LarryMaine
Member
I finally did a compression check on my 850 engine today, having completed the resto. Prior to resto compression was 105 / 95/ 100 / 85 psi for cylinders 1-2-4-3. Engine was not burning oil or smoking, no water in oil or oil in water. But I was not happy with compression. Lots of gasket leaks, so was going to remove head anyway. Did not do a leak down test (did not have the equipment). So I decided to do a valve job, figuring if that did not fix compression then I would do rings/pistons/sleeves later on. I replaced all new springs, all valves, retainers/keepers, valve guides, head gasket, etc. I did not have seats professionally ground but I did hand lap them with compound using the new valves. I also adjusted tappets. Condition was not that bad, just some carbon on the exhaust valve faces, no bent valves or push rods. Grommet for oil pick up was gone, so I replaced that as well. I did not think the valve job would fix the compression as there were no real problems visible. Here are the new compression figures done today, 130 / 125 / 110 / 125. The results were quite impressive and unexpected. IT manuals says new engine compression should be between 120 and 130 psi. I may have a ring problem with cylinder 4, but I can live with it. So, before you assume a full engine refurb is needed, you may want to think about starting with just the valve train. Thanks all to those who helped me on the resto, Larry. (God Bless our Troops).
