Assembled; Pontiac 389/400/421/428/455 Cubic Inch Engine; Aluminum; 204 CC Intake Port/ 145 CC Exhaust Port; 72 CC Chamber Volume; 2.11 Inch Intake Valve/ 1.66 Inch Exhaust Valve; 1.46 Inch Spring Diameter; Single; With Guides/ Seats/ Springs For Hydraulic Roller Cam