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.002 is usually the max recommended rod/crank clearance on a street SBC. Even at that clearance, with the bearing and crank coated with assembly lube or even oil, there should be very little or no noticeable looseness in the assembly.

Plastigauge is a cheap, fairly quick way to check assembly clearances but it is not as accurate as a good set of micrometers. One thing I learned long ago when building engines is that if there is any question during any part of the assembly process……stop right there and figure out what is going on. At this point I would pull at least a couple of the loosest piston/rod assembly and actually measure the rod/bearing and crank and verify what the clearances are. What you find will dictate what your next move is.


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