NASCAR Sportsman Division

[1] The rulebook mandated that all cars had to be American made, and 1937 or newer, with full stock fenders, running boards and bodies if equipped by the factory, but their bumpers and mufflers had to be removed.

Multiple carburetors were permitted, while overhead valves and superchargers were allowed only when factory optional or stock equipment.

[3][5] As a result, the small block V8 engines introduced by the manufactures in the mid-1950s began dominating the Sportsman class, making the pre-war Ford flathead V8 and Chevrolet inline 6 cylinder obsolete.

NASCAR responded by creating an additional "Limited-Sportsman" class in 1959 that provided drivers with the earlier production engines an opportunity to continue competing.

[6][10][11][12] By 1967 the Sportsman specifications had evolved to include small block engines with a 335-cubic-inch limit, which could match speed with the Modifieds on many shorter tracks.