Yeah, I have got a compression question with some heads. Remember that I have a 350 4-bolt IRON block, not an LS1. But I haven't purchased any pistons yet so we can keep that out of mind. But I want to run N/A so I will do high compression. What cc head should I go with? 64cc or 76cc? If I went with the 76cc, what kind of compression would I be looking at? Thanks all

 

well if you are planning on running a high compression motor, obviously you should choose the 64cc and forget about the 76cc.... then get domed pistons if you want even higher. Just throwing out a guess, but w/ 76cc's you'd be looking at around 8-9 CR

 

It's impossible to say without more information. you need to know the piston dish/dome volume, deck hieght, and head gasket thickness to work any of it out.

As a generall rule tho, a smaller chamber is better. Just be sure you get pistons that will keep compression to a reasonable level with it.

 

So maybe with a 383 in the future, I would want to go with the 76cc's, because with that longer stroke, it will raise comprerssion in itself. Also, I plan on some high compression, forged pistons by either TRW or Ross. thanks,

 

Well:
Bore = 4.03
Stroke = 3.48
Head vol. = 76cc
Valve reliefs = 2cc (Flatop Pistons)
Deck Height = .025"
Head Gasket = .040" Thick
Head Gasket Bore Dia. = 4.166

Comp. Ratio = 8.89 to 1

Same eng. with "0" deck = 9.37 to 1

Same eng. with .025 deck and 64cc heads = 10.07

Same eng. with "0" deck and 64cc heads = 10.70 to 1

Auggie

 

thanks auggie, you did the math for me. i appreciate that. That really helped out my decision. thanks,

 

Smaller chamber without a piston dome is more effecient and bigger chamber and a large piston dome. You should always go with a smaller chamber when possible, large chambers simply suck.

 

alright. Now if I can only find out my chamber size. *hand on chin* hmmmmmmm.

 

to generalize a bit you'd be ahead to go with small chambers and dished pistons as long as you can get the compression ratio you desire