Our Gilmer pulley set is the perfect solution for your racing set-up. It requires less tension and eliminates the problem of slippage and disengagement at high RPM. This is for big block chevy engines wit long water pumps. The belt is 1.5" the kit includes Crankshaft Pulley, Water Pump Pulley, Alternator Pulley, and the belt. Fits only applications with 5/8" wwater pump shafts. Fits with stock alternator pulley. WILL NOT WORK WITH A/C APPLICATIONS!