When a driver of the calibre of Sir Malcolm Campbell elects to drive it, interest is increased in an otherwise obscure car, about which enquiries crop up from time to time, although its racing achievements were virtually nil. That car was the Jameson Special, built by J Jameson of the Jameson Engine Company (UK) Ltd, at West Ewell in Surrey. (He should not be confused with Murray Jamieson, designer of the last of the works Austin 7 racing cars, including the wonderful little twin-cam cars, and who died in that unhappy accident at Brooklands, when a Delage plunged amongst the spectators.)
The Jameson Special surfaced in 1933 and the fact that it was a supercharged two-stroke was sufficient to arouse interest even before it made the race tracks. There had been other two-stroke racing cars, the Cozette for example, but the Jameson engine was of sufficiently sophisticated layout to attract attention in this field. Not for Jameson the simple two-cycle configuration with the mixture compressed in the crankcase and then fed to the combustion chamber as the descending piston uncovered the inlet port. His engine went very much further than that, in an attempt to over-ride the known deficiencies of the simple two-stroke power-unit.
By the mid-1930s the supercharger was a practical proposition, applied to many four-stroke engines, and Jameson made use of this to produce his high-efficiency two-stroke racing engine. The charge to the four cylinders was forced into them by this means and as poppet valves closed by normal valve springs would have been hard-pressed to cope with the increased opening and closing speeds necessitated by an engine firing twice every revolution of the crankshaft, Jameson substituted piston-valves in the detachable cylinder head, operated by a miniature crankshaft, driven by a vertical shaft and bevel gears. Two superchargers forced the mixture past the open port in the piston-valve as the main piston neared the bottom of its strokes, the exhaust gas being expelled through ports cut all round the base of the cylinders uncovered by the main piston, the incoming charge assisting by evacuating the burnt gases. As the main piston rose, the fresh charge was compressed in the normal way, within the head, topped by the piston-valves.
The aforesaid vertical shaft at the back of the four-cylinder engine drove a vertically-mounted single-rotor, (vane-type) Jameson supercharger and the crankshaft driving the piston-valves. There was another vertically-mounted supercharger at the other end of the engine, driven from the shaft-drive, and both superchargers fed mixture to the cylinders through short pipes to the two inlet ports. A Solex carburettor was bolted directly to the supercharger casing and there were wide exhaust ports on both sides of the cylinder block. Two magnetos, transversely mounted, were driven from one end of the valve-actuating crankshaft in the head and fired 18 mm sparking plugs angled slightly from the horizontal on opposite sides of the combustion chambers. A water pump was driven from the timing-gear shaft.
This engine had a bore and stroke of 60 x 88 mm (995 cc). The crankshaft ran in six split roller-bearings, being of the 90-deg pattern, well-balanced. The big-ends were also of roller-bearing type. In experimental form the superchargers boosted at 8 lb/sq in, and the blow-off valves were set to open at 25 lb/sq in; these had an important function to perform, because with the ingenious piston-valves, there was no safeguard from a backfire, as these were no conventional poppet valves. The crankcase was of cast iron, with the superchargers mounted neatly on it. Lubrication was of the dry-sump type, the finned aluminium base-chamber containing the delivery and scavenge oil-pumps. A separate oil-pump lubricated the superchargers and yet another small pump, driven from one of the superchargers, sucked oil from the main feed and supplied it via a rotating mixer-valve to the fuel supply to the blowers, so that a mild “petroil” effect was provided, apart from which lubricant was fed to the upper part of each cylinder. Such was this ingenious Jameson two-stroke racing engine, for which 120 bhp at 5500 rpm was claimed, the weight quoted as 350 lb complete.
To accommodate his power-unit Jameson is said in some accounts to have built a special chassis, using for it the axles from a 2-litre GP Delage. Other reports infer that the entire chassis was from a Delage of this type. Two of the complicated V12 cars had been entered for Brooklands races in 1931, one of which WB Scott had found in Sweden and was, I believe, later owned by the Conan Doyle brothers, the other having been bought by Capt JV Nash in the Argentine, from E Forrest Greene. Either could have provided the chassis, or parts of one, for the Jameson Special. It seems likely that the former applied, as modifications like using a Wilson pre-selector gearbox, an ENV differential, and a different axle ratio were described. A very neat two-seater racing body was made for the car by Gurney Nutting, the well-known coachbuilders, giving the appearance of a small Maserati.
With two-stroke racing cars few and far between and belonging mostly to the distant past, the Jameson caused something of a stir when it was entered for the 1933 Light Car Club’s Relay Race at Brooklands, a race of some importance, with the works A7 team running and factory support given to other cars such as the Morgans and the MGs. Dudley Froy, who had won his first Brooklands race in 1927 in one of Sir Alastair Miller’s Wolseley Moths and who gained his 120 mph badge there with a Bentley, was down to drive it. Unfortunately, it was not ready in time.
It was at the 1934 Whitsun Brooklands races that Sir Malcolm Campbell, then at the height of his fame as holder of the LSR at 272.46 mph, was due to drive the black Jameson Special with its red wheels, in the Merrow Senior Short Handicap. The great man had entered it himself, so presumably he thought well of its chances. He had been set to start 23 sec before Chris Staniland in TASO Mathieson’s blown 2-litre Bugatti, which was on scratch. However, the Jameson again non-started. That is not quite the end of the story. When Dunlop’s ran their Jubilee Meeting at the Track in 1938 the substantial prize money (as much as £100 to the winners of the bigger races) attracted many entries. Jameson himself was there, with a blue Jameson Special with silver wheels, its engine dimensions as before, although the capacity was now declared as 1092 cc. Froy at last had his chance in the car, or was it another one; the chassis was now said to be Bugatti, so perhaps the 1933 engine had been transplanted, or a second engine built? Dudley Froy got it round at 98.23 mph, insufficient for a place, and it failed to appear for its two subsequent Campbell circuit commitments.
There the curtain comes down. Unless anyone out there knows more? — WB
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