocated close to the driver, mounted vertically, andavailable to be used quickly. There should be anadditional fire extinguisher located in your pit area.The extinguishers must contain dry chemicals to helpsmother electrical, oil, and gasoline fires quickly andsafely. Many aftermarket companies such as OMPhave complete fire extinguishing systems for virtuallyany race vehicle. These aftermarket companies shouldbe contacted for more information and specificrecommendations.Cas Tanks and Fuel CellsThe biggest danger in racing is a fuel fire. You’ve got tocontain and manage the fuel. For this there are fuelcells, which are steel enclosed rubber bladders whichcan deform in case of a crash and hopefully offer somepuncture resistance. Even if the bladders do puncture,the fuel will drip out at a very slow, controllable rate, asopposed to engulfing the vehicle in raw fuel, which willeventually touch something hot and cause a severe fire.. ..r -T-I

472 MOPAR PERFORMANCE PARTSIf you are using a stock gas tank, make sure that is ingood condition (no rust) and is shielded as much aspossible from possible punctures (for example, makesure you have a good, strong rear bumper). Also, thesolid steel gas tank inlet pipe should be replaced withlonger, flexible hosing or pipe. What happens is that ifyou hit the back end in a crash, the gas tank may bepushed either forward or sideways, and without anyextra length or “give” the solid inlet pipe will pull outof the tank causing a major fuel spill. Flexible hosingor pipe will allow a lot of movement of the gas tankbefore being pulled out.Another option (and a good one for drag racers) is touse a smaller tank, such as a 6 gallon marineboat tank.With any fuel tank, you should build a firewallbetween the tank and the driver’s compartment foradded fire safety.It is recommended that a weld-in roll cage be used. asopposed to a bolt-in. A bolt-in roll cage can easily tearaway from the body by virtue of the fact that since it isbolted in, it is a separate entity from the body and chassis.A welded-in roll cage actually becomes a structuralmember of the body and chassis, giving the driver ultimateprotection, and there is no risk of the cage separating fromthe body or chassis.A word of caution, however. In the United States, chassisbuilders, roll cage constructors, etc., DO NOT have to belicensed or certified. This can create a very dangeroussituation when inferior workmanship is discovered, usuallyonly after a serious crash. It is highly recommended thatyou shop carefully for a reputable chassis shop, one that iswell known for its quality or one that has beenrecommended to you by a reliable and knowledgeablesource. A poorly built roll cage can actually be moredangerous than no roll cage at all.rRoll CageWhy do you have a roll cage? One of the primary functionsof the roll cage, and certainly the most important to thedriver, is safety. As the vehicle body goes throughcontortions, the cage keeps it all in its proper location. Thismeans during a crash the roll cage can bend, but it shouldnot collapse or break.A lot of people think that the roll cage is only for when thevehicle rolls over, and that’s not really true. Most crashesinvolve hitting the side or the front of the vehicle. But it’sthe hidden performance aspects of the roll cage that mostnovice drivers don’t realize or understand. The roll cagekeeps the vehicle stiff, which allows it to work better, lastlonger, and makes the vehicle go faster. But theperformance aspect comes second to the primaryfunction - safety. If the roll cage doesn’t make you safe,then why would you have it at all?1. Roll Cage PaddingEven if a padded head restraint is used, it is mandatory.that any tube in the area of the driver’s head also bepadded with rubber air conditioning insulation(Armstrong-Armaflex). It is also highly recommendedthat all roll cage tubes in the area of the driver’s armsand legs be similarly padded. This padding is availablein 6-foot lengths from Mopar Performance Parts(P452906S).Roll Cage PaddingHere’s a handy way to neatly pad roll cages. Black foamrubber tubing that measures 1 -5/8” inside diaineter and1/2” wall thickness, 6’ length.P4.529065 Roll cage padding.

T -7-7OFF-ROADING AND RACING 4732. Head RestraintA head restraint is required in vehicles that haveinstalled a roll cage. The head restraint should be wellpadded and located not more than 4“ behind thedriver’s helmet. A padded roll bar or cage by itself isnot acceptable as a padded head restraint by most racesanctioning bodies.3. Six Point HarnessIf the roll cage performs its task, then it becomesmandatory to keep the driver securely located withinthe roll cage. This requires both a high quality seat beltand shoulder harness, and they should be securelyattached to the roll cage, not to the seat or floor.Interesting to note, seat belts and shoulder harnessesonly offer so much deceleration time before they giveway and break. They have to or even more seriousinjury could occur to the driver (crushed ribs, etc.). Butby the time they do break, they have absorbed so muchof the impact that the driver can usually walk awayuninjured. Most people don’t realize that seat belts,shoulder harnesses, etc., are designed to break.Therefore, they must be replaced periodically. Checkwith your local track for safety regulations.4. Seat MountingWith padded bars, head restraints, seat belts andshoulder harnesses all located in the area of the driver’sseat, it is absolutely mandatory that the driver’s seatstay in its position. It should be bolted to the frame,preferably passing below the seat. High quality boltsshould be used, and the bottom bolts should be vertical.Warning! Quick pins should NEVER be used toattach the seat to the frame.The seat should be attached in three places: one on thefloor and two on the back. The floor attachment shouldbe to the main frame rails or roll cage structure, not tothe sheet metal floor. (Attaching the seat to the floorwill allow the seat to easily tear out in case of a crash.)The back support should be a vertical bar running fromthe main hoop to the frame rail with the seat attachedto it in two places: as high as possible and midwaybetween the floor and the upper attaching point.The seat should be set into the tube frame and attachedto the previously mentioned three locations. If anaftermarket fiberglass seat is used, the attaching boltsshould run through the seat with metal reinforcementplates on the inside so that the bolt does not pullthrough the fiberglass. Use carriage-type bolts(rounded heads), or weld a stud to the reinforcementplate so that the head of the bolt doesn’t stick into thedriver when he straps himself into the seat.5. Window NetA window net is highly recommended and is requiredby most sanctioning bodies. Its primary function is tokeep the driver’s arms contained within the roll cage incase of an accident. It also keeps flying debris fromentering the driver’s compartment.Attach the net to the inside of the roll cage above thedoor opening. One method is to run a steel rod throughthe net and attach the steel rod through brackets weldedto the roll cage or with hose clamps. The bottom of thesafety net can be held in place with a steel rod that fitsinto a bracket in the rear behind the driver’s left armand has a seat belt end on the front. The net should beas far inboard as possible.6. ParachuteIn drag racing classes that allow the use of a parachute,it should be anchored securely to the roll cage. It is notrecommended that the parachute be attached to the rearaxle or rear suspension members since the rearsuspension attachments may fail and pull out. It shouldnot be attached ahead of the axle. The best choice foran anchor spot is a section of the roll cage at the rearshock crossmember. The rear crossmember, which isused primarily to support the batteries, ballast, etc., if itis very strong, can also be used as an anchor point. Ona stock-bodied vehicle, it may be best to pass theparachute lines through the rear panel to the anchor. Ifthis is done, the hole in the panel should have no sharpedges which might cut the lines anywhere from theanchor to the chute itself.The height of the chute anchor relative to the axlecenterline is extremely important. If the anchor is toohigh, the front wheels will be picked up. If it is too low,the oil pan will scrape. For the correct size and type ofparachute, contact the manufacturer.7. BallastAny material that is added to the vehicle for thepurpose of ballast must be permanently attached to thevehicle’s structure or roll cage. Consult your rulebook’s safety regulations for how much ballast isallowed, its location, and other details.Steering LockFor any race vehicle, be sure to remove all productionsteering locks. This is extremely important because in case ofengine failure or other reason for engine shut down, if youhave not removed the steering lock, you will literally belocked into the steering angle you are in, and more than likelywill go off the track into a wall (or worse, another vehicle).

474 MOPAR PERFORMANCE PARTSWheel LossIt sounds incredibly simple, but check those lug nuts everytime before going out onto the track! You wouldn’t think ofit unless you were a seasoned racer, but wheel loss i s one ofthe most common causes of accidents in racing, not tomention one of the most serious things that could go wrongwith your vehicle. If you haven’t checked them yourselfand you plan on getting behind the wheel, grab a lugwrench and make sure they’re tight! After all, it’s your lifethat’s on the line.Brakes and Brake LinesBrake lines must be routed outside the frame longitudinalsin the bellhousing area, and any holes left in the firewallshould be sealed, not left open. Brake lines should alwaysbe shielded whenever possible.ENGINE AND DRIVETRAIN SAFETYFuel FiltersWarning! Only metal fuel filters should be used on anyrace vehicle. Glass or plastic filters should NEVER be used.In an accident, glass can break, causing a major fuel leak.And in the case of an engine fire, plastic can melt, causingthe same problem. This is very important to rememberbecause any fuel leak under the hood leaks directly onto theengine, almost always causing a severe engine fire.Electric Fuel PumpsIn oval track racing, electric fuel pumps are not legal due totheir extreme danger. If there is a break in the fuel line or arupturedhroken fuel filter, the electric pump will cause thefuel to keep pumping out and when the fuel touchessomething hot - FIRE! Therefore, even if legal, electric fuelpumps ARE NOT recommended for oval track cars.Insl.ead, consider a high volume mechanical fuel pump.Mopar Performance Parts does recommend electric fuelpumps for drag racing. For more information and specificrecommendations, refer to the ‘Fuel Delivery’ section ofChapter 4, 4.0L Power Tech In-line 6.Stuck ThrottlesRacers don’t necessarily think of the engine as a safetyitern. Safety is thought of being seat belts, helmets, rollcages, maybe even fuel systems and brakes, but nobodyever thinks of the engine as a safety item. But if yourthrottle sticks, you are in deep trouble. So you need tocheck the throttle for easy action, worn cables, etc., so thisdoesn’t happen.You also need to use two throttle springs. If you only haveone spring and it breaks or falls off, your throttle is going tostick. If you have two springs, you have twice the chance ofavoiding this. Most newer vehicles have a dual throttlespring-a large thick one with a smaller one inside. This isnot done for spring load, but so that in case one breaks youwill have a back-up.Note: The most common stuck throttle problem is throughinterference, typically with the air cleaner (most of whichare usually homemade). Most racers make the mistake ofchecking interference with the hood up, then when they testdrive the vehicle, they drive off the end of the track. Soremember - check ,for throttle cable interference with thehood down as well as with the hood up...1- - 7 7

OFF-ROADING AND RACING 475Driveshaft LoopA driveshaft loop is used primarily as a safety device. It ismandatory in some classes and governing bodies. It isreasonably common in class competition in drag racing.Driveshaft loops are occasionally put on other bracketvehicles and circle trackhoad racing vehicles, but their useis somewhat spotty. If you are building a race vehicle, youshould have a driveshaft loop. Before we get to the "why,"let's describe the loop itself.A driveshaft loop is a steel circle or loop that goescompletely around the driveshaft. It should be made of 1/4"thick (minimum) steel and should be 2" wide.Approximately 3" of clearance should exist between theloop and the outside of the driveshaft tube. This results inan 8" to 9" inside diameter loop. It does not have to be aperfect circle, but a round loop is recommended because itis considered stronger. It should be located anywhere from1" to 6" to the rear of the front universal joint. The loopshould be securely mounted to the vehicle. This means itshould be welded to the frame, not the floor pan. Usuallyyou run two straps horizontally from the loop over to theframe rail. One strap goes to each sidehil.This is a very simple device to make and install. It doesrequire welding, but the cost should be minimal. If you'vepaid attention you noted that we located our driveshaft loopnext to the FRONT universal joint. Racers know that therear universal joint is more likely to fail. So the obviousquestion is why did we locate it by the front universal'? Therear universal joint moves around a lot on a vehicle so theloop would have to be much larger and heavier. To getbelow the rear joint with a 360" loop, the loop itself wouldbe down too low, taking up ground clearance. Additionally,when the rear fails, it tends to fall on the ground and bangaround. At the worst, if the driveshaft catches on the groundwhile the vehicle is moving forward, it just pulls the wholedriveshaft out onto the ground-or the driveshaft itself mayget bent.The story is completely different at the front. If the front u-joint fails and there is no driveshaft loop, then thedriveshaft falls to the ground. It is still attached at the rear,which gives the driveshaft a downward angle. Assumingthat the vehicle is still moving forward, the downwardsloping shaft will be driven into the ground by the forwardmotion of the vehicle. When it sticks into the ground, itstops. At this point the best that can happen is that you tearout the rear end and rear suspension. The worst is thatyou'll pole-vault the whole vehicle and destroy it. If thefront universal joint fails and you have a loop, then thedriveshaft tube drops down the two to three inches that theloop allows and it stops. The vehicle can now roll to a stopwithout further damage.Automatic Transmission SafetyThere is one very important item to keep in mind whenracing an automatic transmission. If the rear axle ring andpinion, axle shaft, or driveshaft fails under wide openthrottle acceleration, the automatic transmission'soverrunning clutch should be inspected. In many cases, arear axle or driveshaft failure will also fail the overrunningclutch. However, it will not appear failed externally. If thedriveshaft or rear axle that failed is fixed without inspectingthe overrunning clutch, during the next race thetransmission may explode! By definition, a failed ordamaged overrunning clutch is a failed transmission (eventhough it may not look broken externally), and should berepaired before it is used again.Any time that a driveshaft is broken, be sure to check thetransmission tailhousing for cracks. Also check for a bentoutput shaft.Most race sanctioning bodies require a shield or blanketaround an automatic transmission. Be sure to check the rulebook.For more information on automatic transmissions, refer tothe appropriate service manual.l- -7-7

476 MOPAR PERFORMANCE PARTSSAFETY CHECKLISTYESNOHave you contacted thenecessary race sanctioningbodies and obtained their currentlistings of approved safety items/requirements? --Do you have the proper clothing(either loose fitting, treated cottonor fire retardant?) --Do you have an approvedmotorsports safety helmet? ~-Is the driver’s compartmentisolated from the fuel system?Is there a dry chemical fireextinguisher mounted uprightand located close to the driver?Is there an extra fire extinguisherin the pits? --If a fuel cell is not being used,has your gas tank been made assafe as possible? --Do you have a roll cage?Is it padded? --Can the ignition switch bereached when the driver isstrapped in tight? --Have you installed the properhead restraint? --Is your six point safety harnessin good condition and attachedto the roll cage and not the seator floor? --Has the driver’s seat beenproperly mounted?---__.Have you installed a window net?Is it easy to release for both driverand safety personnel?YESHave you removed the steeringlock? -Have you checked all wheel lugnuts for proper tightness?Are your brakes in good workingcondition?Are you using a metal fuel filter?Have you replaced all rubber fuellines?Do all holes in front and rearfirewalls have metal covers?Has a firewall been built betweenthe fuel tank/fuel cell and thedriver’s compartment?Have you installed a driveshaftloop (RWD only)?Have you checked throttle linkagefor clearance with the hood downas well as up?Are you using two throttle returnsprings and a toe return strap onthe throttle pedal?You should have answered “NO” to only one (or maybetwo) of the items on this list. If you have answered “NO’ tothree or more items, chances are you’re compromisingsafety. Ideally, all of these items should be answered“YES,” especially those concerning personal safety.It is recommended that you copy this list and go through itwhile. building your race vehicle, as well as before every race... . .. T -1.1

OFF-ROADING AND RACING 477DRAG RACINGAll drag racing, including brackets, is made up of driversthat leave on time, drivers that generate good times,mechanics that build fast engines and fast cars, plannersand developers. The purpose of this section is to give youthe basic information necessary to be competitive whenracing your DaimlerChrysler product.Bracket RacingBracket (or E.T. Handicap) racing is the fastest growingsegment in drag racing, especially Pro Gas-Super Gas.Several years ago it was a virtually unknown aspect of thesport. Today, bracket racing is really big-time with peoplebuilding special bracket cars, dragsters, trucks,motorcycles, and even snowmobiles (believe it or not).Automotive categories include the following (time shownis for quarter mile):1. Sportsman (14.00 seconds or slower)2. Pro ( 12.00- I 3.99 seconds)3. Super Pro (7.50- 1 1.99 seconds)4. Advanced E.T. (6.30-7.49 seconds)The popularity of bracket racing is easy to understand.There are virtually no rules -you can build the vehicle andengine any way you want. It can be relatively cheap to race(it’s up to you), and a good driver can make a decentamount of money. A bracket racer doesn’t need the exoticcylinder heads or trick transmissions that are required to becompetitive in Competition-Modified Eliminators. It alsodoesn’t require some oddball car such as a 19.52 StudebakerWagon or a 1958 Commander three-door delivery coupe.These specialty types are what are required to win or becompetitive in Stock and Super Stock Eliminators themajority of the time. Bracket racing has no factors, and any“par” that is used is dialed-in by the individual driver. Thissounds like fun and you don’t get outlawed if you win!The majority of bracket racers are doorslammers; that is,race cars similar to Stock and Super Stock class cars. Themost popular cars in this category are big-blockintermediates and small block compacts. In most cases,these cars are not very competitive in Class racing.However, they are very common in bracket racing, andquite competitive. This all seems too good to be true - theremust be some drawbacks for the racer. In truth, there are!There are two basic drawbacks to bracket racing. One isthat because the rules are so open, the racer may spend toomuch money on exotic items that he really doesn’t need.The second is that the demand for mechanical excellence isremoved. For a Super Stocker, the performance standardsare very clearly spelled out and demand mechanicalexcellence, not only using the best parts available such asintake manifolds and torque converters. This isn’t true inbrackets. (For example, if you run 10.50 in a 10.20 class,you’re three tenths off and must do a better job to becompetitive in Class racing, while in brackets you’d dial-ina 10.50 and instantly be competitive-there’d be no reasonto go 10.20.)Bracket Racing Build-Up StrategyTrying to organize the various approaches to Mopar bracketracing is close to an impossible task. The rules are so openthat there are many ways to do the same thing, and manyshades of gray. In most cases what separates these differentapproaches is cost. There are also many aspects to the costquestion. You can calculate the amount of horsepowerrequired to reach your goal based on horsepower-to-weightratios, hut all this amounts to is a number, say 500 hp. Thiscan be either an expensive six cylinder or an econo bigblock V-8. For now we will lay down some generalguidelines for the various aspects of bracket racing, but thefinal decision will be up to the racer.One of the first things to do is decide upon your allowablebudget both in money and time. Budgetary considerationsshould be given to both immediate needs and your longtermgoals. In many cases, a larger investment now cansave money in the long-term. Your immediate and longtermplans and budgets should be laid out now. We willshow YOU how to modify this plan as we go along.

478 MOPAR PERFORMANCE PARTSAnother item to note in your plan is what you expect thevehicle to do; that is, how much highway mileage, howmuch mileage around town, how many trips to the track,and other requirements. Unlike many brands, Mopars domake excellent dual purpose vehicles. The answers to thesequestions will affect the parts that we use, eliminate someand demand others. A general characteristic of bracketracers is that they want to race and race often. This isobviously a strong reason for choosing a Mopar racevehicle. Bracket racers are not particularly interested inmaintaining, rebuilding, or testing the vehicle on a frequentbasis. Class racing demands maintaining, rebuilding, andtesting, which means the amateur racer doesn’t race asoften because he or she needs time to do all this. How oftenyou want to race should be noted on your plan. You shouldalso list what you already have available as far as Moparengines and bodies. Using one or both of these, if available,may result in the lowest cost approach.One of the most important considerations in laying out yourbracket racing plan is to be realistic concerning how fastyou want to go. Overstated, this means that you shouldn’texpect a 150 horsepower engine in a 4,000 pound vehicle togo 150 mph. You also shouldn’t expect to convert a 150 hpengine to 800 hp. An error in basic choice such as this canbe extremely expensive, and in most cases, disappointing.As we progress through this section, we will try to provideguidelines for various performance characteristics. Later inthis chapter we will put all the various Mopar engine partsinto groups that will work well together. It’s important thatall the parts on the vehicle work together as a team. Thiswill increase overall performance, keep costs down, andmake the owner happy with his or her package.The final item in our preliminary plan is to determine howgood your current package is running. Since the rules arenot restrictive, you should be sure that your current Moparrace vehicle is capable of reaching the goal you set beforeyou invest more money in it. If you don’t have a currentrace vehicle, this step is somewhat academic. To keep fromfalling into the poor execution category and spending moremoney than is required, it is necessary to set performanceguidelines and determine if you are getting the most fromthe package that you’ve put together within yourguidelines. This a complex matter and not an easy one tosolve. Basically, with a given horsepower output and agiven vehicle weight, the vehicle should go a certain speed.Stock Eliminator Trucks1991 was the first year for the new NHRA Stock Truckclasses that allow 1980 and newer pickup trucks to competein Stock Eliminator. Trucks in general are red-hot thesedays, so allowing them to compete in drag racing was anatural. And there’s a lot of interest among drag racingenthusiasts because the trucks are rear wheel drive. Thismakes them naturals for drag racing events.In 1998 there were 20 classes for trucks in StockEliminator: ten manual and ten automatic classes. The topclass (ATE, AT/SA) has a class weight break (based onpounds per NHRA factored horsepower) of 12.00 to 12.99.With several different classes, there is room for everyone tobe competitive. Complete NHRA factors andclassifications are published in Ncitionul DRAGSTER. TheIHRA publishes their numbers in DRAG Review.Note: Always be sure to check the rules with your localtrack and sanctioning body before you begin building yourdrag racing truck.How to Build a Stock Eliminator TruckThe first step is to get the Tech Sheet and the WeightClassification Sheet for the vehicle that you have picked.The second thing that you need is the service manual foryour truck. Then, you’ll need a copy of the most recentNHRA or IHRA rule book.The Tech Sheet allows you to check your engine andhave the specifications by which to build it. These arelegal specifications - the sanctioning body’s minimums/maxiimums for head cc’s, deck height and cam lift, and muchmore. The Tech Sheet also has the casting numbers forintake manifolds and cylinder heads. These must be checkedagainst the parts that you’re going to put on the engine.Now that you have gathered all the necessary writteninformation, you can start gathering your parts. We assumethat you already had a truck or that you just bought one. Forthis discussion, we’ll assume that you have the right engine.If yolu bought a separate/spare engine assembly, then youhave to make doubly sure that the numbers match beforeyou start putting it together!As you start to gather parts, it’s a good idea to keep anotebook full of all the information on your particularengine. The first thing to put in the notebook is a name forthe project/engine, or a number, or other description. Thesecond thing is to list all the casting numbers as you takethe engine apart.

OFF-ROADING AND RACING 479At this point, you start getting specific as far as parts areconcerned. Each engine is unique. The specificsubstitutions are listed in the engine chapters of this book.The service manual for the vehicle will tell you how to takethe engine and vehicle apart. It also tells you how to put itall back together. This book tells you how to modify it tomake it go faster/quicker at the drag strip.We’ll assume there is nothing wrong with the truck that youhave. This allows you to put together a basic list of partsrequired. Obviously, you need gasket sets and bearings.You will also need headers, new pistons and rings (probablyoversize), a race ignition (electronic), and a low restrictionair cleaner for the base plate to use as an ideal entrance. Youalso need a fresh set of valve springs and a “stocker” cam.As far as the basic engine building goes, refer to the‘Engine Assembly’ section of Chapter 4, 4.0L Powrr TechIn-Line 6. Be sure to hone the block with a honing plate.One of the keys to making good power in a stocker is thevalve job. It must be good, but also legal. It’s usually bestto send this out to a professional. If you have a carburetor,you’re also going to need some carburetor jets. Stockersmake more power and, therefore, need more fuel from the“stock” carburetor.Now you need to switch your attention to the chassis. Thefirst thing is to weigh the whole vehicle. This lets you knowhow much weight to take out to get down to theclassification weight. While you are weighing the vehicle,push the front wheels off the scale and weigh just the back.This allows you to calculate the weight distribution. Truckshave basically poor weight distribution if no ballast is added.For chassis parts you’ll want a race torque converter and arace manual shift valve body (assuming automatictransmission). You need to get a Sure-Grip rear axle and alower gear ratio. You’ll need racing tires and lightweightwheels. A balance weight set will be needed for the torqueconverter. At this point you can start building up your newrace truck. As you can see, any racc project is really twoprojects. One is the engine and the other is thebody/chassis/drivetrain. Each one is important to makingthe race vehicle successful.Super StreetSuper Street is an entry level category (similar to SuperGas) with a 10.90 second standard (quarter mile). It is forfull-bodied cars only (full fenders, hood, grille, roof,windshield, and functional doors). Any automotive engineis permitted.Basically, a 10.90 bracket is quite simple to define ingeneral terms. With a 10.90 second elapsed time in thequarter mile, we can calculate thc weight-to-power (W/P)ratio that will allow this performance level. The actualW/P ratio factor is a function of the type oftransmission - manual or automatic. The W/P ratio for theautomatic is ,146; manual is ,140.To simplify this discussion, we’ll assume that everyone has anautomatic. This allows us to calculate how much horsepowerour engine has to make to obtain our goal of 10.90 seconds.As long as we stay in this category, our required power levelis ,146 multiplied by the total vehicle weight.For example, if a vehicle weighs 3,200 pounds, then thehorsepower required would be 467. Total weight refers to thecar’s weight added to the driver’s weight. The NHRA uses170 Ibs. for the average driver’s weight. For best accuracy,you should use your driver’s actual weight. So, if our carweighs 3,030 pounds and our driver’s weight is I70 pounds,then our total race weight (vehicle weight) is 3,200 pounds.We can also figure that if we had a 2,330 pound car and thesame driver, we’d have a total weight of 2,500 pounds andwould need 365 hp to go 10.90. Are you getting the picture‘?We saved 100 hp in engine output by taking 700 pounds offthe car. On the other hand, if our car weighed 3,530 pounds,our total weight would be 3,700 pounds and the powerrequired would be 540 hp. It is obviously easier (and lessexpensive) to build a 365 hp engine than a 540 hp engine.In many cases, it is cheaper to reduce the weight of the carthan it is to build-in extra horsepower. Plan your project forbest performance-per-dollars spent.ConsistencyConsistency. Ask any bracket racer what it takes to win andthat’s the answer you’ll get. Consistency. Everybody knowsit, every racer says it. But for the beginning bracket racer,how do you become consistent? How do you get consistentto the point of cutting a Five-0 light (300 second) andrunning the same E.T. every time? Welcome to BracketRacing 101. Class is in session. Let’s dissect “consistency.”We’ll assume that your vehicle is in good mechanical shapeand you can find your way to the race track. The problemis, the vehicle won’t run consistently. Your reaction timesvary from ,501 second to calendar years, and you always goout in the first round because you’re off your dial-in. Whatdo you do now?First, lets look at reaction time. Why is cutting a Five-0light important? Simple. In bracket racing, anything yougive up at the starting line you can’t get back. You “breakout” if you do. Look at it this way-a vehicle traveling at100 mph is moving 146.7 fee per second, or 1.467 feet per100th of a second. If you cut a ,560 light against youropponent’s S10, and you both run right on your dial-ins,you will be 7.3 feet behind him at the finish line(approximately). To close this gap, you must break out.Five hundredths at the starting line means you lost by halfa car length.. .. I.

480 MOPAR PERFORMANCE PARTSWhat does it take to cut a good light? A big powerfulengine? No way. As long as the engine runs reasonablywell, a stock 4.0L In-Line 6 will cut as good a light as a 426Race Hemi. Remember, the vehicle only has to move a fewinches to start the E.T. clock. A good chassis is the way tolower reaction times. When you release the brake (or linelock) and mash the pedal, the vehicle must move forwardinstantly. No wheel spin. Hook-up every time, the sameway every time. Consistently.Keys to a good chassis are listed in Mopar Chassis-8thEdition (P.5249441). What it takes to hook-up varies withengine and vehicle weight, but the basic rules are: a) racethe vehicle as light as you can, b) make the rear suspensionwork to plant the tires, c) run as much tire as you can.Lighter vehicles react quicker, accelerate faster, allowslicks to last longer, and wear out parts slower. Put yourvehicle on a diet. Instead of buying the latest trick enginepart, spend your money on fiberglass parts. Convert yourvehicle to manual brakes and lose the power booster.Remove the power steering pump and cast iron box and putin an aluminum manual steering unit. Or, better yet, removeany parts that aren’t required. Although a street vehicleneeds a heater and windshield wipers, a race vehicledoesn’t. Back seats are dead weight. If you can’t removesomething, can you move it to the rear? The battery is agood example. Weight moved to the rear will help improvetraction. Lighten up. Not only will your reaction timesimprove, but so will your time slips. Remember, 100 lbs. =.100: that is, every 100 pounds you remove will lower yourE.T. by roughly a tenth of a second (and be easier on yourdrivetrain as well).Before we look at the rear suspension, let’s see what‘shappening when you launch your vehicle. First, the bodywants to move in three directions. It wants to rise in thefront and squat in the rear from weight transfer, and it wantsto roll over to the right (passenger side) from engine torque.The rear axle torques in the opposite direction. It wants topick up the right rear tire. This is because the engine anddriveline run in a counterclockwise direction (as viewedfrom the rear). This means the left rear gets planted but theright tire gets “unloaded.” In this condition, the left tiremust provide most of the traction while the right tireprovides very little. Something else happens, too. Thedifferential wants to flip over backwards! The tires move ina forward rotation and the rear end wants to react in theopposite direction. The pinion wants to “climb’ the ringgear, so to speak. These are basic laws of physics and aregoing to happen no matter what. You can’t stop thesereactions, but you can put them to work for you, and biasedleaf springs do it best.Biased leaf springs mean that the right spring has moreleakes and thus more forward stiffness than the left. Theextra stiffness causes the body’s roll to the right to forcethat right tire back on to the track, allowing both tires tocarry an equal dynamic load and provide equal dynamictraction, making both of your rear tires work equally. Anadded benefit is that, with both tires biting, the vehiclelaunches straight and your E.T. gets better.As for tires, more tire means more stick, but there’s no needto .go overboard. A 12 second vehicle doesn’t need 17inches of Top Fuel rubber, but a little extra is better than notenough. Most 1968 and newer vehicles have prettygenerous wheelwells. Remember that wider is not the onlyway to go. Instead of tubbing your racer out and moving thesuspension inboard, try a bigger diameter tire. Largerdiameter tires have a bigger “footprint” than smallerdiameter tires of the same width. Be sure to keep therelationship of tire diameter to rear axle ratio. Largerdiameter tires give the effect of a numerically lowergearset, but new gears can be less costly and certainly fasterto install than wheel tubs and an all new rear subframe andsuspension.Now that we have you off the line and cutting consistentlylow reaction times, how do you get the vehicle to runconsistent elapsed times? Generally, you’ll find that onceyou have the starting line down, your vehicle should berunning much more consistently already. With the rearsuspension working and the tires big enough to hold thetrack during gear changes, your E.T.s shouldn’t vary bymuch. But how do you get them to settle down even more?The answer: attention to detail.The vehicle must be able to make every pass under fullthrottle for the entire length of the track before you caneven consider getting consistent. This is just goodmechanics. If the vehicle won’t, why not? Let’s look atsome possibilities.Does the ignition system provide enough spark? Need newspark. plug wires, higher voltage ignition coil, better ECU,or new distributor cap? As a rule, ignition systems will actup as engine load increases-high rpm in high gear.However, if the vehicle misses in first but then clears up,the trouble is probably not the ignition.. ..-. T -1

OFF-ROADING AND RACING 481Does the fuel delivery system provide a constant supply ofpure liquid fuel (not foam) to the carburetor? Low pressurewill allow carburetors to run lean (dry); too much pressurewill force the needle off the seat and they’ll run rich (flood).Foamed fuel is only slightly better than no fuel at all. A fuelpressure gauge is mandatory if you are troubleshooting apossible fuel system problem. Tee it in right where the fuelline attaches to the carburetor. However, a word of caution.Fuel pressure gauges must NEVER be mounted inside thevehicle unless they are specifically designed to do so. Thisis an extremely dangerous fire hazard. Mount the gauge onthe hood so you can read it with only a glance. If you havetoo much pressure, install a regulator or adjustheplace theone already on the vehicle. Too little pressure, check yourpump for output, both pressure and volume, and check yourfuel lines for kinks and adequate size. Fuel lines for serioussix cylinder race vehicles should be 3/8“. Dual purposevehicles should use 5/16”.Mechanical problems, such as weak valve springs, willusually show up at a given rpm, without concern to engineload or how you got there. If you have a problem at 4,800rpm, regardless of being in 1st or 4th gear or whether yourolled the throttle on or mashed it, it is generallymechanical, not fuel or electrical. Get out your manuals andstart checking clearances, pressures, and preloads.Last, but certainly not least, practice, practice, practice. Didwe say it enough? OK, one more time: PRACTICE. Nowthat you have the vehicle in condition to cut a Five-0 lightand run right on the dial-in, what good is it if the driverdoesn’t react to the tree the same every time? The vehiclecan only run as consistently as it is driven. Drive a goodrace vehicle badly and you have a bad race. When yourvehicle is right, it is all up to you. You might notice that wenever mentioned roller camshafts, clutchless transmissions,expensive cylinder heads, or Pro Stock-style tube framechassis. To become a good bracket racer you don’t needthem. Become consistent first, then get fast. Developcontrol first, then blinding speed. There are plenty of racerswho come to the track every weekend with the “trick-ofthe-week.’’The vehicle changes every week and they can’tstring two runs together within a tenth of each other. Theyget beat the 1 st or 2nd round every time, only to return thefollowing weekend with a new trick to “guarantee” success.Consistency means not only the vehicle’s performancecapabilities and your driving ability, but also the vehicleitself. If you run what amounts to a different vehicle everyweekend, it will be very difficult to learn just what you andthe vehicle are really capable of.That’s it, the basics of bracket racing consistencycondensed into one short course. One last word of advice:read all of your Mopar Performance Parts books (as well asyour service manual) completely. They can save you frommaking poor choices or decisions, especially when you’rejust starting out. No more lecture. Make us proud (beat theFords and Chevys). Class dismissed.

482 MOPAR PERFORMANCE PARTSBUILDING YOUR PERFORMANCE VEHICLE INSTAGESThe large number of racing classes, sanctioning groups, andtypes of performance vehicles makes it impossible todescribe the “perfect” way to modify regular productionvehicles into competitive machines. There’s simply no onebest method. It all depends on what kind of vehicle youstart with, what kind of vehicle you want, how muchmechanical expertise you have, and perhaps mostimportantly, how much money you have to spend.Of course, if you have the money and know exactly what itis you want to do, then you’ll probably want to perform allthe modifications at one time. On the other hand, if you haveto stretch your money and like to tinker and learn as you goalong, then you’ll no doubt prefer building your vehicle insteps. Racers have been doing it this way for years.The following is a general four-step method toprogressively dial-in more performance. It’s based on the“modular” concept, whereby goals are achieved byincrements (phases). Each “phase” involves greaterperformance capability, cost and complexity. Afterward,we’ll list specific Mopar Performance engine packagerecommendations for your Jeep.Stage 1 : Induction, Exhaust and TimingStock induction and exhaust systems generally are notdesigned for performance use. They tend to restrict enginebreathing. And since engines are basically air pumps, this inturn limits performance characteristics. The first step ingetting started on the road to improved performance is toinstall “bolt-on” items such as carburetors, intake manifolds,exhaust headers and high performance computers. There’sno need to get inside the engine to install these parts, andthey allow you to rev freely to 5,000 rpm or more. Thesepieces add a significant, but limited, horsepower increase(unless further engine modifications are made).Stage 2: Cams, Valve Train and ChassisThis second phase allows the full potential to be realizedfrom the Stage 1 modifications. The idea is to install ahydraulic cam with a good mid-range power curve that hasall-around applications. By eliminating travel from thelifter, it’s possible to rev up to 6,500 rpm. Of course, as withany cam installation, it’s important to also installcompatible lifters and associated valve train components.At this point, perhaps as much as SO horsepower has beenadded over the stock engine. Therefore, a number of chassisimprovement items such as shocks, springs and tractionbars should be added.Stage 3: Advanced Engine and ChassisModificationsWe now begin adding some very sophisticated racingequipment. This becomes somewhat expensive. It takes alot !of money to rev out to the 7,500 rpm range, which iswhat things such as mechanical cams, heavy duty valvetrains, forged high compression pistons, and deep sump oilpan:.; allow. In the chassis area, one-piece axle shafts,reinforced axle housings and heavy duty transmissions andclutches should be considered. (Obviously, chassis itemswill vary depending on the type of racing you want to beinvolved in.)Stage 4: All-out Competition ModificationsThis step is for the “big shooters” who run the whole thing.Engines that operate above 7,500 rpm and chassis whichare subjected to tremendous loads require the very bestpieces and optimum know-how. Money is not an objecthere if you want to be competitive. Success requires you togo all the way, especially in paying attention to details andblueprinting specifications.MOPAR PERFORMANCE PARTS ENGINEPACKAGE RECOMMENDATIONSJeep enthusiasts will find these tips helpful in selecting themosl advantageous parts from a cost and performancestandpoint. They were developed by DaimlerChrysler andMopar Performance Parts and represent combinations ofcompatible parts best suited for given performance levels.Refer to the latest Mopar Performance Parts Cutalog formore details.2SL, Jeep 4-Cylinder Engine PackageRecommendationsStage IU n e Packaae ASet Timing for Maximum HorsepowerHigh Performance Hydraulic Camshaft - 240” (P4529656)or 248” (P4529657)Valve Seal Package (P4529661)Valve Spring -Conical (P4529215)Conical Retainer (P4529217)Low Restriction Exhaust(Estimated 10 to 20 hp gain over Stock configuration)T --n 1

OFF-ROADING AND RACING 483Stage IIEnaine Packaae BSame as Engine Puckage A except for the following items:High Performance Hydraulic Camshaft - 256" (P4529658)or 260"Centerline Cam with Bushing Kit (P3690936)Backcut Valves (P45292 12-2 13)Richen CarburetorEngine Oil Cooler (P4529690)Exhaust Headers(Estimated 20 to 30 hp gain over Stage I configuration)Stage 111Enaine Packaae CSame as Engine Packages A & B except for the followingitems:Increase Compression RatioHigh Performance Hydraulic Camshaft (268")Ported Cylinder HeadIntake Manifold Attaching Package (P4529679)Good GasHeavy Duty Rod Bolt and Nuts(Estimated 20 to 30 hp gain over Stage I1 configuration)4.0L Jeep In-line 6 Engine PackageRecommendationsStage IEnaine Packaae ASet Timing for Maximum HorsepowerHigh Performance Hydraulic Camshaft (P4529228-229)Valve Seal Package (P4529240)Valve Spring-Conical (P4529215)Conical Retainer (P4529217)Computer (P4529334)Exhaust HeadersLow Restriction Exhaust(Estimated 10 to 20 hp gain over Stock)Stage IIEnaine Packaae BSame as Engine Package A except for the following items:High Performance Hydraulic Camshaft (P4529230)Centerline Cam with Bushing Kit (P3690936)Backcut Valves (P4529212-213)High Performance Computer (P4529334)Engine Oil Cooler (P4529690)(Estimated 15 to 25 hp gain over Stage I)Stage 111Enaine Packaae CSame as Engine Packages A & B except for the followingitems:Increase Compression RatioHeavy Duty Rod Bolt and NutsHigh Performance Hydraulic CamshaftPorted Cylinder HeadIntake Manifold Attaching Package (P4529680)Good Gas(Estimated 20 to 30 hp gain over Stage 11)360 AMC V-8 Engine Package RecommendationsStage IEnaine Packaae ASet Timing for Maximum HorsepowerHigh Performance Hydraulic Camshaft (240" or 248")Valve Seal Package (P4529629)Valve Spring (P4876063)Retainer (P4529616)4-Bbl. Dual Plane Intake Manifold4-Bbl, Carburetor - 600 cfm with Vacuum Secondary(P4349227)Low Restriction Exhaust(Estimated 50 to 60 hp gain over Stock)Stage IIEnaine Packaae BSame as Engine Package A except for the following items:High Performance Hydraulic Camshaft (256")Centerline CamshaftBackcut Valves (P4.529613-614)Exhaust Headers4-Bbl. Carburetor - 750 cfm with Vacuum Secondary(P4349228)(Estimated 30 to 40 hp gain over Stage I)Stage 111Enaine Packaae CSame as Engine Packages A & B except for the followingitems:Single Plane Intake ManifoldIncrease Compression RatioHigh Performance Hydraulic Camshaft (260" or 268")Ported Cylinder HeadsIntake Manifold Attaching Package (P452968 1)High Performance Mechanical Fuel Pump (P4529594)Good Gas(Estimated 45 to 55 hp gain over Stage 11)ODtional:More Compression RatioBigger ValvesBigger Camshafts..

-484 MOPAR PERFORMANCE PARTSSUSPENSION UPGRADESShock AbsorbersShock absorbers are probably one of the mostmisunderstood components of an automobile. Although it isnot a complicated part, most people just don’t understandwhat the shock absorber does or how it does the job it’ssupposed to do.Actually, the name “shock absorber” is somewhat of amisnomer. The shock absorber really doesn’t absorb shockat all. The spring system, or as it’s more commonly called,the suspension, does the shock absorbing. What iscommonly referred to as a shock absorber is really a deviceto dampen spring movement. In fact, in England andthroughout Europe it’s referred to as a “damper.” However,the name “shock absorber” has been around a long time, solet’s stick with it and discuss what shock absorbers do andhow they do it.Probably the most common misunderstanding is that if ashock absorber is worn out, damaged, or has lost its fluid,the vehicle will sag closer to the ground. However, the factis that the shock absorber does not support the weight of thevehicle body in any way, shape or form. The vehicle bodyis supported completely by the rear springs and frontsprings or torsion bars. While the vehicle is standing still,the shock absorber is static. It doesn’t go into action untilthe vehicle is moving.The suspension does the main job of absorbing road shockas the wheels roll over bumps or go into holes, but someminor road shock is absorbed by the tires before it istransmitted to the suspension. The larger the tires, the moreroad shock they will absorb, but handling and safetyconsiderations limit how large a tire you can use.Basically, there are two spring movements that occur whenthe wheels hit any road surface irregularities. If the wheelhits a bump, the wheel moves upwards towards the body.This action is called jounce. When the wheel moves awayfrom the body, as when going into a rut or pothole, it isreferred to as rebound.Jounce and rebound happen whenever there is enough forceencountered to flex the spring. The spring will thencontinue to flex in opposite directions until the force iscompletely dissipated. If the load that is applied to thespring is great enough, the spring reaction is transmitted tothe body. Body movement is, in most cases, opposite ofwheel and spring movement.When a vehicle travels over a sizable bump, you know thatthe wheels will cause the spring to flex toward the body.The upward flexing happens at the axle, or near the middleof the spring. The weight of the body causes the forces andmovement at the ends of the spring to be in the oppositedirection. The exact opposite happens when the wheelstravel down or away from the body as in a reboundcondition. When this happens, the weight of the body addsto the spring action and makes bouncing even more difficultto control.Installation TipsThere are only a couple tips to follow when installing shockabsorbers, but they are important. One is to make sure theshock is not aerated and the other concerns the bushings.When installing new shock absorbers, always purge theoperating cylinder, or pressure tube, so that the shock is notinstalled on the vehicle in an aerated condition. Air in thepressure tube can make shock operation soft, spongy, orspotty. It’s also likely to be noisy.To purge, hold the shock absorber right side up, or in thenormal operating position, and extend it all the way. Turn theshock over and compress it until it is completely collapsed.Extend and compress the unit at least a half a dozen times.What little, if any, air that remains in the fluid will be purgedafter a short period of operation. Remember - make sure theshock is vertical, and always extend the shock right-side-upand compress it upside-down.When you’re ready to install the shock, always extend it inthe upright position, never in a horizontal or invertedposition. If you do, you’ll aerate the shock all over again. Ifyou remove a shock and plan on reinstalling it, the firstthing to do is to invert it and compress it.Be extra careful not to ever throw any shock around or getcareless and drop it on the floor. The pressure tube could bedamaged or the piston rod bent. A bent piston rod will putabnormal pressure on the rod guide and seal and will ruinthe shock in a very short time. The bushings which are usedinside the mounting eyes of the shock must be installedproperly. There are also a variety of bushings that are usedfor different applications. Make sure you use the correctbushing and tighten the mounting nut to the correct torque.Another important factor about the bushings is that theymust be centered radially in their normal load positionbefore they are tightened. The rubber bushing in the shockabsorber mounting ring twists to allow movement betweenthe shock and the part it’s connected to. The bushing mustbe able to twist equally in either direction from the normalload position as the suspension moves up and down. Thistwisting action is known as “wind-up.”

OFF-ROADING AND RACING 485RS5000 Cellular Gas ShocksYear1984-921986-921986-92Vehicle Raised Height Front RearJeep Cherokee Stock- 3 ‘I PS249310 PS2493 11Jeep Comanche Stock-3” PS2493 10 Ps2493 14”Jeep Wrangler Stock- 1.5” P52493 12 P52493 13If the bushing mounting nut is tightened when the vehicle israised off the wheels, the bushing will wind up in onedirection when the wheels and suspension return to thenormal load position. The resultant wind-up puts a constantstrain on the bushing as well as the piston rod and seal,which can shorten the service life of the shock considerably.Note: Never use any kind of lubricant other than water orsoapy water on rubber bushings before or after they areinstalled. A lubricated bushing may slip and wear outinstead of flexing normally.RS5000 Cellular Gas ShocksOur RSS000 shocks bridge the gap between a comfortablestreet ride and high performance off-road control. This isaccomplished through a combination of our high-temp“cellular gas design” and our unique nine-stage velocitysensitivevalving. (Sold Individually.) Features include:Massive 1-3/8” steel piston head14 mm chrome hardened rodExpanded oil reservoirIncludes shock bootHeavy Duty Urethane Suspension BushingsAll Mopar Performance Parts bushings are manufactured oftough and durable polyurethane which gives the bushingshigher durometers than the production rubber units. Theadded stiffness can make the part stronger but the realadvantage is that the increased stiffness increases thecontrol of the part which can improve vehicle handling inrace situations.Steering StabilizersOur single stabilizers are high performance stabilizers thatwill exceed standard or so-called heavy duty stabilizers.They are engineered to work on standard vehicles duringhighway driving and will withstand the punishment of hardoff-road use.TIRESThe front and rear suspension are the link between thevehicle’s body and the vehicle’s wheels. The suspension andsteering systems control wheel movement and direction.However, it is the tires which actually determine direction.Don’t forget that the only contact the vehicle has with theroad is through the relatively small patch areas of the fourtires. All directional as well as starting and stopping controlis concentrated at these four tire contact areas.Choosing Tires for On or Off-RoadThey’re all round and black and they help propel your car,van or light truck, but the similarity in tires ends there. Anarray of choices await today’s tire buyer. Here are somesimple rules to follow when shopping for tires:First, analyze your tire needs-which aspects of tireperformance are most important to you? What weather,road conditions and passenger/cargo loads characterizemost of your daily driving? What type of vehicle do youdrive, and how far do you generally go? The largeassortment of tires on the market today virtually assuresthere will be several suited to your needs. But choosing thecorrect tire size and type is easier than you might think.If you’re happy with the tires that came on your vehiclewhen it was new, that’s a good place to start. You may wantto consider replacement with the same type and size thevehicle manufacturer selected as original equipment. Ifyour vehicle was made sometime in the last two decades orso, chances are that you have radial tires.Radial tires, known for durability and fuel efficiency thatexceeds their bias and bias-belted predecessors, are originalequipment on all vehicles today. Radial tires may beconventional, all-season, snow, or performance tires, eachdesigned to fit different driver needs and expectations. This iswhere an honest evaluation of your driving habits can pay off.

486 MOPAR PERFORMANCE PARTSYear Vehicle Single1984-921986-921986-92Jeep Cherokee with 0" to 3" liftJeep Comanche with 0" to 2" liftJeep Wrangler with 0" to 2" liftP524929 1P524929 1PS249292Heavy-Duty Urethane Suspension Bushings(Jeep)P4876222P4876223P4876224P4877225Leaf Spring Bushing Set-Front & Rear - CJ5, CJ7, CJ8 and1987-94 WranglerLeaf Springs Bushing Set - Front -CJ5, CJ7, CJ8 and 1987-94WranglerLeaf Spring Bushing Set -Front & Rear - CJ5, CJ7, CJ8, and1974-75 WranglerLeaf Spring Bushing Set - Rear -CJ5, CJ7, CJ8 and 1981-86WranglerP4876226 Body (Cab) Mount Kit - 1987-94CJ5, CJ7, CJ8 and WranglerP4876227 Body (Cab) Mount Kit - 1981-86ICJ5 and CJ7Body (Cab) Mount Kit - 1976-79CJS, CJ7, and CJ8Body (Cab) Mount Kit - 1974-75p4876230CJ5, CJ7, and CJ8Body (Cab) Mount Kit - 1955-73p4876231 I CJ5, CJ7, and CJ8P4876232 Sway Bar Bushing Kit - 15/16" -1987-94 CJ5, CJ7, CJ8 andWranglerP4876233 Sway Bar Bushing Kit - 11/8" -1987-94 CJ5, CJ7, CJ8 andWranglerHeavy-Duty Urethane Suspension Bushings(Jeep)P4876234-P4876236Sway Bar Bushing Kit - 15/16" -1981-86 CJS, CJ7, and CJ8Frame Shackle Bushing Kit - FrontFront & Rear - 1987-92 CJS, CJ7,CJ8, and Wrangler (4 Bushings)1'4876237 Frame Shackle Bushing Kit - Front- 1976-86 CJS, CJ7, CJ8 andW r a n g 1 e rP4876238 Frame Shackle Bushing Kit - Rear- 1976-86 CJS, CJ7, CJ8 andWrangler1'4876239 Transmission Torque ArmGrommets - 1973-86 Jeep CJ(2 per package)1'4876240 Track Arm Bushing Kit - Front orRear 1987-94 Wrangler-1'487624 1 Control Arm Bushing Kit - Front -1993-94 Grand Cherokee1'4876242 Control Arm Bushing Kit - Rear -1993-94 Grand Cherokee1'4876243-1'4 8 7 6244Sway Bar Bushing Kit - Front -1993-94 Grand CherokeeSway Bar Bushing Kit - Rear -1993-94 Grand CherokeeP4876245 Track Bar Bushing Kit - Front -1993-94 Grand Cherokee1'4876246 Track Bar Bushing Kit - Rear -1993-94 Grand Cherokee

OFF-ROADING AND RACING 487General Performance StrategiesCheck your vehicle’s door pillars or glove compartment fora tire information placard that lists the size, type andinflation pressure of tire recommended for your vehicle byits manufacturer. It may list other tire size options, butcheck with a tire dealer before making any modifications.The tire sidewall can also be a good source of informationfor the consumer. Molded into each sidewall by the tiremanufacturer is an alpha-numeric code such asP195/75R14. While this may seem like alphabet soup to tirebuyers, the codes are fairly simple: P is for passenger tire;195 is the width from sidewall to sidewall, measured at thewidest point in millimeters; 75 is the ratio of tire height towidth; R means radial; and 14 is the rim diameter in inches.Another tool for shopping comparison is the Uniform TireQuality Grading System (UTQGS). Under UTQGSguidelines, tire manufacturers test their passenger tires forthree performance factors: tread wear, traction, andtemperature resistance. The grades, which are reported tothe National Highway Traffic Safety Administration(NHTSA), are molded in the sidewall and appear on paperlabels affixed to the tire tread. All tires must also conformto federal safety standards.However, the UTQGS ratings are relative only within agiven manufacturer’s tire line. They may not be useful forperformance comparison among manufacturers due towidely varying driver habits and tire maintenance. Treadwear ratings cannot be translated into specific tire mileageguarantees, according to the NHTSA and the Federal TradeCommission.Since lateral stability is very closely related to tires andwheels, it is easy to understand why the largestrecommended tires, maximum duty ply rating andmaximum wheel rim width all contribute to directionalstability. This is particularly important on fully or heavilyloaded vehicles.Some of the following points were made earlier but they areworth repeating because of their effect on handling. Don’tput an oversize tire on an undersize rim. If the rim is toonarrow for the tire, the sidewalls will bulge excessively andYOU won’t gain anything in load-carrying capacity orstability. For every stability problem, be sure to check tiresize and type as well as tire pressure first.If you are in doubt about the brand, size, or type of tire ona vehicle with handling problems, install a set of tires andwheels from another vehicle (ask a friend). Make sure thesesubstitute wheels and tires are of the recommended size andinflated to recommended pressures. Road test to see if thecondition has improved.M 0 PAR P E R FORM AN C E PARTS I N FO R MATI 0 NAND SOURCESMopar Performance Parts Race TeamIn March of 1983, Mopar Performance Parts began its RaceTeam in an effort to keep in touch with more Moparenthusiasts and to get our latest engineering informationdispersed faster. At this writing there are over ten thousandmembers and we’re continuing to grow.Eighteen dollars is all it costs to get a full year’ssubscription to Mopar Perjormance News. MPN has all thelatest on new products, performance tips, race results, andmore. And we’ll toss in all the following items (including acurrent Mopar Pe@ormance Parts Catalog, a $5.00 value!)at no extra cost. And with your own personal ID cardnumber, you’ll be entitled to special incentives during theyear. Join now!One year subscription to Mopar Perjormance News(10 issues)Mopar Perjbrmance Parts CatulogMopar Sportswear CatalogRace Team Membership CardRace Team Member DecalDiscounts on Mopar Sportswear and CollectiblesRace Event Ticket Discounts

488 MOPAR PERFORMANCE PARTSTo enroll, call our toll free number (1-800-348-4696), orsend your $18.00 check or money order (made payable toDaimlerChrysler) to the following address:IMopar Performance Parts Catalog Center, Dept.NCTSP.O. Box 360445Stongsville, Ohio 441 36Note: The items listed in the Race Team package arecurrent as of August, 1999. Future packages may changesomewhat. Refer to the latest Mopar Performance PartsCatalog, Mopar Petjormance News, or call the MoparPerformance Parts Technical Assistance Hotline ( 1-248-969- 1690) for the most up-to-date information.Mopar Performance Parts Racing BooksThese speed secret performance books are the bibles ofMopar racing. They are filled with technical information,schematics, and other data you’ll need to build a winningrace vehicle. Let our factory engineers and MoparPerformance Parts race teams put their knowledge andexperience to work for you.~~Mopar Chassis - 8th EditionThis book is a compilation ofengineering information for thefull range of chassismodifications of rear wheeldrive cars. This 8th Edition hasbeen revised, rewritten andupdated to keep youcompetitive. DaimlerChryslerengineers have removed datedinformation and added 125 newpages to produce a book full ofhelpful hints forDaimlerChrysler enthusiasts, including some tips for racetrucks. Racers will find this book invaluable forsuspension, body components, axle, transmission, anddrivetrain build-up, plus much more. (370 pages)PS24944 1Mopar ChassiJ-8th EditionIMopar Oval Track Modifications - 3rd EditionThis is the book every Moparoval track racer must have. Itincludes complete engine andchassis build-up information.Speed secrets and racing tipsare directed primarily towardChrysler-Plymouth-Dodge V-8engines (273-318, 340-360 ‘A’engines; 361-383-400 ‘B’engines; 413-426W-440 ‘RB’engines; 5.2L and 5.9LMagnum engines). Additionalchapters include information on automatic and manualtransmissions, driveshafts and rear axles, front and rearsuspension, steering and handling, brakes, shocks, wheelsand tires, body and chassis. Late Model, Sprint Car, andNASCAR Truck racing specifications and performancerecommendations are also included. Summarizes morethan four decades of Chrysler-Plymouth-Dodgeinvolvement in oval track engineering and on-trdcktesting. (500 pages)P5249959Hemi@ EnginesMopar Oval Track Modifications-3rdEditionIf you currently own or haveever dreamed of owning aHemi-powered vehicle, youwant to get this new book fromMopar Performance Parts. Itincludes an extensive chapter onHemi development and racinghistory, as well as detailedinformation on 33 1-354-392Hemis, 426 Street and RaceHemis, Hemi Crate engines,carburetion, ignition systems,racing secrets, engine blueprinting, performancemodifications, and more! Contains hundreds of photos,illustrations, tables, and charts. The most comprehensivebook ever published on the Hemi engine from thecompany that built it! (456 pages)P48 7 6 8 24HemiB Engines

I- - 7 1OFF-ROADING AND RACING 489Magnum EnginesThis book from MoparPerformance Parts containsbook is a must for everyMagnum engine ownerhacer. (400 pages)P4876668Magnum EnginesSmall Block ‘A EnginesThis new book from MoparPerformance Parts contains~!i!E!%EI.__./MAQNUM ENolNESBig Block ‘B-RB’ EnginesThis new book from MoparPerformance Parts contains bigblock engine speed secrets andperformance modifications,highlighted by hundreds ofphotos, illustrations, tables, andcharts. Covers 361-383-400 ‘B’and 413-426W-440 ‘RB’engines. Also includesinformation on blueprinting.carburetion, ignition systems,oval track and drag racingpackage recommendations, and more! The mostcomprehensive book ever published on DaimlerChrysler‘B-RB’ engines. A must for every big block ownedracer.(424 pages)P4876825Six Cylinder EnginesBig Block ‘B-RB’ EnginesIf you own a 1986-91, 3.9L V-6engine or any 170- 198-225Slant Six engine, you’ll want toget this new speed secrets andracing modifications book fromMopar Performance Parts. Italso includes chapters on 3.0Land 3.3/3.8L V-6 engines, aswell as our new family of 2.7L,3.2L, and 3.5L aluminum V-6engines. This book is packedfull of six cylinder-onlyinformation, highlighted by hundreds of photos andillustrations. Includes horsepower tips, engine blueprintingprocedures, performance modifications, and racing secretsfrom our factory engineers and racers. (344 pages)P4876827Six Cylinder EnginesIblueprinting, carburetion,ignition systems, oval track and drag racing packagerecommendations, and more! The most comprehensivebook ever published on DaimlerChrysler ‘A’ engines. Amust for every small block ownerhacer. (400 pages)P4876826Small Block ‘A’ Engines

~ ~~~ ~ ~490 MOPAR PERFORMANCE PARTSNeon Performance ModificationsThis book from MoparPerformance Parts is a must forevery Neon owner and racer.Contains technical help andengineering informationcovering every aspect of vehiclepreparation, including 2.0Lengines (SOHC and DOHC),transmissions (manual andautomatic), body, chassis, andsuspension build-up. Covers alltypes of Neon racing. (350pages)P48766672.a2.5 FWD - 3rd EditionThis is the book for those ofyou who want to modify yourChrysler-Plymouth-Dodge 2.2Lor 2.5L FWD car. Includestechnical help and engineeringinformation covering everyaspect of vehicle preparationfrom engine and transmission tobody, chassis, and suspensionbuild-up. Indispensable forserious 2.2L and 2.5L FWDracers. Covers all types ofracing. (380 pages)P52495 85Neon Performance Modifications2.2/2.5 FWD-3rd EditionViper Crate Motor Installation Manualproject right, highlighted byover one hundred detailed photographs and illustrations.In addition to step-by-step installation procedures, themanual includes detailed package drawings showingengine and transmission mounting points, overalldimensions, critical clearances, etc., as well as importantinformation on the following systems: fuel delivery, fuelinjection, electrical, intake, exhaust, cooling, and oiling.Additional information includes long and short termstorage procedures, general specifications charts,troubleshooting tips, and available performance upgrades.Straight from the engineers who designed and developedthe now-legendary Viper! (94 pages)P5007220Viper Crate Motor Instrillation ManualMopar Performance Parts Catalogs~ ~~2000 Mopar Performance Parts CatalogThe Mopar Performance Parts Catalog is updated yearly,and includes hundreds of pages of parts for any Chrysler-Plymouth-Dodge-Jeep engine that you may have. Thiscatalog is a must for every Chrysler-Plymouth-Dodge-Jeep owner and racer.hote: The part number for this catalog changes each year.The number listed below is for the 2000 catalog. Refer tothe latest copy of Mopar Performance New$ or contactyour local Chrysler-Plymouth-Dodge-Jeep dealer for thelatest information.P50074002000 Mopar Pegormance Parts Catalog

~~OFF-ROADING AND RACING 491Sportswear Collection from MoparFor the DaimlerChrysler enthusiast in you. For completeinformation on the Sportswear Collection from Mopau,contact Collection Headquarters at P.O. Box 185,Southfield, Michigan 48037-018s. To order with a majorcredit card, call 1-888-267-2 187, or fax your order bycalling 1-888-452-9 197.Mopar Performance Parts Technical AssistanceIf you find that you need further assistance, or have anyperformance andlor modification questions you would liketo ask, you can contact Mopar Performance PartsTechnical Assistance.Write to:Mopar Performance Parts Technical AssistanceP. 0. Box 597Oxford, Michigan 4837 1-0597Or call:1-248-969- 1690Monday through FridayS:O0 a.m. - 12:OO p.m.1 :00 p,m. - S:OO p.m. (EST)Or fax:1-248-969-3342Mopar Performance Parts WebsiteBe sure to check out our new website. You’ll find all thelatest Mopar Race Team results, our on-line parts catalog,and a forum to ask our tech experts any questions you mayhave regarding your DaimlerChrysler product. The addressis: http:Nwww.performanceparts.mopar.com.Mopar Car Club DirectoryFor the latest and most up-to-date listing of Mopar car clubsthroughout the world, refer to recent issues of MoparPerj%rmance News. The entire club listing is updated on aregular basis.Mopar National EventsPerhaps the best way of all to find those rare vehicles andparts you’ve been looking for is to attend a major Moparnational event during the race season. The granddaddy ofthem all - the Mopar Nationals - keeps setting new recordseach and every year it’s run.You say you like Street Rods? Pro Mods? Trucks?Convertibles? Street Machines? Muscle Cars? Top Fuelers?Pro Stockers? Whatever your fancy, Mopar-sponsorednational events have them all! Keep up on all the events(times and places) by checking the latest issues of MuparPe rfo rmunce N e~xADDITIONAL SOURCESDaimlerChrysler Sources1 . D~iirnlerChrysler Service PublicationsOwner’s and service manuals for various Chrysler-Plymouth-Dodge-Jeep modela are available from 1975through the current year with only a few exceptions.For more information, write to:Service PublicationsDaimlerChrysler Corporation20770 Westwood RoadStrongsville, Ohio 441 36To obtain additional Chrysler-Plymouth-Dodge-Jeephistorical production information, write to:Walter P. Chrysler Museum800 Chrysler DriveAuburn Hills, Michigan 48236T -1-7

492 MOPAR PERFORMANCE PARTSDrag Racing Organizations1. NHRA(National Hot Rod Association)2035 Financial WayGlendora, California 91741www.nhraonline.com2. IHRA(Internationul Hot Rod Association)P.O. Box 3029Bristol, Tennessee 37625www.goracing.comlihraOval Track Racing OrganizationsNewspapers and MagazinesFor information on racing or where to buy vehicles andparts. some of the best sources are:1.2.3.4.5.6.7.8.Hemmings Motor NewsP.O. BOX 100-S19698Bennington, Vermont 05201www.hmn.comCars & Parts MagazineP.O. Box 482Sidney, Ohio 45367www.carsandparts.comOld Curs Weeklyc/o Krause Publications, Inc.700 East State StreetIola, Wisconsin 54990www.krause.comNational DRAGSTER2035 Financial WayGlendora, California 9 1741www.nhraonline.comDRAG ReviewP.O. Box 3029Bristol, Tennessee 37625-3029www.goracing.com/ihraDrag Racing MonthlyP.O. Box 420234Palm Coast, Florida 32142-0234Mopar Muscle MagazineSubscription Fulfillment CenterP.O. Box 334Mt. Morris, Illinois 61054-7937www.moparmusclemagazine.comShort Track Racing71 Wansley Drive, Suite ACartersville, Georgia 301201.2.3.4.5.NASCAR(National Association for Stock Car Auto Racing)P.O. Box Bin KDaytona Beach, Florida 32015www.nascar.comARCA(Automobile Racing Club of America)8 1 I7 Lewis AvenueTemperance, Michigan 48 182CASCAR, Inc.(Canadian Association for Stock Car Auto Racing, Inc.)117 SuperiorKomoka, OntarioNOL 1ROUSAC(United States Auto Club)4910 West 16th StreetSpeedway, Indiana 46224ASA(American Speed Association, Znc.)P. 0. Box 2500Anderson, Indiana 4601 1Sports Car Racing OrganizationsSCCA(Sports Car Club of America)National Office9033 E. Easter PlaceEnglewood, Colorado 801 12www.scca.org

Chapeer 9Additional Infomationl- - 7 7

494 MOPAR PERFORMANCE PARTSRACING FORMULASThere are many mathematical formulas used by racers for various performance calculations. For your reference, we havereprinted several of the most often used formulas.For reference:I1pi = 3.1415927-Pi= 0.7853982l 4ICylinder VolumePi 2- x bore x stroke4Compression Ratiorcylinder + chamber volumechamber volumeCylinder DisplacementChamber VolumePi- x bore 2 x stroke x number of cylinders4cylinder volumecompression ratio - 1 .OStrokeDisplacement Ratiodisplacement- Pi x bore’ x number of cylinders4cylinder volumechamber volumeBoreHorsepower1I ~~ displacement$ x stroke x number of cylindersrpm x torque5252

ADDTIONAL INFORMATION 495TorqueQuarter Mile E.T. Estimate5252 x horsepowerx 5.825Bhp Losselevation in feet1000x 0.03 x bhp at sea levelwhere:weighthp =(E.T.t 5.825)3(:Jweight = ___xhpDetermining Optimum Overall Quarter MileGear RatioQuarter Mile mph Estimatetire diameter rpniManual transmission = X-340mph mphtire diameter rpmAutomatic transmission = X-335mph mphwhere./ mph=3- hp x234weighthp = (s)3x weightweight =3x hp

~~~~~~496 MOPAR PERFORMANCE PARTSCHRYSLER-PLYMOUTH-DODGE-JEEP BODY AND ENGINE TYPESRear Wheel Drive and Four Wheel DriveTerminology Cross ReferenceBody TypeA-BodyB-Body1964-76 Valiant1964-69 Barracuda1964-76 DartAll DusterDemonsportScampSwingerCoronetSatelliteRoad RunnerChargerGTX R/TBelvedereSuper BeeCordoba1976-78 Fury1977-78 Monaco1978-79 MagnumE-Body 1970-74 Barracuda- Challenger~-~ ___ _ _ ~ _ ~ - ~F-Body 1976-80 Volare and AspenRoad Runner and R/TJ-BodyM-BodyAN-BodyDN-BodyR-BodyXJ-BodyYJ-BodvTJ-BodyZJ-BodyWJ-BodyT300-BodyVIPER-Body1980-83 Mirada andCordoba1977-88 DiplomatLeBaronGran FuryFifth Avenue1987-99 Dakota1998-99 Durango1979-81 New YorkerSt. Regis1984-99 Cherokee1987-96 Wranaler1997-99 Wrangler1992-98 Grand Cherokee1999 Grand Cherokee1994-99 Ram1992-99 Viper RT/lO1997-99 ViDer GTSRear Wheel Drive and Four Wheel DriveTerminology Cross ReferenceEngine TypeFour Cylinder 2.5LSix Cylinder170 (Slant Six)198 (Slant Six)225 (Slant Six)4.0LV-6 3.9L (through 1991)Magnum V-63.9L (1 992-present)‘A’ Engine 273318 (1967-91 only)340360 (through 1992)Magnum V-8‘B’ Engine 3613834005.2L (1 992-present)5.9L (1993-present)‘RB’ Engine 413426 Wedge440Hemi 426Magnum V-10 8.0LTerminology usage example:A 1973 Challenger equipped with a 340 engineis considered an ‘A’ engine, E-Body.

ADDTIONAL INFORMATION 497METRIC TO ENGLISH CONVERSION TABLEMultiply BY To Get Multiply BY To Getin-lbs x 0.11298 = Newton-Meters(Nom) (Nom) x 8.851 = in-lbsft-lbs X 1.3558 = Newton-Meters (Nom) (Nom) x 0.7376 = ft-lbsInches Hg (60°F) x 3.377 = Kilopascals (kPa) (kPa) x 0.2961 = InchesHgPoundslSq-in x 6.895 = Kilopascals (kPa) (kPa) x 0.145 = PoundslSq-inInches x 25.4 = Millimeters (mm) (mm) x 0.03937 = InchesFeet x 0.3048 = Meters (M) (M) x 3.281 = FeetYards x 0.9144 = Meters (M) (M) x 1.0936 = YardsMiles x 1.6093 = Kilometers (Km) x 0.6214 = MilesMilesIHour x 1.6093 = KilometerslHour (Krnlh) (Kmlh) x 0.6214 = MileslHourFeeVSecond x 0.3048 = MeterslSecond (MlS) (MS) x 3.281 = FeeVSecondKilometerslHour x 0.27778 = MeterslSecond (MIS) (MS) x 3.600 = KilometerslHourMileslHour x 0.4470 = MetersEecond (MlS) (MS) x 2.237 = Miles/HourCommon Metriic Equivalents1 Inch = 25 Millimeters 1 Cubic Inch = 16 Cubic Centimeters1 Foot = 0.3 Meter 1 Cubic Foot = 0.03 Cubic Meter1 Yard = 0.9 Meter 1 Cubic Yard = 0.8 Cubic Meter1 Mile = 1.6 KilometersT- T

T --- 1 -Jeep Engines-3rd Edition was written and edited by Larry S. Shepard andMichael J. Gingerella. Produced by Erin Kuechenmeister. With special thanksto all of our Mopar racers and enthusiasts who volunteered their time and effortin helping us make this book possible.ITIPrinted in the U.S.A.