Years ago a friend had a back yard mechanic do a carb kit and tuneup on his 62 Pontiac. Smoked like crazy when he picked it up. The guy would do nothing. I was still in high school but a gear head. Pulled the plugs and found one with oil on it. Removed the head and found the imprint of a carb mount nut in the piston. Cast piston crown had a crack in it letting oil into the cylinder. Pulled the oil pan and that piston/rod assembly. Got a new replacement piston installed and new rings for that cylinder. Got the engine machine shop to check the valve seal in that cylinder and it was good. Put it back together with a slight deglaze and he drove it gor years.
