Posted by Steve in KY on Tuesday, November 26, 2002 at 11:31AM :
In Reply to: More compression questions posted by Gil Huguley on Tuesday, November 26, 2002 at 10:36AM :
OK, we use a compression tester which has two guages, and a regulator. Hook this thing up to the air hose with at least 100 PSI. Screw adaptor hose into one of the plug holes. Other plug still in place. Magnetos OFF!!!! Usually all cylinders should have one plug out at this point. Swing prop until you come to compression stroke. You can tell by rush of air coming out of adaptor hose. Turn prop slowly until air rush peters out and magneto goes "Click!" This means you are at TDC. (or darn near) Now "Clear Prop!!!" and hook the adapter to the tester and turn on the air flow. Adjust regulator to 80PSI. You can now read the "compression" on the other guage. It is OK to move prop slightly to find best reading. Typically 70/80. Less that 60/80 is cause for serious concern. However, it varies from engine to engine. Continental is far more concerned with variances between cylinders. You can have blow-by the rings, but no "static" leaks. You can listen to the intake and exaust to see if your valves are leaking....if one is...no go. Cylinder to head leak....no go.
This is a good test because if there is a problem, you know where it is and what to fix.
Have a nice day
Steve