Interesting stuff. I knew that bigger capacity engines had a lower reading but I wasn't aware that it could be as low as the figures quoted here. I have a modified small capacity car engine that has a compression pressure of 225 psi.
A & C,
What does the term "staking" a valve mean? Thanks.
Ah, I think I see why now, so the test is done differently, by pumping compressed air into the cylinder using the 80 psi as a datum and effectively doing a leakage check. On a car engine you crank it over on the starter and see what you get, comparing the differences between cylinders that way.
And "staking" means giving it a bit of persuasion to seat properly. Surely though, as a valve pounds up and down due to normal engine operation, does this really work to improve the seal with the seats?
Just curious.