Rumblings, September 1970

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Two-Wheeled “E”-Type

Sitting in a traffic jam the thought occurred that it was ridiculous that one person was using 4-2-litres of engine and a sizeable motor car to occupy an area of road 14 ft. 6 in. x 5 ft. 6 in., and looking around there were other cars taking up even more space for only one person. Musing on the thought of small single-seaters for road use it became very obvious that a return to motorcycling was called for when traffic jams were inevitable, and one such occasion was obviously the British Grand Prix at Brands Hatch, so a motorcycle was sought. Norton-Villiers came up with a real motorcycle in the shape of a 750-c.c., vertical-twin Norton Commando and from the moment of leaving the E-type with them at their Andover factory and taking the Commando, traffic problems disappeared. It was gratifying to have to wait for Bob Manns, the Norton Sales Director, for he was not away having tea or at a conference, he was out on the open road on the Commando in question, just seeing if all was well. As the green and chrome bike zoomed up to the front of the factory and the Sales Director removed his crash hat and Barbour suit he said “there it is, it’s a good one”, which was much more satisfying than being told by a sleek young man in an office that “our man has tested it and assures me it is all right”.

The man behind the rejuvenation of the name Norton is Dennis Poore, who used to race Formula Two Connaughts and works Aston Martins and before retiring set a high standard in VSCC racing with his 3.8-litre Alfa Romeo. The name Norton in the motorcycle racing world is akin to Ferrari in the car world, it is a name that breathes performance and racing, and the latest 750-c.c. Commando is no disappointment. The object of the loan was to remove the traffic and parking problems involved with three days of South London and Brands Hatch, and while a 50-c.c, moped would have done this, it was so much more satisfying to have a bike that really accelerated its way out of traffic problems or out of the way of wandering saloon cars that were changing direction without warning. The old adage “when in doubt, open out”, usually applied to trials riding, was never more right than when in traffic on the Commando, and as the taxi in front is about to make a U-turn (and then signal) a quick squirt of the 750-c.c. engine and you are gone. It is all so much easier and safer than having to stand on the brakes and try and stop, with the risk of being hit up the back by a following car, which is what would happen with an under-powered 50-c.c. bike.

Before returning the Commando, rather reluctantly, the opportunity was taken for some open road riding around Hampshire and Wiltshire and being used to the roads with an E-type Jaguar, it was pleasing to find the Norton had the same sort of long-legged open road gait and all the performance of high speed and high-speed acceleration that the E-type owner is used to. These Commandos have the engine, gearbox, rear suspensions and rear wheel mounted on rubber on the main frame, a system that makes for ironing out high-speed vibrations and so 80 m.p.h. cruising is effortless, with sufficient squirt left in the twist-grip for getting by things in the shortest possible time. It is a real motorcycle for motorcyclists, but that does not mean the car enthusiast would not like it. It was once said of the old chain-driven Frazer Nash that it was like a four-wheeled motorcycle. The Norton Commando is a two-wheeled E-type Jaguar.

A Full Circle

Looking at a Chevrolet V8 engine used in a Can-Am car we were intrigued by the fact that four of the eight inlet trumpets were shorter than normal by quite a few inches. On this type of Chevrolet the inlets rise vertically in a solid bunch with bell-mouth ends, and alternate cylinders had the short inlets. (See colour page 976.) Enquiry found that this was to assist the torque curve at around 5,000 r.p.m., the engine running to 6,800 r.p.m., but it was only effective with slightly retarded ignition on those four cylinders. The immediate question was how to retard the ignition on four cylinders out of eight, when an eight-cylinder Scintilla Vertex magneto supplied the sparks, and it was explained that it was done with special plug adaptors that recessed the plug and caused its effective spark point to be about three degrees later than the normal plugs that protruded into the combustion chambers. Study of the comparative torque figures taken on the test-bed, with and without this tweak, showed that they climbed steadily through the 5,000 r.p.m. point instead of dropping and rising again. This had no effect on maximum power and torque, or maximum speed of the car, but it made it much easier to drive out of corners, with an improvement in lap times.

Talking to some vintage Riley enthusiasts at a later date we were discussing magneto timing on a 1929 Riley Nine engine that was using a rather rare cylinder head with the sparking plugs recessed in masked holes, rather than protruding into the combustion chamber. It was pointed out that the engine would need a lot more advance on the ignition timing as the masked plug effectively fired later. Riley had experimented with this head in 1929/30 but not found it of any great value. In 1970 Chevrolet found the old masked-plug phenomenon on ignition timing very useful.