Aug 31st, 00, 10:21 AM
I had recently put a descent rebuilt 350 in my '69. After about 8,000 miles, it started burning oil and severely fouling the plugs with carbon buildup. I burned 6 quarts of oil and two sets of plugs on a trip from Daytona Beach to Louisville, KY. The strangest but maybe the most reasonable answer I got from one mechanic was that because I had a Edelbrock carb (which he said was junk) it was pouring too much raw gas into the cylinders and washing the oil from the cylinder walls and rings. This kept the rings from seating and allowing oil blow by. The strangest part is there is no tail-pipe smoke at all! None blue or black! I had previously never heard of this. Does this make sense to anyone?
Aug 31st, 00, 10:40 AM
I'd do at least a compression check and if that looks good I'd go over the valve seals and check the valve guide condition. If you aren't up on how to do it or what to look for get some good help from a good engine guy.
A leak down test would be the better than a compression test. You would hear air leaking out of the crankcase or intake or exhaust valves if they were leaking. This wouldn't tell you if you had a bad guide or leaking valve seal, just the condition of the top piston rings and valve seats.
I got one intake valve seal in wrong once, and used a quart of oil in one tank of gas.
An engine with good compression can burn a fair amount of oil without showing it in the exhaust.
If the carb was rich enough to wash the rings, you'd have black smoke coming out the tail pipe and terrible fuel consumption.
Also probably fuel diluted oil.
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67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Can Am Vintage Racer
Aug 31st, 00, 05:53 PM
I am with David on the black smoke, and rich carb.
It sounds to me more like a lean carb that has over heated the rings. If that is the case you probably won't detect it with leak down or compression test. The reason being the oil ring gives up because of heat and the weakness in the compression ring don't show up unless the engine is running. The oil ring has little affect on leak down.
I also agree with David check the guides and valve seals first.
Aug 31st, 00, 05:54 PM
did you put the oil rings right side up ?
Sep 1st, 00, 02:10 AM
<BLOCKQUOTE>quote:</font><HR>Originally posted by DEVIL'S LAKE:
did you put the oil rings right side up ?<HR></BLOCKQUOTE>
It was built by a machine shop that "supposedly" built high quality racing engines. If they did, I sure got screwed.
Sep 1st, 00, 02:48 PM
Something must have happened to cause the problem after 8000 miles of running ok. Rings , valve guides, etc. normally do not fail "suddenly"... they slowly wear and get worse and worse. If your problem started all of a sudden, there must have been a cause. Did the motor overheat ? Did the Edelbrock carb decide to flood for some reason, dumping a load of gas into the cylinders and scoring the rings and cylinders due to lack of oil ? I personally cannot believe that it burned 6 qts of oil without some type of smoke...just not happening ! You need to have someone follow you while you accelerate and de-accelerate...I bet they will see some smoke.
A couple of things I can think of to check are the PCV / breather system and the intake manifold bolts. If it is fouling all the plugs, I doubt that it is the intake , but it could be. My first stop would be back to the engine builder and ask for his help in trying to figure out what happened. At least I hope that is what you would do if you were my customer. And a bit of advice...dont go to him acting like you just know its something he did wrong...it gets everything off to a bad start. Tell him you are having a problem and would like his help in solving it.
Hope this helps,
Advanced Automotive Machine
[This message has been edited by BillK (edited 09-01-2000).]