since i am going to be pulling the heads off to cheak the block for cracks i need to know how to get more compression out of my 383 3.905 bore 4.0 stroke it has mms stage 2 heads milled .030 with the stock 98 head gasket .040 i think the cr ratio is about 10.5 i think i need to get to 11.0 i need to know how to do this because i dont know if you can mill the heads more or run a thinner head gasket?

 

what casting heads are these, your not 10.5 unless you failed to mention you have dished pistons.

going by what you'v given and assuming a 806 castings milled .030, 3.905 bore, 4.00 stroke, .040 gasket, 3.910 gasket bore, -.008 deck height i get 12.05 CR

 

sorry they are ross dished -9 with 806 casting

 

You can always mill the heads.

 

can mill the heads .010 and run a .030 gasket or mill the heads .020.

but i'd just start off with a new casting, 5.3 you'll have the smaller chamber to start off with.

 

They are milled .030 allready so i could go .010 more what would that give me for cr?

 

the stock 98 gasket is carbon composite it has a 4.135 bore and a .053 thickness

 

have you gone to www.smokemup.com? All the math calculations are there.

 

http://www.rbracing-rsr.com/compstaticcalc.html

 

http://camaroz28.com/services/calcs/

Mine is 11.7:1 with 65cc heads, .042 Cometic, +.007, -2cc, 6.125x4.00 and I run 92 octane no problem.