After the start of World War II, the UK was looking to manufacture complicated parts — notably the crankshafts — of the Rolls-Royce Merlin in the United States, but negotiations with Packard stalled, because the company insisted on making complete engines.

The intention of this design was to help Ford break into the anticipated large market for aircraft engines.

[citation needed] With the approach of war, increasing orders for M4 Sherman tanks were causing supply issues with the 9-cylinder radial Wright R-975 Whirlwind engine used.

The U.S. Army decided it needed to establish additional engine suppliers, choosing a version of the Ford GAA cut down from twelve cylinders to eight for various vehicle applications.

It was a liquid-cooled Vee similar to the Meteor, but two-thirds the size and Rolls-Royce executive W. A. Robotham doubted its reliability at 600 bhp.