Chevrolet BB Gen 6 454-502 1996-1999 Advertised Duration: 286/300 Duration @ .050": 233/247 Valve Lift w/1.70 Rockers: .601/.612 Lobe Separation Angle: 114 Intake Centerline: 110 2500-6500 Mild idle, Hot Street. Great mid-range performance. Small blower or NOS OK.