AFR 24° BBC Cylinder Head 305cc Partially CNC Ported, 117cc Chambers, Race Ready

The AFR 305cc BBC Rectangle Port Cylinder Head is engineered for moderate street or street/strip applications, supporting displacements up to 509 cubic inches while operating at or below 6500 RPM. This high-performance cylinder head features partially CNC-machined intake and exhaust ports, with combustion chambers available in either partial or full CNC machining, including a precision bowl blend. Capable of flowing up to 368 CFM at 0.700" lift, this head delivers excellent power and efficiency.

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 (275 lbs. on seat, .850” max lift, Max RPM 7400-7600) – AFR #8031
10° Steel Retainers – 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

Performance Flow Chart

**305cc As Cast Flow Chart (CFM @ Lift)**

Lift	.200	.300	.400	.500	.600	.650
Intake	146	215	272	310	341	358
Exhaust	129	179	215	239	253	260

Specifications & Features

Material: A356 Aluminum
Intake Port Volume: 305cc
Combustion Chamber Size: 117cc (as cast) / 121cc (full CNC)
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 Compliance Notice

THIS PRODUCT IS NOT LEGAL FOR USE ON PUBLIC HIGHWAYS. These cylinder heads are only intended for dedicated race vehicles. Violation of this restriction may result in penalties up to $37,500 per violation, DMV registration revocation, and proof of correction requirements.