Piston Ring gap

I always use file-to-fit rings... If you're using stock replacement pistons stock rings are fine. If you are running a performance piston then you should get file-to-fits. A basic spec for ring gaps is .004" per inch of bore for top ring(non hypereutectic piston) and .006 for the second ring, always rounding up to the next whole number. So your 4.06 bore would need on top ring: 4.06x.004=.0162 rounded to .017... Second ring 4.06x.006=.0243 rounded to .025. You will need to file fit the stock type ring for these specs.