These budget friendly hydraulic roller springs work with our stage 2 and 3 cams. They are not designed to work with short installed height stock valves. They Install at 1.650" and work with Boport or other valves with .450" or .400" tip length valves. No machine work is required to the factory spring pockets when using correct tip length valves. These springs are 125lb closed pressure and 300lb open at .525" lift. Not designed for flat tappet slider cams. Price is for set of 8.