basically heres my problem. im trying to figure out what my current compression is and without pulling everything apart and cc;ing and everything else. and then im trying to figure out what a cometic gasket would do to help me.

I was shooting for a 9:1 compression.

i have a 383 that has 9:1 compression pistons in it.
Diamond Racing Dish Piston built for 20+psi boost w/XHD H-13 piston pin .927",2.500",.155 wall and custom Plasma Moly File piston rings 3.905 bore

ok heres the catch. that would be 9:1 cr on a ls1/6 with 241 heads with
Combustion Chamber Volume: 66.67cc

but i dont have 241 heads I HAVE 706 heads which have a
Combustion Chamber Volume: 61.15cc


the specs i got from https://ls1tech.com/forums/generatio...ead-guide.html

i also found this:
The below CR numbers are with the stock GM 5.7L displacement LS1 graphite head gaskets installed.
72.27cc = 9.1 CR
71.71cc = 9.2 CR
71.05cc = 9.3 CR
70.59cc = 9.4 CR
70.03cc = 9.5 CR
69.74cc = 9.6 CR
68.91cc = 9.7 CR
68.35cc = 9.8 CR
67.79cc = 9.9 CR
67.23cc = 10.0 CR
66.67cc = 10.1 CR (stock LS1 head spec)
66.11cc = 10.2 CR
65.55cc = 10.3 CR
64.99cc = 10.4 CR
64.43cc = 10.5 CR (stock LS6 head spec)
63.87cc = 10.6 CR
63.31cc = 10.7 CR
62.75cc = 10.8 CR
62.19cc = 10.9 CR
61.63cc = 11.0 CR
61.07cc = 11.1 CR
60.51cc = 11.2 CR
59.95cc = 11.3 CR
59.39cc = 11.4 CR
58.83cc = 11.5 CR
58.27cc = 11.6 CR

so the question is with my heads and pistons what is my compression ratio currently with a stock head gasket because being that i have 9:1 pistons and less ccv the compression would be a wash or higher or lower i would imagine higher.... is it 9.5:1 10:1???

next question. asuming i have stock replacement head gaskets. what head gasket would i need to keep my cr at 9:1.

Thanks in advance for any help.

 

What cc dish is the piston? Either way, going from a 67cc head to a 61cc head will raise the compression by .52.