Too much compression with vortec heads?

[inglewatt102]

I have a '70 350 with flattop pistons and about to put my 906 vortec heads on fresh from the shop thing is the machinist thinks I might be making too much compression with these pistons.Do I have to get dished pistons now or is there another way to lower it without retarding the timing too much for pump gas?Thanx again guys

[toddman67]

If you could get some fel-pro gaskets that are 0.40 thickness(crushed), you could realize a reduction in compression. Search around and look for different thickness gaskets.
When I originally put my 355cu engine together, I used 0.18 metal gaskets. They worked fine on 100+ octane gas or xylene mix, but I wanted to use pump gas so I changed the gaskets.
At the time I was using 63cc chamber heads and Manley flat tops. Now I am running 68cc AFR aluminum heads with no problems on 93 octane pump gas.
Check www.summitracing.com or engine parts warehouse, they generally offer a variety of gaskets.

[maxwedge]

What is too much compression?

[inglewatt102]

Too much for pump gas is what I meant.Its a daily driver just got the vortec heads to try an get some torque ya know.So a thicker gasket might bring down the compression?Just dont wanna have to replace perfectly good pistons and spend even more money than I originally thought.(Too late for that allready tho)

[toddman67]

The thicker the gaskets, the more area you have, so the compression ratio will decrease.

[toddman67]

I would use the felpro #1003 head gasket. 0.041" compressed thickness. If the block was not 0-decked it should change the compression ratio from say 9.7 to almost 10.5. Not knowing all the peticular specifications on your engine, it would be hard to determine. These gaskets work good and should solve your issue.
Don't quote me on these compression ratio numbers. Deck height, stroke, bore, valve reliefs, pistons, head chamber size and cam spec's all work into the Dynamic equation.

[inglewatt102]

Alright thanx for all the help guys

[novaboy22]

run a cam with more overlap, as long as you dont have more than 200psi or so of cranking compression you shouldnt have a problem with 93 or even 91 octane gas, im in norther cali were the gas is crap and my 190 psi of cranking compression doesnt give me an issue, mind you my cam is at 14 degrees retarded initial. lol but yes a thick gasket would be an alternative also.

[novaboy22]

Originally Posted by maxwedge

What is too much compression?

compression=power, power=happiness