The ring break-in procedure I described was reccomended by Perfect Circle piston ring company as early as the mid-1950's that I can remember, and probably for some time before that. The majority of a piston ring's sealing happens due to combustion pressure getting above and behind the ring and forcing the ring against the cylinder wall and the ring lands of the piston. Only a small fraction of the ring seal against the cylinder wall is from the spring tension of the ring itself. The second ring on a piston usually serves a dual purpose- - - -sealing whatever compression gets past the top ring on the upstroke of the piston, and flexing to become a secondary oil control ring on the downstroke. To function properly, a ring needs a smooth, straight cylinder wall to bear against. Taper-worn cylinder walls result in very short ring life, and more than normal leakage during both compression and combustion.
Jerry
