AFR 24° BBC 300cc Oval Port Fully CNC Ported Cylinder Head – Competition Package

Designed for aggressive street, street/strip, or race applications, the AFR 24° BBC 300cc Oval Port Cylinder Head is the ultimate performance upgrade for big block Chevy engines up to 540 cubic inches operating at or below 6800 RPM. Featuring 100% CNC-machined intake runners, exhaust ports, and combustion chambers, this competition-ready cylinder head flows an impressive 388 CFM at 0.700” lift—offering superior power without requiring a rectangular port design.

Included Components

100% CNC Ported Combustion Chambers
100% CNC Ported Exhaust Ports
100% CNC Ported Intake Ports
Competition 5-Angle Valve Job
Intake Valve: 11/32", 2.300" x 5.500" O.A.L (AFR #7626)
Exhaust Valve: 11/32" Nail Head, 1.880" x 5.450" O.A.L (AFR #7630)
Valve Springs: PAC Racing #1940 1.550" OD Hydraulic Roller Dual Valve Spring (175 lbs. on seat, .725" max lift, Max RPM 6500-6700) with #8511 Steel Retainer and #8044 Spring Cup (AFR #8002)
Rocker Studs: ARP 7/16" Intake (AFR #6407) & ARP 7/16" Exhaust (AFR #6406)
Valve Seals: 11/32" Viton (AFR #6613)
Guide Plates: Adjustable 3/8" (AFR #6109)
Valve Seats: Intake 2.450" O.D x 1.950" I.D x .375" Deep (AFR #9065), Exhaust 2.000" O.D x 1.580" I.D x .375" Deep (AFR #9064)

300cc Competition Flow Chart

Test conducted at 28" of water (pressure) on Superflow 1020. Bore Size: 4.500", 3/4" radius plate exhaust, 1 7/8" curved pipe.

Lift	.200	.300	.400	.500	.550	.600	.650	.700
Intake (CFM)	161	238	298	342	359	374	384	388
Exhaust (CFM)	139	191	234	266	275	289	294	298

Specifications & Features

Material: A356 Aluminum
Intake Port Volume: 300cc
Combustion Chamber Size: 112cc (Full CNC)
Exhaust Port Volume: 135cc
Deck Thickness: .750"
Valve Angle: 24°/4° Int, 15°/4° Exh
Spark Plug Dimensions: 14mm x .750" w/Gasket Seat
CARB Status: Not legal for sale or use on emission-controlled vehicles—intended for dedicated race vehicles only.

Performance & Compatibility

The AFR 24° BBC 300cc Oval Port Cylinder Head is engineered for big block Chevy enthusiasts who demand the best in airflow efficiency and durability. Whether you’re running an aggressive street build, a street/strip setup, or a full race application, this cylinder head delivers high-performance results with exceptional reliability. Perfect for engines up to 540 cubic inches, it maximizes power and efficiency without sacrificing drivability.