Ok, all you engine rebuilders, I need help. About 7 years ago, a freind of mine and I rebuilt a 283 Chev. New cam bearings, new rings, new cam, new lifters, new valve springs, pretty much just a standard rebuild. He only started the motor once, but never got the car he was going to put it in finished, so the motor sat. Before he stored it, he sprayed WD-40 inside the cylinders. I recently acquired the motor for my 50 chev. I took the heads off to make sure there were no mouse nests or anything inside. The walls were still shiny, and the motor turned over just by wrenching on the harmonic balancer, so it was not froze up. I installed the motor, and it fired right up. I have about 500 miles on it, now all of a sudden, it is starting to smoke. Blue smoke, so that means oil. It seems to be getting worse. I notice it more as I am sitting idling, but if I rev it up, I will get a puff of blue smoke, then nothing until I let it idle again. What could it be? Valve guide seals dried up? Rings not seating? I need help, I want to drive the car to Hunnert Car pileup, but this has me worried. Any suggestions?
Could be dried up valve seals...especially if they were the old "umbrella" type. Do a standard compression test...mark down your readings, then squirt a little oil into each cylinder and recheck it. If your reading goes up, your rings aren't seating. If the reading stays about the same, it's a valve guide or valve seal problem.
A guy at work told me to do that, also, I used 10w40. He told me to use just straight 10w for the first 1000 miles or so, have you heard of this?
Straight 10w??? He probably meant straight 30 or 40 weight. I've heard of that, but I always used your basic 10-W-40 or 20-W-50 oil in new (rebuilt) engines and it worked out well for me. Some guys like to run the straight weight oils for a thousand miles or so...it really wouldn't hurt to do it either way...but I don't think that's your problem.
The stock[rubber band type]O ring lookin- valve stem seals are prone to split and fall off the grooves in stems-leaving no oil control in the guides. you can easily fix that situation in an afternoon,by adapting an air fitting to spark plug hole and turning engine to TDC on each cyl and removing the springs and keepers one cyl at a time and install a set of Perfect Circle Umbrella type stem seals over the exposed stems. this sounds likely as you did say it sat quite a while. you can prove the point with a compression test/bad rings stuck rings would show up on that test and this seal problem would not.
I also agree with it sounding like valve guide seals, if it doesnt smoke at an idle only when you rap it up it puffs blue smoke... Jonney
One more vote for valve seals. During high vacuum situations is where they'll suck oil in and cause smoke. Have someone follow you and look for smoke when you're decelerating, completely off the gas (maximum engine vacuum).
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