AFR’s 260cc LS3 “Mongoose” heads 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.
afrls3
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.
| width="522">260cc Aluminum LS1
Cylinder Heads
Part #
|
Description
|
Combustion
Chamber
|
1841
|
CNC Ported w/o parts 6 Bolts |
69cc
|
1846
|
CNC Ported
w/o parts 4 Bolts |
69cc
|
| width="522">260cc Street Head
Flow Chart
|
.200
|
.300
|
.400
|
.500
|
.600
|
.650 |
.700
|
Intake
|
159
|
234
|
293
|
336
|
366
|
377
|
384
|
Exhaust
|
112
|
158
|
207
|
235
|
248
|
251
|
255
|
color="#ffffff" size="4">Basic Package
Components |
color="#ffffff" size="4">Part # |
100%
CNC
Ported Combustion Chambers
100% CNC Ported Exhaust Ports
100% CNC Ported Intake Ports
Competition 5-angle Valve
Job |
|
color="#ffffff" size="4">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 |
color="#000000">href="http://www.airflowresearch.com/arp-134-3610-6-pt-2004">color="#000000">AFR #6334
|
Head Studs
(04+), ARP 234-4317 |
AFR
#6335 |
Head Bolt
Washers, Manley |
AFR #6320
|
Suggested
Manifold |
style="float:right;">
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.
