Using 0.039" compressed for the gasket, zero deck, 5 cc's in the piston eyebrows I get 11.08:1 static c.r. I don't see how you could get to 11.72 with flat-tops in a 350. Even at 11.08, the cam's too short.
Anyway, with that much compression, start with a gap of 0.035". Widen it a little at a time to experiment, depending on your ignition system and the coil you're using.
With that much static you have more than plug gap to be concerned with. I would immediately change the cam to the comp 292 to bleed off some of that cranking pressure.
The squish or quench area is the gap between the piston flat and the head flat @ TDC, which allows the flame to accelerate and cool during ignition. The wider the quench area the more resistance you have to detonation. Also, the quench is a safety net so that your piston doesnt make contact with the head. You cant just deck blocks, shave heads and throw in some domed slugs. Life is not that easy.
Well, actually, the narrower the squish is, the more resistant the motor is to detonation. But there is a mechanical limit to how narrow you can go. That's why I was saying I don't see how you can build a 11.72 motor with 59 cc heads and flat-top pistons.
Timothy, how far down in the bore is the piston at top dead center?
The heads are already bolted down and I sat the engine in the car yesterday. This is my first real build. Watched and helped many times but this is my first time to do it and even then I had a friend that is familiar with Mopars help out. SO it is all new to me.
.025" might work on a Mopar, but on a Chevy, you're just begging the pistons to hit the heads.
GM makes .026" shim gaskets for less than $10 each, and .028" composition gaskets for a little more. I'd be more comfortable with one of those.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Hot Rod Forum
2.2M posts
175.6K members
Since 2001
A forum community dedicated to hot rod owners and enthusiasts. Come join the discussion about restoration, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!