Did the engines on the industrial take a bigger piston, or was it a standard piston like that of a normal A?? I am overhauling my IND A and one of the pistons was smaller than the rest (probably why it was blowing oil). I went to NAPA and he gave me 3 1/8 pistons, but they are what I call POP - UP pistons, and there does not look like there will be any clearance between the top of the piston, and the head, and spark plug.