Founder’s Day at Stanford Hall produced overhead camshaft machinery from around the world, but also provided a reminder that the British contribution was not just restricted to the Norton, AJS, and Velocette racing models
The theme for the VMCC Taverners’ Stanford Hall meeting this year was ‘overhead camshafts’. The venue is close to home for PUB, but she has missed recent years due to clashes with other events. It clashed again, but for unconnected reasons it was the other event that lost out this year, so she went along. She took (trailered of necessity) a suitably themed racebike, obviously not from the House of Vincent – although it may surprise readers to know that they did make one. Just one. It was an Earl’s Court show model NSU-Vincent Max, but costings showed that this Anglicised model – to reduce import duties – would not be profitable although the 98cc ohv and 123cc 2-stroke Foxes were marketed.
It is popularly supposed that the British industry was always conservative, and made worthy plodding go-to-work bikes at best, unlike the Japanese with their exotic and well equipped bikes that brought electric starters, indicators, etc to our market. But it ain’t necessarily so. Overhead camshafts are a case in point, and overhead camshafts were the theme at Stanford Hall. For that reason PUB took along her Grand Prix dohc Mondial, accompanied by B44 Clive’s justbeing-completed Parilla restoration. Actually, the Parilla is not technically overhead cam, as its camshaft is situated at the top of its camshaft tunnel just alongside the head, instead of over it. This necessitates tiny little pushrods, inside inch long rubber bellows, the arrangement giving most of the ohc advantages of reduced valvegear reciprocating weight, but still permitting the head to be removed without disturbing the camshaft drive or timing. Velocette and Vincent used ‘high camshafts’ as high inside their timing cases as they could easily
Founder’s Day at Stanford Hall produced overhead camshaft machinery from around the world, but also provided a reminder that the British contribution was not just restricted to the Norton, AJS, and Velocette racing models
accommodate, but nowhere near as ‘high’ as the beautiful Italian Parilla.
The 1920s was the era when British factories were hot with ohc developments. Everyone knows about Manx Nortons (derived from the Arthur Carroll replacement for Walter Moore’s original CS1 of 1927), and the cammy Velo which actually preceded it, originating in 1925, but they were not by any means the only examples, nor even the first. Le Vack had already gone record breaking in France in 1923 with one of Val Page’s JAP dohc race engines with the slightly unusual layout of cams and followers/ rockers. Rolls Royce are credited in some circles for sparking off UK ideas, since their Eagle aero engines had been very successful in WW1 (but they had only adopted the idea from elsewhere). However, the motorcycle world had plenty of precedents of its own, especially the racing dohc Peugeot of 1913.
At Stanford Hall the area marked out for ‘theme machines’ was very limited, and certainly inadequate for such a wide ranging theme. Even allowing for it being a VMCC event, and thus only for over 25 year-old machinery, that included most of the Japanese brigade (Honda arriving with theirs over 50 years ago, and the other Japanese factories going 4-stroke around ten years later). A few interesting machines did assemble, in addition to the Mondial and Parilla. These included the expected Nortons, Velocettes, AJS ‘boy racer’, but also Arthur Farrow’s MV 600cc four – an example of the first model that MV released to the market, and purposely with shaft drive and only 600cc to discourage customers from trying to race it. But for a reminder that ohc was once espoused even by the British industry it was necessary to keep the eyes open when looking around.
Cammy Velos, of course, abound, not least because for some years they were the mainstay of the Velocette range, and not just the racing models in the catalogue. But the irrepressible Rhodes team (Ivan and Graham) also had the 1939 supercharged contrarotating twin Roarer not only on show, but started up for the crowd. In 1930 the idea of ohc for the roadgoing models was not confined to Velocette, and both Matchless and Ariel showed ohc fours at Olympia – the 600cc V4 Silver Hawk from Matchless and the 500cc Square Four from Ariel. The latter lived on a little longer of the two in ohc form, but regressed to pushrods by the later Thirties. It is doubtful whether either of those fours could usefully benefit from their overhead cams given their tortuous intake plumbing, and pushrods made less demands on the lubrication and cooling systems of the time, as well as easing head removal for decoking (no disturbance of the valve timing). Nevertheless a number of the ohc Ariels were to be found at Stanford Hall.
From the smaller factories, the Excelsior Manxman is probably the best remembered ohc (and with most survivors), but others were also giving it a try. The old firm of Chater Lea (like BSA a maker of lugs and fittings to the industry before being manufacturers themselves) produced a face-cam engine that had some success breaking records, before they faded from the market in the recessionary 1930s. OK Supreme also tried a novel approach, launching their new 250cc machine with the cams fitted to the vertical tower (with an inspection window to see if oil was reaching the cams – hence the name ‘Lighthouse’). This made its first appearance at the 1930 TT where it broke the lap record from a standing start, nevertheless it also faded quickly away in the Depression. However, the factory still offered a more conventional shaft-and-bevel ohc from the mid-Thirties, of which one was on show at Stanford Hall.
Another rare example of the ohc breed, which also appeared on Founder’s Day, was the Humber version. A tale, quite possibly apocryphal, told that Humber in 1930 were on the skids, soon to be part of the Rootes Group, which had no interest in motorcycles. The Humber designer had his new ohc design burning a hole in his pocket, and knew that under the new regime it would not see the light of day – so he got it into production as quickly as possible just to see it in the metal. A peculiarity of their advertising was that they referred to it is a 3.49 h.p. OHV (camshaft type).
The post-war UK years were dedicated to worthy transport and currency earning exports, so real glamour disappeared from the UK motorcycle scene (save for the Vincent, PUB must add), with only the ohc race-bred Norton, AJS, and Velocette (soon to disappear itself ) continuing. But it was so nearly not so. Val Page’s parallel twin designs of 1939 had planned for both pushrod and ohc versions, no doubt the latter as a sporting competitor to Turner’s Triumph, but the war intervened. An ohc BSA twin is illustrated in Hopwood’s ‘Whatever Happened To The British Motorcycle Industry?’, which may be such a prototype, but as Page, Turner, and Craig all served spells at BSA in those turbulent times exactly whose hand was in which prototypes may now be difficult to unravel.
So, in the post-war era, it was Italy, and for a while Germany, who led the way with new ohc designs. In the small classes FB Mondial, in rather antiquated cycleparts (with girder forks) took the 125cc world championships in 1949/50/51 with dohc works models, and after a less successful period returned with a revised design housed in more upto-date cycleparts to blitz both the 125cc and 250cc championships in 1957. In the
large capacities it had been Gilera dohc fours (by Remor, who had designed the pre-war Rondine four) that had deposed Norton even with their Featherbed frame development, such that even Duke had to defect in order to win. Only after the Gileras pulled out in 1957, together with Moto Guzzi and Mondial, did the MV fours become unbeatable. Ducati obtained the services of one-time Mondial employee Fabio Taglioni, who promptly set them onto a winning trail in the lightweight classes with the ohc Ducatis that sired a long line of sohc, dohc, and desmodromic singles, before commencing the L-twins that are still the mainstay of Ducati today.
For a time, Germany also provided some leading designs, although with few ohc models. BMW continued their ohc boxers, just for racing as they had pre-war, but NSU provided novelty with their 250cc Max design, in which the camshaft is driven by a pair of connecting rods (rather like the wheels of a steam railway engine). This was developed into a potent racing iron (which Hailwood rode in his early years), of which one was displayed at Stanford Hall. The Grand Prix winning NSUs were much more complex and sophisticated twin cylinder designs, now of exceptional rarity.
The German industry collapsed rather earlier and more dramatically than that of Britain, in spite of its engineering reputation – but not without a legacy. Not only the Ariel Arrow, but also Yamaha’s two-stroke twins were influenced by Adler, and during their ‘copy’ phase the Japanese made models clearly patterned on German and British machines. However, when Honda went racing, they obtained a racing dohc Mondial (which is reputedly still in their museum) for examination, but their first TT machines were twin cylinder shaft and bevel dohc machines with something of the look of the GP NSUs about them.
There was one more ohc machine at Founder’s Day, to remind us that even in the post-war era at least some designers remained forward thinking; the 4-valve MC1 racer. Technically, this might be referred to as
‘double overhead cam’ because it does have two camshafts, but practically they operate more like a single camshaft but ‘bent’ (using a pair of shallow bevels) so as to engage with rockers aligned with the radial four valves. Nevertheless its performance impressed Geoff Duke sufficiently that he planned to race it, spooking the conservative BSA board, who had not approved his venture, so much that they canned the project when the technical team could not guarantee it would win. This was a throwback to BSA’s 1921 humiliation when all six of its specially designed and prepared TT machines failed even to finish.
Reputedly six sets of parts were again made, of which Hopwood’s book says that three were assembled, and now it appears that there are three again. One complete machine is on show at the National Motorcycle Museum, and another at Sammy Miller’s museum, but it was neither of these on the Rudge stand at Stanford – badged both as BSA and Rudge. The why of that may be connected with that board’s fear of humiliation, as apparently they considered racing under the Rudge name, said the owner. Sadly none of that was to happen, development stopped, and the machine that Hopwood says was designed for exploitation as a catalogue model disappeared.
Nor was that the only ohc that got canned, although it was perhaps the most adventurous and interesting. But Royal Enfield prototyped a 175cc job, which has survived and crops up from time to time having just featured in ‘ The Classic MotorCycle’. Velocette, so often thought of as living in the past in spite of their many attempts to break the mould, also designed a 250cc ohc engine around 1960. Unfortunately it fell into abeyance due to pressures of work elsewhere (Bertie Goodman did not remember exactly why). A 5-speed gearbox was proposed, using the then new Royal Enfield cluster, but RE would not play ball, so the unit was designed and machined to accept an Ariel/Burman cluster from the Leader/Arrow – but never completed. Then, in his final years the great designer Val Page (whose JAP dohc of 1923 was mentioned earlier) planned a 50cc unit for the Pixie, using a then fairly novel belt drive ohc. That was over-ruled by Edward Turner.
Then there was the Triumph ‘Bandit’ and BSA ‘Fury’ – but the less said about them the better…