Agree with all the previous Mike, especially that if getting the engine hot to do the test. I
might add the even if your valves are hand lapped and seal perfectly and hold water you
will still have some leakage past the rings, no cylinder seals perfectly. Cold the ring gap
isn't closed up and you will have more leakage past the rings, warm and there will be a
minimum of leakage. Also when the engine is running the combustion pressures force the
ring out against the cylinder wall for a better seal so you will never get a perfect seal
during a leak down test.
As Jerry posted, a 90% reading would be excellent. 8-10% on a normally aspirated engine
knocks it out of the ball park and variation of 4-5% cylinder to cylinder is normal, but
even a 10% variation isn't anything to worry about unless your building an engine to run
at Indy.
Denny Graham
Sandwich, IL
Denny Graham
Sadnwich, IL
