Pontiac specified forged-aluminum pistons for its Super Duty and Ram Air IV engines. The SD-455 piston was a unique design specific to that application. It contains many features aimed at maximizing durability; among them is a single-trough valve pocket, which displaces just over 3 cc. Federal-Mogul offered this piston (number L2423F) in various over sizes in its Speed Pro line, but was discontinued in February 2007.
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