OM cars - model designations

[TimD]

A trifle obscure, I'll admit, but...

Frustrated by the determination of period reports to refer to cars by their attributes rather than their model designations, I am trying to get to the bottom of this one.

When someone refers to a two-litre sidevalve OM type, is this description an adequate summary of the OM 665 and no other model? Or are there other OM's that used the same engine.


If I get to the bottom of this, be warned. My next query will be on six-litre Minervas!

[AUSTRIA]

Founded in 1899 in Milan (as a result of the fusion of 'Grondona Comi & C' and 'Miani Silvestri & C'), OM (its full name was 'Societa Anonima Officine Meccaniche') made various railway materials amongst other heavy engineering products. In 1918 OM took over the Zust car company and thus obtained a car factory at Brescia in Northern Italy.

The first OM car, the Tipo S305, appeared in 1918 with a 4712cc four-cylinder side-valve in-line engine with 30bhp. This was primarily an old Zust model. A completely new car, the Tipo 465, appeared in 1919, with a 1327cc four-cylinder engine. Generally produced with a four seat torpedo body this was well received and sold in large (for the time) numbers.

This engine was gradually increased in size, first to 1410cc in the Tipo 467 (of 1921) and then shortly afterwards up to 1496cc in the Tipo 469. Both these cars were also built in 'Sport' versions.

1923 saw an all new car, the Tipo 665 'Superba' with an all new 2-litre six-cylinder engine released. This model greatly increased the standing of the company, helped also by its significant successes in motorsport and occasional world record ! Notable were top five positions at Le Mans in both 1925 and 1926 and the 1927 victory of the first Mille Miglia, where OM Superbas filled the first three positions. Development included supercharging and an increase in engine size to 2.2-litres in 1930.

In 1933 the car production facilities were absorbed into the Fiat group. 1934 saw the display of a new car, the Tipo V, with a six-cylinder overhead-valve 2130cc engine, but production did not follow. OM became dedicated to producing commercial vehicles (as part of the Fiat group) until it was absorbed into IVECO in 1975.

Want know more about, Tim ?

[fines]

I belive that all (or at least almost all) OMs had side valve engines, and I don't know of any 2-litre OM other than the 665 'Superba', which was being produced for ten years, during which the design may have altered a bit though. BTW, the type numbers of OM cars were (again, almost) all defined by the formula 'xy', whereby 'x' was the number of cylinders and 'y' the bore in mm.

The OM V 'Alcyone', which AUSTRIA mentioned, had, strictly speaking, not an ohv engine, since it still used inlet valves at the side of the engine.

With 6-litre Minerva, do you mean the 32CV 'AKS' of 1927?

[Ray Bell]

Ricardo made overhead valve conversions for them, too, which were used by R F Oates for L C Laurence and Co. Courtesy Georgano...

[TimD]

Well spotted, Ray. You are quite right in guessing that my interest stems from Richard Oates' long association with OM in competition.

Thanks, Egon, for a most excellent summary. Answered everything I think I needed to know.

Now then, Fines, I suspect that the Minerva I was interested in is indeed an AKS. The individual car is GL Baker's machine, run with surprising success on the Brooklands banking. Certainly it's a 32CV car, but I'm also finding references to an "AK" as well. Was the AKS a sporting type of the AK, or a short-wheelbase, or what precisely was the difference, if any?