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Chevy small-block v-8
Splayed-Valve Aluminum Race
CYLINDER Head
GM Performance Parts Splayed-Valve Aluminum Race Cylinder
Heads are extremely aggressive, all-out competition heads and
not intended for street use. Splayed valves point both intake and
exhaust valves at the center of the cylinder bore. As the valves
open, they move away from the edges of the bore. That allows
maximum-size valves to be installed without increasing bore size.
The result is dramatically increased airflow, compared to inlinevalve-design
cylinder heads.
The castings have a 0.240-inch minimum port wall thickness,
which leaves ample room for extensive custom porting. Intake
valves are angled 16-degrees to the deck surface and splayed
4-degrees. Exhaust valve angles are 11-degrees with a 4-degree
splay. Making more than 1000 naturally aspirated horsepower
with these cylinder heads is easily achievable.
Aluminum Splayed Valve Race Head Technical Notes:
• Made of 355-T7 aluminum
• No valve seats or guides provided
• Extra-thick decks for angle milling or heavy flat milling
• Extra port material (0.240") for professional porting
• Completely revised intake and exhaust ports provide ultimate
airflow potential
• 45cc “as cast” combustion chambers
• Modified valve angles (16° x 4° intake, and 11° by 4° exhaust)
• Designed for longer-than-stock 2.20" and 1.65" valves
• Valve spring pads accommodate 1.625" diameter springs
• Revised location angled spark plugs (14mm, 5/8" hex, 3/4" reach,
gasketed plugs)
• All pistons have the same orientation
• Designed for aftermarket shaft-mount rocker systems
• Custom-fabricated intake manifold required
• P/N 10185042 intake manifold gasket required
• Valve cover P/N 10185045 and valve cover gaskets
P/N 10185043 required
12480146
Rough-Machined Splayed-Valve Aluminum
Cylinder Head (not shown)
• Main surfaces are machined, exhaust bolt pattern is
machined
• Head bolt and dowel holes, intake bolt holes, spark plug
holes and pushrod holes are not machined
• Valve guides valve seats, valve spring seats and rocker
stands are not machined
• Valve locations and angles may be relocated
• 240cc “as-cast” intake ports
• 78cc “as-cast” exhaust ports
• 45cc “as-cast” combustion chambers
A
Splayed-Valve Head (exhaust)
Splayed-Valve R0X Cylinder Head (intake)
Splayed-Valve R0X Cylinder Head (combustion chamber)
B
B
B. 12480153
Splayed-Valve R0X Aluminum Cylinder Head
• Semi-machined aluminum race head
• Great for NHRA competition with dual carburetors
• As cast ports and combustion chambers for
professional finishing
• Use mid-deck block P/N 25534429 with 4.500" main
bore machining
• Special larger head-bolt pattern, 3/8" fasteners, 19 holes
• 240cc “as-cast peanut” intake ports
• 78cc “as-cast peanut” exhaust ports
• 40cc “as-cast” combustion chambers
88958684
Splayed-Valve R0X Aluminum Cylinder Head
Cubed
• Great for NHRA competition with dual carburetors
• 240cc “as-cast peanut” intake ports
• 78cc “as-cast peanut” exhaust ports
• "Cubed" aluminum race head
• Bare head, no seats or guides
SB2.2 NASCAR Race cylinder Heads
The GM Performance Parts SB2 NASCAR racing head was
designed to improve durability, simplify preparation procedures,
and reduce the overall cost of building and maintaining a Small-
Block Chevrolet racing engine. It is ideal for single-four-barrel
carburetor applications due to having “mirror” design intake ports
and all eight ports being angled toward the center of the engine.
Spark plug holes were moved toward the bore center for improved
combustion efficiency. 48cc combustion chambers permit
12.1:1-compression-ratio flat-top pistons.
Chevy small-block v-8
A
Splayed-Valve Head (intake)
Aluminum SB2.2 NASCAR Race Head Technical Notes:
• 355-T7 X-rayed and “hipped”* aluminum competition
cylinder heads
• Extra-thick decks for heavy flat milling
• Extra material around ports for professional porting
• Combustion chambers are very small, shallow and
wedge shaped
• Precision T-washers installed in all four center head bolt bosses
• Designed for longer-than-stock 2.15" and 1.625" valves
• Valve spring pads accommodate 1.625" diameter springs
• Modified valve angles, 11° x 4° intake and 8° x 0° exhaust
• Designed for aftermarket shaft-mount rocker systems
• Revised location angled spark plugs (14mm, 5/8" hex, 3/4" reach,
gasketed plugs)
• Requires specific left- and right-hand pistons
• Valve cover P/N 12480006 or P/N 12480012 required
• Replacement AN -08 intake port plugs available as P/N 12480171
12480147
Semi-Machined Splayed-Valve Aluminum
Cylinder Head (not shown)
• Main surfaces are machined; exhaust bolt pattern, valve
guides and spark plug holes are machined
• Head bolt holes, dowel holes, intake bolt holes, pushrod
holes are not machined
• Valve seats, spring seats and rocker stands are not
machined
• 240cc “as-cast” intake ports
• 78cc “as-cast” exhaust ports
• 45cc “as-cast” combustion chambers
• Same casting as P/N 12480146
A
Splayed-Valve Head (combustion chamber)
SB2.2 Cylinder Head (exhaust)
SB2.2 Cylinder Head (intake)
C
C
C. 12480011
Semi-Finished SB2.2 Aluminum Cylinder Head
• Aluminum NASCAR-accepted head
• Bare head, no seats or guides installed
• Standard .500" guide holes
• As cast “peanut” ports
• 48cc “as-cast” combustion chamber
A. 24502517
Splayed-Valve Aluminum Cylinder Head
• Semi-machined aluminum race head
• 240cc “as-cast” intake ports
• 78cc “as-cast” exhaust ports
• 45cc “as-cast” combustion chambers
• Same casting as P/N 12480146
B
Splayed-Valve R0X Cylinder Head (exhaust)
SB2.2 Cylinder Head (combustion chamber)
C
* HIP is the acronym for Hot Isostatic Pressure. This process puts the heads in a
sealed vessel where a vacuum is first used to remove room air and any possible
contaminants. The vessel is filled with high pressure nitrogen (up to 30,000-psi)
and then heated to the required temperature and sustained for a determined
amount of time. The cooling process is also a controlled procedure to insure maximum
strength and proper heat treat. This extreme high pressure and heat removes
almost 100% of the internal porosities that are generated during the casting
process. The material integrity, strength and fatigue life increases significantly.
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Available for purchase online at
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153