Found another nice one...
In the 1926, Amilcar made an overhead cam inline six of 1096cc. Here's a little detail from one site about it:
Another version of the Amilcar was the beautiful little twin-cam 6-cylinder Roots-supercharged model, it was much more exciting than the Grand Sports, It appeared in 1926 and was a pure racing car, which you could buy for £695. The 1,094 cc. engine possessed dry-sump lubrication but relied on plain bearings. The Amilcar Six looked like a small G.P. Bugatti but it was another half-dozen years before Bugatti went over to a twin-cam engine! An out-and-out small racing car which was soon in demand amongst British amateurs, and in the hands of professional drivers was dominating the 1,100 cc. class, the Amilcar Six could be had with sketchy sports equipment, and even before this was freely available Vernon Balls evolved a means of endowing these very rapid little cars with a dynamo and starter.
Seven main bearings, sound pretty tough and very interesting to me.