Last time I saw something like this happen was on a 292 in a Chevy bus a guy did an in frame overhaul on. He didn't take the ridge out of the top of the cylinder, said it was fine. When he started the bus, they couldn't use it because it looked like a mosquito fogger going down the road. He broke the rings and rings landings on the piston when it started up.
Was there a ridge, at the top, and did it get cut out? Did some rings get broken while putting the pistons in? My bet is broken rings on start up or installation.
Let us know what you find.
