big block wrist pin fit

hi guys, we tore down a 383 expecting to just re-ring with rods& mains and a cam change. I noticed some of the pistons seemed free and some were tightish. This boy has been over reved when a timing chain went out earlier in life. There are some valve smacks on the tops of of the piston but no real damage. Piston are running about .003 cl in the middle of the bore. Any way getting to the point. The pin bosses in the piston are measuring .001-.0015 clearance. and the pins slid in and out of the piston easy. You guys think we'll have a pin knock at temp. The pistons that seemed tight had some galling. Thanks for your help. Bruce

I wood not worry about 001/0015 ... that should tighten-up a tad when the piston get warm.

hey doc, was just kinda worried about it my sunnen gage recommends .0003/.0005 fit and its double the high side. thats new of course. doesn't the hole get larger rather then smaller? BT

.001 floating pin to rod is good. The .0003-.0005 that's not for floating or do you not have floaters?

Yes, the aluminum piston will expand and increase the clearance slightly. You will probably not have any issues immediately, but you will wear the pin bores more rapidly with the extra clearance. So longevity could be called into question.

Hey Rapid,its the piston fit I'm concern about. The rods are press fit.

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I wood not worry about 001/0015 ... that should tighten-up a tad when the piston get warm.

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Holes get bigger as the temperatures increase they do not "tighten up". Since the pin is steel and the piston aluminum the clearances will only increase as it warms up.