I set mine up at 250 to 275 on the seats and end up with 630 to 650 lbs open at .730 lift at the retainers, Comp Cam lobes, springs and retainers and locks on a set of Eddy RPM heads,this combination is run a street motor that I shift at 7000+ RPM I put two years of racing on the first set and have near that on the second set, 100 or more runs per year and 300 to 600 street miles. I had been using the Mopar brand of solid rollers and had two lifter wheels break in two so I have switch to a set of Engle now Don't skimp on the springs or roller lifters