Compression test results below. Also, while turning the engine over at one point I got a little bit of what I think was lifter tapping. Is it possible the low compression could all be due to the valves or is it more likely a problem with the rings as well? Does anyone know what kind of compression readings I should be seeing?

1 = 37
2 = 30
3 = 25
4 = 30
5 = 20
6 = 10
7 = 40
8 = 45