Jeep Engines - Oljeep

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.