If I'm using new pistons and wrist pins with press fit rods I have the pistons and pins pin fitted to make sure that the wrist pin to piston clearances are at least .0008 to .0010, if there going in a rod that has wrist pin retainers where the wrist pin floats in tthe rod and piston I have the rods done also to the same specs. Race motors like a tiny bit looser, the piston alloy also plays into how much to use and room temperature can play into reading the clearances also, depending on which gauges your using