AC Cars 12HP Price Guide

The AC 12HP was one of AC’s earliest production models, built from 1920 to 1928. It introduced John Weller’s overhead-cam six-cylinder engine — the powerplant that would define AC for the next four decades and eventually power the Ace that spawned the Cobra.

Significance

The Weller OHC six was remarkably advanced for 1920: aluminium construction, overhead camshaft, and a design philosophy that prioritised efficiency and mechanical refinement. It initially displaced 1,447cc and produced around 40bhp. In 1924, a 12HP set a world 24-hour distance record at Montlhéry. The engine was progressively enlarged over the following decades but retained its fundamental architecture through the Six, the 2 Litre saloon, and into the Ace and Aceca of the 1950s and 1960s.

Today

The 12HP is a rare and historically significant veteran car. Its importance lies in being the first AC to use the Weller engine that would serve the company for over forty years. Any surviving example is of considerable interest to collectors of early British cars and historians of AC’s engineering legacy.