260cc LS3 Mongoose Street Aluminum Cylinder Heads LSX Chevy Block

Name: 260cc LS3 Mongoose Street Aluminum Cylinder Heads LSX Chevy Block
Brand: AFR - AIRFLOW RESEARCH
SKU: 033-1840
Price: 3188.00 USD
Availability: InStock

^$3,188⁰⁰

Ships on 10/30/2026

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^$1,342⁸⁰

555-514050K

Cylinder Head Kit for GM LS3 Engines [w/Head Bolts]

^$1,845²⁰

LSX Blocks

Six Head Bolts Per Cylinder

LSX 6-Bolt Chevy Blocks
69cc Combustion Chambers
Rectangle Intake Port
Assembled

Sold in Pairs, 2/pkg.

LS Chevy 260cc LS3 Mongoose Basic Package Components
100% CNC Ported Combustion Chambers
100% CNC Ported Exhaust Ports
100% CNC Ported Intake Ports
Competition 5-Angle Valve Job
8mm Bead Lock Intake Valve, 2.165" x 5.195" Overall Valve Length
8mm Bead Lock Exhaust Valve, 1.600" x 5.200" Overall Valve Length
PAC Racing Spring 1.270" OD Hydraulic Roller Dual Valve Spring, 155 lbs. on seat, Max RPM 7000-7200
7° Titanium Retainers 1.245" O.D x .885" I.D x .655" I.D
7° Bead Lock Valve Keepers
Viton Valve Seals .600" O.D x .495" I.D.
Hardened Valve Spring O.D Locator 1.380" O.D x .570" I.D.
Ductile Iron Intake Valve Seats 2.200" O.D x 1.750" I.D x .375" Deep
Ductile Iron Exhaust Valve Seats 1.650" O.D x 1.350" I.D x .375" Deep
8 mm Bronze Valve Guides .502" O.D x 2.550" O.A.L.
Rocker Rail Stand
LS Chevy 260cc LS3 Mongoose Street Head Specifications
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
Valve Cover Bolt Pattern	Center Bolt
Valve Angle	12°
Valve Spring Pocket Diameter	1.490" O.D.
Max Valve Spring Pocket Machining	1.510" O.D.
Deck Thickness	0.750"
Minimum Bore Diameter	4.000"
Flat Mill - 65cc chamber	.006" per cc 62cc Maximum
Minimum Cross Sectional Area	2.875 sq. in.
Spark Plug Dimensions	14mm x .750" w/Gasket Seat
Carb EO#	D-250-5
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
Head Studs (04+)	ARP 234-4317
Head Bolt Washers	Manley
Suggested Manifold	FAST 92mm or 102mm
Spark Plug Starting Range	NGK TR55
Rocker Arms	Use full roller rocker arms, roller tip rockers with stock style bodies are NOT recommended.
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.
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)

Modeled After the GM LS7 Aluminum Head

AFR's 260cc LS3 "Mongoose" heads feature 12° valve angle, 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 cubic inches, operating up to 7000 RPM. Emissions legal for 2008 to 2015 vehicles under CARB #D-250-5.

260cc LS3 Mongoose Street Cylinder Head Features:

100% CNC Ported Combustion Chambers
100% CNC Ported Exhaust Ports
100% CNC Ported Intake Ports
Competition 5-angle Valve Job
260cc Intake Ports, Stock Location (2.610" Tall x 1.300" Wide x 7/16° Radius)
95cc Exhaust Port, Stock Location (1.540" Tall x 1.760" Wide)
69cc Combustion Chambers
8mm Bead Lock Intake Valve, 2.165'' x 5.195'' Overall Valve Length
8mm Bead Lock Exhaust Valve, 1.600'' x 5.200'' Overall Valve Length
PAC Racing Valve Springs: 1.270'' OD Hydraulic Roller Dual Valve Spring, 155 lbs on seat, Max RPM 7000-7200
7° Titanium Retainers 1.245" O.D x 0.885" I.D x 0.655" I.D
7° Bead Lock Valve Keepers
Viton Valve Seals, 0.600" O.D x 0.495" I.D
Hardened Valve Spring O.D Locator, 1.380" O.D x 0.570" I.D
Ductile Iron Intake Valve Seats
Ductile Iron Exhaust Valve Seats
8mm Bronze Valve Guides, 0.502" O.D x 2.550" O.A.L
Rocker Rail Stand
CARB E.O. # D-250-5