dlt76028

iTrader: (13)

yea tomorrow im doing a compression test. and the codes are p0300, p0135, p0327. and the preassure is really high all the time anytime i give it to much gas the dipstick blows out i think my pressure gauge is going to atleast 80. im starting to think its a cracked piston making to much preassure in the block. the poping and hesitation still beats me?

Rafedial

iTrader: (7)

Did you check the supply voltage to the the ignition coils? The missfire could just be one cylinder. A Tech2 would be able to pinpoint that cylinder.

Have you had the valve covers off? Sounds like maybe one set of valve are bent.

Think about it logically. During normal rotation of an engine all pressure is eventually relieved in the exhaust stroke. Since you are blowing the dipstick out, you are not completely relieving that pressure. So something is holding it in, like a set of valves not opening. If you got time, pull the rockers off and check the pushrods, roll them on a flat surface.

Do you have an unburnt exhaust smell/rotten egg? Could be a partially clogged catalytic converter. This is cause by a missfire/dead cylinder that has been missing for a while, cause unburnt fuel to collect in the cat.

My last idea is a clogged injector, causing no ignition.

Try running the engine and removing a plug wire one at a time, then replacing each time you remove one. If you remove one, and the engine sound changes, then you have pinpointed the miss. If it doesn't change, go to the next wire. Good luck!!!

nonnieselman

iTrader: (10)

I think you mean if you remove a plug wire and the engine doesnt make a different sound then there is your problem... if you remove one and it shakes a lil and changes notes... then you know that one is good.....

Rafedial

iTrader: (7)

Yes, that's what I meant.

That's enough brew for the night for me!!

dlt76028

iTrader: (13)

just did a compression test and left bank 1,3,5,7, had between 78-105 and the right side 2,4,6,8 had 205-220? why is the right side so high and the left side so low and their all consistent? could it be head gasket wrong or valves bad on the low side?

BlackGMC

iTrader: (31)

Did you remove the heads before you installed it?

dlt76028

iTrader: (13)

the engine was a short block and i put new gaskets and heads on it.

dlt76028

iTrader: (13)

I just had a thought. when I did the rockers and pushrods i just dropped the pushrods in and then bolted the rockers down all the way BUT i didnt turn the cam over and tighten the rockers down more that were higher on the cam lobes. so that would mean the valves arent opening and closing right and making the poping i hear and the misfire and possibly explain why that whole side only has 78-100 compression? what do you guys think?

Wide Open

I don't think that would be your whole problem. The LS motors are supposed to be torque tightened not adjusted with a certain amount of preload like the Gen II an older SBC's. Maybe the valves are sticking or maybe the motor was over on its side during storage and the rings in the left bank are not sealing well as mentioned before.

dlt76028

iTrader: (13)

I did squirt oil in the cylinders that had low compression and re tested and the numbers didn't change at all. also the engines not using any oil. and i know that valves that dont close all the way cause backfiring and running rough like mines doing.