Bare; Unported; These Cylinder Heads Can Not Be Used Without Professional Head Preparation; For Use With Big Block Chevy Engines; 12 Degree Valve Angle; 1.53 Inch X 2.14 Inch Intake Port Entry; 1.84 Inch X 1.50 Inch Exhaust Port Exit; Use With 2.45 Inch Intake Valves And 1.85 Inch Exhaust Valves; Hot Isostatic Pressing (HIP) Process; Natural; Aluminum; Single; Valve Guides Included But Not Installed