Jeep Engines - Oljeep

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