Vintage postbag, July 1984

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Valve Gear

Sir,

Your article about Arab valve gear was very interesting, and I hope you will keep passing on your knowledge of early engines in many similar articles. Of course, there are several controversial points. First, you say that valve overlap is hardly possible with a single cam. This is not so, as one cam follower need not have left the cam before the other hits it. Also, if the cam followers are of different profile, then the total exhaust period can be longer than the inlet period. I have just looked inside a JAP (Prestwich) motorcycle engine which has a single cam and has considerable overlap.

Perhaps you are thinking of an engine with a single push (pull) rod to work two valves, as on Salmson, Crossley stationary engine, Le-Rhone rotary engine. With this, there cannot be overlap.

Next, in the photograph of the Hooker Thomas engine, the camshaft is chain driven, and I am supposing the chain is at the front of the engine. Then if the engine turns clockwise, the camshaft turns clockwise. Thus the cam hits the top rocker (in the picture) first, and so this has to be the exhaust valve, ie the exhaust manifold is on the offside of the car. If the camshaft turns in the opposite direction to the crankshaft, as with gear driven eccentrics, then the exhaust manifold must be on the nearside of the car, or two cams (180 degrees apart! have to be used if it is desired to keep the exhaust on the offside.

Some years ago, I had a small foreign car (NSU? —Ed) with a two cylinder, air cooled engine in the boot. This had the overhead camshaft driven by two eccentrics and rods. and this system is not easy to balance, whereas with three eccentrics, it is in balance. I am told that it will not run backwards, unless it has been assembled incorrectly .

Finally, I vaguely remember seeing an engine with horizontal valves (vertical engine, closed with tapered leaf springs, and I wondered if you can recall this, and can refresh my memory. Also I have never seen hairpin springs (as used on racing motorcycles) used on motor car engines. If not, then I wonder why not, as they are claimed to prevent surging, and can be easily replaced.

Again many thanks for all your enjoyable articles.

Cabourne John Linegar

[The 1912 Delage racing engines had horizontal valves and so did production model Lanchesters some 10 years prior to this and in post-WWI years the American Roamer used a Duesenberg engine with this valve layout, but I do not think leaf valve springs were fitted. The Vanwall GP and F2 Ferrari racing engines used hairpin valve springs, however. — Ed.]

More On Amatol Speedway

Sir,

I was very interested in Mr Hendley’s letter concerning the Atlantic City Speedway at Amatol, New Jersey.

He is in error, however, in saying that Ernest Eldridge, Douglas Hawkes and John Duff took part in races on this speedway. The only foreign driver to race on this speedway was Count Rachewsky, on a Type 35 Bugatti, who competed in the inaugural 300 mile race on May 1st 1926, but retired on the 16th lap.

The three British drivers did take part in the 500 mile race at Indianapolis that same year, and while Eldridge and Hawkes returned to Europe after the race, Duff remained in America taking part in a 250 mile race at the Altoona Speedway on June 12th, finishing third. Three weeks later, in the 200 mile race at the Rockingham Speedway at Salem, NH, he crashed badly, suffering such severe injuries that he never raced again.

Vichy, France T. A. S. O. Mathieson

Continuity of Car Ownership

Sir,

My grandfather, father, son and I have all owned Austin cars. Four generations owning the same make is unusual but not rare. There must be a number of five generation families extant, but six generations seem to be the practical maximum.

Nevertheless, as the centenary of the motor-car approaches, is there a family so prosperous and virile that it can boast a seven-generation tradition?

Can your remarkably well-informed readership give examples of six and, perhaps, seven generation families with, of course, the makes of car owned?

Troy, Virginia R. H. Wyllie

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