i got some stock bore wiseco pistons for a good deal. I was going to use them in my build. the spec sheet calls for clearance of .0025. I have access to a machine shop so today i took my block in to clean up the bore i got it all cleaned up and the clearance is .0045. i have built many other engines and used clearance of .0045 with no problems other than slight slap on cold start ups. I just think 0025 seams tight for forged pistons.I talked to a engine builder that does the machining for Darrel *** he told me i would not get all bent out of shape on piston to wall clearance unless its over .008. He told me he has tried all kinds of clearance from .003 to .010. He said that over .008 he had to much oil burning and it would detonate on the dyno. just want some more opinions.

 

I am running .0035-.0045 around there on my arias..Measure down low on the skirt.. Total clearance piston to walll ring clearance was like .018" on the second ring and .021 on first ring

 

We just had a bit of a discussion about this on here, and decided that in the 400hp range, .0045" might be perfect.