1926 Willys-Knight roadster
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Story and photo by Bill Vance

The Willys-Knight car, built by the Willys-Overland Company of Toledo, Ohio, from 1914 to 1932, is remembered above all for its ultra-quiet sleeve valve engine. Although Knight-type sleeve valves were used in Europe and America in the early part of the century, it was Willys-Knight that really popularized them.

The sleeve valve principle was invented by Charles Yale Knight of Chicago in 1903 to replace the noisy poppet valve then used in engines. Knight received a British patent in 1908, and a United States patent in 1910.

Knight was motivated by dissatisfaction with the valves in his personal cars. Those valves, which opened mechanically (or in very early engines, by atmospheric pressure), and closed by a spring, were noisy, prone to burning and leakage, and subject to bouncing and floating (getting hung up between open and closed).

Familiar with the sliding valves used in steam engines, Knight thought the principle could be applied to gasoline engines. He invented two concentric cast iron sleeves, or tubes, which were interposed between the engine’s pistons and cylinder block, with the pistons sliding on the inner one. These sleeves were reciprocated by short connecting rods operated by a crankshaft-rotated eccentric shaft.

The sleeves were about 3 mm (1/8 in.) thick, with a stroke of about 25 mm (1.0 in.). Slots at the tops lined up with intake and exhaust ports at the appropriate times to flow the gasses in and out of the cylinder. Although pistons and sleeves all sliding up and down at once sounds complicated, it worked very well.

Sleeve valves had several advantages. Their fully lubricated sliding motions made them extremely quiet compared with the impact clatter of poppet valves. Positive opening and closing eliminated valve bounce and float. Combustion chambers could be ideally shaped with a centrally located spark plug, and no valve adjustment or de-carbonization was required (in fact a little carbon accumulation made them more efficient).

The disadvantages were that sleeve valves were more expensive to manufacturer, were subject to higher oil consumption, added reciprocating mass, and made the engine harder to turn over for starting.

Finding little enthusiasm for his sleeve valves in America, Knight headed for Europe. To gain prestige he approached the makers of luxury cars where the quiet operation of the sleeve valves would be highly valued.

By 1913, Knight licence customers included Daimler of England (used in its V-12 “Double Six”), Panhard et Levassor, Peugeot and Mors of France, Mercedes of Germany, and Minerva of Belgium. Of all the European countries, France would pursue the development of the Knight engine most vigorously.

Knight returned to America to try again, this time with more success. Among others, the Stearns Company of Cleveland, Stoddard-Dayton of Dayton, Ohio, Columbia of Hartford, Connecticut, Russell of Toronto, Ontario, and Edwards of New York contracted for Knight licences.

John North Willys and the Knight engine crossed paths in 1913 when he purchased the Edwards Motor Company of New York City. The purchase included a Knight sleeve-valve licence. Willys had been an Elmira, New York, Overland dealer, and when his supply of Overland cars had stopped in 1907, he journeyed to Indianapolis to investigate. He found a moribund Overland company, which he proceeded to take over, and under his management production reached almost 500 cars in 1908. In 1909 he moved the operation to Toledo, Ohio and changed its name to Willys-Overland, and by 1914 production was number two in America, second only to Ford.

With the Edwards Knight licence, Willys plunged into the sleeve valve world with his customary enthusiasm. He introduced his new four cylinder, sleeve valve Willys-Knight car in 1914 with production starting in Elyria, Ohio, but soon moved to Toledo. The Willys-Knight would also be built in Toronto for Canadian sales, and for export. With the Willys-Knight, W-O brought sleeve valve silence into the affordable price range, and W-O would ultimately produce more Knight-engined cars than all other Knight users combined.

The Willys-Knight was almost lost in a glut of models from W-O, but by 1919 things settled down and the company decided to concentrate on three lines. These were the low priced Overland, the medium priced Willys-Knight, and a new Willys Six that was under development.

Many buyers were captivated by the ultra-quiet operation of the sleeve valve engine, and Willys-Knight became a successful mid-priced car with annual sales said to run as high as 50,000. The four was soon joined by a sleeve valve six cylinder, and even in 1917 by a V-8 for a three year stay. Willys-Knight would go to sixes exclusively in 1926.

Willys-Overland did well through the 1920s, but in the early 1930s it was hurt by the Depression. Although W-O would make it through the ’30s, the Willys-Knight was allowed to die in 1932.

Advances in metallurgy and lubrication, and the development of such improvements as hydraulic valve lifters, gradually made the poppet valve quiet and reliable. Sleeve valves lost their advantage, and although they would continue to be used for several years, especially in aircraft applications, they gradually disappeared. The Willys-Knight and other Knight-engined cars are fondly remembered as the quiet voices among the clatter.

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