The RCA Engine Story. Part One By Peter Hogan
R.Christoforides and Associates Ltd (1956-1978)
In 1954, my brother John and I had a small engine tuning business in Pinner Green, specializing in two stroke engines. We were approached by Richard Christoforides, who was manufacturing an ultra light four wheeled car called the JARC. Powered by a 250cc Excelsior Talisman Twin air-cooled motorcycle engine, it was suffering from carburettion and other problems associated with its use in a car. The problems were quickly resolved, and I was invited to join the company as development engineer. The performance of the car however, was very poor, so I designed a new, more powerful engine especially for it. The choice of a two-stroke twin was automatic for this class of vehicle, but with power characteristics that were particularly suitable for light car use. Every effort was made to ensure that the motor would pull strongly from the lowest revs, and combine a good all round performance with reasonable economy.
The initial arrangement of this engine, as intended for use in the JARC, was for full unit construction, with the crankshaft, gearbox and differential, housed in a single aluminum casting. This was to be split horizontally in the manner now generally adopted on Japanese motorcycles, and would have included a complete set of Burman gear pinions, together with the differential from the JARC. The air-cooled aluminum cylinder block was to have been cast in one piece with the crankcase top half, and the bores hard chrome plated. Assembly could be achieved by inserting the gudgeon pins through the exhaust ports, which were located in an ideal position on the sides of the block. With this port arrangement, split skirt pistons may also be used. Before it could be built however, the company went into liquidation, and the engine project was shelved.
Two years later Richard Christoforides suggested forming a new company to produce this unit and so R.Christoforides and Associates was formed, with offices close to Paddington Station. Richard was Managing Director and his brother Benjamin and I were the other two Directors. For providing the design I received 9% of the shares, plus a 10-Shilling Royalty (50P) for each engine sold.
To make the engine suitable for a greater range of applications and simplify production, various changes were proposed. The full unit type of construction was abandoned. The aluminum cylinder block was no longer cast in one piece with the crankcase, but now took the form of a well-finned iron casting, flanged and bolted to the aluminum crankcase which now merely contained the crankshaft. This was bolted up to an Albion gearbox to form the familiar, semi unit construction arrangement as used by Villiers, and many other British motorcycle engine manufacturers.
By choosing a suitable gearbox, the motor could be offered as a light car unit with three speeds and reverse. With a reversing Dynastart replacing the single direction unit, a four-speed gearbox could be used (as no rotary inlet valve was used, the engine ran equally well in either direction). A motorcycle gearbox version would provide a four speed foot change and kickstarter unit, which could retain the electric starter too if desired, or be fitted with a Wico Pacy alternator and contact breaker set, which was adapted to fit on the standard crankshaft taper.
Once the new company was formed, Richard Christoforides set about promoting the engine. He was the son of a Greek millionaire, and the brother of Lady Beaverbrook. Educated at Winchester, he possessed what is best described as presence. He was a wonderful draftsman, and was able to produce a splendid set of detailed engine drawings. These he initially used in an attempt to download the entire project to great and well-established engineering companies such as Rubery Owen, BRD and Alpha Bearings. When he failed, they were used in an attempt to raise capital and to seek partners.
Benny Rood, already famous for his racing motorcycle successes, owned a small precision engineering business in Walthamstow, and he agreed to machine two sets of engine components to enable prototypes to be completed and run. He further agreed to tool up the engine for production, in exchange for a Directorship, 10% of the RCA shares, and the machining contract for all future production. Benny was not required to make the crankshaft assembly, as Alpha Bearings Ltd. had offered to make these for us, and they were the acknowledged experts in that field, neither was he required to make the cylinder heads or pistons.
At this point, orders were placed for the production of the pattern equipment and the dies for the con-rod forgings. I quit my employment with British Anzani, and joined RCA on a full time basis. Richard explained to me that it would be helpful to draw only subsistence money until the company was established, so I settled for £4 a week (a quarter of my Anzani salary!).
RCA had no premises other than Richard’s Paddington office, so the High Torque Head workshop at Pinner Green was pressed into service, and it was there that the first prototypes were assembled and tested. Whilst waiting for parts to arrive, I constructed an engine test bed, ready to receive the first motor, and this drove a Walker Fan Brake. The cylinder heads were tooled for production, and castings machined with a range of compression ratios. Alpha Bearings produced two types of crankshaft to our drawings, a high and a lower (and cheaper!) compression version for selection after testing. I intended to finalize the balance factor by experimentation. Specialoid made the pistons to our drawings, but to save the cost of new dies, they used the castings from the 10 hp Hillman Aero Minx. These were OK but a bit heavy, (I intended to try split skirt pistons once all the normal development work had been completed).
The first prototype ran uneventfully on 05/08/1957, and after running in, time was spent sorting out the carburetion and optimum ignition timing. Before long, one cylinder stopped firing, and the motor was stripped to investigate. The crankshaft, or to be more accurate, the flywheel assembly (for it was a built up assembly of flywheel disks and pressed in shafts), had slipped out of phase. Dismantling the crankshaft further revealed that the mainshafts were a relatively loose fit in the disk, and could easily be driven out with a light hammer! Alpha Bearings were contacted, but were unable to help, as they had just landed the order to manufacture the crankshafts for the new Ariel Leader and Arrow. This massive order also meant that they would not be able to make our production crankshafts, after all. A bitter blow! I pressed the mainshafts back into their correct position, and had them arc welded in place.
Testing was resumed on this single carburetor engine version, but I felt sure that the Siamesed inlet port was holding things back. With a spot of clever welding from Benny, the engine went back onto the test bed, equipped with the twin Amal carburetors borrowed from my own personal Bantam Twin 250cc racer. Power was now 21.6 BHP, compared with the 15.7 BHP obtained from the Excelsior engine that had just been removed from the Berkeley we had purchased, for use as a test vehicle. Running very nicely now and without any further problems developing, the motor was ready to be installed into the Berkeley car for road testing.
After further extensive testing both on the test bed and in the car, the financial need to offer engines for sale became pressing, and so development was halted and the design frozen ready for production. I never did get round to trying the cheaper type crankshaft, or split skirt pistons. There was nothing wrong with the ones in use however, for they were nice and quiet, if a little heavy!
This then, was the engine that was tested by The Autocar magazine in the Berkeley, and then removed and fitted into a Greeves motorcycle, and tested by Vic Willoughby of The Motor Cycle magazine. I was completely satisfied with the Berkeley test, which confirmed that the RCA had ideal characteristics for a car. The whole motorcycle test however, was rushed through in a great hurry, as the borrowed Greeves machine was only available to me for one week. I regret that it was just the same car engine that was tested by Vic Willoughby, without the slightest modification to make it more suitable for motorcycle use. With the benefit of hindsight I now know that quite minor alterations would have raised the maximum test speed by about 10-MPH without seriously impairing the tractability that so impressed Vic Willoughby. This would have made the test altogether more memorable! It should be remembered though, that Richard Christoforides was expecting to sell mainly car engines, and was never much interested in motorcycles.
Before production could get under way, it was necessary to alter the cylinder block patterns to incorporate the twin inlet ports, and other alterations that development had shown to be desirable. Parallel induction tubes were screwed into the new inlet ports on centers especially chosen to neatly carry a handed pair of stub fitting, type six Amal carburetors, exactly as used on the prototype. I was very disappointed that his tidy arrangement was subsequently abandoned, when Amal insisted on us using only Monobloc instruments in the future.
Benny Rood solved the crankshaft production problem by making them himself, and to ensure that no further trouble would be experienced with slipping mainshafts, the flywheels and mainshafts were made in one piece, from forgings. Alpha Bearings were prevailed upon to machine con-rods, and supply crankpins.
We were now ready for production, and a suitable factory was rented for the purpose, in Harlesden, London N.W.10.
The Production Engine in 1958
The first engine to be sold (numbered RC 102), went to the DOT Motorcycle Company, who intended to race it as a scrambler! Since we knew nothing about scrambling, we hastily completed the second prototype (numbered RC101), installed it into a Greeves scrambler and went racing! The poor motor quickly became caked in mud, and ran dreadfully hot. Trouble was experienced with piston ring pegs coming adrift, and allowing the rings to jam and break up in the ports. A complete cure was to remove the standard Specialoid pegs, and replace them with our own shouldered type. The ring material was changed from normal 4K6 to racing grade DTD 485 at the same time, and superior Vandervell thin wall small end bushes were adopted. These modifications were standardized in all subsequent engines.
The engine was now reliable, but as an alloy cylinder block would have been preferable, an order for one was placed with the foundry. I attended the Gloucester Grand National Scramble, when, ridden by Don Rickman, the DOT scrambler had its first outing. Les Archer, riding a modified Manx Norton in the 350cc race, narrowly led the DOT for three quarters of the race until the mud encrusted RCA overheated and seized on one piston. To enable Don to ride the same machine in the 500cc race, one replacement piston was fitted and the main jet size increased slightly. In this form the machine ran reliably for the rest of the day, and finished third in the 500cc final! Had the scrambler engine been fitted with an alloy block it would have run appreciably cooler and this in turn would have permitted further tuning. Whether it could ever have been developed into a successful engine we will never know, for Richard Christoforides decreed that development cease forthwith! I would have certainly liked to at least try out the one alloy block that had by now been completed, but still awaited plating on the bores, but personally did not relish the thought of the RCA being used for scrambling. Since there was no class for 350s, except for International racing, the whole exercise seemed a bit pointless.
RC 103 was sold to a Berkeley owner, and I installed and tested it personally. This was the first chance that I’d had to try out the standard production engine, which was smoother, quieter, sweeter and more powerful than the prototype that had been the subject of the road tests. This was hardly surprising, for the crankshafts that Benny produced were superbly true running, and the cylinder blocks incorporated refined porting.
The Prototype engine (RC 100) had been loaned to the Bond Minicar people, who first reported back with enthusiasm! Soon they discovered that their car was breaking up with the extra power, and the engine was returned to us. It was now fitted with the standardized production crankshaft and block, and reinstalled into our Berkeley. This became our demonstrator, and was thrashed by anyone who could be persuaded to get behind the wheel.
The Panther Motorcycle Company sent us a complete machine, less engine, and a very neat installation was completed. Villiers’ silencers were used to advantage, and a thoroughly nice motorcycle resulted, far better than the test Greeves. We returned the machine to them by train, with high hopes. A couple of weeks later, the engine was returned to us in a crate, with a note to say that they could not get it to start! A phone call confirmed that they (accustomed only to magnetos), had not realized that it was necessary to turn on the coil ignition and had failed to notice the switch, neatly tucked away under the seat! Of the other motorcycle manufacturers, only Cotton expressed any interest, but they failed to take up our offer of a loan engine for test purposes.
DOT Motors were taking delivery of about six engines a week. Some were scramblers, but most were for normal road use. I was able to try one of these, fitted with engine no RC128, and found it to be most pleasant!
RC 105 was supplied as a bare engine, to be tried in a light aircraft!
RC 106 was sold to a firm who manufactured air cooled, outboard engines. These could be used in foul water, which was not suitable for cooling a normal outboard.
RC 109 DOT’s second scrambler. No alloy block on this one either. Richard had declined to sponsor further work on the scrambler, and he was probably right!
RC 155 & 156. Methanol burning scrambler engines for export to Canada. These should have run nice and cool, and might have been successful.
RC 157. A private sale of a tweaked scrambler engine, for use as a road racer by Mr. G Brown.
RC 162. A private sale of a tweaked scrambler for Pankhurst’s of Weymouth.
All the missing engine numbers can be assumed to relate to standard road going DOT motorcycles. It is amusing to note that only one production engine finished up doing the job for which it was specifically designed, i.e. driving a light car
ONLY 66 AIR-COOLED ENGINES WERE PRODUCED. AFTER YEAR 1959, ALL WERE WATER-COOLED!
The Hoganrood hydroplane racing engine project.
RCA Director of Engineering Benny Rood and I had both been keen to try the RCA engine on a hydroplane, but the initial performance proved disappointing. Although quicker than the British Anzani’s, with which I was familiar, it was much slower that the all conquering German Konigs. By the end of the season we had decided that what was needed were new water-cooled cylinders, with ports modified to permit the motor to run at much higher RPM. As Richard Christoforides had refused to finance any further development work, Ben and I did it anyway, as a private venture, calling the modified engine The Hoganrood as Richard specifically asked to be disassociated from the project! In the Spring of 1959 this engine was simply a Methanol burning, air-cooled RCA motorcycle unit RC 107, but by mid season it had been fitted with separate aluminium jacketed cast iron barrels, with modified porting and twin Amal 1.062 inch carburetters. Coil ignition was used, and the end main shafts were altered to accept a rope start spin ring on top, and a single main bearing drive end (to lower the C-of-G). By the end of the season we had started to win races with these settings
Ex. 80.5 BBDC. Trans.60 BBDC. Inlet 74 BTDC for the whole port width, but 84 BTDC in the centre to provide a slow opening. C.R raised to 18 to1, although trouble was experienced at this ratio when one cylinder parted company from the crankcase just above the base flange! Best advance 0.200- 0.225 inch, BTDC. Fuel: Methanol AM1 Plus Castrol R at 50/1. Internally, the hydroplane motor was very much like the Yamaha’s that were to appear a decade or so later.
We would have preferred to use short open exhaust pipes, but all U.K. Hydroplanes are obliged to use the same MMA silencer. We still used the short open pipes though, but curled them up inside a substantial expansion chamber which in its turn, discharged into the compulsory silencer. The Radice propeller (5, 5/16 inch Dia X 10 inch Pitch) ran at crankshaft speed which equals 81.5 MPH at 8,500 RPM without slip. The hull was an Italian Molinari, and the underwater unit, a Konig.
For 1960 the cylinders were stiffened up with extra ribbing at the base flange, and the C.R reduced to 14.0/1. No other changes were made to the engine. A larger American Swift hull was used, which together with an extra big fin that was added to the underwater unit, slowed things down a bit, although it was still much faster than the Konigs. The Championships it won were both in the 500cc C class, and so it seemed pointless to complete the two Hoganrood 500cc Triples that were under construction, and they were abandoned. Astonishingly the 350cc B class championship eluded us each time, with a broken propeller and ignition failure, stopping the boat on each occasion, when it was leading.
For 1961 the ignition system was changed to a gear driven magneto, and larger carburettors were fitted. I also reconditioned the crankshaft, the first time it had been touched since 1958! All the moving parts remained quite standard
The whole outfit was sold at the end of the 1961 season when the owner, Mike Crisp, bought a ten-ton ocean racing yacht. This was soon fitted, at his request, with a lightweight marine version of the hydroplane engine, which was so satisfactory that it became our sole product. Known as the Dolphin Yacht Auxiliary, it was still in production 40 years later! It is interesting to speculate on just how well the motorcycle engine would have performed had it been fitted with the new cylinders, though this was never tried, as all production by now was concentrated on marine engines. In this roll the engine excelled, and several thousand units were produced.
