Ford introduced its flathead V-8 engine in its 1932 models. Ford's 1932 three- and five-window coupes equipped with the V-8 gained popularity in early postwar North America, when car enthusiasts modified them as hot rods. There are three types of flathead V-8s: the original 136-cubic-inch V-8, the 221 to 255 versions and the big Lincoln 337 flatheads.
Since the mid-1920s, Ford sought to build a powerful engine in a compact block. Henry Ford assigned Mil Zoerlein, Ray Lard and Carl Schmaltz to produce a V-8 capable of serving as a template for larger cubic inch displacements and greater horsepower in the future. The original flathead, so named for its flat cylinder heads, debuted in March 1932. It came with cast-iron block, two water pumps and a Detroit Lubricator carburettor. The early flatheads suffered from cracks, casting pinholes, overheating and a tendency to burn oil. It took Ford most of the 1932 model year to iron out the problems with extensive testing.
The 221-cubic-inch featured a 3.06-inch bore and 3.75-inch stroke. It developed 65 horsepower, which was bumped to 75 for 1933. A dual-downdraft Stromberg carburettor boosted the horsepower again to 85 in 1934. The engine came with 21 studs for each head. The 1932 versions had cast-iron heads, but Ford switched to aluminium heads in 1933. Hex nuts fastened the heads to the cylinder block and Ford used an eggshell-shaped distributor. Ford enlarged the cubic inch displacement to 239 in 1939, and later to 255, with horsepower increases up to 112. The flathead V-8 had no stamped serial numbers on the block. Instead, Ford stamped the serial numbers on the transmission bell housings. The transmission serial number on a V-8-powered 1932 Ford Model 18 should read 18-001 to 18-203126. On the 1936 Model 68, the number should read 18-2207111 to 18-3331856.
Ford introduced the smaller and more economical 136-cubic-inch flathead in 1938. It generated 60 horsepower and featured heads fastened with 17 studs. For only 1937, the engine had sheet metal sides on the engine block. The tapered water pumps were at the front of the engine. Late 1937 and later V-8s had non-tapered water pumps. Ford lengthened the crankshaft by two inches in 1940 and installed non-flanged rod bearings. The 1937 and 1938 versions had flanged rod bearings. Ford equipped the engine with a smaller generator, internal parts and carburettor, which were not compatible with the 221 V-8s. Serial numbers atop the transmission bell housing ran from 54-6602 to 54-358334.
Ford's big F-7 and F-8 trucks, and Mercury and the Lincoln luxury cars received the 337-cubic-inch flathead V-8 in 1948, with horsepower ratings up to 154. This version had 27 studs per head. It was a big engine, tipping the scales at 386kg. The in-house designations for these engines were "8EL" for Lincoln and Mercury, and "8EQ" for the trucks. Ford mounted the distributor at the rear of the engine. The new V-8 was equipped with hydraulic lifters and a forged steel crankshaft. Most parts were not interchangeable with the 221 to 255 flatheads. Serial numbers for Mercury/Lincoln started at 899A-2005028 and 8H-174290 for the Lincoln.