GMC 366 Engine Specifications

by Susan Revermann

General Motors Company introduced the 366 gasoline engine beginning in the 1960s and continued production until the mid-1990s. The 366, which is considered a tall deck motor because of the elevated shape and design, has a small bore and long stroke, making it a powerful workhorse that doesn't produce particularly high rpm.


The GMC 366 is a 6.0 liter, V8, long block engine. The bore is 4.0 mm and the stroke is 3.6 mm. The compression ration is 9.6:1. There are 16 valves with an OHV configuration and three compression rings on the pistons. There is a chain driven cam on this engine. The gas fuel delivery is sequential electronic fuel injection (SEFI).


The GMC 366 engine produces 366 horsepower at 5,500 rpm and 380 ft-lbs of torque at 4,300 rpm. No turbocharger or supercharger was offered with this type of engine.


The 366 engine was produced by General Motors from the 1960s to the mid 1990s. This engine was used for medium duty trucks and school buses.

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