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MG MGA - compression test results

Dear folks,

Here are results of compression test on the MGA MGB 1800 engine).

Cyl Before w/ Oil
1 188 205
2 180 185
3 185 198
4 175 190

I suspected a problem after using oil and noticing oil vapor exiting my valve cover breather. However, there are no crankcase or other engine leaks. Otherwise, power and performance are good.

Time for a ring job, or is this not too unusual?

C.T. Irwin

The rear cylinder runs a bit hotter on the 1800 MGB engine. I would not worry too much about your test results as long as the engine runs fine. Don't be in a hurry to do rings etc. (in my opinion) You may have a couple of rings stuck in #4. If you have access to a bore scope, look down the cylinder through the spark plug hole and assess the general condition of the cylinder.

I would try one of the many oil treatments that are available just to clean things up a bit, then see what happens.

Seems a lot to tear down an engine just because one reading is a little light.

C.R. Tyrell

Numbers are not bad for normal c/r engine. No big swings in readings, numbers nice and high. The difference could be to how much oil actually covered the rings in each test and how strong the engine was turning over.
I agree with Colin.
D Hanna

This thread was discussed between 05/07/2014 and 06/07/2014

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