Measure skirts close to the bottom. Sounds like quite a bit of clearance for a cast piston IMO. Did you zero the gauge off the mic after measuring a piston skirt? If you're going off the supposed bore measurement on the gauge, it'll most likely be wrong
That's where I measured the skirts. I set my mics to 4.0185 and zerod the bore gauge off of that,then subtracted whatever the dial indicator read to get my 4.016 etc. Is that wrong?
OK fellas, double checked my bore measurements and 4.016-4.017 is correct. Haven't figured out what the spec for ptw is yet.