Compression Test

I did my first compression test on Sunday. The correct procedure is subject to a lot of debate but I did what I had seen others do. First, the car was cold. I removed the plugs and wires and tested the first cylinder first. I turned the engine over 10 times and recorded the value on the meter.

The results from the front to back were: 145, 140 140 145. The engine currently has about 116k on it. These numbers are pretty good. The nice folks over at MGExp suggested that these are well in line with where they should be. As a reference point a brand new rebuild should be around 150-160.

The important thing is that there is little variation between the cylinders. I could have done a wet test (putting oil in) to see if any variation was due to rings or valves, but given that these numbers were good, I decided not to worry about it.

Finally the front plug was a little sooty. I may be running too rich - remember I just put in bigger jets in the weber. So perhaps the next size down would be better. On the other hand, I haven't done much distance driving and most of the trips of late have been on cooler days with more choke, so that might be part of the issue.