S&S Cams are tested on the dyno, street and track before being offered to the public, Bolt in cams that provide excellent torque with stock or ported heads, Recommended for modified engines up to 89" displacement and compression ratio of 9.0:1 to 10.5:1, Will work in 89" - 100" engines with less than 9.0:1 compression ratio, 2000 to 6000 rpm, Works with stock valve springs and stock non-adjustable pushrods, Models with stock flywheels require use of '91-'99 style pinion gear (sold separately)., Installer must check coil bind, valve to valve clearance, valve to piston clearance and cam lobe to case clearance.