AC was on a roll. Its roadster, the AC Ace, had taken the 1953 London Motor Show by storm, and was having a similar effect on race track competition during the 1954 season. What better way to keep the magic happening than by produ8cing a grand touring version of the Ace?
The AC Ace, after all, was a Spartan contrivance, base as it was on the specials built by John Tojeiro for the English club racers. A good basis for a car, actually, with the body a Tojeiro interpretation of the Ferrari Barchetta and the frame/suspension freely borrowed from the Cooper-MG specials built by the father and son team of later Formula One and Mini-Cooper fame.
So it fell to an AC staffer by the name of Alan Turner to design the coupe. It debuted in 1954, dubbed the AC Aceca. Say ah-seek-ah. In addition to the fixed roof, cosmetic changes were made to the fender line, and real luxury touches were added: Roll-up windows, for example, and door handles on the outside.
Structurally, the AC Ace and AC Aceca were very similar, based on two parallel longitudinal three-inch diameter tubes. The Aceca then received a framework of steel tubing supplemented by tongue-and-groove ash framing. The door framework and that of the Perspex-windowed rear hatch is all ash. And over it all were placed hand-formed aluminum panels.
The suspension, identical front and rear, consisted of a lower A-arm with a transverse left spring serving as the upper locating member. Add Armstrong telescopic shocks and—that’s it. It was simple but revolutionary. It was fully independent at a time when independent front suspension was new. And even Ferrari didn’t have independent rear suspension on a street model until the 275GTB—that introduced in 1964, two years after the Ace/Aceca went out of production.
In the beginning, brakes were huge 11-inch Alfin aluminum drums front and rear, virtually filling the 16-inch center lock wire wheels. Front disc brakes became an option in 1957, along with separate master cylinders for front and rear circuits as a guard against total failure.
The better brakes were in part a response to the Bristol engine which became an option in 1956. It seems the two-liter AC six, in spite of its aluminum block and overhead cam cylinder head, was a bit gray in the whiskers. It was a 1919 design, originally producing 40 horsepower, but by 1954 it was producing 105 bhp. At that it was stretched tight, and the TR-2s and Austin Healy 100s were closing on the race track. The solution was the Bristol, nee BMW, 1971cc six.
For lovers of mechanical complexity, what a marvelous engine it is, enough to make Rube Goldberg weep. What look like covers for twin overhead cams actually hide rocker arms for a convoluted OHV system. The intake valves, at 40 degrees from vertical, are operated by rocker arms pivoting outboard of the vertical pushrods, the motion carried over and around. The exhaust valves operate as follows: Vertical push rod to rocker pivoting outboard, around and under by means of the rocker to another pushrod crossing the head to another rocker which, pushed horizontally, pushes the exhaust valve set at 40 degrees from vertical. Tubes for the pushrods pass between the two banks of valve covers, and are visible from above.