1963 Chevrolet Impala NASCAR

The Mark IV 'big block' engine first appeared as an MK II in Robert Glenn 'Junior' Johnson's 1963 Chevy Impala on the NASCAR circuit as an engineering prototype. During the 1963 season, the Impala won 7 Grand National victories, nine pole positions, 14 top-10 finishes in 33 races, 13 top-5 finishes, and set nine speed records. After the 1963 season, production of the MK IV 427 began, which made the MK II engine ineligible for NASCAR competition and limited Johnson's racing efforts for the 1964 season.

Roughly 50 examples (possibly as few as 18) of the Mark II 427 CID engine were built before GM ended production due to the racing ban.

By mid-1965, a production version (the Mark IV) of the engine became available, with 396 cubic inches of displacement. In full-sized cars, it replaced the truck-based 409. A limited run of 200 was installed as the Z16 package in the Chevelle SS-396, whetting the appetite of speed enthusiasts before the stampede of SS-396s to come starting in 1966. In regards to the Corvette, it replaced the 365-horsepower fuel-injected engine in mid-1965 and remained available until 1974.

by Daniel Vaughan | Feb 2020