Mercruiser is the inboard marine engine division of Mercury Marine. The typical Mercruiser engine is an inline 4-cylinder, V6 or V8 engine produced by General Motors and based on existing automotive engine designs. However, during the 1980s, Mercruiser designed and built an engine that was not a pre-existing automotive engine. This engine displaces 3.7 litres and uses the head, connecting rods, pistons and flywheel from the Ford 460 engine.
The Mercruiser 3.7 L 224 cubic inch engine is an inline 4-cylinder. It uses one cylinder head from the Ford 460 V8 and the same 4.36-inch bore as the 460. Stroke is 3.75 inches, which is shorter than the 3.85 inches of the Ford engine.
The Mercruiser 3.7 was available in five different horsepower ratings: 165, 170, 180, 185, and 190 horsepower. All were designed to operate in the 4,000 to 4,600rpm range.
Because other Mercruiser engines are sourced from General Motors, Mercruiser designed the 3.7 L engine with a GM bolt pattern on the motor mounts and bellhousing. Therefore, the 3.7 is interchangeable in boats with other Mercruiser engines.