The most common method to induce lifter rotation is to put a slight radius on the lifter bottom, and slightly offset the lifter centerline in relation to the cam lobe centerline. As the lifter is taking up the slack caused by clearance on a solid lifter cam, or the lightly-loaded acceleration ramp portion of a zero-clearance hydraulic lifter, the wiping action of the lobe on the off-centered lifter spins it. Only roller lifters are designed not to spin in their bores. Lifters that are worn flat on the bottom are worn out. Concave lifters are definitely junk! A straightedge held across the bottom of a good lifter should rock slightly. Also, NEVER swap lifters to another lobe of a camshaft, or put them onto a different cam, once they've established a running fit on a particular lobe. The advice about running-in a new cam for 20 minutes at a fast idle is to provide enough splash lubrication to the cam and lifters to prevent scuffing while they're breaking in.
Jerry

"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
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