Fully machined billet steel camshaft and crankshaft sprocketsRoller chain designed with .250" diameter rollersNine keyway steel crankshaft sprocket enabling different settings: 0?, +/- 2?, +/- 4?, +/- 6?, +/- 8?Camshaft sprockets are machined for and include a captive Torrington thrust bearingNo grinding/modifying of timing cover requiredNOT recommended for valve spring pressures exceeding 450 lbs.