OM: Italy's budget sports car

Motor Sport’s readers must be aware that Italy is in the forefront of sportscar manufacturing nations, and has been thus for a very long time. Reputations backed up with racing victories by Ferrari, Alfa Romeo, Fiat and Maserati have endorsed this. But, in addition to the top makes in this context, there have been other excellent Italian cars of this type. Ansaldo, Ceirano, Diatto, Itala and OM have provided fine sportcars for those unable to attain ownership of the more costly makes. Of these the OM is possibly the best remembered in this country.

Made by the Officine Meccaniche, which dated back to 1899 and which made railway locomotives and rolling stock, the first OM car arrived in 1918, after the Milan company had acquired the Brixia-Zust factory in Brescia. It was followed a year later by the sports Tipo 469 with a fourcylinder side-valve engine with the classic 69x100mrn (1495cc) cylinder dimensions, and wire wheels on Rudge-Whitworth hubs.

The OM occupied much the same place as the 12/50 Alvis did, but it was entered for more important races. It was the type of car with which British amateur OM owners made competition entries.

Best remembered, perhaps, is the six-cylinder Tipo 665 OM Superba, with a 65x100mm (1991cc) engine which developed 45bhp at 3800rpm on a 5-to-1 compression ratio, its valves still modestly at the side of its cylinder block. All types of bodywork were available, and in four-seater form it was a good-looking, practical fast car. Known here as the 15/45, it could do 80mph, with its single Zenith carburettor feeding through the cylinder block. The four-bearing crankshaft had water-cooling of the centre bearings.

The OM had a six-brake system, so-called because the handbrake had its own shoes acting on the rear wheels, these being unlined. Apparently, such shoes were inadvertently fitted to the TT car Oats drove at Phoenix Park in 1930; he ran off the road, but won his class there in ’32. The smart appearance must have assisted L C Rawlence and Co Ltd, of Sackville Street, Piccadilly, W1, to sell the car, for which it had the UK concession.

For those who took note of Mille Miglia performances, OMs finished 1-2-3 in 1927, second in ’28 behind an Alfa Romeo and ahead of the third-placed Lancia. Balestrero had also won the ’25 Tripoli GP.

In 1924, this 15/45 OM cost from £675. Its wheelbase of 10ft 2in made for comfortable bodywork The specificaton was conventional, but well-contrived. The normal gear ratios, low as befitted an Italian car, were 15.1, 11.2, 7.2 and 5.0 to 1, while the tyre size was 765×105. By 1929 the OM Six was available in Sports, Special Sports and De Luxe shortchassis and De Luxe long-chassis forms, the wheelbase of the last increased by a foot.

In earlier times, Rawlence had done work on racing cars for select customers, and he now introduced a pushrod overhead-valve conversion, designed by R F Oats, for the 2-litre OMs. He kept interest alive by racing at Brooklands and elsewhere, with Oats his accomplished driver whose mechanic was Dunkeley.

The OM won many Brooklands races, and the special single-seater with the ohc conversion lapped at 98.62mph in 1927. They also ran at Le Mans before British small sportscars such as Alvis and Lea-Francis did so, the two Danielis and Foresti/ Bassiaux finishing fourth and fifth in ’25, and Minoia/Foresti and the Danielis likewise in ’26, the first named winning both the Index of Performance and Biennial awards. Six cars were sold with the pushrod valve-gear and dural conrods, and were eligible for the Ulster TT in which Oats won his class in 1928 and Ramponi/Minoia were fourth and fifth in class in the 1929 race.

OM also built straight-eight roller-bearing dohc supercharged cars to the 1926/7 1.5-litre GP formula, but these are outside a recall of production OMs, though the eight-cylinder cars appeared at Brooklands and elsewhere after private buyers had acquired them.

In those days Dugdale, Blackstone, Clark and TASO Mathieson were among those who owned OMs and, when he was not driving a Bugatti, the late Hamish Moffatt ran a smart four-seater in VSCC and other events; his family still owns the car.

Production of these desirable cars ceased in 1931. Fiat took over the firm by 1933, and Rawlence then sold Oldsmobiles instead.