The Ford Flathead V-8 is a side-valve mono-block design with a cast steel crankcase. It features a simple crankshaft with three main bearings and a complex exhaust passage route. The Ford Flathead was the first mass-produced engine to pour the block and cylinder assemblies in a single casting process.
Built in 1932, the first Ford Flathead V-8 had a 221-cubic inch displacement, was fit with a single barrel carburetor and had water pumps located at the front of the heads. This original Flathead produced 65 horsepower. By 1934 the engine's compression ratios were increased and a two-barrel down-draft carburetor fed the Fathead. The 1934 version delivered 85 horsepower and 144 pounds of torque per foot. Models built for 1937 and 1938 relocated the water pumps, mounting them to the engine block.
In 1939 Ford released the 239-cubic inch Flathead V-8 for the Mercury vehicle line-up. The engine's increased displacement volume and increased compression ratios delivered 95 horsepower and 170 pounds of torque per foot.
Ford introduced the 255 BG model Flathead in 1948, which used a 4-inch stroke crankshaft in the engine block of the 239 Flathead. Used for Mercury cars and service trucks, the Flathead 255 produced 110 horsepower and 200 pounds of torque per foot. This same year, Ford released the 337 Flathead as an alternative for heavy service trucks. The 337 featured a 4.3-inch stroke and delivered up to 154 horsepower. The 337 Flathead was also adapted for Lincoln passenger cars.