[Old Truck Man]

Excessive blow by like stated previously is compression. usually rings. could be a bad piston. sometimes they burn part of the top away? Ive seen broken rings and cracked ring lands on just one cyl. run a compression check. a seeping head gasket can cause smoke also. many times a engine that isn't used but for short trips (city driving) and doesn't get thouroughly warmed up will collect significant condensation and that evaporating looks similar to blow by. A 250 in a 65 that was perfect before I left home burnt a piston in Dallas Tex traffic. I made it home but the blow by was teriffic burnt a gallon of lucas oil additive on the way home.