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AFR 305 BBC "As Cast" Rectangle Port Magnum Heads

  • AFR BBC 305cc
  • AFR BBC 305cc
Your Price:
$2,495.99 (You save $77.00)
76.00 LBS
Calculated at checkout

Product Description

Air Flow Research 305 Rectangle Port "Magnum" BBC 24°

AFR’s Torque Monster

These AFR 305cc rectangle port cylinder heads feature partially CNC ported intake, exhaust & chambers. Manufactured from A356 aluminum castings and premium quality valvetrain 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.

These heads may have the smallest intake runner volume in AFR's lineup, but don't let their size fool you. These AFR Magnum 305cc "as-cast" heads with a CNC bowl blend will provide you with flow numbers that most medium sized heads and some larger, can only dream about. This line was designed to optimize low and mid-lift airflow, while still generating impressive peak figures. Their application should be focused on smaller cubic inch Chevy big blocks (396-502) with a primary operating range of 2,500-6,800 RPM. This range is an average and will vary with engine displacement, as well as component selection.

AFR 305cc "Magnum" big block Chevrolet heads should also be given strong consideration in larger street driven or marine applications up to 555 cubic inches, where low-rpm power and drivability are factors. These cylinder heads would be a great choice if you're looking for big torque and strong low RPM performance and still have good RPM capabilities.

The big block 305 heads come standard with AFR's trademark 3/4 inch thick head deck, reinforced rocker stud bosses and premium one-piece stainless steel 2.250" intake valves and 1.880" exhaust valves. Standard combustion chamber volume is 117cc however, these heads are available with an optional 114cc combustion chamber as well.

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

Big Block Chevy 305cc Rectangle Port 24° Magnum Basic Package
100% CNC Ported Combustion Chambers
Bowl Blended Exhaust Ports
Bowl Blended Intake Runners
Competition Multi-Angle Valve Job
Stainless Steel Intake Valve - 2.250'' x 5.500'' Overall Length
Stainless Steel Exhaust Valve - 1.880'' x 5.448'' Overall Length
1.625'' PAC Racing Solid Roller Dual Valve Spring, 275# Seat - .850'' max lift
10º Manley 4140 Chromemoly Spring Retainers
Hardened and Machines 10º Valve Locks
ARP ProSeries 7/16'' Rocker Studs
AFR Adjustable 3/8'' Guide Plates
Steel Shell Viton Valve Seals
Hardened Valve Spring Seats
Ductile Iron Intake Valve Seats
Ductile Iron Exhaust Valve Seats
Bronze Manganese Valve Guides
Big Block Chevy 305cc Rectangle Port 24° Magnum Head Specifications
Head Torque w/Moly Lube 75 Ft. Lbs.
Rocker Arm Stud Torque 55 Ft. Lbs.
Intake Port, 1.72'' x 2.45'' w-1/2'' radius Fel-Pro 1275
Exhaust Port Gasket AFR 6858
Head Gasket Mark IV 4.540'' Bore, Fel Pro 1017
Head Gasket Mark V - VI Up to 4.500'' Bore, Fel Pro 1047
Head Gasket Mark V - VI 4.50'' to 4.60'' Bore, Fel Pro 17049
Head Bolts & Studs Standard ARP
Head Bolt Washers Manley Standard
Stud Girdle AFR 033-6210
Suggested Intake Manifold Edelbrock 2907, 2927
Spark Plug Starting Range Champion C59C, Autolite 3932
Combustion Chambers 121cc Fully CNC'd
Intake Runner Volume 305cc - Partially Ported
Exhaust Port Volume  
Spring Pocket can be cut to 1.750 diameter but no deeper.
Valve Spacing Standard
Rocker Arms Standard
Valve Angle 24°/4° Intake - 15°/4° Exhaust
Angle Mill, 104cc Maximum .009'' per cc
Flat Mill, As Cast 108cc, CNC 114cc Maximum .006'' per cc

Milling may require a thicker head gasket.




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