Hmmmm? Well, now that this came up, I went to the shelf and pulled a A40 A piston and a 506 B piston and did a measurement. Yes, Chris is right the difference is very little – the “A” piston diameter measured just above the ring grove was 53.761 – the “B” piston (which I though was supposed to be slightly larger), is actually measuring smaller at 53.745mm. What gives – this screws up my plan! LOL
What would be the benefit of using a smaller piston Chris? I could see going larger after enough wear in the cylinder, but smaller? How much sidewall clearance is “required”? Why wouldn’t one want to start with “B” piston and progress to an “A”?
We may not be the fastest on the track...but we're having the most fun!