I have a question I can't find the answer to about cylinder bore and piston diameter.

I see that the pistons I want to use, the Wiseco 1400 HD series need a PTW clearance of .0035" for 85.5mm... However my question is, does that mean the piston is actually 85.4111mm

or is the piston 85.5mm and the bore needs to be 85.5889mm?

trying to pick out whether I need to stay 85.5 or go up to 86mm based on the piston since my block is already bored over .02"

 

The piston is normally undersized, but it is best to verify the nominal dimension with the manufacturer. It may not be as low as 85.4111 mm. Also I would aim for a clearance of 4 thou instead of 3.5 thou.

 

You need to have the cylinders measured for roundness and taper to determine what you need to for the bore.

But yes, the number is the bore size, not the piston size.

 

Perfect, this was my suspicion but could never find clarification. Thank you!