4-5 months ago the 307 in my '70 4dr. tore up the original timing set. Prior to this it was running pretty good at 130,000mi. I pulled the engine and replaced the timing set, cam, lifters, pushrods, freeze plugs, oil pump, and had the valves done. Machine shop replaced the O ring stem seals AND put the umbrella seals on also. Shop guy said the valve guides were "serviceable". The bores looked good, no ridge. I put it back together with an old HEI distributor in it and it runs pretty good again for a 307, 2bbl. BUT, at expressway speed it'll use a quart+ of oil in a hundred miles. It doesn't leak, smoke much, or seem to have much pan pressure, foul plugs--they're a little dark but still tan colored. Had a breather on one valve cover and a PCV to the manifold in the other. I deleted that and put 40wt. oil in it---still drinking. The exhaust isn't wet. My son pulls a little enclosed utility trailer with the car and the front of it doesn't get oily. I haven't run a compression/leakdown test, but it starts and runs mighty good. Seems to be using a LOT of gas too. I know a fresh 350 would probably fix it right up. Any Ideas or suggestions will be greatly appreciated, thanks in advance. Howard

I had a problem like that with my 97 Dodge Ram. It turned out that the plenum pan gasket under the intake manifold went bad and was sucking oil into the intake manifold and was burning it off. It wasnt buring it bad enough to the point where you saw blue smoke out the exhaust but you could tell the exhaust was getting rich with black soot around the exhaust tip. Maybe you have a similar problem with an intake gasket problem?

I had always heard that if you take a high mileage engine and get the heads redone, you take a chance on the rings starting to push oil. May be an old wive's tale, but I've seen a fair amount of anecdotal evidence to suggest there might be some truth to that theory.

Hind sight being 20/20, I sure wish I'd at least done a dingleball hone re-ring while I had it on the stand. I'd never heard the fresh valves/oil ring theory(wive's tale), but there is a some truth to a lot of them. When I took it apart the stem seals were missing from several valves and the rest were real brittle. It wasn't noticibly using much oil before.
Brian, I'm trying to figure out how to check for an oil sucking intake leak without taking the manifold off. A/C makes it harder to work on. Everything was pretty clean when I reassembled it with just a very light clean up slice on the heads.
I didn't have a very good attitude working on this 4dr 307 car anyway :( and this mess isn't helping. It does drive pretty nice, though.

You NEED the breather/PCV valve. To delete this makes your problem worse. Check that the "filter" is clear and clean and install a new PCV valve. Blocking these causes greater crankcase pressure which will cause leaks and possibly "issues" with the oil rings. I'm not really one for "overhaul in a can" fixes, but an oil change (to 10w30) including Marvel Mystery Oil "might" clear up your problem. It can clean the oil ring gooves slightly, and if it is a ring sticking, may fix it.

Dave, It's still got the breather on one side, I just plugged the PCV hose in case it was drafting oil out of the baffled stock valve cover--highly unlikely I know. I may change the oil/filer and give it a good swig of Marvel Mystery Oil. I know the engine is clean inside so it won't break loose a bunch of sludge. My Dad always used Marvel and that Wynn's Top Oil too. Don't know if they helped, but he always got good service out of engines. I'm still wondering about an intake leak sucking oil out of the lifter valley. I'm thinking about scrubbing it up good and the next time somebody says "Hey, ya' wanna sell that 'ol Chevelle" doing it.

RB,

Best way to know is to have someone do a leakdown test. After that you will know if it's rings, or some other issue.

Mike