The Norton Manx was developed in 1937, in both SOHC and DOHC form, to compete in and win the Isle of Man TT. Before fully developed, World War II intervened, and production of the Manx was delayed until 1946. The Manx quickly gained a reputation for its speed and reliability, allowing it to dominate the motorcycle Grand Prix racing and the Isle of Man TT for decades.
The Manx engine has an aluminum alloy cylinder block and head with a single overhead camshaft (SOHC) driven by a vertical shaft and bevel gears. They were hand assembled engines. The 1948 Norton Manx was the first to benefit from telescopic front forks and massive twin leading shoe (TLS) front brakes. 1949 was the first year for the Norton Manx Grand Prix models, purpose-built for road racing, and in 1950, they introduced the legendary "Featherbed Frame". It was made of all-welded steel tubing instead of the common practice of heavy cast iron brazed lugs. It saved weight and made the bike lighter, and they handled like nothing else on the market. The 1952 Norton Manx was the last to use the 'long-stroke' engine. The following year, the engine received a major rework using a shorter stroke (86mm) and larger bore (85.6mm) making the ratio nearly "square".