Another compression question

picked up this old 70 MGB sat 10years compression as follows
130-30-30-30

not good !!!
all valves are free barey runs!!! any thoughts before I pull the head?? Stuck rings?

Try some Marvel Mystery Oil and see if it loosens anything up.....you're only out the cost of the can if it does not....

Solarman Wrote:

You might do a leak-down test prior to teardown to determine exactly where the compression leaks are.

In addition to Marvel Mystery Oil other's have had luck with Sea-Foam(tm)

the rings do tend to rust to the bore and also gunk themselves in the lands. pouring seafoam or MMO into each spark plug hole (an ounce or so) then let it sit for a day and crank it, followed by a repeat can often loosen them up. While you are at it, set the valves.

The valaves that sat open foerver are likely rusty and not sealing. Looks like the #1 cylinder valves were closed. You can try running it to see if it "laps" the valves on its own? Risky though - especially if that's not the issue.

Try running it with the valve cover off. You'll be able to see if the valves are actuating as they should. As Jesff said, one or more might be stuck partially open, as well as not seating properly. A few shots of PB Blaster and some small taps with a hammer might free them up more.

Well I soaked her with brake fluid let her soak 24 hours ,extracted the oil. gave her a wet test and 120psi, gas her up, turn the key and it starts runs ruff 12-15 min then it start to clear up and purr like a english kitten, the clutch works,brakes work, so out I go around the block this old girl is a keeper!!!

I'd be interested to hear what your compression numbers are in a week or so!

Jeff I will keep you posted. What is your guess?

I'd guess the rust on the open valve seats will get cleaned off and allow the valves to seal much better. Maybe a 10-15% variation in the numbers next time around?