Before this engine’s introduction, almost all mass-produced cars affordable to the “average mass-market consumer” (which was a concept that Ford helped invent) used inline-four and inline-six cylinder engines. Since French engineer Léon Levavasseur’s invention of the V8 engine in 1902, multi-cylinder V-engines (V8s, V12s, and even V16s) were produced, but were used in luxury models and their production runs were thus limited (relative to downmarket production volumes). For example, the first Cadillac V8 engine was in that category. When Ford Motor Company assumed operations of Lincoln in 1922, they were already producing a flathead engine with Fork and Blade connecting rods which remained in production after Ford took over until 1932.
Even though Ford had an engineering team assigned to develop the engine, many of the ideas and innovations were Henry Ford’s. The Model A, its variants (B and 18), and this V8 engine were developed between 1926 and 1932, and this period was the elder Ford’s last central contribution to the company’s engineering.
Mercury’s 239 cu in (3.9 L) version was introduced in 1939. Aftermarket heads were available from Barney Navarro, Vic Edelbrock, and Offenhauser.
An economizing design feature of this engine was the use of three main bearings to support the crankshaft, rather than the customary five bearings used with most V-8s. The flathead mounted the camshaft above the crankshaft, like later pushrod-operated overhead-valve engines. Valves for each bank were mounted inside the triangular area formed by the “vee” of cylinders. The intake manifold fed both banks from inside the vee, but the exhaust ports had to pass between the cylinders to reach the outboard exhaust manifolds, since it did not use a t-head configuration. Such an arrangement transferred exhaust heat to the block, imposing a large cooling load; it required far more coolant and radiator capacity than equivalent overhead-valve V8 engines. Ford flathead V8s were notorious for cracking blocks if their barely adequate cooling systems were overtaxed (such as in trucking or racing). The simple design left much room for improvement, and the power available after even low cost modifications was usually substantially more than could be obtained from an overhead-valve inline six-cylinder engine of similar displacement.
The Ford flathead V8 was licensed to other producers. It was used by Simca in France until 1961 and in Brazil until 1964 for cars and until 1990 in the Simca Unic Marmon Bocquet military truck. In the United States, the flathead V8 was replaced by the more modern overhead-valve Ford Y-block engine in 1954. During World War II, the engine was used on the first prototype of the Romanian Mareșal tank destroyer, but was considered too weak and thus replaced by more powerful engines for later versions of the vehicle.