Here's the way I figure compression ratio- - - -

Add cylinder volume + combustion chamber volume + deck clearance volume + head gasket volume = total volume

Divide total by: chamber + deck + head gasket. That's coming out somewhat over 12:1 on this engine.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!