Historic Engines – The Fabulous Ford Flathead


In the history of automotive engines, it’s impossible to overstate the importance of the V8 design. By dividing the eight cylinders into two banks of four, engineers achieved a powerful, yet compact unit that could fit into the vast majority of engine bays also sized to fit four or six-cylinder engines.

Ford did not invent the V8 engine, but it can be fairly said that they brought it into everyday use. Some European marques and Cadillac had V8 engines decades before Ford developed the engine that would yield affordable performance and create the basis for hot rodding.

First Generation – 1932-1938

The first of the Ford L-head (flathead) V8 engines left the factory on March 9, 1932. This engine used a 90-degree block, with the valves located next to the pistons, pointed upwards. The heads are not truly flat, having four spade-shaped combustion chambers to accommodate the motion of the valves. The gear-driven cam was located in the engine block above the crankshaft and between the cylinder banks, driving solid lifters that acted directly on the valves. There were two water pumps – one for each cylinder head.The_Valve_In_Block_Design_or_Flathead_Block

The piston bore was 3.0625 inches, and the crank gave a stroke of 3.750 inches, for a total displacement of 221 cubic inches. Compression with stock heads was a conservative 5.5:1, which yielded 65 horsepower at 3,400 RPM.

Stock induction on the new flathead V8 was by a single throat downdraft carburetor and an aluminum intake manifold that sat between the banks of cylinders. A typical stock 65-horsepower flathead V8 should yield fuel economy at about 20 MPG.

This engine can be identified in the field by counting the cylinder head studs, of which there are 21 per side. Later improvements reduced the number of studs to 17.

The flathead V8 was very much under development in the early years, and modifications came annually. Early 1932 Model 18 engines had a reputation for using oil, porous castings, and cooling problems. In 1933, a change to aluminum heads raised the horsepower rating to 75 for the Model 40. Cooling was also revised and improved.

1934 saw the advent of a two-barrel Stromberg carburetor, raising output to 85 horsepower in the Model 40A. A cast steel crankshaft improved reliability. This was the generation of the V8 famously praised by bank robber Clyde Barrow in a letter to Henry Ford.


For 1935, the Model 38 received an updated camshaft. By this point, over 2 million Ford flathead V8 engines had been produced for Ford automobiles and trucks, and for commercial use in other vehicles. By 1936, the engine was called a Model 68 and production passed the 3 million mark.

In the 1937 model year, the Ford V8 buyer was offered a choice of aluminum or cast iron heads on the Model 78 engine. The cast iron heads offered a higher compression ratio of 7.5:1 and resulted in 94 horsepower compared to 6.2:1 and 85 horsepower with aluminum heads.

Also in 1937, Ford brought out the smaller 136 cubic inch Model 74 engine, rated at 60 horsepower and 94 pound-feet of torque. This engine became known as the V8-60, and can be identified by the 17 head studs. This engine became popular in racing and for general use because it provided better fuel economy than the larger engine. 1938 saw continued production of both the V8-85 and the V8-60.

Second Generation – 1939-1942


For 1939, Mercury added a new variant of the Ford flathead V8 design. The new engine was larger, displacing 239.4 cubic inches by virtue of a longer 3.1875-inch stroke. At a stock compression ratio of 6.3:1, the new Model 99A offered 95 horsepower. V8 production passed the 6 million unit mark during this year.

Both the 239 and 221 cubic inch engines switched to a 24-stud head bolt pattern for 1939, making them visually distinct from engines made prior to this time. Production continued in 1940 and 1941 with few changes. Mercury buyers received the 239, and Ford buyers got the V8-85.

By the beginning of 1942, America had entered the Second World War, and very few civilian cars of any kind were produced before Ford transitioned all its facilities to the war effort. Of course, many engines including V8s were produced throughout the war to power various military vehicles, but further development essentially ceased until the end of the war.

The period right after the war was a boom time for automakers as pent-up demand for new cars was satisfied. However, automakers simply cranked up production of 1942 designs until new cars could be developed. Ford abandoned the V8-85, giving all Ford and Mercury vehicles the 239 cubic inch engine, now compressing at 6.8:1 and rated at 100 horsepower.

Third Generation – 1948-1953

47flatheadAAs Ford was producing cars to meet postwar demand, no changes to the engine came until 1948, when a new large truck version of the flathead V8 was released. Displacing a whopping 336.7 cubic inches, the new engine featured a 3.5-inch bore and 4.38-inch stroke. This engine produced 145 horsepower and 225 pound-feet of torque.

For 1949, Lincoln took up the 336 cubic inch engine and produced 152 horsepower and boosted torque to 265 pound-feet. Mercury added a quarter-inch of stroke to the 239, raising total displacement to 255.4 cubic inches and achieving 112 horsepower.47FlatheadB

All Ford V8 engine designs changed substantially in this year, reflecting the first fruits of postwar engineering development. Visually, you can spot these engines easily because the bell housing is no longer part of the engine block casting, but rather a separate piece. These engines also use a modern distributor design mounted at the front of the engine. These engines offer dramatic improvements in cooling, oiling, and virtually every function.47flatheadC

Performance got a bump for the 1952 model year, up to 125 horsepower in the 255, and up to 110 horsepower for the 239, but by this point in history, the Y-block overhead valve V8 engine was in development, and the flathead V8 was dropped for 1954 models in the United States.

Flatheads Forever


The Ford flathead V8 engine continued in production for world markets until 1973, giving it a 50 year production run with well over 10 million units produced. There are still millions of unrestored flathead V8 engines out there in the world, sitting the back corners of barns and garages across America.

Stock parts are still readily available for the Ford V8, and speed equipment is easy to find. Multiple-carburetor manifolds, improved distributors, and high-compression heads are the most common modifications, as well as high performance pistons and cams. Because of the flathead design, there can never be any interference between pistons and valves, making the engine an excellent candidate for period-correct hot rods.

Many books have been published on how to rebuild and modify the Ford flathead V8 for performance, and dedicated engine builders are numerous. If your dream is to power your rod or custom with an original Ford engine, you’ve got plenty of support out there for your project.

About the author

Jeff Zurschmeide

Jeff Zurschmeide is a freelance writer from Portland, Oregon. He covers new cars, motor sports, and technical topics for a variety of newspapers, magazines, and online outlets. Additionally, Jeff is the author of eight published books on automotive topics, including photo histories of Portland International Raceway and Portland Speedway. His current automotive passion is divided between his Mazda Miata, 1976 Mini Cooper, 1920 Model T Ford, and 1971 Fiat 124 Spider.
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