Once the largest independent manufacturer of automotive engines, Detroit’s Continental Motors Corporation purchased the rights to a single-sleeve valve engine design in 1925, believing this technology might replace poppet valves in aircraft engines. However, after considerable testing with U.S. Navy support, the company only became successful in aviation after reverting to poppet valves. Continental’s future success began in 1931 when it began production of four cylinder horizontally opposed engines.

Derived from the earlier A-50 and A-65 engines and designed by the innovator Harold A. Morehouse, the Continental A-75-3 engine was certificated in 1939. The bore and stroke was the same, and the higher power of the A-75 resulted from increased speed. Early in 1940, Continental introduced a fuel injection system adaptable to the A-65, A-75, and A-80 engines. The A-75 powered light Stinson, Piper, and Luscombe aircraft. Introduced following World War II, the larger bore C-75 powered the Erco Ercoupe 415.