If the compression goes up when you put a little oil in the cylinder it
means the rings are leaking. Too much oil could change the compression some
I suppose. Make sure you crank each cylinder until the gauge stops rising.

I would not worry about it if you are happy with the performance and the oil
consumption is not much. There is no good number, what you are looking for
is all the cylinders to be about the same. My 350 has 65# in all the
cylinders, think that is bad ? :-) It's not, I have a high overlap cam.

"F330 GT" wrote in message
...
Hi Tom,

I have been working on reciprocating engines for over 40 years as a
hobby.
My grandfather, father and uncle were professionally trained mechanics. I
have taken lots of compression tests in my day but have never heard of a
"wet test"? If you have 150# in all 6 cylinders and it is not burning oil
and goes pretty good, I don't think I would rebuild it unless you are
going
to do a real high-end rebuild or a brand new motor.

--
Bill Kiene

Kiene's Fly Shop
Sacramento, CA
www.kiene.com

"tom clark" wrote in message
. com...

My 1972 Mercruiser in-line 6 cyl. has pretty good dry compression
..approx 150 in all 6 cylinders. In a couple of cylinders the wet test
shows 210 and 185. It doesn't burn much oil though ( can smell some
blow by) and the oil pressure is still good. Top end RPM's are good
too although top speed is not what it should be but still ok.

Perhaps I screwed up the wet test but is this common... to have bad
numbers on a wet test and good on the dry test?

Should I be thinking of a rebuild?


I agree with you Bill. I've never heard the "wet test" one either. I think
any
mechanic would know you squirt a couple drops of oil down a cylinder with
low
compression to tell you whether or not it's bad rings or a valve.

A couple of squirts of oil in a high compression engine would certainly
increase the compression. You'd be changing the compression ratio. A
couple of
more squirts and you could easily break something.

In building a high performance engine you can increase the compression
ratio
just by going with a thinner head gasket. Can you imagine how much
difference 3
or 4 squirts of oil will do?

Barry