AFR 377cc Fully CNC Ported Magnum BBC Cylinder Heads

Sale: $3,745.08
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AFR 377cc Fully CNC Ported Magnum BBC Cylinder Heads

AFR’s Magnum Series

BBC 377cc Fully CNC ported Cylinder Heads
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Our 377's are ideal for large cubic inch combinations (540-615 CID) that are looking for more airflow but want to retain a 2.300 intake valve. This head will also work well on smaller very aggressive applications (489-532 CID) turning over 8000 RPM's. The 377 is very efficient and moves a lot of air early in the curve (415 @ .600) making it an ideal choice if your limited to how much cam lift you can run, such as a big inch marine engine with a hydraulic roller cam and a limited RPM ceilling. With close to 440 CFM of peak flow it should be extremely eas to clear 950 HP in asingle four barrel aggressive applications and even mor ein well sorted out combinations (especially with tunnel ram/sheet metal dual quad combo's). The exhaust ports are also notably stronger making the 377 an excellent choice in a forced induction or nitrous car that could benefit from the stronger exhaust flow. Of course the 377cc comes standard with AFR’s trademark .750” thick cylinder head deck, reinforced rocker stud bosses, PAC 1.625 racing springs rated to .850 lift, and are equipped with premium one piece stainless steel 2.300” intake valves and 1.880” exhaust valves. Standard combustion chamber volume is 121cc for our 377cc BBC. Properly selecting the correct cylinder head depends on a large number of variables. Please consult with one of our sales technicians to assist you in making the best decision for your particular application.



Optional stud girdle required for 2° rolled valve angles and 1” longer head bolts needed on four bottom exhaust bolt holes. Longer pushrods might also be required.(see footnotes here)

AFR 377cc BBC CNC Aluminum Cylinder Head Flow

377 BBC Cylinder Head Flow Chart

Basic Package Components
Competition 5-angle Valve Job
100% CNC Ported Chambers, Exhaust, and Intake
AFR #7626Intake Valve, 2.300" stainless steel
AFR #7631Exhaust Valve, 1.880" stainless steel
AFR #80311.625 O.D. Solid Roller PAC Racing Spring #1224, 275lbs on seat, .850 Maximum Lift
AFR #850710° Titanium Retainer
AFR #900510° Valve Locks
AFR #6109Guide Plates
AFR #6611Viton Valve Seals
AFR #8046Hardened Spring Cup
AFR #9062Intake Valve Seats
AFR #9064Exhaust Valve Seats
AFR #9045Bronze Valve Guides Intake
AFR #9046Bronze Valve Guides Exhaust
AFR #6406AFR BB Chevy 7/16 Exhaust Studs
AFR #6407AFR BB Chevy 7/16 Intake Studs

Specifications, Features, and Optional Supporting Components
75 ft. lbs.Head Torque
AFR #6856Intake Port Gasket, 1.720" x 2.450" with 1/2" radius, Fel-Pro #1275
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 #6850Head Gasket, Bore 4.540 Fel-Pro #1017
Mark V-VI-up to 4.500 Bore Fel-Pro #17048 or #1047Head Gasket
Mark V-VI-4.500 to 4.600 Bore Fel-Pro #17049Head Gasket
AFR #6306Head Bolts
AFR #6307Head Studs
AFR #6308Head Bolts
AFR #6320Head Bolt Washers
AFR #6210Stud Girdle
AFR #5500Suggested Manifold
Edelbrock #2927Suggested Manifold
Dart #6200, #6201, & #6203Suggested Manifold
Brodix HVH #2000, #2001, #2005, & #2006Suggested Manifold
Champion C59C Autolite 3932Spark Plug Starting Range
121ccCombustion Chambers
Can be cut to 1.750, no deeperSpring Pocket
StandardValve Spacing
StandardRocker Arms
24°/4° Intake, 15°/4° ExhaustValve Angle
.009" per ccAngle Mill (milling options available), 104cc Maximum
.006" per ccFlat Mill (milling options available), 114cc Maximum

Note: Milling head deck will affect flow numbers. Angle mills might require a .120 thick intake gasket.

Add to Cart:

  • Model: 2012
  • Shipping Weight: 95lbs