VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 216 engine burning oil

I've posted here before about this engine. Now it's time to make a decision about how extensive of a rebuilding it needs. (1946 Chevy Fleetmaster 216 engine built in Jan. 1947) Appears to be the original engine. It was seized up and full of water when I got it freed and running. Lot of smoke and steam the first time. Three oil changes (the last with lucas additive), and 200 miles later it still throws about 1/2 quart for 50 miles out the exhaust. The compression is about 100 on each cylinder. More smoke when it is warmed up and not much when I just start it. If it idles for a while it make much smoke when I put it in gear and go. Other than that, it runs smooth,no external oil leaks, no oil in the coolant. My question is: what do I need to do to fix the oil burn? Just valve seals? New oil rings? Both? More?

I'd say that the oil rings have lost tension at best, you could have had rust in the cylinder walls and the corrosion could be significant enough to cause the oil usage. I'd start by pulling the cylinder head and taking a look, then you have a better idea of whats next.

You need to replace the rings. The cylinder walls may be bad but it will be necessary to remove the head to check farther.If that much oil was going down the valve guides it would be fouling the spark plugs.

I'm hoping to just have to install valve seals and not have to remove the head. I took compression readings today as follows:
1=112, 2=125, 3=120, 4=120, 5=122, 6=130. Plugs were black on the rims, insulator still white and electrodes were still clean except no.6 which had some black buildup. I don't understand how I could have good compression figures and still need to replace rings, unless the oil rings are fouled up and not working. If those valve seals are visible from under the valve cover, I don't see anything that looks like them, if they are there. What do they look like?

The 1946-47 did not have valve seals. You would have to trade up to a 1948 to get valve stem seals.

The 1942-47 had the tin umbrella cap that sat on top of the valve stem and covered the valve spring retiner cap. As miles piled up the caps would cause the valve train to be noisy and most mechanics discarded them. The majority of those engines today are running around without them. There absense could (will) cause a litle extra oil consumption, like a Qt. in 1000 miles, but not what you are experiancing.
The compression rings (top two rings) are a solid piece (unless the rings have been replaced) then the middle ring will have an expander and a wafer type rind added) and the original oil ring was a one piece steel ring with oil retuen slots in it (the slots would plug up with carbon causing oil burning)...If it has replacement oil rings they will be made up with two wafer type ring, an open wiggly seperator between and expander behind....this is typical, depends on what kind og ring was insatlled. It was not uncommon for a 1946 to have the rings replaced by 45,000 miles and the wear plus the carbon build-up was the problem Now add this to the fact the the engine was "stuck" had water in it, etc. and the cylinder walls could be pitted, the rings stuck or have weak tension and you will have smoke. Would advise have the valves ground, new piston pins fitted and adjusting the rod and main bearings......to end your problems. There are some seales that can be placed around the valve guides to prevent the oil from running down the valve stems .
A rebore may also be necessary.