Originally Posted by John_Kunkel
From my experience, rocking back and forth from TDC a little does improve the test results.

I've seen 3 to 6% shruggy
The piston and ring design has a lot to do with leak down results.
All the stock aircraft pistons I've seen have tapered rings sides, (not square or parallel like car motors have) like some H.D. diesel motors do, correct John ?

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)