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Discussion Starter #1
I would like to know how to calculate compression ratio. My engine is a standard bore/stroke 1967 327using stock cast flat head aluminum alloy, 4 dimple pistons. My heads are stock '461 castings with a combustion chamber of reportably 62.076 cc's.
The AMA specs rate the 327/275 at 10.0:1. This engine originally had the '462 head which also has the 62.076 cc. Is this a valid compression ratio? What is the formula for calculating compression ratio? What octane gas do I need to keep from detonation?

thanks
 

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You can download Comp Cams Camquest software from their page for free. It has many utility programs that come in handy as well as a cam selection program. One of the programs calcs CR.

Dave
 

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Compression ratio is the total volume of a cylinder at bottom dead center compared to the volume at top dead center (including combustion chamber and head gasket thickness).
 

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Discussion Starter #6
Thanks guys...looks like I'm at about 9.7....I better start saving for that high octane...

mo.
 
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