Dual Conical Valve Springs. As opposed to dual cylindrical spring systems, COMP Cams Dual Conical Valve Springs require no interference fit to dampen spring surge. The self damping characteristic of conical geometry, along with the lower spring kinetic energy of the upper coils, provide a game-changing breakthrough in valve spring design. COMP Cams Dual Conical Valve Springs are constrained at the top and bottom with stepped retainers and spring seats to create separation. The result is that the springs naturally progressive nature can provide outstanding damping without rubbing friction or the associated heat and surface damage. These springs are designed for circle track, road Race and drag racing Applications, as well as all-out, high-RPM street/strip hydraulic Roller valve train systems with optimized lifters.Dampen coil oscillations, increase RPM limit and reduce resonanceImproves valve train stabilityFewer parasitic horsepower losses and more powerSuperfinish surface processingNon-interference fitThe reduced oscillation in the Dual Conical Springs translates to less applied force and stress to the springs. This increases the lifespan of the spring and the valve train. It also allows the use of more aggressive Camshaft profiles. Seat LoadOpen LoadCoil BindRateODIDRetainersSeatsShims 150lbs @ 2.00" 630lbs @ 1.20"1.115" 600lb/in1.442".646" 716-1, 1738-1 4668-1, 4669-1 47561.657".861"