Pete, you got some good resposes by our "guys" Try going on line to Chevy Hi Performance and get all there articals on vortecs. I have a bunch of them and would be happy to copy them and send them to you, they will answer all your questions. As others addressed the max lift is the difference between the bottom of the "inside" diameter of the retainer and the top of the valve seal. You can ck this by removing a spring, reinstalling the valve with the keepers and retainer (use some vasalene to hold the keepers/retainer up and on the valve) and measure from the bottom of the inside of the retainer adjacent to the valve stem to the top of the valve seal. As someone else said reduce that # by .060 for coil bind/clearence and you will have the max lift possible for that valve. The beehives and retainers are great and are going to work up to their .600 lift with no additional mods (grinding,cutting) on a set of heads I'm working. Call Comp Cams and ask questions,I've been pleased! Roy