28-01-2020, 08:59 AM
Someone mentioned (Chris KC I think) compression ratio of Speedex head as being roughly 10.5 to 1.
I have been measuring combustion chamber volume on my Speedex head which is 35cc with spark plug fitted. This with a standard HC gasket 0.025” (used, therefore already squashed) and assuming pistons at TDC are level with top of cyl block, (they are below in fact) and a +.060” oversize bore gives less than 6.5 comp ratio.
Cheers,
Dave.
I have been measuring combustion chamber volume on my Speedex head which is 35cc with spark plug fitted. This with a standard HC gasket 0.025” (used, therefore already squashed) and assuming pistons at TDC are level with top of cyl block, (they are below in fact) and a +.060” oversize bore gives less than 6.5 comp ratio.
Cheers,
Dave.