LS1 275 cc 4.125"+ CNC Cylinder Head

  • Sale
  • $ 1,399.99


When the rectangular port LS heads came out many people cast out the cathedral port design.  Mast knew the potential of this design and developed a BIG cathedral ls head to work with our stellar LS1 4500 intakes.  In conjunction with displacements of 427ci+ this combination has proven to be extremely successful.  With the advent of better aftermarket cathedral intakes such as the MSD Atomic Airforce the street potential of this head is seeing new heights.  If you are running a 4.125 bore shortblock and want really good low-end torque without sacrificing peak power, the Mast LS1 275 head just might be the head for you.    

  • Mast Rocker Stands required to run factory LS7 rocker arms
  • Designed for any new Gen IV short-block with 4.125" bore or larger
  • The 6-Bolt design is compatible with GM LSX, RHS & World LSX blocks
  • Utilizes GM Gen IV LS7 valvetrain
  • Fits any GM LS cathedral port intake manifold
  • Uses a 2.200" intake valve and 1.600" exhaust valve
  • 12 Degree Valve angle
  • Has a 275cc intake port
  • Has a 70cc combustion chamber standard
  • Has a deck thickness of .750"
  • Cast & Machined in the USA!
Flow Data 275cc Large Bore
Lift Intake Exhaust
0.100 78 55
0.200 147 108
0.300 223.5 159
0.400 294 200
0.500 341 228
0.550 354 236
0.600 360 243
0.650 361 249
0.700 372 252
0.750 373 255
0.800   258
0.900   260
1.000   263