Other products by AFR
Item #: 3670
Reg. Price: USD $3,141.00
Our Price: USD $3,133.00


300cc Oval Port 24° "Magnum" BBC

The Ultimate Street/Race Weapon

AFR's 300cc heads feature 100% CNC ported intake, exhaust & chambers, A356 aluminum castings and high quality components throughout. Recommended for aggressive street, street/strip or race builds with displacements up to 540 cubic inches, operating up to 6800 RPM.


1" longer head bolts needed on four bottom exhaust bolt holes.

300cc BBC Aluminum Cylinder Head Flow Chart

Tested on 4.310 Bore

300cc BBC Cylinder Head Flow Chart

Included Components
100% CNC Ported Exhaust Ports
100% CNC Ported Intake Ports
100% CNC Ported Combustion Chambers
Competition 5-angle Valve Job
AFR #762611/32" Intake Valve, 2.300" x 5.500" O.A.L
AFR #763011/32" Nail Head Exhaust Valve, 1.880" x 5.450" Overall Valve Length
AFR #80021.550 O.D. Hydraulic Roller Dual Valve Spring 160 lbs. on seat, .680 maximum lift, Max RPM 6500-6700, Uses #8511 Steel Retainer and #8048 Spring Cup
AFR #8031PAC Racing Spring #1224 1.625 O.D. Solid Roller, 275lbs on seat, .850 Maximum Lift, Max RPM 7400-7600, Uses #8518 Steel Retainer (upgrades available)
AFR #8511 for spring #8002Manley 10° Steel Retainers 1.500" O.D x 1.120" I.D x .705" I.D
AFR #8518 for spring #8031Manley 10° Steel Retainers 1.500" O.D x 1.168" I.D x .844" I.D
AFR #900510° 11/32" Valve Locks with lashcap recess
AFR #6406ARP 7/16" Rocker Exhaust Studs
AFR #6407ARP 7/16" Rocker Intake Studs
AFR #6109Adjustable 3/8" Guide Plates
AFR #661111/32" Viton Valve Seals
AFR #8046Hardened Valve Spring I.D Locator 1.550" O.D x .780" I.D
AFR #9065Intake Valve Seats 2.450" O.D x 1.950" I.D x .375" Deep
AFR #9064Exhaust Valve Seats 2.000" O.D x 1.580" I.D x .375" Deep
AFR #904511/32" Intake Bronze Valve Guides .531" O.D x 2.10" O.A.L
AFR #904611/32" Exhaust Bronze Valve Guides .531" O.D x 2.25" O.A.L

Specifications & Features:
A356 AluminumMaterial
300ccIntake Port Volume
2.055"H x 1.840"W x1/2 RadiusIntake Port Dimension
StockIntake Port Location
135ccExhaust Port Volume
1.770"H x 2.010" WExhaust Port Dimension
.375" RaisedExhaust Port Location
112ccCombustion Chamber Size(Full CNC)
Perimeter BoltValve Cover Bolt Pattern
24°/4° Int, 15°/4° ExhValve Angle
1.725" O.DValve Spring Pocket Diameter
1.750" O.DMax Valve Spring Pocket Machining
.750"Deck Thickness
4.250"Minimum Bore Diameter
.006" per cc/ Maximum 102ccFlat Mill
.009" per cc/ Maximum 97ccAngle Mill
Note:Angle mills might require a .120" Thick intake gasket.
3.020 sq. in. Minimum Cross Sectional Area
14mm x .750" w/Gasket SeatSpark Plug Dimensions

Recommended Components:
Mr. Gasket #107 or GM #12366985Intake Port Gasket
Important: Do not port match your intake manifold to Fel-Pro gasket as it does not precisely fit AFR heads.
AFR #6858Exhaust Port Gasket
AFR #6849Head Gasket, Fel-Pro #1047 (Mark V and VI)
AFR #6850Head Gasket,, Fel-Pro #1017-1 (Mark IV)
AFR #6306Head Bolts, ARP 135-3703 (Mark IV)
AFR #6308Head Bolts, ARP 135-3707 (Mark V)
AFR #6307Head Studs, ARP 235-4713
AFR #6320Head Bolt Washers, Manley
AFR #6202Stud Girdle, (AFR Specific)
Victor JrSuggested Manifold
RPM PerformerSuggested Manifold
Autolite 3932Spark Plug Starting Range



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