your rocker arms multiply the cam lobe lift by 1.6. so if your cam lobe lift is .3125", then multiply that by 1.6 and you would have .500" lift at your valves. .3125 x 1.6 = .500" If your springs are good for .500" ( due to coil bind) then you want a cam with less then 0.500" lift (at the valve). Most advertised lift specifications for cams is at the valve, figureing in the rocker arm factor for that specific engine. They have done the math for you.
