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Discussion Starter · #1 ·
My 396/350 continues to be sick. (69 Chevelle SS) Had car 2 months, seller stated recent rebuild. Problems started out as 2 qt overfill on oil, lead to gaskets replacement. Had carb rebuilt, still running rough, compression all Cyldnrs are 154-155, exception #1 is 55. Question, could the oil overfill cause my problem, or could the fact that the guy working on my engine stated that when he reassembled my engine, he originally had the distribtr trn 180 degrees. It is correct now. Or did I buy a worn out engine. Thoughts valves or piston rings...........or will I have to rebuild? Is it possible for one to be so far off from the others?
 

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What gasket failed due to 2qts. of overfill? That #1 cylnder definetly has a major problem. It's either a cracked/broken ring or the valves are shot in that cyl. If the rings are the problem then there will be scaring on the cyl. walls. It's best to tear it down now.
 

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Discussion Starter · #3 ·
Not sure had minor seapge before overfill, but really leaked from oil pan gasket, while had it apart replace main rear seal. HE tells me he hooked up compressed air and he can feel air from #1 and that if it were the valve, it would come thur the carb. or around the valve....he says he is 90% piston prblm?
 
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Hmmmm, I would remove the valve cover and have a look at the rockers, springs etc. You could have a vlave tat is hung open or bent. Worst case there is hole in the piston but that would cause a lot of smoke to pour out the back.
 

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Harry,

If you have a hole in a piston, you will be pressurizing the crankcase.
You will have major blow-by.

If it is a ring seating problem, you could have smoke from the exhaust
AND have blow-by.

Do a proper compression test on #1 to determine what the cranking
compression is. If it is low, it could be a valve off of the seat. Hopefully
it will not be a cracked/holed piston or rings.

Good luck with it.
 

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I had a similar problem with the 350 in my Chevelle ... way back when it was my daily driver. It had a "surge" at 45+ mph. Chased my tail for several weeks trying to figure it out. Finally took it to a mechanic, and he did a compression test. All the cylinders were good, except #1, which was reading ZERO compression. Long story short, my Dad and I did a cam swap, and got both #1 valves a wee bit too tight. Mechanic adjusted all the valves, and the car never ran so good. Lesson learned.
 
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