I measured the bores on the Perrin EZ30R motor, as well as the pistons. This is a sleeved block with Darton sleeves.

There are some flaws with my technique…. I do not have a torque plate, so the bores will certainly distort after the head is installed. The factory bore size if 3.512″, and the size of the pistons new from Supertech is ~3.5085″, which would be a clearance of 3.5 thousandths.

These bores are all slightly bigger, averaging around 3.5138″. While there certainly was some wear, it would appear it was originally setup with larger PWCs. I’m not that concerned about the 5.5 thousandths PWC, as it is a race motor. I’m not looking for quiet.

I will probably get the pistons coated, which depending on the coating can add 1 thousandth.

Comments?