By checking off RPO Z11 on a 1963 Chevrolet new car order form, you could buy a factory-built racecar. Only 57 people made that choice before GM pulled the plug. Hemmings’ Mike McNessor writes about the rare RPO Z11: CHEVY 427 LIGHT HEAVYWEIGHT.
She’s so fine my… 427? Clearly not 1960s radio gold. But among Chevrolet W-engine enthusiasts, more poetic words were never written. The 427-cubic-inch Mark I big block was part of the factory-lightweight 1963 Z-11 package built to win rounds in quarter-mile competition. Unlike the ’63 Mark II 427 “Mystery Motor” of NASCAR fame, the Z-11 427 shared the combustion-chamber-in-block design of the 348 and the 409.
Chevrolet’s 348-cu.in V-8 rolled out in 1958 as the division’s top-shelf passenger car engine. The Mark I big-block was designed to provide effortless low and mid-range performance, particularly when outfitted with power-demanding accessories tailored to suit luxury-minded ’58 Impala buyers (like an automatic transmission, an A/C compressor, and a compressor for the optional air suspension). The engine’s design had a flip side as well—it needed to be versatile and durable enough to power Chevrolet’s commercial trucks.
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For the complete history of the RPO Z11: CHEVY 427 program, check out https://www.amazon.com/Day-One-Automotive-Journalists-Muscle-Car/dp/0760352364/ref=sr_1_1?s=books&ie=UTF8&qid=1493561421&sr=1-1&keywords=Day+One+by+Martyn+L.+Schorr