Chevy 350 backfires?

Question

I got a 78 scottsdale truck, with a 350, I recently got some work down on both of the heads, it was running before but running rough, it had a bad valve. Anyways, got the heads re-done both, I got one side shaved and the other I didn't. It's got a brand new carb on it edelbrock carb, new head gaskets all that. New plug, etc. My d**n plugs keep getting fouled though, I guess cause I haven't tuned the carb yet. my timing is all good. But the question is why would it be backfiring like this? Timing is right, could it be my valved not adjusted right? Or either one of the heads, not being shaved. On the left side the heads put about 180 psi compression, on the other it's puting out about 130 and little higher numbers, Whats the problem?

Answer 1

Hey, it sounds like you are having valve issues. I'd readjust your valves and double check your valve timing. As far as shaving one head and not the other, you've changed your compression ratios on one side of the engine and not the other. You need to shave the other head the same, or you need to get a thicker head gasket for the side you shaved to make up for the missing material.

Answer 2

Recheck your spark plug wire firing order. You may have crossed 2 wires when re assemblying.

Answer 3

personally i never would have put monies in an old gas hog like that.

check the vacuum advance hose if it has one for leaks.