Comp ratio change

[vettasy]

Can someone help me here. I'm looking at a set of heads for my L48 to replace the stock 76cc chambers with 70cc chambers. What will that do to my comprssion ratio currently 8.5. What is the formula to work this out.

 

[78SilvAnniv]

Not sure...

...but you may find something to assist you in working out the formula at the top of the page under "Tools".
I know there are 'tools' for other calculations, but I'm not sure if this particular calculation would be included.
Heidi

 

[Jack]

This one works well if you're lazy (like me)

http://www.smokemup.com/auto_math/compression_ratio.php

Or, if you're not ... some formulae are right here at CACC

http://corvetteactioncenter.com/tech/tools/formulas.html

note 1: your pistons are probably dished & have 4 valve reliefs ... and yields a "dish volume" of about 10cc.

note 2: unless your block has been resurfaced (decked) ... the pistons are about 0.025" "down in the hole" ... yielding a deck height of about 0.025".

note 3: standard head gasket is about 0.039" thick and has a bore of about 4.166" ... this varied somewhat from year to year & mfg to mfg & lot to lot.
JACK:gap