AFR 24° BBC Cylinder Head 265cc Oval Port - Partially CNC Ported, 109cc Chambers, Race Ready

The AFR 265cc BBC Oval Port Cylinder Head is the ultimate upgrade for high-performance street, street/strip, and towing applications. Designed as a cost-effective alternative to reworked factory heads, these high-velocity cylinder heads feature partially CNC-machined intake and exhaust ports, as well as optional full or partial CNC-machined combustion chambers with a bowl blend. Capable of flowing an impressive 354 CFM at 0.650” lift, these heads support big block Chevy engines up to 468 cubic inches, operating at or below 6200 RPM.

Key Features

265cc Oval Port for increased airflow and efficiency
Partially CNC-machined intake (80%) and exhaust (75%) ports with bowl blend
Choice of 109cc (partial CNC) or 112cc (full CNC) combustion chambers
Capable of flowing 354 CFM at 0.650" lift
Competition 5-angle valve job for superior sealing and performance
Designed for use with solid roller camshaft applications
High-strength A356 aluminum construction

Included Components

Intake Valves: 2.190" x 5.460" (AFR #7601)
Exhaust Valves: 1.880" x 5.450" (AFR #7630)
Valve Springs: PAC Racing 1.550” OD Solid Roller Dual Valve Springs (AFR #8000)
Steel Retainers: 10° 1.500" OD x 1.120" ID x .705" ID (AFR #8511)
Valve Keepers: 10° 11/32" with lashcap recess (AFR #9005)
ARP Rocker Studs: 7/16" Intake (AFR #6407) & 7/16" Exhaust (AFR #6406)
Guide Plates: Adjustable 3/8" (AFR #6109)
Valve Seals: 11/32" Viton (AFR #6613)
Valve Spring Cups: Hardened 1.655" OD x 1.565" ID (AFR #8044)
Intake Valve Seats: 2.450" OD x 1.950" ID x .375" Deep (AFR #9065)
Exhaust Valve Seats: 2.000" OD x 1.580" ID x .375" Deep (AFR #9064)

Technical Specifications

Material: A356 Aluminum
Intake Port Volume: 265cc
Exhaust Port Volume: 132cc
Combustion Chamber Size: 109cc (Partial CNC), 112cc (Full CNC)
Valve Angle: 24°/4° Intake, 15°/4° Exhaust
Deck Thickness: .750"
Minimum Bore Diameter: 4.125"
Max Valve Spring Pocket Machining: 1.750" OD
Minimum Cross Sectional Area: 2.640 sq. in.
Spark Plug Dimensions: 14mm x .750" w/Gasket Seat

Flow Chart Data

265cc As Cast Flow Chart

Lift (in.)	Intake (CFM)	Exhaust (CFM)
.200	154	127
.400	278	200
.650	335	260

265cc w/ 100% CNC Chamber Flow Chart

Lift (in.)	Intake (CFM)	Exhaust (CFM)
.200	164	135
.400	291	230
.650	340	280

Legal Disclaimer

CARB Status: These products are illegal to operate on any public highway, roadway, or park. They are only legal for dedicated racing vehicles. Violators may be subject to fines, registration revocation, and loss of use on public roads.