low compression

I checked the compression today and my number were 120,125,105,120.

The engine appears to be leaking or has lead from the head gasket. It is hard to tell b/c it is so greasy.

I have talked with two mechanics and their response varies from tune up to valve adjustment and possibly the cylinder head.

What I am trying to do is see if there is a way to pin point the problem without spending money one this and that trying to figure it out.

Interestingly the compression on my buddy's MG is lower but it is running great. So, my variables seem to be the weber carb, the valves, timing?

Also, if I have a weber carb should the timing be advanced further from the original specs????

Thanks!

johnathan

gojohnnygo Wrote:

A leak down compression test will tell you where you are loosing compression. It should pinpoint if the problem is piston rings, intake valves, or exhaust valves.
While the test isn't free, it is very inexpensive and can tell you a lot about what is going on in your engine.
You can also buy a leak down tester at harbor freight and do the test yourself if you have a compressor.

MT-B Wrote:

If you can do it yourself, reset the valves. it could be #3 or 4 is a little too tight, which could account for that lower value value.

A leakdown test would pinpoint where the lost compression is going.

next least expesive would be a head gasket replacement. again, you can do this yourself.

If you can's do it yourself, then it's all expensive.

otherwise the 125 is not dead yet...so drive it.

- Did you do the test with the engine hot or cold?

- Were the throttles wide open during the test?

- How long did you crank the engine to build pressure?

Before spending any money, I would suggest you retorque the cylinder head and check the valve clearances.

Great guys! Thanks for the advice. I already have a head gasket and a valve gasket. So I am going to read up on my Haynes and see what I need to do to check the valves.


Thanks!
johnathan