Had my buddy do a leak down and all cylinders are at 20% when is it time for a rebuild. At what percentage do you say time for a rebuild
especially if he's using rings with big gaps. i've got a pretty good size gap on top and bottom, i leaked 10% at 3hrs on the motor, and after about 30hrs, its down to 8%. the rings broke in and sealed up alil more over time. still have 240psi cranking compression across the cylinders, and i've put alot of nitrous thru it.An engine in great condition should generally show only 5 to 10% leakage. An engine that’s still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates trouble.