[Keith True]

I had a Chevy six that did exactly what yours is doing.The owner pulled it out of a 55 Chevy in 1967 and had it rebuilt.He put it back in,ran it around the yard for an hour or so,he said probably 5 minutes at a time.Parked it in the garage while he spent a couple of years in Southeast Asia.When he came home he bought a new Camaro and had lost interest in the 55.I bought it in 1976 and after I got it running it only ran for a few minutes.It slowed down,squeeked,and died.All the top rings had some white powder behind them,and would not compress into the grooves.The other two rings,compression and oil,had what looked like asphalt behind them holding them out.The guy that had built the engine was willing to look at it,just to advise me.He said,clean the corrosion out of the top ring grooves,the tar out of the rest of them,and then show me the pistons.He gave me six new top rings and told me to put it back together.It had not been run enough to melt out the assembly lube and burn off the condensation when first fired up.It had not hurt the walls one iota,because I had not attempted to run it again after it quit.