Severe Pinging

[cdaniels3]

Greeting everybody! I am in the process of building a 327 for my 91 cheyenne truck. The problem right now is the the current engine, a 4.3 v-6 has a bad case of preignition. I have adjusted the timing according to the manufacture spec and no change. Any idea's?

Thanks

Chuck

[WRENCHD]

you mite try to replace the knock sensor if you are running the tbi and the stock ignition. if that don't work then maybe check the timming chain to see if it jumped. wrenchd

[WRENCHD]

well i agree with you about the timming chain and that it is unlikely that it jumped and that it would run, althrough i have had acouple engine's run with a chain that has jumped 1 tooth, just very poorly. i was just tring to help him check all the bases thats all. it does sound like an ignition problem, and if he has a cat on the vechile then i would check out the poss of pluged exhaust also jmo.

[artinla]

It could be carbon caked on the piston tops either glowing or causing the compression ratio to go way up.

Rev the engine up and slowly drizzle some water down the intake. When the engine slows down, stop and let it catch it's breath. Do this with about a beer can full of water and it should knock a lot of the carbon loose. DON'T do it all at once or you can bend a rod, just drizzle the water in slowly.

If you have that much carbon, you can bet that the catalytic converter is plugging up and you have oil control problems.

[DONNY43]

Greeting everybody! I am in the process of building a 327 for my 91 cheyenne truck. The problem right now is the the current engine, a 4.3 v-6 has a bad case of preignition. I have adjusted the timing according to the manufacture spec and no change. Any idea's?

Thanks

Chuck

HI,YOU NEED TO USE PREMIUM GAS! AND MAKE SURE YOU ARE TIMING TO SPECS,,IF ENGINE IS OLD YOU MAY NEED TO FIND TUNE HER BY EAR,BECAUSE YOUR ORIGINAL MARKS MAY HAVE CHANHED WITH NORMAL WEAR AND TARE!