CAMSHAFT GEAR DRIVE KITS INCREASE VALVE TIMING ACCURACY BY ELIMINATING TIMING CHAIN LASH AND LOOSELY FITTING STOCK CHAIN DRIVE REVERSES THE REAR CAMS DIRECTION OF ROTATION, PROVIDING ADDITIONAL OPERATING CLEARANCE BETWEEN CAM LOBES; AS A RESULT, HIGHER CAM LIFTS ARE POSSIBLE WITH THE GEAR DRIVE KIT KITS INCLUDE CAMS, INNER GEARS, OUTER DRIVE GEARS, INNER AND OUTER BEARINGS, GASKET AND INSTRUCTIONS MATERIAL MUST BE REMOVED FROM THE INNER SURFACE OF THE STOCK GEAR COVER TO INSTALL S&S GEAR DRIVE CAMS A HYDRAULIC PRESS AND OTHER PROFESSIONALLEVEL TOOLS ARE REQUIRED TO INSTALL THESE KITS S&S RECOMMENDS THAT ADJUSTABLE PUSHROD/COVER KIT CAM BEARINGS AND GASKETS MUST BE REPLACED WHEN INSTALLING NEW CAMS MADE IN THE U.S.A. KITS REQUIRE HIGHPERFORMANCE VALVE SPRINGS. INSTALLER MUST CHECK COIL BIND, VALVETOVALVE CLEARANCE AND VALVETOPISTON CLEARANCE. DUE TO THE INHERENT CHARACTERISTICS OF GEAR DRIVES, YOU MAY EXPERIENCE MORE VALVE TRAIN NOISE.