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Chevrolet Performance 12480147

Splayed-Valve Aluminum Cylinder Head, Semi-Machined

Chevrolet Performance 12480147

809-12480147

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Estimated ship date 11/29/17 if Ordered Today
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Chevrolet Performance 12480147 Splayed-Valve Aluminum Cylinder Head, Semi-Machined $1,375.79
Splayed-Valve Aluminum Cylinder Head
  • Semi-Machined: Main surfaces, exhaust bolt pattern, valve guides, and spark plug holes

  • Chevrolet Performance 12480147 Details

    Standard 4.400" Bore Spacing

    Semi-Machined Detail:
  • Machined: Main surfaces, exhaust bolt pattern, valve guides and spark plug holes
  • Not Machined: Head bolt holes, dowel holes, intake bolt holes, pushrod holes, valve seats, valve spring seats and rocker stands
  • Same casting P/N 12480146

  • Specifications:

    Manufacturer's Part Number:
    12480147

    These small block Chevy splayed-valve aluminum cylinder heads are a radical departure from standard in-line valve heads. Their splayed-valve arrangement angles both the intake and exhaust valves inward toward the center of the combustion chamber, allowing maximum valve sizing to dramatically improve airflow without increasing bore diameter. Castings have a 0.240" minimum port wall thickness so, for even greater flow, extensive modifications can be made. Sold individually, these aggressive all-out competition cylinder heads are designed to get the most power from your small block Chevy with no regard for "streetability." NHRA Competition Eliminator participants routinely produce over 1000 horsepower (naturally aspirated) with these race cylinder heads.

    Features
  • 355-T7 aluminum
  • No valve seats or guides
  • "As-Cast" Intake Ports: 240cc
  • "As-Cast" Exhaust Ports: 78cc
  • Extra-thick deck for angle or heavy flat milling
  • Valve spring pads accommodate 1.625'' springs
  • Modified Valve Angles: 16° x 4° Intake, 11° x 4° Exhaust
  • 4.400'' Bore Spacing: 45cc "As-Cast" Combustion Chambers
  • 4.500'' Bore Spacing: 40cc "As-Cast" or Unfinished Combustion Chambers
  • Spark plug location revised for angled 14mm, 5/8" hex, 3/4" reach, gasket seat plugs
  • Designed for longer-than-stock 2.200''/1.650'' valves and aftermarket shaft-mount rocker systems

    Requirements
  • Valve Cover Gaskets #809-10185043
  • Intake Manifold Gaskets #809-10185042
  • Custom-fabricated valve covers and intake manifold

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