The Aceca 2.6:
The Rarest and the Fastest
Built in the final years of production and fitted with a tuned Ford engine, the Aceca 2.6 is the last and rarest of the line — just eight were made. It is also the fastest Aceca, and the closest of them all to the car that came next: the Cobra.
A new engine for the end of an era
The Aceca 2.6 was AC's answer to a supply crisis: by 1961 both of the coupé's established engines were running out of road — AC's own Light Six had reached the end of its development and Bristol was winding down its two-litre supply. AC turned to Ford. The 2.6 used a 2,553 cc straight-six from the Ford Zephyr, extensively reworked by Ken Rudd's Ruddspeed concern — not an AC engine, and not an "enlarged" AC unit, but a thoroughly re-engineered Ford. It breathed through three Weber or SU carburettors and could be specified with a modified cast-iron head or a special alloy "Mays" head, and in various states of tune.
The fastest Aceca of all
In its hottest specifications the Ruddspeed engine produced as much as 170 brake horsepower — far more than either the AC or Bristol units — giving the 2.6 a top speed around 130 mph and a 0–60 mph time of roughly 8.1 seconds. Fitting the taller Ford engine was not the simple drop-in that the Bristol unit had been; it required modification to the frame and a relocated steering box. It is often said that the lower Ford engine also allowed AC to restyle the nose with a lower bonnet line and a smaller grille, but the AC Owners' Club regards this as unproven folklore and states that the intended nose revision for the Aceca 2.6 was not actually carried out.
“Only eight were built — making the 2.6 the rarest Aceca of all.”
The bridge to the Cobra
The Aceca 2.6's historical significance lies in the modifications its Ford engine demanded — a reworked frame and a relocated steering box. It was into this modified, Ford-ready chassis that Carroll Shelby's V8 would soon go, creating the AC Cobra in 1962. The 2.6 is, in a very real sense, the last civilised step before AC's most famous car; to understand the Cobra's origins is to understand the 2.6.
Identity and rarity
Ford-engined cars carry chassis numbers beginning RS, or RSX for left-hand-drive export. With only eight Acecas built this way, the 2.6 is by a wide margin the rarest variant — a footnote in the numbers, but a fascinating and fast one, and the direct link between the elegant Aceca and the thunderous Cobra that ended its story.
About the author
An independent classic-car enthusiast in North Yorkshire with decades of hands-on experience on British classics — including the AC Aceca — writing the single-model reference he always wished existed. Read the full bio.