Ford Model A engine
The Ford Model A engine – primarily developed for the popular Ford Model A automobile – was one of the most mass-produced automobile engines of the 1920s and 1930s, widely used in automobiles, trucks, tractors, and a wide variety of other vehicles and machinery.
A four-cylinder, carbureted, gasoline-fueled, piston engine, derived from the Ford Model T engine, the Ford Model A engine – with a bigger bore and stroke, and higher compression ratio – was twice as powerful as the Model T engine. Some derivatives, with improvements, were produced until 1958. Tens of thousands of the original design remain active even in the 21st century.
Design and development
Development and production history
The Ford Model A engine was an evolution of the Ford Model T engine, but with double the power. It was developed in secret at Ford's Rouge Plant, in Michigan, and unveiled – with the Ford Model A automobile – December 2, 1927. The first Model A engine was completed earlier, October 20, 1927, and eventually installed in a 1928 Model A Fordor sedan, which Henry Ford gave to his friend, inventor Thomas A. Edison. There was immediate market demand for the Model A, but by January 1, 1928, just 5,275 Model A engines had been built – some not yet installed in a chassis, let alone shipped to a dealer.However, by February 1929, production of the engines reached 1,000,000 units. At the end of Model A production in March 1932, 4,849,340 Model As had been built. Model A historian Steve Plucker, using Ford company records, calculates that 4,830,806 production engines were built between October 1927 and November 1931.
All Model A engines built in the U.S. were built in the Rouge plant, however some were built at Ford plants in Canada and Europe. During that time, the Model A and AA engine cylinder block, went through various external and internal changes.
The Model A was replaced by the 1932 Ford Model B, with an updated 4-cylinder engine, and by the 1932 Ford Model 18, with its new Ford V8 engine.
Basic design and characteristics
Like the Model T engine, the Model A engine was a water-cooled L-head inline-four, "cast-en-bloc"-type piston engine. It had a displacement of .This engine provides at 2,200 RPM – but at 1,000 RPM produces substantially more torque:. SAE-rated horsepower is 24.03, and compression ratio is 4.22:1.
The cylinder bore and piston stroke were also enlarged from the original Model T engine; they measured. Cylinder firing order is 1-2-4-3.
The engine has a 5-quart oil capacity. The crankcase is filled through an engine fill/breather tube mounted on the engine's left side. Modern 10W30 oils are recommended for newly rebuilt engines. The recommended oil change interval is 500 miles.
Comparison to modern designs
The Model A's engine has three main bearings, and they are smaller diameter, and longer, than bearings in a modern engine. The bearings are poured babbitt bearings, rather than modern replaceable insert bearings.Rather than a full pressure oil system typical of a modern engine, the Model A engine's oil system lubricates the main bearings by gravity feed, and lubricates the piston connecting rods by them dipping into the oil during motion.
A Model A engine has no crankshaft counterweights. There are no cam bearings. The Model A engine lacks valve seats, versus steel ring seats typical in a modern engine. The engine has a rather restricted intake port design, as compared to a modern engine.
Equipment, accessories, and drivetrain
Intake, injection, and fuel
Normally, the Model A engine was supplied with a Zenith one-barrel, up-draft, float-type carburetor, which was gravity-fed from a tank in the engine cowl. The carburetor underwent many modifications during its relatively short production run.The Zenith has features, advanced for that era, that solved some early engine performance problems. The carburetor is designed to run lean, to allow for high-altitude driving. To allow better performance at low altitudes, and in cold weather, the fuel/air mixture ratio is controlled by a manual choke and "Gas Adjusting Valve". To ensure adequate fuel flow during starting or acceleration, a secondary well momentarily provides an extra supply of fuel. A manual fuel shut-off valve is also supplied, and some also have a manual throttle.
Although the Zenith Model A carburetor was fitted to the engines in the vast majority of Ford Model A cars, it was not the only carburetor used. Another 19 brands were fitted to various Model A engines – either as original equipment or aftermarket retrofits – and some Model A engines were retrofitted with the slightly larger, more sophisticated Zenith designed for the Ford Model B engine.
The engine works with modern unleaded regular gasoline.
In rare instances, the Model A engine has been powered by wood gas, produced in a wood gas generator, such as a "Gazogene," typically a large, sealed, stove-like cylinder mounted on the vehicle, or towed, which heated or burned wood, to produce fumes of flammable wood gas, as a minimal substitute for gasoline. The resulting gas was routed to the engine's intake manifold, via a duct and special induction system.
Engine electrical system
The electrical system supporting the engine typically consisted of a 6-volt battery, a 6-volt DC generator, starter, lights, ammeter, and ignition system with connecting wires. A manual spark lever advances or retards the ignition, particularly retarding the spark plug ignition during engine starting.The Model A was configured with a positive-ground system – opposite of the norm in modern "negative-ground" vehicles, often causing technical confusion.
Engine cooling system
The Model A engine uses a centrifugal water pump, mounted to the engine cylinder head, and it works with the engine fan. The Model A engine uses plain water to cool the engine; antifreeze coolant is not recommended because the original Model A radiator is not a pressurized system. The pump circulates radiator-cooled water into the lower engine, and as the water becomes heated in the block's water jacket, it is forced out of the water jacket through the upper radiator hose, and back into the radiator, where it cools, and settles, and the cycle repeats.Drivetrain
Model A automobile
When implemented in the Ford Model A automobile, the Model A engine was coupled, via a 63-pound flywheel, and clutch, with a traditional three-speed, sliding gear, manual transmission.The Ford three-speed, selective sliding gear transmission initially came with a multiple-disc clutch, but it was eventually replaced with a single-plate clutch. There were no synchronizers, making "double clutching" a useful skill for Model A drivers.
The drivetrain ended at the wheels with the final drive ratio of 3.77:1. On a typical Model A, this typically provided 25–30 miles per gallon, and speeds up to 65 miles per hour.
Model AA truck
When the Model A engine is implemented in the 1.5-ton Ford Model AA truck, the engine serial number – normally preceded by the single letter "A" – is, instead, preceded by "AA", denoting the implementation of a stronger clutch spring, to accommodate multiple-disc clutch units, or the AA-7563 clutch pressure plate and its cover assembly, or units with the 4-speed transmission and clutch.Various transmissions and other drivetrain options were offered. Combinations of drivetrain equipment affected the top speed which an AA could reach, while slower, lower-geared AA's could pull with greater torque.
The AA trucks were typically supplied with the 3-speed transmission of the Model A automobile, or an optional AA truck 4-speed transmission. If equipped with the 3-speed transmission, a "Dual High" factory-option underdrive for the AA was offered. The AA's rear axles were available with two different gear ratios.
Various aftermarket drivetrain options were available, including the Warford 3-speed transmission.
Operational history and adaptations
The Ford Model A engine, produced in the millions, was one of the most mass-produced automobile engines of the 1920s and 1930s, used in automobiles, trucks, tractors, farm machinery, industrial applications, boats, military vehicles, and even aircraft.With an already established dealer-and-servicing network created by Ford for the Model T, the Ford Model A and its engine had the advantage of a pre-positioned distribution-and-support network. This superior support system further enhanced sales. As the Ford system grew, and as economies of scale made the engine more competitive against rivals, the Model A engine rapidly became increasingly popular for a wide range of applications, across the United States, and around the world. The vast quantities of Ford Model A engines produced, during a short time, flooded the market.
Even after the engine was superseded by Ford's Model B engine, and discontinued by Ford in 1932, demand for used Model A engines, or license-built copies, continued – for a growing range of applications, with some Model A engines remaining in service for decades. Some derivatives, with improvements, were produced until 1958. Tens of thousands of the original design remain active even in the 21st Century – particularly powering Ford Model A cars preserved as recreational antiques.
Automobiles
Range of application
Primarily developed for the popular Ford Model A automobile, the Ford Model A engine was the engine almost universally installed in that automobile, of which 4.8 million were built by 1932, in a wide range of styles and configurations: Coupe, Business Coupe, Roadster Coupe, Sport Coupe, Convertible Cabriolet, Convertible Sedan, Victoria, Tudor, Phaeton, Town Car, 2- and 3-window Fordor, Station Wagon, Taxicab, Commercial and Truck.Controls and adjustments
In automotive applications, the Ford Model A engine originally used a complex assortment of controls, including accelerator pedal, manual throttle, choke and mixture control, gas shutoff, ignition key-switch, starter pedal, and manual spark advance.These controls were mounted on the floor, or steering column, or on the dashboard. Reportedly, the State of Pennsylvania required the gas shutoff valve to be mounted inside the engine compartment, instead.
Starting the Model A engine commonly requires a detailed sequence of manipulation of all these controls, and properly shutting down the engine is almost as complex.
Additionally, occasional adjustment of the idle throttle and idle mixture controls, mounted on the carburetor, may be required.