AFR 260cc LS3 Aluminum Cylinder Heads, 69cc Chambers, 4 Bolt, No Parts

The Ultimate Bolt-On Emission Legal Street/Strip Weapon!
AFR’s 260cc LS3 “Mongoose” heads are the ultimate rectangular port for the LS3 and L99 engines. They feature 100% CNC ported intake, exhaust and chambers using our advanced engineering and flow techniques to produce the ultimate Rectangle Port head available today. Featuring A356 aluminum castings, titanium retainers and the highest quality components, throughout. They’re designed for 4.000 or larger bore applications up to 454 CI, operating up to 7000 RPM. Emmisons legal for 2008 to 2015 vehicles under CARB #D-250-5. Component upgrade and machining options are available to customize AFR Heads to your specific build.

Basic Package Components	Part #
100% CNC Ported Combustion Chambers 100% CNC Ported Exhaust Ports 100% CNC Ported Intake Ports Competition 5-angle Valve Job

Specifications, Features, and Optional Supporting Components

Head Torque	11mm ARP 70ft. lbs. w/ Moly
Intake Port Gasket	Factory GM or Aftermarket
Exhaust Port Gasket	GM #12558573
Head Gasket	Cometic 4.160 Bore Size
Head Bolts (04+), ARP 134-3610	AFR #6334
Head Studs (04+), ARP 234-4317	AFR #6335
Head Bolt Washers, Manley	AFR #6320
Suggested Manifold	FAST 92mm, or 102mm
Spark Plug Starting Range	NGK TR55
Material	A356 Aluminum
Intake Port Volume	260cc
Intake Port Dimension	2.610"H x 1.300"W x 7/16° Radius
Intake Port Location	Stock
Exhaust Port Volume	95cc
Exhaust Port Dimension	1.540" H x 1.760" W
Exhaust Port Location	Stock
Combustion Chamber Size	69cc
Flat Mill - 65cc chamber	.006" per cc 62cc Maximum
Minimum Bore Diameter	4.000"
Minimum Cross Sectional Area	2.875 sq. in.
Spark Plug Dimensions	14mm x .750" w/Gasket Seat
Carb EO#	D-250-5

          AFR LS3 - 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.
• 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.
• 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)
• Rocker Arms - Use full roller rocker arms, roller tip rockers with stock style bodies are NOT recommended.

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.