Tapered shims were used more frequently back when engines got an "in the frame" ring job about every 30K miles or so. The common practice was to adjust the bearing clearance by shimming behind only the bearing shell in the rod or main cap, not all the way around. The tapered shims allowed excessive clearance to be taken up by moving half the bearing closer to the crankshaft by reducing the radius. There's more to the process than meets the eye, such as filing a little off the ends of the bearing shell to retain the proper "crush" on the bearing.
Jerry

Last edited by Phak1; 05/16/2023 1:27 AM. Reason: Edited by Moderator to remove inappropriate comments
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!