My 468 seems to be using oil worse and worse, I got about 250 miles my last quart. I get a major embarrassing puff on start up, but you cant really see anything other times. The engine is extremely strong.

The engine has about 10K miles on it, it was built in 1992 with all the best stuff. The guy I bought the car from is an old friend, who I trust completely. He says it never burned any oil. It sat for 3 years before I bought it, he would only start it periodically.

I talked to the guy who built the engine yesterday, and he mentioned lead substitute in the gas. I said, "huh?" He said I should have been using a substitute, and probably wore out the valve guides. The previous owner only said to use good old premium. I have driven it about 1000 miles.

Could I have worn the guides that quickly? I can't figure out why any guides purchased in 1992 for the build up would have not been no-lead compatible, or is the upper end high performance stuff soft or something? Could I have also eaten the rings, or are they not as sensitive?

I'm no expert but here's my $.02.

With that few of miles, I doubt the guides are shot. Assuming they were replaced when the engine was rebuilt. If they were replaced, they should have been the no-lead compatible type (steel or bronze, I can't keep them straight). My guess is that the valve stem seals are shot. The smoke at start-up indicates that. However, 250 miles to one quart seems like a lot for just bad valve seals. I would start there anyway. They are not hard to replace without removing the heads. You will need access to an air compressor and a spark plug hole adapter.
Good luck,
Phil

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Phil Wise
67 SS Convertible
(now on the down slope of the resto curve)

Gib,
Unleaded gas has nothing to do with valve GUIDES. It does require hardened valve SEATS and if they are not used, after a while the seats get worn ral bad, causing the valve to rock all over the place and wear out the valve guide.
However....in your situation, I would bet it is something else. If the car sat for several years, one or more rings may have gotten stuck, not allowing proper oil control. Now a puff at start up usually indicates valve seals but it can be caused by other things. One in particular is an intake manifold gasket leaking (on the under side). Another posibility is PCV valve.
There are plenty of Big Blocks running around with just some o-ring seals on the valves and they puff a bit at start up but do not consume a bunch of oil. The amount of oil you are talking about is, in my opinion, more than would be caused by valve seals or guide wear. For example, we have rebuilt many a motor that has 150,000 miles on it but they still do not use that much oil !
I think you need to start out by having someone follow you down the road. I think you will find that the car is smoking while you are either accelerating, or de-accelerating, and probably even at normal speeds. It almost has to be ! If that much oil is getting into the combustion chamber, is has to get burned and it will smoke. Next do a compression test, dry and then wet, or better yet a leakdown test and see what kind of results you get. This should get you started in the right direction. Let us know what the results are.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

Gib,

Using that much oil should leave a residue in the tail pipe. Look at each tailpipe to see if both sides are wet with oil or just one side. If only one side is wet this would indicate a cyclinder on that side. I had somewhat the same problem with oil usage with only one side of the exaust wet with oil. BillK helped me pinpoint the problem. Keep posting your findings and someone will point you in the right direction.