Afr 305cc Bbc Marine Rectangle Port Cylinder Heads, Partially Ported

AFR is proud to announce their new BBC Marine Cylinder Head! This AFR 305cc marine rectangle port heads feature partially inconel exhaust valves, hydraulic roller springs, hard coat anodizing and high quality components throughout. Recommended for moderate street, or street/strip builds with displacements up to 509 cubic inches, operating up to 6500 RPM. Also available with 100% CNC chambers for increased air flow (see chart). Component upgrades and machining options are available to customize AFR Heads to your specific build.
AFR has been manufacturing BBC Marine Cylinder Heads for over a decade with great success. Many of the top marine engine builders in the industry rely on AFR for the performance in their engines. Today we are pleased to announce that you too can receive the same great AFR performance with an easier way to order your AFR cylinder heads. These cylinder head assemblies will come complete with Inconel Exhaust Valves, Hydraulic Roller Springs, and Hard Coat Anodizing. Basic Package Components Part # 50% CNC Ported Exhaust Ports
20% CNC Ported Intake Ports
30% CNC Ported Combustion Chambers
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" Overall Valve Length AFR #7630 Manley 10° Steel Retainers 1.500" O.D x 1.168" I.D x .844" I.D AFR #8518 PAC Racing Spring #1224 1.625 O.D. Hydraulic Roller, 275lbs on seat, .725 Maximum Lift, Max RPM 6500 AFR #8061 10° 11/32" Valve Locks with lashcap recess AFR #9005 ARP 7/16" Rocker Exhaust Studs AFR #6406 ARP 7/16" Rocker Intake Studs AFR #6407 Adjustable 3/8" Guide Plates AFR #6109 11/32" Viton Valve Seals AFR #6611 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 #9062 Exhaust Valve Seats 2.000" O.D x 1.580" I.D x .375" Deep AFR #9064 11/32" Intake Bronze Valve Guides .531" O.D x 2.10" O.A.L AFR #9045 11/32" Exhaust Bronze Valve Guides .531" O.D x 2.25" O.A.L AFR #9046
Specifications, Features, and Optional Supporting Components Head Torque 75 ft. lbs Intake Port Gasket AFR #6853 (.120" Thick) or AFR #6855 (.060" Thick) Exhaust Port Gasket AFR #6858 Head Gasket, Fel-Pro #1047 (Mark V and VI) AFR #6849 Head Gasket, Fel-Pro #1017-1 (Mark IV) AFR #6350 Head Bolts, ARP 135-3703 (Mark IV) AFR #6306 Head Bolts, ARP 135-3707 (Mark V) AFR #6308 Head Studs, ARP 235-4713 AFR #6307 Head Bolt Washers, Manley AFR #6320 Suggested Manifold Super VictorVictor Jr.,  Spark Plug Starting Range Autolite 3932 Combustion Chambers 121cc w/ CNC Chambers or 117cc w/ As Cast Chambers Valve Spring Pocket Diameter 1.725 O.D Intake Port Dimension 2.380"H x 1.680"W x 11/32 Radius Exhaust Port Dimension 1.720"H x 1.920" W Valve Angle 24°/4° Intake, 15°/4° Exhaust Angle Mill .009" per cc/ Maximum 104cc as cast or CNC Chamber Flat Mill .006" per cc/ Maximum 108cc as cast or 114cc CNC Chamber Stud Girdle, (AFR Specific) AFR #6202 Important: Do not port match you intake manifold to any Fel-Pro gasket as it does not precisely match AFR heads.
Note: Milling head deck will affect flow numbers. 1" longer head bolts needed on four bottom exhaust bolt holes. Angle mills might require a .120 thick intake gasket.