Chevrolet BB Mark IV 396-502 1965-1996 Advertised Duration: 281/281 Duration @ .050": 249/249 Valve Lift w/1.70 Rockers: .663/.663 Lobe Separation Angle: 110 Intake Centerline: 106 3000-7000. Lopey idle, pro-street cam. Works well with small NOS system.