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Our largest and most powerful 60/40 head for the small block Chevy features 100% CNC machined intake runners, exhaust ports and  combustion chambers. Capable of flowing 350 CFM at 0.800" of lift these heads come equipped with Titanium retainers and high quality components throughout, the 60/40 valve spacing which requires shaft mounted rocker arms for optimum valve train geometry and extra machining for 3/8" pushrod clearance. NPP stands for "no pushrod pinch."

245cc NPP Aluminum SBC Cylinder Heads
Part # Exhaust Port Porting Finish Combustion Chamber
1137-TI Stock Competition 70cc
1138-TI Stock Competition 80cc
1139-TI Spread Port Competition 70cc
1140-TI Spread Port Competition 80cc

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245cc Race Head Flow Chart
  .200 .300 .400 .500 .550 .600 .650 .700 .800
Int 165 232 278 310 321 330 336 341 350
Exh 128 181 214 235 242 247 251 254 256

Test conducted at 28" of water (pressure) on Superflow 600
Bore Size: 4.155", 3/4" radius plate exhaust, 1 7/8" curved pipe

Included Components
100% CNC Ported Combustion Chambers
100% CNC Ported Exhaust Ports
100% CNC Ported Intake Ports
Competition 5-angle Valve Job
8mm Bead Lock Intake Valve, 2.125" x 5.000" Overall Valve Length
8mm Bead Lock Exhaust Valve, 1.600" x 5.030" Overall Valve Length
PAC Racing Springs 1.550" OD Solid Roller Dual Valve Spring Pac #1225, 250 lbs on seat, .800" maximum lift, Max RPM 8000-8200
10° Titanium Retainers 1.490" O.D x 1.115" I.D x .745" I.D
10° Bead Lock Valve Keepers with lashcap recess
Viton Valve Seals .600" O.D x .495" I.D
Hardened Valve Spring I.D Locator 1.550" O.D x .780" I.D
Ductile Iron Intake Valve Seats 2.200" O.D x 1.750" I.D x.375" Deep
Ductile Iron Exhaust Valve Seats 1.696" O.D x 1.325" I.D x .305" Deep
8mm Bronze Valve Guides .502" O.D x 2.100" O.A.L
Specifications & Features:
A356 Aluminum
Intake Port Volume
Intake Port Dimension
2.200" H x 1.300" W 7/16 Radius
Intake Port Location
Exhaust Port Volume
Exhaust Port Dimension
1.465" H x 1.570" W
Exhaust Port Location
.250" Raised
Combustion Chamber Size
70cc or 80cc
Valve Cover Bolt Pattern
Perimeter Bolt
Valve Angle
Valve Spring Pocket Diameter
1.580" O.D
Max Valve Spring Pocket Machining
1.680" O.D
Warning: Do not machine spring pad any deeper.
Deck Thickness
Minimum Bore Diameter
Flat Mill
.006" per cc 65cc Maximum
Angle Mill
.009" per cc 60cc Maximum
Note: Angle mills might require .120" Thick intake gasket.
Minimum Cross Sectional Area
2.730 sq. in.
Spark Plug Dimensions
14mm x .750" w/Gasket Seat
Carb EO#
Non Emissions Compliant