If your using Ross pins in the Ross pistons I believe they recommend .001 or more for N/A gasoline motors drag racing. I would open them up a little more on a street/strip motor on the rod to pin clearances, .0010 to .0013. I went out to my shop and looked at several sets of instructions for Ross pistons in my motors, the instructions do not make any reccommendatios on wrist pin clearances Both sets of instructions are for Ross custom made pistons, Ross does not include the wrist pins with thier custom made pistons, you have to order them seperate and pay extra for them Try taking one of the pistons, if you can, and measure the wrist pin bore at room tempature and then heat it up in a oven for twenty minutes at 200 F and see how much the wrist pin hole grows or schrinks