Leak Down Test Results

first part, no, compression readings can vary depending on wear in the timing set, camshaft, valvetrain, even a weak starter or battery can effect it. Same with vaccum leaks, wrn carb shafts, you name it.

Second part. When rings are new, there will be some leakage. after they have seated, they should leakdown in the 3-4% area. as they get tired, the walls get scored, out of round, etc, the amount they leak goes up. Keep in mind, the the leak tester is a percentage. A good cylinder that cranks 165psi, and has 4% leakage, is fine. One that cranks 120, but has 35% is pretty bad. If you cranked 135psi, but had 4% leakage, it means you may have a larger cam, or a weak starter, and the cylinder is still fine. That's why leakdowns can tell you more. They take more variables out of the equasion, so the answer is that much more concrete..