I'm running a solid roller in my 451. The specs are 253/263 @ .050, .610/.610 lift after lash. I believe my spring pressure is in the neigborhood of 550 lbs/in. Luckily this rocker just broke at an idle and the car was shut off immediately. What are you guys using? I need a new set of 1.60 ratio rockers. I like the sound of the Comp Pro-Magnums, but they don't offer them in a 1.60 ratio.