A debt repaid?
In 1952 I interviewed the great Talbot designer Georges Roesch, the articles which followed (Motor Sport, November and December 1952) throwing fresh light on his cars and driving Anthony Blight to write his authoritative work The invincible Talbot (Grenville, 1970).
Now the January 1989 issue of the STD Journal contains a report of the interview Hugh Conway, more usually associated with Bugatti affairs, had with Roesch on behalf of the Institute of Mechanical Engineers some seventeen years later. What interests me here is that, in the course of this Conway interview, Roesch revealed for the first time that, between refining Louis Coatalen’s 8/18 Talbot into the 10/23 and getting to grips with his revolutionary 14/45, he had discovered a solution to operating inclined overhead valves without the use of an overhead camshaft (or twin ohc).
This engine must have surfaced between 1922 and 1925 as a four-bearing six-cylinder. Roesch never used his revolutionary valve-gear, finding normal push-rods adequate if they were sufficiently light and the rockers properly designed, but his inclined push-rod system was patented in the name of his friend at the Coventry Chain Company, Mr Harry Watts.
In these days of efficient camshaft drives by cogged belts, there is little excuse for not using single or twin overhead camshafts if a designer so desires. But, in the days when Roesch evolved his ingenious solution, driving a camshaft remote from the crankshaft invariably gave rise to several problems, not the least of which were noise and expense. So it is hardly surprising that angled push-rods with a “downstairs” camshaft came to be used by Peugeot, Chrysler, Humber, Armstrong Siddeley, Fiat and Ardun.
So what is the conundrum? Well, when the late Laurence Pomeroy was discussing these things in 1958 as technical editor of The Motor, he amused us by remarking that the debt Sunbeam owed to Peugeot (Coatalen having blatantly copied the 1913 twin-cam Peugeot racing engine for his 1914 Isle of Man TT-winning Sunbeam) was repaid by 1948 when Peugeot used angled-push-rod/base-camshaft valvegear, which was said to have been a feature of a 1928 Sunbeam bus engine, for its new 203.
When I wrote of this and other valve-gear (Motor Sport, March 1959), I published what Pomeroy had been unable to find, which was diagram (courtesy of Bus and Coach) of a Sunbeam commercial vehicle engine with the kind of valve-gear he suggested the Peugeot engineers had copied. And I discovered that what he was describing was, in fact, a 1928 Sunbeam bus job which had the Riley/ERA two-camshaft short-push-rod valve operation and, moreover, “underhead” camshafts as on a 2-litre Lagonda. However, a year or two later there had been an angled-push-rod hemi-head Sunbeam bus engine, and Tony Lago used a similar layout six years after that for his Talbot-Lago.
That was the currency with which Pomeroy felt Wolverhampton had repaid its long-standing debt to Sochaux. But the conundrum is whether Coatalen pioneered such an engine, which Roesch then saw while working for him, or whether Louis the plagiarist cribbed the idea from Georges Roesch? Whether Peugeot knew anything of this when planning the 203 and 403 models which were such excellent cars in their day can only be a matter for conjecture. Incidentally, in 1924 Rover used yet another means of prodding inclined overhead valves with push-rods and rockers from a single base camshaft, as did BMW for its great 328 of 1936. But I hesitate to suggest that Rudolf Schleicher “borrowed” from Peter Poppe! WB