Thread: compression

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Using a 0.030"-over 350 as an example, cylinder volume would be 727 cc's, chamber volume would be 76 cc's, eyebrows in the stock-type flattop pistons would be 7 cc's and the gasket volume at 0.039" compressed would be 9 cc's. We'll assume a zero deck. Adding all volumes together (819) and dividing by compressed volumes (92) yields a c.r. of 8.9:1

A change to 64 cc heads with all else being equal would result in dividing (807) by (80) and would yield a c.r. of 10.08:1

Here's a paper I wrote on figuring c.r.
http://streetmachinesoftablerock.com...opic.php?t=124

As far as the cam goes, let me try to explain....
The most important aspect of any cam is the intake closing point on the intake lobes. This is the point that determines how much of the mixture that has been drawn in by the piston on its downstroke will be trapped and compressed as the piston moves to top dead center and the spark plug fires. This intake closing point is directly tied to the static compresssion ratio of the motor.

Contact your favorite cam grinder for a recommendation when you have all your figures together and know exactly what you want the motor to do and when you want it to do it.