AFR 23° SBC Cylinder Head 245cc Competition Package Heads

Our largest and most powerful 60/40 head for the small block Chevy, featuring 100% CNC machined intake runners, exhaust ports, and combustion chambers. Designed for extreme performance, these heads are capable of flowing 350 CFM at 0.800" of lift. Equipped with titanium retainers and high-quality components, the 60/40 valve spacing requires shaft-mounted rocker arms for optimal valvetrain geometry. Extra machining is done for 3/8" pushrod clearance. NPP stands for "no pushrod pinch."

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 (AFR #7253)
8mm Bead Lock Exhaust Valve, 1.600" x 5.030" Overall Valve Length (AFR #7254)
PAC #1225 Racing Springs, 1.550” OD Solid Roller Dual Valve Drag Race Spring (AFR #8001)
10° Titanium Retainers 1.500” O.D x 1.120” I.D x .705” I.D (AFR #8505)
10° Bead Lock Valve Keepers with lashcap recess (AFR #9009)
Viton Valve Seals .600" O.D x .495" I.D (AFR #6612)
Hardened Valve Spring I.D Locator 1.550” O.D x .780” I.D (AFR #8048)
Ductile Iron Intake Valve Seats 2.200" O.D x 1.750" I.D x.375" Deep (AFR #9060)
Ductile Iron Exhaust Valve Seats 1.696" O.D x 1.325" I.D x .305" Deep (AFR #9070)
8mm Bronze Valve Guides .502" O.D x 2.100" O.A.L (AFR #9051)

Performance Flow Chart

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

Lift	.200	.300	.400	.500	.550	.600	.650	.700	.800
Intake	161	224	261	301	311	320	331	337	345
Exhaust	128	165	214	228	237	238	243	245	250

Specifications & Features

Material: A356 Aluminum
Intake Port Volume: 245cc
Intake Port Dimension: 2.200" H x 1.300" W 7/16 Radius
Intake Port Location: Stock
Exhaust Port Volume: 80cc
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: 23°
Valve Spring Pocket Diameter: 1.580" O.D
Max Valve Spring Pocket Machining: 1.680" O.D (Do not machine spring pad any deeper)
Deck Thickness: .750"
Minimum Bore Diameter: 4.000"
Flat Mill: .006" per cc (65cc Maximum)
Angle Mill: .009" per cc (60cc Maximum)
Minimum Cross Sectional Area: 2.730 sq. in.
Spark Plug Dimensions: 14mm x .750" w/Gasket Seat

Important Notes

Do not use your AFR gasket as a template to port match your intake manifold, as one AFR gasket is used for many AFR runner volumes.

Legal Disclaimer

These products are illegal to operate on any public highway or roadway. They are only legal for dedicated racing vehicles. Violations are subject to fines up to $37,500 per vehicle, revocation of DMV registration, and loss of public roadway use.