Serene

Well what is the biggest the chambers can be made while still having sufficient material left in the chamber?

slp223

Anyone have any answers years later?

Lonnie Pavtis

It is 64-65cc on a stock LT1 head.

I have built quite a few supercharger motors using this configuration without problem.

simple

i thought stock was in the high 50's?

and Lonnie, whats the Optispark replacement going too be thats mentioned on your website?

turbo_Z

I believe stock is 56 or 58cc but why would you want to open it up any more than that? Just buy dished pistons if you want to lower compression.

Injuneer

Stock is 54cc. Lonnie is telling you how far you can open up a stock head.

Gripenfelter

I had a set gouged out to 58cc no problem. Could have gone a little bigger.

Lonnie Pavtis

The reason for enlarging the combustion chamber is to get a certain compression ratio without custom pistons.

You can achieve approx 9.6-9.8:1 with flat top pistons using a 65cc chamber on a 350ci. Great for a 10# or less boost application while still being very responsive on the street.

The common 16cc dish SRP on a 383 will give approx. 9.3-9.5:1 with the same chamber. These work very well up to the 15# boost range on pump fuel.

Most common dish pistons drop compression below 9:1 & you will lose some power & drivability on a mild street motor. This bridges the gap between the 10:1 & above flat tops and the low compression setups.

CANTONRACER

Before I would touch my combustion chambers...I would want to know what the head gasket thickness is, quench & deck height.

Then running flat tops, how many cc's do the valve reliefs add?

I believe in running flat tops...but a little more planning I would be needed before I personally would open my combustion chamber...if anything, just around the exhaust valve to unshroud it.