Oldman, first you will need a leak down tester, snap-on has a nice one, also saw one in the summit racing catalog for $70.00. I have the snap-on , to doo a leak down test first you will have to remove spark plugs, bring cly to test to t.d.c.
screw adaptor hose in to spark plug hole, hook tester to air supply(you need a compressor) zero tester gage then hook to adaptor hose you wiil get a reading of the percentige of air leaking past the rings.
2-3 % is perfect. Anything over 10-15 % and I would be tearing it apart for a inspection. It will show a cly or piston ring problem way before a compresion tester will.