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Our small port, high velocity 265cc cylinder heads are a cost effective choice compared to re-worked factory big block chevy cylinder heads. The intake runners and exhaust ports are partially CNC machined, while the combustion chambers are offered with partial or full CNC machining with a bowl blend; this torque monster is capable of flowing 354 CFM at 0.650" lift. Recommended for street, street/strip and towing applications with displacements up to 468 cubic inches operating at or below 6200 RPM. AFR heads are available bare (without parts), call our tech line for details. Please see footnotes for additional information.

265cc Aluminum BBC Cylinder Heads
Part # Description Combustion Chamber
3610 CNC bowl blend, Partially CNC Chamber
w/ Hydraulic Roller Springs
3620 CNC bowl blend, Partially CNC Chamber
w/ Solid Roller Springs
3610-1 CNC bowl blend, Fully CNC Chambers
w/ Hydraulic Roller Springs
3620-1 CNC bowl blend, Fully CNC Chambers
w/ Solid Roller Springs

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265cc Partial CNC Chamber BBC
  .200 .300 .400 .500 .550 .600 .650
Int 154 218 278 323 339 347 354
Exh 127 164 200 230 250 255 260
265cc Full CNC Chamber BBC
  .200 .300 .400 .500 .550 .600 .650
Int 164 236 291 326 335 342 345
Exh 135 190 230 258 265 274 280

Test conducted at 28" of water (pressure) on Superflow 600
Bore Size: 4.310", 3/4" radius plate exhaust, 1 7/8" curved pipe

Included Components
75% CNC Ported Exhaust Ports (Bowl Blend), 75% CNC Chambers
80% CNC Ported Intake Ports (Bowl Blend)
Competition 5-angle Valve Job
11/32" Intake Valve, 2.190" x 5.460" Overall Valve Length
11/32" Nail Head Exhaust Valve, 1.880" x 5.450" Overall Valve Length
PAC Racing Springs#1940 1.550" O.D. Hydraulic Roller Dual Valve Spring, 175 lbs. on seat, .725" maximum lift, 473lbs @ .600 lift, Max RPM 6500-6700
PAC Racing Spring 1.550 O.D. Solid Roller Valve Spring, 220lbs on seat, ..710" Maximum Lift, Max RPM 7200-7400 (upgrades available)
Manley 10° Steel Retainers 1.500" O.D x 1.120"I.D x .705" I.D
10° 11/32" Valve Locks with lashcap recess
ARP 7/16" Rocker Exhaust Studs
ARP 7/16" Rocker Intake Studs
Adjustable 3/8" Guide Plates
11/32" Viton Valve Seals
Hardened Valve Spring I.D Locator 1.550" O.D x .705" I.D - For 8000 Spring
Hardened Valve Spring I.D Locator 1.655" O.D x 1.565" I.D – For 8002 Spring
Intake Valve Seats 2.450" O.D x 1.950" I.D x .375" Deep
Exhaust Valve Seats 2.000" O.D x 1.580" I.D x .375" Deep
11/32" Intake Bronze Valve Guides .502" O.D x 2.10" O.A.L
11/32" Exhaust Bronze Valve Guides .502" O.D x 2.25" O.A.L
Specifications & Features:
A356 Aluminum
Intake Port Volume
Intake Port Dimension
2.030"H x 1.830"W x1/2 Radius
Intake Port Location
Exhaust Port Volume
Exhaust Port Dimension
1.770"H x 2.010" W
Exhaust Port Location
.375" Raised
Combustion Chamber Size(Partial CNC)
Combustion Chamber Size(Full CNC)
Valve Cover Bolt Pattern
Perimeter Bolt
Valve Angle
24°/4° Int, 15°/4° Exh
Valve Spring Pocket Diameter
1.725" O.D
Max Valve Spring Pocket Machining
1.750" O.D
Deck Thickness
Minimum Bore Diameter
Flat Mill
.006" per cc/ Maximum 102cc as cast or CNC chamber
Angle Mill
.009" per cc/ Maximum 97cc as cast or CNC chamber
Note:Angle mills might require a .120" Thick intake gasket.
Minimum Cross Sectional Area
2.640 sq. in.
Spark Plug Dimensions
14mm x .750" w/Gasket Seat

Installation Instructions


  1. AFR Big Block Chevy

    • With some domed aftermarket pistons, it may be necessary to slightly clearance or modify the piston due to our more efficient heart shaped combustion chamber design. Most of the newer designed dome profiles will clear. AFR strongly recommends material be removed from the piston and not the cylinder head. Our combustion chamber shapes are very critical to flow and altering the cylinder head can adversely affect flow and power production. It is the customers responsibility to verify proper piston to head clearance.
    • Heads are designed for 3/8" pushrods. Larger pushrods will not fit without clearancing and is not recommended since some areas are very thin. AFR recommends the use of .120" thick-wall pushrods.
    • For ideal geometry and wipe pattern AFR strongly recommends AFR stud mount rockers part #6043 for applications below 7400 RPM and .790 lift. For applications above these limits shaft mount rockers are typically advised.
  2. General Recommendations for AFR Cylinder Heads:

    • Bar Codes - Please keep the bar code & paperwork shipped with your head, these contain all the specs for your heads when calling AFR.
    • High Volume/Pressure Oil Pumps - If you are using a high volume or high pressure oil pump it can submerge the valve seals in oil causing smoking or oil consumption. Your block manufacturer or engine builder can recommend oil restrictions to the top end/valve train components.
    • Pushrods - Different length pushrods might be required, always check pushrod length. Check pushrod clearance with heads placed on the block before final assembly. Larger pushrods will not fit without clearancing and is not recommended since some areas are very thin. AFR recommends the use of .120" thick-wall pushrods.
    • Mills - Flat or angle mills could affect flow numbers and might require a thicker intake gasket.
    • Stud Girdles - Due to many available factory OEM and aftermarket style/variations your existing stud girdle may not fit (AFR heads require AFR Stud Girdles)
    • Boosted/Nitrous Applications - We strongly recommend considering Inconel exhaust valves and AFR's optional heavy duty intake valve for power adder applications. Since boosted or nitrous oxide applications accelerate RPM quickly, additional spring pressure is required. We strongly recommend upgrading your valve springs or increasing your valve spring pressures since boost pressure on the valve reduces spring tension. For example, 15lbs boost on a 2.125 OD valve reduces the springs closed seat pressure by approximately 40-45lbs.
    • All MARINE Applications - We strongly recommend Inconel exhaust valves & also offer a hard anodized coating to slow the effects of corrosion. Please see note on guide clearance below.
    • Valve Guide Clearance - Your AFR Heads come with proper guide clearance (.0012"-.0016") for most applications. Boosted/Nitrous or marine applications might require additional clearance and it is the customer's responsibility to verify proper clearance in these applications.
    • Valve Springs - Forced induction, nitrous oxide and cams with aggressive ramp rates may require additional spring pressure. We offer optional valve springs for these types of applications. AFR also recommends the use of billet cam cores and short travel Hydraulic Roller lifters which tolerate higher spring loads. Please don't hesitate to contact us directly if you question which spring is correct for your application.
    • AFR Titanium Valves - Might require lash caps and different length pushrods. Titanium valves are coated, do not grind valves because it removes the protective coating.
    • Piston to Valve - AFR assumes no responsibility for damage if the end user builds an engine without properly verifying he has enough piston to valve clearance (depth and radial clearance both checked). We recommend a minimum depth of .080" on the intake valve and .100" on the exhaust with a radial clearance of .020" minimum around the perimeter of each valve. Clay is recommended to visually verify both depth as well as radial clearance. Just checking depth is not enough, the position of the valve pocket must also be addressed. It is the customers responsibility to verify proper piston to valve clearance.
    • CNC Porting - Occasionally a 100% CNC ported head might have a very small area left "as cast", this in no way affects performance.
    • Shaft Mount Rockers - Shaft mount rockers might require additional clearance for proper pushrod fitment. Do not clearance the push rod area as the wall is .060" thick. If you use Jesel Shaft Mounts, AFR only recommends their Pro Series.
    • Comp Cams Pro Magnum Rockers - Typically these rocker arms do not clear a 1.500" O.D retainer. A lash cap is required to space up the rocker arm.
    • Spring Installation - To ease installation with 1.550" O.D or larger springs, 12 pt head bolt or studs are recommended for extra clearance. Beveled or ground washers might be needed (ARP #200-8504 comes with smaller O.D and doesn't need to be ground)
    • Valve Spring Installed Heights - AFR valve spring installed height spec is +/- .015 which is the smallest shim available for adjustment.
    • Rocker Arms - Use full roller rocker arms, roller tip rockers with stock style bodies are NOT recommended.