Until the engine can be put under a driving load, the rings won't exert enough pressure against the cylinder walls to burnish themselves into a proper fit. The old idea of needing to position compression ring gaps in a certain way has no merit at all, since the rings rotate at random around the piston as the engine runs, and the gaps will align themselves with each other momentarily. At 2000 RPM, the pistons are traveling the full length of the cylinder 60 times a second. Even if the gaps align at times, there's very little time for any serious leakage to happen. Ring gaps are also unimportant, as long as they're not so close as to let the ring ends butt together as the engine heats up. If that happens, severe cylinder scoring will happen. Two or even three times the minimum gap will have virtually no effect on compression.
Rings actually seal against the cylinder walls by compression and combustion pressure getting behind the ring and forcing it against the cylinder wall, and down against the bottom of the ring lands on the piston. The spring tension of the ring helps a little, but the dynamic seal caused by combustion pressure does most of the work.
Jerry
