Reducing oil to the camshaft?

On solid roller lifters.

Some lifters it may require bushing the lifter bores and drilling a .030" hole in the bushing. Some lifters get the oil for the rollers from an EDM hole that is feed from a .250" hole that goes sideways through the lifter body. On those I cut a piece of steel tube longer than the hole, but not so long it hits the lifter bore, and swage the ends of the tube open to hold the tube into the lifter body. The tube is slightly smaller than the main .250" hole and still allows some oil to the roller.