Back in the mid-1950's, Some Buick V-8's came from the factory with blocks that were .005" oversize. Apparently, there was a mistake in the honing process for a run of several hundred blocks. No problem- - - - -a "standard" ring set is supposed to handle an overbore of up to .010", right? Wrong! Those engines used oil from day one! The factory fix was to install a set of .010" oversize rings, and file the end gaps to fit. The oil consumption got worse! The only way those engines ever got better was to rebore them, and install a ring set that matched the bore size.
Rings are ground perfectly round to fit a specific bore size, and then an end gap is cut to allow them to be installed on the piston. If the ring is so big the ends butt together as it goes into the cylinder, filing the ends will allow it to be installed, but it will never fit the cylinder properly. Changing the circumference of the ring causes it to create gaps where it meets the cylinder wall. The only exception I can think of to that rule are "file-fit" rings for racing engines, and they aren't expected to run more than a few miles before the engine wears out or blows up. A round track engine with 1,000 miles on it is an antique, and some drag race engines get torn down and re-ringed after 3 or 4 1/4 mile runs, maximum.
Jerry
