How to Identify a 427 Chevy Engine


The Chevrolet big-block 427-cubic-inch engine was available on some Corvettes, Camaros and full-size Chevrolet Cars produced from 1966 to 1969, when the engine was replaced with the 454. The 427 engine is a variation of the Chevrolet Mark IV big-block engine family and can appear outwardly similar to other engines in the Mark IV family such as the 396 and 402. The surest way to identify a 427 engine is to decode the engine casting number located on the engine block.

  • Locate the engine casting number on the rear of the engine block on the bell housing flange.

  • If the number is 3909802, it is a 427 produced from 1966 to 1967.

  • If the number is 3917215, it is a 427 produced in 1968.

  • If the number is 3919842, it is a 427 produced from 1968 to 1969 with an aluminum engine block.

  • If the number is 3931063, it is a 427 produced in 1969.

Tips & Warnings

  • If you are having trouble locating the casting number, use an automotive solvent to clean the bell housing flange. Road grime may be covering the number.
  • Aluminum-block 427 engines (known by Chevrolet enthusiasts as the ZL1) are rare. If you are thinking about buying what someone claims is a ZL1 or aluminum big-block Chevy engine, have an experienced Chevrolet restorer or mechanic examine the engine.


  • Ultimate American V-8 Engine Data Book 1949-1974; Peter C. Sessler; 1999
  • Photo Credit Webbaliah/
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