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(310) 781-2222 ext. 2915

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Edelbrock RPM Xtreme™ B/b Chevy Cylinder Heads Deliver CNC Perfected Air Flow in a Bolt-on Package

The new Edelbrock RPM Xtreme Cylinder Heads for 427 - 572 cid Big Block Chevy engines strive to provide race level performance in a streetable design envelope. CNC machined runners and combustion chambers achieve flow numbers nearly on par with the Victor series professional race head, while maintaining compatibility with off-the-shelf or even stock components including headers, pistons and rocker arms. The deck has been rolled 1.5° to improve the intake valve angle and consequently port velocity, while ensuring that the 2.25" (oval) / 2.30" (rect.) intake and 1.88" exhaust valves will still clear the factory valve reliefs. The exhaust flange has been raised less than 1/8" to improve flow around the short turn without causing conflicts with off-the-shelf 2" primary tube headers designed to work with stock heads. The 300cc (oval) / 325cc (rect.) intake ports and 110cc chamber volumes will ensure that the performance potential of these heads is sufficient for nearly any street driven application. The rectangular port heads are even available with a larger 118cc chamber to support forced induction and pump gas friendly compression ratios.

Rectangle port RPM XT heads #51559 testing on a 555 cubic inch big-block Chevy with 10.0:1 compression, hydraulic roller camshaft [248°/256° duration @ .050] and Edelbrock RPM XT EFI system produced 697 HP and 643 lbs./ft. of torque.

Edelbrock aluminum cylinder heads are sand cast at our private foundry in San Jacinto, CA and are hand assembled at our Torrance, CA headquarters. They carry a one year warranty against any manufacturer defects, and are sold complete with valves, springs and guides pre-installed. Installation is the same as factory cylinder heads, making this an easy bolt-on upgrade with results you will feel on every pull.

    Features Include:
  • CNC ported combustion chambers, intake and exhaust runners improve air-flow and performance
  • Fully CNC machined combustion chambers
  • 25-degree valve angle
  • 5/8" thick deck for extreme durability
  • Outstanding flow; up to 385 cfm (rectangle port) and up to 356 cfm (oval port)
  • RPM XT heads accept most stock port location exhaust headers

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Founded in 1938, Torrance-based Edelbrock, LLC is recognized as one of the nation's premier designers, manufacturers and distributors of performance replacement parts for the automotive and motorcycle after markets. For more information please visit us at

Edelbrock, LLC. .:. 2700 California St. Torrance CA. 90503