Wondering why cars don't use solid lifters anymore? Here's when they faded out and how hydraulic lifters took over for ...

This diagram is a lobe profile "map" (with the 454 Chevy's 1.72:1 rocker ratio factored in) of the hydraulic, solid, and roller lifter cams tested in the 290-degree-advertised-duration range.

Factory hydraulic lifter preload figures compress the lifter plunger by 1 to 11/2 turns after zero lash. Assuming a 24- thread-per-inch rocker stud, one full turn is equal to 0.040 inch of preload ...