Pontiac Repair: 3100 pontiac ring size, pontiac ring, piston rings

Question
Im rebuilding A 3100 engine that is giving me fits!! Ive got two diffrent sets of piston rings and neither are fitting. checked the bore and the diameter of the piston, ridge reemed and honed the cylinders. they are standard bore.Did GM put more than a couple of pistons in this engine? the car in question is a 1997 Pontiac Grand Am GT.The engine was replaced. I have been a mechanic for 33 yrs and hope it a part error and not someting I missed.Thanks for any input.

Answer
Hi William:

when you say they do not fit what's the issue? they do not fit in the piston or they do not fit when you put the piston into the bore with the rings on the pistons? what type of fit issue are you haveing? To my knowledge a 3100 is a 3100 wether it'a a 1994 or a 1999. the only difference I know of with the pitsons on the engines is the later year engiens had a blask coating sprayed on the piston skirts to cut down on the slap noise on a cold start, The pistons should all be the same I would think. I assume your using aftermarket parts here. Are they name brand rings or a store brand "cheapo" ring kit?