The Moto Guzzi V-8
THE MOTO GUZZI V-8
The Most fabulous Racing Motorcycle Ever Made—
CARLO PERELLI
QUIETLY SEATED in the meadow near the famous “parabolic” bend of the Monza autodrome, Ing. Giulio Cesare Carcano, the valiant chief of the Moto Guzzi experimental and racing department since pre-war days, was watching the 500cc class riders practicing for the 1954 Italian Grand Prix on a fine September day.
That year hadn’t been a very good one for Moto Guzzi in the 500cc class: the four-cylinder in line with indirect injection and shaft drive, designed two years before by Ing. Giannini of Rome (also responsible for the pre-war “Rondine,” later to become the Gilera 500cc four) was proving unreliable and difficult to ride, especially on twisty going, because of the notorious torque reaction common to shaft drive bikes. On the other hand, the second racing model fielded by the Mandello del Lario factory, the horizontal “single” developed through the years by Ing. Carcano and his team of brilliant assistants, although excellent on twisty courses, lacked the top speed necessary to challenge the Gilera and M.V. fourcylinders over the fast circuits. But Ing. Carcano still had much faith in the “single lunger” and had already made many plans to improve it for the next season. So, while lying in that meadow, Ing. Carcano’s attention was attracted by a rider on a four-cylinder machine who was making a big riding mistake while negotiating the bend and, even worse, didn’t show any sign of improvement with the passing laps. That mistake was repeated at each bend. Actioning his stop-watch, Ing. Carcano registered for curiosity the lap times of that rider: these were far better than the ones set up by the Moto Guzzi riders who negotiated that bend (and all the others) with perfect technique, flat out to the limit! Surprised by this ascertainment, Ing. Carcano said to his assistant: "That’s too much. The four is beastly to ride and it’s now useless to make any more efforts trying to improve the single. We must start with a clean sheet of paper and design a new multicylinder job.”
And so it was. The four-cylinder model was scrapped at the end of that season and work started on a highly unorthodoxengined mount, which was later to be known as the "V-8”. The new machine featured eight cylinders arranged in two blocks of four, angled at 90 degrees. The axis of the engine was transverse to the frame, to easily fit a chain final drive as in the ordinary motorcycles (more practical and causing no power transmission troubles). A double ohc timing gear system was chosen.
The reasons for this complex èngine
design? Cubic capacity fractioned to the maximum for very high rpm and consequent high power output (this was the main target of course), originality of design with great possibility of development in a new field (nobody had ever attempted such an arrangement) and power unit overall dimensions — both longitudinally and transversally — still quite reasonable, enabling the use of a “normal” double cradle frame.
The project was readied in the winter of 1954/1955 with great secrecy and then Ing. Carcano, who has a brilliant, versatile (he is a yacht champion and has improved his boats with ingenious features) and sometimes funny character, sent to friends and the press a drawing of his new machine seen from the right hand side, asking them to guess what it was. Nobody guessed the truth and many strange things were written by the specialized press about it; somebody even ventured to state it was a turbine powered machine! First outing of the “V-8” was during practice for the 1955 Senigallia circuit in Italy. Of course the machine caused a great sensation, but it didn’t race; and the same happened after a second appearance. Main teething troubles were encountered with carburetion, ignition and crankshaft lubrication.
Bore and stroke dimensions were 44 x 41 = 62.3 lcc x 8 = 498.48cc and
the engine was thus an “oversquare” with a .932 bore to stroke ratio. In the early stages of development, power was about 65 bhp at 12,000 rpm but gradually this figure grew and at the end of 1957 season when Moto Guzzi unfortunately decided to withdraw from G.P. racing (together with Mondial and G ¡lera), it was very near the 80 bhp mark at 14.000 rpm; i.e. about 10 bhp more than the most potent 500cc four cylinder, and still unsurpassed. It is remarkable that at 14.000 rpm the linear speed of the tiny pistons was still lower than that of a single cylinder 500cc engine (like the Norton Manx or the G50 Matchless) turning over at 7000 rpm!
Owing to its arrangement, the engine required water cooling and the radiator was placed in front of the crankcase. The water pump was driven by one of the timing gears and there were six of them (set in an oil bath case on the right hand side of the engine) to operate the twin ohc for each band of cylinders. At the left hand side of each inlet camshaft were the distributors with four contact breakers each for the ignition. The coils, one for each cylinder, were mounted in banks of four each at the sides of the frame front down tubes. Twin 6V batteries were carried on either side of the rear wheel and the firing order was 1, 8, 3, 6. 4, 5, 2, 7. To have more space for the valves in the hemispherical combustion chambers 10mm spark plugs were mounted.
The very short and massive, forged, nickel-chrome crankshaft with circular flywheels was supported by five caged roller bearings, the races between each throw of the crankshaft being split. Split roller bearings were also used for each of the 90mm long connecting rod big ends. The crankcase was a wonderful onepiece casting in elektron and the cast iron "wet liner” cylinders were finned at the top, within the water jacket, in order to improve cooling. The valves, working in split guides, were set at an included angle of 58 degrees to one another, their diameter being 23mm for the inlet and 21mm for the exhaust, with two coil springs each, over which the large tappets were fitted in direct contact with the cams. The domed pistons, deeply recessed for valve clearance and also to get a squish effect, carried two compression and one scraper ring. Lubrication was by dry-sump system, with double gear pump driven at half engine speed, old traditions for Moto Guzzi racers; another tradition, but more recent, was the oil tank (capacity 9 pints) in the large diameter top frame tube.
Each cylinder was fed by one 20mm Dellorto carburetor and two float chambers on the left hand side served four carburetors each. A single cable from the twistgrip operated the eight throttle slides with a system of levers which reduced effort to the minimum. The multiplate dry clutch was located outside the crankcase on the left hand side and primary drive was by means of two spur pinions in oil bath giving an engine to gearbox ratio of 2.75:1. There were four, five and even six-speed gearboxes (always in unit with the engine) to be employed according to the various circuits. But it was found that, thanks to the tremendous pulling power of the eight cylinders from low rpm ranges, the six-speed type was practically useless. Incidentally, this high torque feature of the engine at low rpm was very useful on twisty circuits and so the bike was equally at ease on every type of racing ground.
The frame was of the double cradle, tubular type with the pivot point of the rear swinging arm incorporated in the crankcase casting to reduce the machine wheelbase. As with all post-war Moto Guzzi racers, front suspension was by mean of leading links, with exposed shock absorbers. The front brake had four “shoes" (two on each side, like the M.V. 500) and tires were 3.00-19 (front) and 3.25-20 (rear). In the later stages of development it was found that an Avon rear type tire fitted to the front wheel improved the road holding further. The “anatomically” shaped light alloy fuel tank had a capacity of 8 gallons and the weight of the machine, with full light alloy streamlining, was no more than 319 lbs. Top speed was believed to be around 168 mph!
Its racing debut was made in the 1956 Imola "Gold Cup,” ridden by the Australian Ken Kavanagh. The exceptional qualities of the machine were at once evident. In spite of wet weather, the Australian was in the lead for the first six or seven laps recording the record lap in this stage, but he was then stopped by a broken water temperature thermometer. Anyway, the 1956 season was still considered a development one and successes were few, but next year the "V-8” started some successful record breaking. Without special tuning or the use of dope fuels. Bill Lomas dashed along the Terracina (Rome) straight and set up a respectable 244 kmph (151.4 mph) figure for the 10 km (6.21 mile) record, still unbroken. Italian rider Giuseppe Colnago won the 500 Italian Championship and Dickie Dale took the Imola “Gold Cup" race, beating all the best men and machinery of those days. A dolphin fairing was prepared for the twisty circuits and Dickie Dale used it for the Senior T.T. where, in spite of ignition troubles, he finished fourth. But on the ultra-fast Francorchamps circuit for the Belgian G.P. the full type streamlining was employed again and Australian Keith Campbell proved the tremendous possibilities of the V-8 : after the fastest lap of the day at 190.130 kmph (118 mph) he thrashed all the opposition only to retire with a minor snag when comfortably in the lead (a broken wire from the battery).
Racing accidents to the best men on its team prevented Moto Guzzi from fielding the V-8 at Monza at the end of the 1957 season. It would have been a wonderful swan’s song because this machine was superior to all the others although the factory bosses, in great secrecy, had already decided to abandon G.P. racing.
So the most fabulous racing machine ever built, at a cost of millions of Lira, wonderful proof of Italian technical skill, was never to be seen and heard (and a fascinating noise it was) again on the world’s most famous racing grounds. All the Moto Guzzi racing material from those glorious days was stored away in a factory shed at Abbadia Lariana, on the shores of Lake Como, and the occasional visitor who can manage access to it is melancholy at the sight of deep dust covering the Moto Guzzi V-8, along with a growing rust which successfully attacks everything ...»
