Norton motor cycle engine, 1928.
© Science Museum / Science & Society Picture Library
The overhead camshaft (OHC) engine first appeared in 1928, and proved to be almost unbeatable at the important road races, especially the Senior and Junior Tourist Trophy (TT) races held on the Isle of Man. For over twenty years it was regarded by racing enthusiasts as one of the most efficient engines built in Britain. The engines were made by one of the most prestigious British motorcycle manufacturers, Norton Motors Ltd, until 1948.