I just bought a compression tester from Sears (Actron model cp7827, $24.99). As soon as I got home, I had to try it out, using the info in my FSM, and some additional info I got from this site. The results were as follows:
Cylinder 1
Dry Test 142psi
Wet Test 139psi
Cylinder 2
Dry Test 115psi
Wet Test 123psi
Cylinder 3
Dry Test 128psi
Wet Test 133psi
Cylinder 4
Dry Test 127psi
Wet Test 133psi
This test is for the 1.9l in my '73 GT, and I have never taken off the head, so I don't know the condition of the cylinder walls, valves, valve seats, or the type of pistons I have. So, I am wondering if any of you have any opinions on this data? When I first saw the dry test data for Cylinder #1, I thought, "Woohoo, maybe I have the high compression pistons!". Then, Cylinder #2 brought me back to reality. Luckily, Cylinder #2 is 80+% of #1, so according to the FSM, this is acceptable. The wet tests are only 2% (Cylinder #1) to 7% (Cylinder #2) higher than the dry tests, so I don't think I have any ring problems. But I am wondering whether anyone can tell me if they think the results of this test is an indication of high compression pistons? I tried to look into the spark plug holes to see if there are flat top pistons, but I couldn't see anything (I didn't think it would work). Or do you think the readings are still far enough apart that I need to think about looking at the valve seats or guides?
Randy