<VV> Compression ratio for 140HP Engine

[john frugoli]

          Can anyone tell me about OEM specs on combustion chamber volume for 140 heads? Also cylinder seating surface depth in inches for same, and anything on squish or quench area  to piston top clearance for optimum turbulence with out risk of detonation using pump gas (91 Octane max). My performance book says around 0.025" is optimum, although, this book was published many years ago when we had higher octane fuels (including leaded fuels) at the pump. I don't know what is safe for 91 octane unleaded and a Corvair air cooled engine with 140 heads. I would also like to hear about solutions for detonation in these air cooled engines today? What is acceptable compression ratio for pump gas with these engines? Thanks. John 

       
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