I had to have my last 400 block stroker motor lifter bores bushed using one of Bullitt, Ultra Dyne custom ground solid roller camshafts with Comp Cams solid roller lifters for pushrod oiling, I tried a set of Crane solid body solid roller lifters also which had no oil pressure priming it It had 20 lbs. with the Comp lifters All the other 400 block solid roller cams and standard Comp Cams lifters I've used had 75+ lbs. priming