Norton Model 7
Norton Model 7 Background & History
The Norton Model 7 was Norton’s first twin-cylinder motorcycle. Like most British motorcycle manufacturers of the day, they had focused exclusively on single-cylinder machines until then. Triumph shocked the world with the release of its 500c 1938 Triumph Speed Twin and soon nearly every other manufacturers rushed to bring their own vertical twins to market. Just as work got underway World War 2 intervened before things really heated up, and all production went into the war effort for the next several years (1939-45). But when civilian production resumed again in 1946, the rush was on. BSA launched their first twin in 1946, Ariel followed in 1948, Matchless/AJS, and Royal Enfield in 1949. Norton’s first entry into the vertical twin fray was also in 1949 with theNorton Model 7.
This 1952 Norton Model 7 shows the plunger rear suspension, which replaced the rigid frame.
By this time Triumph was just a year away from shocking the market once again with Britain's first mass production 650, the 500cc 1950 Triumph 6T Thunderbird. Brainchild the genius designer Edward Turner, who also designed the first Ariel Square Four engine, created an engine that just resonated with people. They loved it! Now they were hopping it up and enlarging it. And again, the market rushed to follow. Triumph led the way throughout this era and never really stopped. Out of all the British makes, Norton probably did the best to challenge Triumph's supremacy, certainly performance-wise. Even parent company BSA struggled to keep up with Triumph, and they had the inside track! Triumph's boldness certainly inspired others in the industry, but also gave them a much-needed kick in the pants. Triumph always just seemed to have it right, they knew that the market hungered for, and especially the all-important US market where Triumph ruled. BSAs still outsold Triumphs in their UK home market, but in America Triumph was king! However, Norton fielded a range of bikes that the public loved and while they didn't sell in the volumes that Triumphs did, they did well in the marketplace and earned the respect of riders everywhere. Norton had a great reputation.
1952 Norton Model 7 at the Quail Motorcycle Gathering in Carmel CA.
Norton Model 7 Engine Design
Norton poached engine designer Bert Hopwood from Triumph to design their new vertical twin engine. Hopwood had worked under legendary designers Val Page at Ariel, and Edward Turner at Triumph. He had assisted Turner in the design of the seminal Triumph 5T Speed Twin. Where Triumph used gears to run its two cams, Hopwood positioned the single camshaft in the front of the engine, chain driven off the crankshaft. Spark was supplied by a Lucan magneto located behind the cylinders and driven by a chain. For lights, a Lucas dynamo was located in front of the cylinders and also chain driven. The crankshaft rode on two main bearings (no center main bearing) with the timing side on the right and the drive side on the left. The cylinder block and head were cast in iron, and the head featured cast-in rocker boxes rather than bolt-on boxes like the Triumph twin.
This engine was so well designed, so robust, and so expandable that it served as the platform upon which every future Norton twin would be based. This little 500 was quickly expanded to 600cc then 650cc then 750 then finally in 1973 all the way to 850cc! How many engines have ever been expanded that far? One comes to mind, the BSA C15, a 250cc single that was bored and stroked to 350 then 500cc. It doubled! But, this takes nothing away from the Norton twin. It remained non-unit construction throughout its entire existence, never converting over to unit-construction as BSA and Triumph did. While the non-unit look is more 'old world' it worked for Norton, no one seemed to mind. In fact, it gave their bikes a muscular look that worked for Norton. Their bikes were always among the fastest, they should look tough. When this same engine, now running 750cc in the Norton Atlas, was enlisted for the Commando, Norton set the engine in the frame such that the cylinders weren't vertical anymore. They slanted forward slightly and it gave the ancient engine a whole new look, a 'modern look' the Norton engineers thought. And again it must have worked because the Norton Commando is one of the most gorgeous motorcycles ever built (our opinion, of course).
The new Norton Model 7 engine proved itself so much so that Norton built every twin-cylinder motorcycle around this motor. Over the years it grew from 500cc as seen here all the way to 850cc in the 1973 Commando.
Norton Model 7 Leads to Other Models
The Norton Model 7 stayed in production from 1949 through the 1955 model year. By this time, it had been supplanted by the 500cc Norton Dominator 88 which used the excellent Featherbed Frame rather than the old garden gate frame of the Model 7. In the 7 years of Norton Model 7 production, the bike went from being Norton’s premium motorcycle to becoming its entry-level twin, once the Dominator 88 and Dominator 99 and other subsequent models filled in the higher positions in the product lineup.
The new Norton Model 7 engine would be fitted into the frame and running gear of Norton’s single-cylinder ES2. This included Norton’s ‘garden gate’ frame with rear plunger suspension instead of a swing arm.
Norton Model 7 Books
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