Ok I have read the sticky on compression ratios but I just get confused and dont know what formulas to use. I have a 408 stroker motor I am putting together. It has 4.030 bore, 4.00 stroke, and -2cc flattop pistons. I will be using the .04 cometic head gaskets. My question is I am trying to get 11.5-11.7 compression ratio. I have 6.0L p.p. heads with the 72 cc chambers. What size chambers do I need for this compression. When I calculate it I come out with 64cc chamber gives me 11.5:1 comp. Is this Right? Any help would be great.

Thanks
Zach

 

Your 72 cc chambers should be good for what you want.
It all depends on what your piston to deck measurement is, and what you meant by -2cc on the piston.
Are you at zero deck with 2cc valve reliefs?

Here's one calculator, and there are many out there.
http://www.torinocobra.com/Randys_tools.htm

 

Looks like you currently have 11.14 to 1

That is based on a 72 cc chamber, piston out of the hole .008, and a 9cc gasket volume...about .040 -.045 thick depending on diameter.

You would need a 68 cc chamber to achieve 11.66 (.018 mill)

Tony M.

 

thanks for the help that all the info i needed

Zach