LS3 12 Degree 3.900"-3.930" Small Bore CNC Unassembled Heads

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 1.060" Exhaust Valve
Has a 245cc Intake Port and 85cc Exhaust Port
Has a deck thickness of .750"

Heads are available assembled with either solid or hollow stem Mast Racing Valves, steel or ti retainers, and four valve spring options. Please refer to the assembled item on the site.

Easy bolt on to convert your GM Gen III to GM Gen IV cylinder head technology.

Flow Data w/ 3.900" Bore Plate
Lift | Intake | Exhaust
.100 | 73 | 57
.200 | 155 | 114
.300 | 228 | 164
.400 | 281 | 204
.500 | 320 | 222
.550 | 333 | 228
.600 | 343 | 232
.650 | 351 | 236
.700 | 355 | 240