LIFE E back into CLARA CLA ARA
In the earlythirties there was a bike that was an important part of Velocette’s race programme, but it vanished for many years. When it was finally rediscovered, the remains were bought by Ivan Rhodes, but it took even longer to restore it.the machine con
Initially, the cammy Velocette was anonymous. The bike came about as the result of a discussion between two of the company’s top engineers. It was based on a standard, 350cc overhead camshaft KTT engine but among many others of that ilk the supercharger made this one a unique example. Designer Phil Irving and technical director Harold Willis were the two engineering minds involved and the idea for the bike began during an ‘after-hours’ discussion at the local pub. The broad subject was the evolution of the KTT models. Irving had only joined the company in 1930, but he had already addressed problems experienced with earlier KTT engines, where ever-higher states of tune were causing blow-ups that had barrels separating from crankcases. In trying to pre-empt future weaknesses, Irving wondered if the relatively small main bearings were the next potential problem area. The pair decided to experimentally increase the stress on an engine by fitting a supercharger. Supercharging a single cylinder engine is not easy. The supercharger provides a steady charge of pressurised air, or fuel/air mix, depending on where the unit is fitted into the induction layout. The pressurised gas is delivered all the time the engine is turning, but it has nowhere to go on the engine’s ignition and exhaust strokes. This can be partly overcome by having a plenum chamber – a holding tank – as part of the intake system. The majority of motorcycles were single cylinder at the time, so supercharging was not a popular method of improving performance and the market place offered few suitable units.
Messrs Irving and Willis found a vane-type Foxwell unit, which was never intended for use with internal combustion engines (see page 34). Factory records show that engine KTT 240 was booked out to Willis. The experimental set-up employed a simple biscuit tin as a plenum chamber, but when the engine was tried on the testbed the output measured 30hp, compared to the 22 of a normally aspirated engine. It was a remarkable result, although it should be noted that the engine was getting the full benefit of the more intense inlet charge, as the supercharger was being driven by an external power source. With such a positive result, and as the bottom end assembly appeared to be adequate, the decision was made to continue the experiment with a complete motorcycle. Using the same engine as the basis, the drawing office came up with various necessary modifications. Feeding the carburettor with pressurised air means the entire fuel system, from the carburettor and up to and including the fuel tank, also has to be pressurised to function. A special frame was created, although it used various lugs from the factory parts bins. Heavy fuel consumption was anticipated, so a special fuel tank offered increased capacity. When it was fitted it looked similar to the ‘Pistol Grip’ style adopted by New Imperial. As well as his talent for engineering, Willis was also an excellent rider, posting second pllace finishes in both the 1927 and 1928 Junior TT races. Perhaps hhis most memorable legacy is his large lexicon of words for mmotorcycles and their constituent parts. Thus Willis referred to th e unusually-shaped fuel tank as a ‘cow’s udder’. Following a ride e, when the pressurised fuel system had to vent, it did so with a ‘w whiffling’ sound, hence the ‘Whiffling Clara’ sobriquet. Clara’s s engine used the standard cast iron cylinder head with coil valve spr ings. Behind the engine, on the right side of the gearbox, was the ‘O Official Receiver’, Willis’s appellation for the large tank that acted as plenump chamber for the pressurised fuel/air mix. The Fox xwell blower was mounted low down in front of the engine aand was driven by chain from the crankshaft. With the ‘Officia al Receiver’ behind, the whole system required a lot of plumbi ing. Initially, the bike was fitted with Willis’s four-speed gearbo ox unit with rack and pinion selector, but this was changed to a four-speedf constant-mesh version. Apparently, hard ridin ng could result in the iron cylinder head glowing with the he at. A new design with hairpin valve springs cast from al uminium bronze (‘doorknob metal’ according to Willis) a ided heat dissipation and the same head was eventually usedu on production KTT Mk. IV models. The supercharger arrangementa was soon changed, with the carburettor working at atmospheric pressure and the, now down-stream, blower compressing the fuel/air mixture. Uneven fuelling remained a problem. Under riding conditions the plenum chamber filled with a fuel-rich mixture on the over-run, choking the engine when the throttle was opened again. This was addressed with a special pressure relief valve, apparently an item developed byb Amal for the Air Ministry. This was connected to a valve l ifter-type lever that had to be operated manually by the ri ider, clearing the surplus gas and allowing the engine to ru un cleanly. After some encouraging test results, hopes were high
that the bike would show its mettle at the 1931 Isle of Man TT Junior race, but Willis was not happy with the performance of the engine. Apparently, poor weather during practice meant he could not tune the engine and supercharger arrangement satisfactorily. Although press reports said he removed the supercharger, it seems he simply used another KTT with a normally-aspirated engine to achieve a finish in 11th place. Next year, Clara returned to the TT and this time Willis persisted with the bike. Seemingly the fastest of the entire entry off the start line, by lap two he was reported as ‘making adjustments’ somewhere on the Mountain, and was soon posted as a retirement near The Bungalow. From the event reports of the time, it seems the supercharger gave Clara an impressive top speed, but the acceleration could be a variable quality. Exactly who rode Clara is not clear. Les Archer was the regular jockey at Brooklands, but it seems the South African JG Lind may have ridden Clara in the Isle of Man, although it should be noted that Willis was usually extremely protective of his projects. Primarily set-up for road-racing, the bike could be a bit of a handful around Brooklands, but it was apparently timed in a sprint event at an impressive 114mph. Les also rode the bike in the Ulster Grand Prix, a one-off occasion, and from which he retired, famously declaring: “I am not a fish,” as the race was run in what the Irish call ‘liquid sunshine’. Photos exist of Clara taking part in the 1933 Brooklands Grand Prix, with Les Archer aboard as usual, but by then the project seemed to have run its course and after that the bike essentially vanished. Many years later, the Perks Brothers, of Bilston in Staffordshire, had quite a collection of bikes and bits stored at the back of their garage premises. Some of this had come from the Veloce factory, as the brothers were friends of the factory owners, the Goodman family. Titch Allen was writing his ‘Velocette Saga’ – a series of magazine articles – and someone had tipped him off that the collection included remains of ‘Whiffling Clara’. Titch and Ivan Rhodes went to look and certainly, one of the bikes had elements of the long-lost machine. But was it the genuine article?
The truth will out
Looking like a very down-at-heel Thirties KTT, the bike had been modified, presumably to keep it competitive, as it had apparently been used for grasstrack racing. The unique fuel tank was the most obvious clue and the engine number – 240 – appeared to confirm these were, indeed, the remains of Clara. The engine had the bronze bevel housings that Willis was known to prefer. The frame showed signs of repair, where the original was known to have broken at one point in its history. This was in 1970 and the British motorcycle industry was sinking rapidly, but Ivan Rhodes was taking a keen interest in historic Velocettes. He managed to negotiate the purchase of the bike, together with a number of other bits and pieces. Ivan had every intention of restoring it, but there were many other jobs with greater priority. Some years later, when Clara might have received attention, further delays were caused when Ivan and his team were obliged to work flat out on the bikes damaged in the disastrous fire at the National Motorcycle Museum in 2003. However, Clara had not been completely out of mind, as Ivan had been accumulating parts to replace the worn, or incorrect, components. The absent Foxwell supercharger was a major stumbling block. Appeals through the press and even advertising brought no response – even parts for such a device seemed to be unobtainable. Eventually, other Velocette enthusiasts came to the rescue and making a replica supercharger enabled the project to move forward. The engine had been updated with a Mk VIII crankshaft, so this was exchanged for a nicely set-up, and heavier, assembly that had been removed from Maurice Cann’s ‘Dirt Track’ engine some years previously. Apart from that, the engine and gearbox rebuilds were straightforward. When the factory ceased to use ‘Whiffling Clara’ for development, it seems the frame was altered at the factory to return it close to standard specification, although it still retained some of the original features, such as some additional lugs. The sub-frame had been exchanged for a 1934 version. This made restoration less than straightforward. Careful study of all the available photos revealed what was required. The engine had to be moved back an inch from the standard position and the front down-tube re-worked to provide a mounting lug for the supercharger locating plates. Ivan said: “Much juggling took place to determine the position of the blower relative to the rest of the unit. The front down-tube had to be shortened, the length of it was critical. This was a two-man job, but I was ably assisted by a pal from New Zealand, Pete Butterworth, a vice-president of the Velocette Club. Pete is an engineer in his own right and a very good rider. He spent a week or two with us to help out with Clara and the museum bikes.” When found, Clara was fitted with a Mk IV front wheel. Period photos showed a 1931 KTT hub was correct. Ivan managed to buy a new replacement from Tom Bartlett, a model engineering enthusiast living in Kent. Ivan takes up the story: “We were very lucky to have a brand new Avon 3.25x20 rear tyre that
had been specially produced in the Nineties, but is, regrettably, no longer available. All the control cables were made up from my stock of original period material and only two features remain incorrect. The front brake should have a rod and wing-nut adjuster to complete it. We used a Bowden period twistgrip, instead of the original lever control favoured by both Harold Willis and Alec Bennett, according to a letter from high authority – Percy Goodman.” Meanwhile, Ivan’s son Grahame was kept busy with the stove enamelling. Jim Plant donated a primary chaincase, which was re-worked appropriately with an additional cover protecting the chain drive to the supercharger. Ivan had discovered from Irving’s notes that this was driven at half crankshaft speed. Suitable sprockets came from Derek Stride attd Cross in Birmingham. Most of the work was done ‘in house’ and Ray Pettitt of Nottingham made the final components. Sheet metal skills were needed to re-create the plenum chamber and oil tanks. The lugs that once located them had also been removed, but these were re-instated from Ivan’s stock of ex-factory parts. John Goodall was yet another person who helped with the project, locating and modifying an oil cooler to try and match the photographed original. He made the pressure relief valve that bolts into the plenum chamber. John was also responsible for the inlet manifold and the air filter body that is a distinguishing feature of the timing side of the bike. One tricky part was the pipe that fed from the blower to the plenum chamber.this led under the engine and the restricted space allowed little room for error. The exhaust pipe was another fabrication project. The work was completed in 2010 and the bike was soon fired up. After further experimenting, it was found that the engine runs nicely on a mix of petrol/methanol in an 80:20 ratio. Usefully, this also works satisfactorily with the ‘Roarer’, another of Ivan’s high-profile Velocette restorations. With 5psi boost, the engine performs extremely well. It climbed the Brooklandstest Hill with some aplomb! Perhaps, in isolation, ‘Whiffling Clara’ was not a success, as no other bike was similarly modified. However, the lessons learned in supercharging doubtless proved valuable for Velocette’s later experiments, as well as guiding future developments of the KTT. Whatever the conclusions – it’s good to have her back.
Above: Clara as found – at one time, the bike might have been secured for a fiver! Right:the distinctive tank took some work to bring it back to original factory standard.
The gearbox support stay has been stiffened following a frame breakage.
Top: Harold Willis and Clara at the TT weigh-in Right:the Restoration Team! Left to right, Sam Rhodes, Grahame Rhodes, Geoff Berry, John Kidson, Ivan Rhodes on bike, Harold Beal, Rob Wiggins, John Goodall (the late) Brian James, Bob Higgs and David...
Above: Les Archer, possibly at the 1933 Brooklands Grand Prix, Pa Archer is far left, Harold Willis third from left, then Eric Fernihough.
Ivan demonstrates Clara at the 2012 International West Kent Run.