Hi-performance lifters are the perfect match for any performance camshaft- these pre-clearanced and lightweight followers will help reduce valve float at high RPM's- The first choice of most top engine builders. You must replace the cam followers when installing a new camshaft .Cam and followers mate too each other- so when you use used followers with a new cam- the worn lifters will ware out the lobes of the new cam. All warranties for any new cam can only be offered if you buy and use new followers from C.I.P. at the time you purchase your new cam. Stock followers are not designed to work with performance camshafts. You will need to check the clearance between the tip of the cam lobe and the lifter to make sure there is a minimum of .040 inch clearance.