AFR 24° BBC Cylinder Head 305cc Partially CNC Ported, Race Ready, w/121cc CNC Chambers

The AFR 305cc BBC Rectangle Port Cylinder Head is designed for moderate street or street/strip applications, supporting engines up to 509 cubic inches operating at or below 6500 RPM. Featuring partially CNC-machined intake runners and exhaust ports, the combustion chambers are available with partial or full CNC machining, ensuring optimal flow and performance. These high-performance cylinder heads are capable of flowing 368 CFM at 0.700" of lift, making them an excellent choice for racing and high-performance builds.

Included Components

50% CNC Ported Combustion Chambers
20% CNC Ported Exhaust Ports
30% CNC Ported Intake Ports
Competition 5-Angle Valve Job
11/32" Intake Valve, 2.250" x 5.500" O.A.L - AFR #7620
11/32" Nail Head Exhaust Valve, 1.880" x 5.450" O.A.L - AFR #7630
PAC Racing #1224 1.625” OD Solid Roller Dual Valve Spring - AFR #8031
10° Steel Retainers 1.500" O.D x 1.168" I.D x .844" I.D - AFR #8518
10° 11/32” Valve Keepers with Lashcap Recess - AFR #9005
ARP 7/16” Rocker Studs Intake - AFR #6407
ARP 7/16” Rocker Studs Exhaust - AFR #6406
Adjustable 3/8" Guide Plates - AFR #6109
11/32" Viton Valve Seals - AFR #6613
Hardened Spring Cup 1.740" O.D / 1.650" I.D - AFR #8046
Intake Valve Seats 2.450" O.D x 2.000" I.D x .375" Deep - AFR #9065
Exhaust Valve Seats 2.000" O.D x 1.580" I.D x .375" Deep - AFR #9064
11/32" Intake Bronze Valve Guides .502" O.D x 2.10" O.A.L - AFR #9041
11/32" Exhaust Bronze Valve Guides .502" O.D x 2.25" O.A.L - AFR #9042

Flow Chart (305cc As Cast)

Intake (CFM): 146 @ .200", 215 @ .300", 272 @ .400", 310 @ .500", 341 @ .600", 358 @ .650"
Exhaust (CFM): 129 @ .200", 179 @ .300", 215 @ .400", 239 @ .500", 253 @ .600", 260 @ .650"

Flow Chart (305cc w/ 100% CNC Chamber)

Intake (CFM): 154 @ .200", 225 @ .300", 280 @ .400", 316 @ .500", 345 @ .600", 362 @ .650"
Exhaust (CFM): 133 @ .200", 187 @ .300", 223 @ .400", 249 @ .500", 259 @ .600", 264 @ .650"

Technical Specifications

Material: A356 Aluminum
Intake Port Volume: 305cc
Intake Port Dimensions: 2.380"H x 1.680"W x 11/32" Radius
Exhaust Port Volume: 132cc
Exhaust Port Dimensions: 1.720"H x 1.920"W
Combustion Chamber Size (As Cast): 117cc
Combustion Chamber Size (Full CNC): 121cc
Valve Cover Bolt Pattern: Perimeter Bolt
Valve Angle: 24°/4° Int, 15°/4° Exh
Deck Thickness: .750"
Minimum Bore Diameter: 4.250"
Spark Plug Dimensions: 14mm x .750" w/Gasket Seat

CARB Status

These products are illegal to operate on any public highway. This includes any public paved or unpaved roadway or public park. These products are only legal if used on a dedicated racing vehicle. Violations may result in a maximum penalty of $37,500 per violation per vehicle, revocation of registration by DMV, loss of use on public rights of way, and proof of correction of the tampering.