Jeep Engines - Oljeep

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.