List of GM bellhousing patterns

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The following is a list of GM bellhousing patterns. Though General Motors has manufactured many different engines, it has kept variance in the bell housing patterns to a relative minimum.

Chevrolet V8 pattern

So named because it began with Chevrolet's V8 engines.

  • Chevrolet big-block V8's
  • Chevrolet small-block V8's
  • GM Vortec 4300 90° V6
  • GM Iron Duke RWD inline 4 (Early RWD Variants, later versions may use a FWD pattern, and have two possible starter locations)
  • Jeep 2.5L/151 in³ Jeep used the GM Iron Duke inline 4 1980-1983. These use a Chrysler Torqueflite 904 automatic transmission with a Chevrolet bellhousing.
  • Chevrolet Inline 6 (1963 on)
  • Chevrolet 153 Inline 4 (Chevy II, pre-Iron-Duke)

GM metric pattern

GM 60deg V6 bellhousing.JPG
Also called the GM small corporate pattern

This pattern has a distinctive odd-sided hexagonal shape.

Northstar pattern

Nearly identical to the GM small corporate/metric pattern, except that the starter is located between the cylinder banks, and the lower right bolt hole is moved outward by roughly one inch. Being nearly identical, it too has the distinctive odd-sided hexagonal shape.

Pre 1965 Buick and Rover V-8 Round pattern

Buick, Oldsmobile, Pontiac (BOP) V8 pattern

225 231 jeep buick bellhousing.JPG
  • Post-1965 Buick/Oldsmobile/Pontiac RWD V8's
  • Buick pre-3800 90° RWD V6's
  • Jeep "Dauntless" 225 in³ oddfire V6 (1967-1974)
  • Cadillac cast iron V8s after 1967 (1968-85 472 and 500, 368 and 425)
  • Starters are on the left side on Olds and Pontiac and the right on Cadillac and Buicks.

Cadillac V8 pattern, pre-1967

Early Cadillacs manufactured before 1965 used a "round top" bellhousing much similar to early Buicks; around 1965, the bellhousing pattern was revised until the BOP bolt pattern was adopted in 1968.

GM 4-cylinder pattern

GM Ecotec 4-cylinder pattern

External links