Like many British manufacturers, AC Cars had been using the Bristol straight-6 engine in its small-volume production, including its AC Ace two-seater roadster. This had a hand-built body with a steel tube frame, and aluminium body panels that were made using English wheeling machines. The engine was a pre-World War II design by BMW which by the 1960s was considered dated. Bristol decided in 1961 to cease production of its engine and instead to use Chrysler 313-cubic-inch (5. 1 L) V8 engines. AC started using the 159-cubic-inch (2. 6 L) Ford Zephyr engine in its cars.