Site Information

 Loading... Please wait...

AFR’s 315cc heads feature 100% CNC ported intake, exhaust & chambers, A356 aluminum castings and high quality components throughout. Recommended for aggressive street, or street/strip builds with displacements up to 540 cubic inches, operating up to 6800 RPM. AFR heads are available bare (without parts), call our tech line for details. Please see footnotes for additional information.

315cc Aluminum BBC Cylinder Heads
Part # Description Combustion Chamber
2000 Fully CNC Ported 121cc

Click part # to add product to your cart

315cc Competition Flow Chart
  .200 .300 .400 .500 .600 .700 .800
Int 163 239 301 349 380 386 387
Exh 138 184 238 271 285 293 299

Test conducted at 28" of water (pressure) on Superflow 600
Bore Size: 4.600", 3/4" radius plate exhaust, 2 1/8" curved pipe

Included Components
100% CNC Ported Combustion Chambers
100% CNC Ported Exhaust Ports
100% CNC Ported Intake Ports
Competition 5-Angle Valve Job
11/32" Intake Valve, 2.250" x 5.500" O.A.L
11/32" Nail Head Exhaust Valve, 1.880" x 5.450" O.A.L
PAC Racing #1224 1.625” OD Solid Roller Dual Valve Spring 275 lbs. on seat, .850” maximum lift, Max RPM 7400-7600 (upgrades available)
10° Steel Retainers 1.500" O.D x 1.168" I.D x .844" I.D
10° 11/32” Valve Keepers with lashcap recess
ARP 7/16” Rocker Studs Intake
ARP 7/16” Rocker Studs Exhaust
Adjustable 3/8" Guide Plates
11/32" Viton Valve Seals
Hardened Spring Cup 1.740" O.D / 1.650" I.D
Intake Valve Seats 2.450" O.D x 2.000" 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
2.450"H x 1.755"W x 13/32 Radius
Intake Port Location
Exhaust Port Volume
Exhaust Port Dimension
1.780"H x 2.025" W
Exhaust Port Location
.375" Raised
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 114cc
Angle Mill
.009" per cc/Maximum 104cc
Note: Angle mills might require a .120" Thick intake gasket.
Minimum Cross Sectional Area
3.151 sq. in.
Spark Plug Dimensions
14mm x .750" w/Gasket Seat
CARB Status: This product is not legal for sale or use on emission-controlled vehicles and intended for dedicated race vehicles only.

Installation Instructions


All returns/warranties need to be sent directly to AFR, do not return your merchandise to the location purchased from. Call AFR toll free, (888) 549-2211 for a RMA #.

(661) 257-8124 FAX (661) 257-4462


Check all machined surfaces for nicks, burrs, etc, that might have occurred during shipping or storage. If necessary, carefully dress with a file, or sandpaper supported flat by a straightedge. This is especially important on the head deck and intake manifold flange to have an effective trouble-free gasket seal.


It is the customer’s responsibility to check and make sure that spring pressures are correct for his/her camshaft application. We recommend a minimum of .060” clearance from coil bind at full valve lift.


Our typical valve guide clearances are .0013”-.0016”. In some severe applications (nitrous, marine endurance racing, supercharged or turbo) looser guides might be required. Check with your engine builder.

Important: Apply anti-seize to all bolts and spark plugs to ensure long thread life.


Piston dome to combustion chamber clearance MUST be checked prior to final engine assembly. This is especially important for pistons that have a .700” + dome height which are common on high compression 427-511 based engine configurations. Pay special attention to the crest in the chamber directly across from the spark plug. Consider .040” minimum clearance with 7000 rpm or less. Slightly more would be required for motors that are turned higher.


With some domed aftermarket pistons, it may be necessary to slightly clearance or modify the piston due to our more modern (efficient) heart shaped combustion chamber design. Most of the newer manufacturer’s dome profiles will clear. Note that usually less than 1cc of aluminum is removed which only equates to a weight reduction in the piston of one to two grams. If your rotating assembly is already balanced, this is a non-event and creates a VERY slight overbalance which in theory brings your engine into a better balance at slightly higher RPM. While some of you might be inclined to remove the material from the actual cylinder head note that all of the combustion chamber shapes are very critical to flow and altering the cylinder head can and will effect flow and power production. The easiest way to check for this is by turning the engine over slowly with the cylinder head installed without the head gasket.


It is your responsibility to check and make sure you have adequate piston to valve clearance before final engine assembly. Don’t forget to check radial (side) clearance as well.


In the event your engine has extremely tall piston domes, it might be necessary to index the plug electrodes and/or slightly clearance your piston domes to provide a minimum of .060” from piston dome to electrode tip. Do not use projected tip plugs with extremely tall dome designs (unless you are certain you have enough clearance).

NOTE: While on the subject of clearance, it is vital that you check clearance of ALL moving parts due to the vast array of rocker arms, lifters, cams, springs, etc. Don’t forget to check pushrod to head clearance as well as any potential interference from your rocker arms and spring assemblies prior to final engine assembly.


AFR BB Chevy heads require two different length rocker studs. The (8) shorter studs (referring to the coarse thread length that screws into the head) must be installed on the intake side with a small amount of teflon or some other non-hardening thread sealer. Without thread sealer oil is drawn into the intake port under vacuum and will cause excessive smoking. Conventional bolt thread lubricant can be used on the longer (8) exhaust studs. Never use a shorter stud on the exhaust side.

NOTE: Torque Rocker Studs to 55 – 60 ft./lbs.


Verify that your rocker arm has a minimum of .015 clearance to the retainer. For proper geometry we recommend AFR #6043 stud mount rockers. Other brands will yield improper wipe pattern that is too wide and not centered properly. On shaft mount rockers we recommend Crower, Jesel “Pro Series” or T&D.


Both intake and exhaust valve seats are heat treated ductile iron and are compatible with unleaded fuels.


Only AFR guide plates will properly fit our AFR Big Block Chevy cylinder heads. We carry them in stock under AFR part #6109. The Comp Cams part # is 4806.


All AFR heads will require pushrods that are longer than stock length. The most common lengths are a +.200” to a +.250”; however, due to a large number of variables (deck height, cam base circle, lifter height, etc.) ALL pushrod lengths must be physically checked to achieve proper valve train geometry. See website under FAQ for detailed information on pushrod length.


All of our BB Chevy cylinder heads have been designed with valve angles rolled over two degrees from stock location to provide better flow characteristics. Stud girdles produced for stock Chevy castings as well as other aftermarket pieces that have standard valve angles will not fit properly. We stock a high quality girdle in a convenient two piece design that will fit our heads correctly.


AFR BB heads take one inch longer fasteners along the exhaust port (bottom) side of the cylinder head. AFR stocks complete kits or partial kits (studs or bolts) for the eight additional longer fasteners.

NOTE: We recommend the use of studs due to the higher clamping load they place on the cylinder heads. Blown, turbo, or nitrous engines should always use studs due to the much higher cylinder pressures they create.



  • Mark IV Block 4.540” Bore Felpro 1017-1
  • NOTE: 1017-2 is .051” compressed thickness
  • Mark IV Block 4.630” bore Felpro 1057
  • Mark IV Block 4.625” bore Felpro 1093
  • NOTE: 0-ring perfectly round, .051” thick, Typical “pro-stock” style gasket
  • Mark V-VI 4.540” bore Felpro 1047 or 17048
  • Mark V-VI 4.630” bore Felpro 17049

INTAKE GASKETS: (For best fit)

  • AFR #6855 for 305, 315, 325, 335cc Felpro #1275
  • AFR #6856 for 345,357cc Mr gasket #121

NOTE: Only use AFR’s gaskets for port matching. Most other gaskets have a slightly larger entrance. You will see NO PERFORMANCE GAIN by opening your heads or intake manifold to the larger gasket opening. Use gasket cinch to adhere and center gasket and port openings.


  • AFR #6858.


(Flat seat with gasket, .750” long reach, 5/8” hex head) Do not use a tapered seat plug.
  • Autolite #3932 Std. Tip, Race Application
  • Champion #C59C Std. Tip, Race Application
  • Champion #C59YC Projected tip, Race application
  • Champion #RC12YC Projected tip, Street Application

NOTE: Other Spark plug manufacturers offer plugs that will also cross-reference and fit our AFR BBC castings. Always consult with the manufacturer for the heat range that best fits your application.


All AFR BB Chevy heads should be torqued to 75 ft/Ibs. This should be done in the proper General Motors sequence in 15 Ib. increments beginning at 30 ft/Ibs. Moly lube should be applied between fasteners, washers, threads, and areas around head bolt to prevent galling and improper torque values. Sealer should be applied to all thread areas of fasteners that enter into block water jackets. Sealer is unnecessary with blocks that have “blind holes” in the deck surface and do not go into water.


If using ARP fastener’s re torque is not necessary as long as you follow ARP instructions. However, it may be necessary under certain circumstances if the head gasket manufacturer’s instruction require it. In particular if a fire ring has been installed.


Intake Valve 5.500” (+.250) Exhaust Valve 5.450” (+.100)

IMPORTANT: Apply anti-seize to all bolts and sparkplug threads to ensure long thread life.


It is important to maintain 50/50 mix of antifreeze in the cooling system to prevent corrosion of aluminum heads. Do not use tap water, Use distilled water instead. Most supermarkets sell purified or distilled water. Check labeling to verify purified through deionization.


Be aware that an aluminum headed/iron block combination usually requires approximately .006 tighter lash when it is cold. An all aluminum engine could be as much as .010 – .020 tighter when the motor is cold. Every motor is different, but these guidelines should get you in the ballpark.


Do not grind your valve tips. Some AFR heads have harden stellite tips which cannot be re ground. If ground, the tip will mushroom over causing severe damage. If your valve tips are magnetic, you can grind a maximum of .015 from the tip.


If you have upgraded to AFR Titanium valves in SB Chevy, SB Ford or BB Chevy applications they are coated with Chrome Nitrate (CrN) on the stem and seat area for longevity purposes. This is the same coating GM uses in the LS7 ZO6 applications and is designed to last 50,000 plus miles. YOU CANNOT GRIND, REFACE OR LAP IN THE 45 DEGREE SEAT AREA. If you grind or lap in the valve, the coating is removed and the seating area on the valve seat will wear prematurely reducing the service life substantially.


  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.