Hall-Scott Model A-7a

The Hall-Scott Motor Car Company was formed in 1910 after San Francisco businessman Bert Scott was impressed by the 1909 Comet car and engine designed by Elbert Hall. Initially the men produced gasoline-powered railroad cars, but soon expanded to aircraft engines. This came from Hall’s success with making the lightweight, but powerful engines. The 4-cylinder Comet engine produced up to 25hp for an engine that weighed only 130lbs. (The Ford Model T engine produced 20hp and weighed…?) These engines helped Hall win many auto races around San Francisco. Hall’s engines became increasingly desirable due to his use of overhead camshafts and valves, hemispherical and cross-flow cylinder heads, interchangeable parts between models, and aluminum pistons and crankcases.

The Hall-Scott aircraft engines evolved from the Comet. Their first engine, the A-2 V-8 engine was essentially two Comet engines with an additional tank as an oil pan. This A-7-A inline engine was primarily used on the Standard J-1 training airplane.

Due to his innovative designs, Hall worked with Packard engine designer Jesse Vincent to create the primary design of the US government-funded Liberty engine. The Liberty Engine project called for tens of thousands of engines to be produced, but the company was too small compared to other manufacturers to build some of the 20,000 produced in 1917-8.

After World War I, Hall-Scott stopped making aircraft engines, but continued making engines for boats, buses, trucks, and other uses until 1960.