Mast Motorsports Rectangular Port LS3 11 Degree Small Bore CNC Assembled (3.900″-3.960″ Bore)

• Easy bolt on to convert your GM Gen III to GM Gen IV head technology
• Perfect for LS1 and LS6 engines and short-blocks
• Accepts LS3/L92 valvesprings, rocker arms, and intake manifolds
• Outflows any aftermarket cathedral cylinder head on the market
• Uses a 2.080″ intake valve and 1.570″ exhaust valve
• Has a 63cc combustion chamber standard
• Has a deck thickness of .750″

Each Mast Black Label cylinder head assembly includes:

• A fully CNC machined Mast Black Label aluminum cylinder head
• Mast micro finished .650 lift beehive valve 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/3.900″ Bore Plate

Lift Intake Exhaust

0.100 72 55

0.200 148 107

0.300 224 155

0.400 282 203

0.500 322 214

0.550 338 222

0.600 342 227

0.650 346 231

0.700 353 257