Home › Forum › Ask A Member › Another TD 20 idling question › Reply To: Another TD 20 idling question
New rings alone will not solve a compression problem if the cylinders are also worn badly. TD’s rarely have compression as bad as the numbers you listed because they ran on 16:1 fuel mix and the worn out original primer seals put the motors out of service long before the rings and cylinders wore out. It’s possible that someone ran the motor without sufficient oil and wore it out. If you properly installed the new rings and LIGHTLY honed the cylinders, it is also possible that the compression will improve when the new rings get seated. But for sure until your compression is better it is not going to idle “good” or at all.
I’m aware that there are several causes for low compression. Your post got me thinking though, because I did hone the cylinders lightly to get the glazing of. Once I had it running yesterday I kept it running for about half an hour, then let it cool down. This morning I retorqued the cylinder head bolts to specs and did a new compression test. The results are 74.5 for top and 77.6 for the bottom cylinder. I hope this rules out too low compression.
Surprisingly the bottom cylinder has higher compression now than the top. The previous 2 times I measured it, the bottom cylinder had the lowest compression, as one could expect.