Mast Motorsports Rectangular Port LS3 12 Degree 6-Bolt Large Bore CNC Assembled (4.125″+ Bore)

• Utilizes the Gen IV LS7 OEM rockers, but accepts the LS3/L76 intake manifold
• Designed for any new Gen IV short-block with 4.125″ bore or larger
• The 6-bolt design is compatible with GM LSX and World LSX blocks
• Uses a 2.200″ intake valve and 1.600″ exhaust valve
• Has a 280cc intake port
• Has a deck thickness of .750″
• Has a 70cc Combustion Chamber Standard

Each Mast Black Label cylinder head assembly includes:

• A fully CNC machined Mast Black Label aluminum cylinder head
• Mast micro finished .700″ Lift Dual Springs
• Mast lightweight stainless steel intake & exhaust valves
• Mast lightweight steel retainers
• Mast machined locks

NOTE: Gaskets, valve covers, rocker arms and pushrods not included

Flow Data w/4.125″ Bore Plate

Lift Intake Exhaust

0.100 78 55

0.200 147 108

0.300 227 159

0.400 300 200

0.500 352 228

0.550 366 236

0.600 380 243

0.650 384 249

0.700 387 252