I've got a winter project. My 216 from 1941 had a problem with the compression on one cylinder - the other five read between 120 and 130. Number 5 was around 40. So I took off the head and found a broken oil ring but no visible damage to the cylinder.
I am pretty green with this kind of work. The engine is in the car and I hope to leave it there. The car has under 80 000 miles on it, this is confirmed. I suspect that the more work I do on the engine the greater the risk that I screw something up.
So first question - with everything opened up I suppose I would be wise to plastigage the mains and rods bearings and of course replace all the rings?
Another question is why is the compression on 5 so low when the two compression rings are good?
Yet another question is what rings to order. The engine has never been bored. There is a little edge at the top of the cylinders, so I will have to do a little honing- deglazing, but I hope to get by with as little work as possible, ha ha. Must I measure the cylinder to order rings? Is this a process with the pistons and feeler gauges?
The engine has been running fine its whole life but leaves a lot of blue smoke. It was purchased new by my great-grandfather.

Karl

It may not be the easy way, but it is the Cowboy Way - Ranger Doug
Beware of the stories you read or tell; subtly, at night, beneath the waters of consciousness, they are altering your world. - Ben Okri
1953 Chevy 3100
1960 Volvo PV 544
1941 Chevrolet Special Deluxe