LT1 Pair Black Label Cylinder Heads - 4.065 (+) Bore - For Direct Injection or Port Injection - Stainless Steel or Titanium Valves

---->Download the cylinder head spec sheet<---- The Mast Motorsports cylinder head product line is completely manufactured from a raw casting to a finished cylinder head in the USA located in Nacogdoches Texas.  Mast refuses to compromise on materials and methods that may jeopardize longevity, performance, and quality.  When buying Mast Cylinder heads, you are getting the highest level of quality and performance on the market.  Full Send, no compromises, no shortcuts, ever. Dimensional Specs Bore Size: 4.065" (+) Weight: 30 lbs. Intake Valve Size: 2.165" Exhaust Valve Size: 1.600" Valve Stem Diameter: 5/16" Valve Length: 5.550" Intake Valve Angle: 12.5°x2.5° Exhaust Valve Angle: 12°x2.5° Valve Spring Pocket Diameter: 1.400" Valve Spring Install Height: 1.800" Head Stud Size: .530" Valve Guide OD: .570" Valve Job Type: Newen CNC 5 Angle Air Flow & Performance Criteria Intake Max. Flow: 355 CFM @ 0.700" Exhaust Max. Flow: 224 CFM @ 0.700"