zimmstoy

Hey everyone,

I figured that before I dive into my project I would check the compression on the motor. Here are the results:

1 - 130
2 - 140
3 - 120
4 - 140
5 - 140
6 - 130
7 - 100
8 - 150

Are these descent numbers? Should I be worried about cylinder 7? The plug that came out of that hole had a bit more carbon than the others. Is this a motor worth throwing a tune up at and driving some more or am I throwing good dollars after bad?

olds 307 and 403

Number 7 is a bit low. Try a tune up, plugs, wires, cap, rotor, points and put some engine flush in just before your next oil change. If it runs fine, just drive it till you can afford a rebuild.

TripDeuces

If you put a tablespoon of oil in number 7 and try the test again to see if it goes up. Then you'll know if it's rings or valve seats

ah64pilot

The standard in the 1972 Service Manual says the lowest cylinder should not be less than 70% of the highest, and no cylinder should be less than 100 psi. I would imagine this was the same for all the years.

For 150 being the highest, the lowest cylinder should be no less than 105 psi. I would say you have a problem with #7...follow Trip's advice to figure out what's wrong.

zimmstoy

Thanks guys. Will try it next time I am out in the shop.