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Splayed-Valve 4.500 Bore Center Aluminum Cylinder Head

$1,421.84

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  • Extremely aggressive, all-out competition head
  • Semi-machined aluminum race head
  • As-cast ports and combustion chambers for professional finishing
  • Great for NHRA competition with dual carburetors
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Splayed Valve 4.500 Bore Center Aluminum Cylinder Head

P/N 12480153

– 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 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

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° x 4° exhaust)
– Designed for longer-than-stock 2.200″ and 1.650″ valves
– Valve spring pads accommodate 1.625″ diameter springs
– Revised location angled spark plugs (14mm, 5/8″ hex, 3/4″ reach, gasketed plugs)
– Designed for aftermarket shaft-mount rocker systems
– Custom-fabricated intake manifold required
– P/N 10185042 intake manifold gasket required
– Valve cover gaskets P/N 10185043 required

Weight 28 lbs
Brand

Splayed-Valve Aluminum Cylinder Head

12480153 Chevrolet Cylinder Head

4.500 Bore Center

Chevrolet Performance 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 inline-valve-design cylinder heads.

GM engineers have designed the castings to 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.

Splayed Valve 4.500 Bore Center Aluminum Cylinder Head

P/N 12480153

? 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 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

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? x 4? exhaust)
? Designed for longer-than-stock 2.200″ and 1.650″ valves
? Valve spring pads accommodate 1.625″ diameter springs
? Revised location angled spark plugs (14mm, 5/8″ hex, 3/4″ reach, gasketed plugs)
? Designed for aftermarket shaft-mount rocker systems
? Custom-fabricated intake manifold required
? P/N 10185042 intake manifold gasket required
? Valve cover gaskets P/N 10185043 required

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Prop65WARNING: These auto parts can expose you to chemicals including phthalates and lead. Installing or using these parts can expose you to other parts containing these chemicals and to engine exhaust, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.