Severe Duty Exhaust ValveSmall Block Chevy1.600'' Diameter5/16'' (0.3110'') Stem Diameter5.040'' Overall Length (+.100)15� x 1/2'' Underhead Angle/RadiusStainless Steel1/pkg. Installation Note: These 5/16'' (.311'') stem valves are ONLY available with Bead Loc keeper grooves. Bead Loc valve locks are REQUIRED.Type: Exhaust Valve XH-428 MaterialHead Diameter: 1.600''Stem Diameter: 5/16'' / 0.3110''Installed Height: +.100'' LongerOverall Length: 5.040''Tip Length: 0.290''Underhead Angle / Radius: 15° x 1/2''Margin: 0.080''Seat Width: 0.100''Top of Head: 9° DishWeight / Grams: 94