Super tuning car runs good shooting for great

Make DAM sure the journals are round & also make triple sure of your bearing clearance! The old school way of poor boy crank polishing is to wrap some 1000 grit sand paper around the journal. (With lube) then wrap an old leather shoe lace around the paper & pull back and forth a few times. Its getto, but it works if the journal is round. Pulling the spark plug is a real good/quick way to isolate it down to eather the piston pin or as you found a smoked rod/bearing.