Owen Finch's racing Amilcar Sixes
Some “Stable Information” relating to his ex-Humphreys and ex-Clayton cars, compiled from notes contributed by H. L. Biggs, with his friend Finch’s co-operation, and supplemented by some additional data on these famous little cars.
Since the war Owen Finch, of Weybridge, has run his Amilcar Sixes in sprints and races with such success that one quite overlooks the fact that the basic design of these cars dates back to 1926 or earlier.
The Amilcar Six is becoming legendary to the more youthful enthusiasts, so it is worth while recalling that it was introduced in 1926, when a team of these cars came over to this country from France and dominated the 1,100-c.c. class of the J.C.C. 200-Mile Race. Martin won the class at 66.65 m.p.h., followed home by his team-mates Duray and Morel. In 1927 these cars were even more in the picture, for Morel’s finished second in the race as a whole, averaging 75.17 m.p.h., or only 1.45 m.p.h. less than the race-winning average of Campbell’s Bugatti. Vernon Balls was third on general classification and Martin third in the 1,100-c.c. class, in which Morel and Balls had, of course, finished first and second, the average speeds of Balls and Martin being 73.78 and 71.15 m.p.h., respectively.
The design of these little cars was that of the G.P. racing car of the period, and, naturally, immense interest was aroused when a chassis was exhibited at Olympia and the type offered for sale to the public in the ordinary way, with a 2-seater racing body and A1 sports-car equipment. The engine was seen to be a six-cylinder of 56 by 74-mm. bore and stroke (1,093 c.c.), with a seven-bearing crankshaft, the end bearings being ball-type, the remainder plain, and two o.h. camshafts, each running in four bearings, the outer ones again being ball-bearings. The camshafts operated inclined o.h. valves, two in each combustion chamber of the detachable head, with triple springs. Oil was conveyed to the valve gear via the hollow camshafts. The big-ends were plain bearings, and dry-sump lubrication was employed. The engine was supercharged at 12 lb./sq. in. by an Amilcar-Roots blower lubricated from a separate oil-tank and filter. Ignition was by magneto, the crankcase incorporated three large breathers, and cooling was by pump. A rev-counter was driven from each camshaft.
The drive went through a plate-clutch with 36 springs, to a four-speed and reverse gearbox giving ratios of 11.75, 8.2, 6.2 and 4.5 to 1, with a 16.1 to 1 reverse. The chassis was sprung on 1/2–elliptic front and 1/4-elliptic rear springs, with shock-absorbers front and back, and there was a housing for the Hardy-Spicer universal joint of the propeller-shaft. The ribbed brakes on all four wheels were pedal-operated, via Perrot-mechanism and cables at the front, and an outside handlever applied the rear shoes only. Well-base rims carried 27 in. by 4.40 in. Dunlop tyres, and a six-branch outside exhaust system with Brooklands silencer was standard. The Amilcar Six was sold with hood, screen, wings, dynamo lighting, self-starter, spare wheel, clock, speedometer, twin rev-counters, air-petrol feed by hand-pump, and a set of tools—one of the most desirable sports-racing cars it is possible to imagine. The wheelbase was 6 ft. 2 in., track 3 ft. 8-1/4 in., overall length 11 ft. 2 in., and overall width 4 ft. 2-1/2 in. The makers claimed speeds of approximately 40, 60, 80 and 105 m.p.h. in the gears, with a fuel consumption of 24 m.p.g. and an oil consumption of 800 m.p.g.
It might be thought that this very attractive “1,100” would rival the G.P. Bugatti in popularity, but in reality only a very small number was imported to this country, possibly because the price was on the high side, being £725 for the chassis when first introduced, falling to £695 for the complete car from 1928-29.
Nevertheless, those cars that did get to England were extensively raced, not only in short events but in our long-distance classics and also in such sports-car events as the T.T., “Double-Twelve” and Six Hour races. At Brooklands Amilcar Sixes were handled by Balls, Harcourt-Wood, W. B. Scott, Miss Machonochie, Major A. T. G. Gardner, Brian Twist, H. T. H. Clayton, Byrom, Payne, Humphreys, Faulkner, Courtney, Oats and F. Monkhouse. After this passage of time we do not intend to trace the histories of these cars, especially as Mr. Biggs does not do so in his notes, but someone may like to get out a “family-tree” and establish the identity of those cars still in existence. For the present, it suffices to say that most of them ran in more or less standard form, stripped of equipment, and that in 1928 Miss Machonochie’s car lapped during a race at 104.41 m.p.h., the only other Amilcar Six that had exceeded the century at that time being Vernon Balls’, at 103.76 m.p.h.
There is no doubt but that the most successful of these cars were those raced by Henken Widengren, the late “Bill” Humphreys and H. T. H. Clayton, and this lends point to this article, for Mr. Biggs’ notes deal with the two latter cars, raced at the present time by his friend Owen Finch, of Weybridge.
Widengren’s car was endowed with a well-streamlined single-seater body, and in Motor Sport for April, 1940, Biggs told how he accompanied this car to Montlhéry in 1933, when it took the Class G hour record at 115.54 m.p.h. Widengren also lapped Brooklands at 110.92 m.p.h. during a 1933 short-handicap race. This car was prepared for racing by Alec Francis, and at the same time he prepared W. E. Humphreys’ black, normally-bodied car.
The modifications included special camshafts, and six separate, small-bore, water off-take pipes rising from the head above each bore to cure local overheating round the valves. Humphreys chromium-plated the chassis of his car while it was stripped down and had a special Amherst-Villiers supercharger built up, which was interchangeable with the standard Roots layout, but which blew at 16 lb./sq. in., an increase of 4 lb./sq. in. Widengren’s car sheared its camshaft timing-wheel key on one occasion, so Francis made up a vernier coupling for these wheels and this modification was also applied to Humphreys’ car. On this car, too, Francis re-balanced the crankshaft, removing 7 oz. from each crank web during this operation.
Humphreys’ Amilcar made its Brooklands debut in 1931, lapping on two occasions in a short handicap at 105.97 m.p.h. In the 500-Mile Race of that year it was leading the 1,100-c.c. class with three laps to go when the front axle broke. It had been going round consistently at nearly 100 m.p.h. before this occurred.
Whereas Widengren retained his car and ran it at Brooklands at odd times, Humphreys disposed of his Amilcar to R. F. Oats. With an eye on short-handicap races, Oats removed the blower, substituting two carburetters, after replacing the camshafts with new ones specially devised by Francis for the unblown engine. In this form the car was extremely successful, lapping at 96.33 m.p.h. during the 1934 season.
The car next changed hands to H. T. H. Clayton, who, with F. C. Monkhouse, was to race two of these Amilcars, the other being the red car which Major A. T. G. Gardner had first run at Brooklands in 1929, and with which he lapped at 96.71 m.p.h. on three separate occasions during 1930. With it Clayton improved to 99.61 m.p.h. in 1931, and 107.57 m.p.h. during 1932, the car, now entered as a Clayton-Amilcar, improving to 116.09 m.p.h. in 1934. In 1935 Monkhouse did a lap at 101.02 m.p.h. in the ex-Humphreys car, still unblown.
Clayton and Monkhouse continued to run their two Amilcars, and when the Campbell and Crystal Palace circuits were opened Clayton modified his cars to meet the special requirements of such racing. He put the engine from the ex-Humphreys car, now with the Villiers blower refitted, into the ex-Gardner car, and completed the swop by using the ex-Gardner engine in the ex-Humphreys car,
At the same time both cars were given Lockheed brakes, and here it should be mentioned that after Humphreys’ front axle had broken in the 1931 500-Mile Race, Francis designed an I-section axle for Widengren’s car, which was made up by Vickers. During this time he was developing Jack Bartlett’s Salmson at Automobile Supertuners, and for this car a similar axle, with new stubs, was made. The Salmson’s axle was acquired by Clayton and used on the ex-Gardner car when the new brakes were fitted, but the normal U-section axle with rounded ends was retained on the ex-Humphreys car. It seems that a rebored engine, of 56.1-mm. bore (1,097 c.c.), was used at times in both Clayton’s cars. The Clayton-Amilcar, Villiers-blown, went from strength to strength, Clayton lapping at 121.47 m.p.h. in it during 1937, his best standing lap being at 105.29 m.p.h.
During the war both Clayton’s Amilcars were acquired by Owen Finch and Harold Biggs continues the story from this point.
Finch bought the ex-Humphreys car in February, 1946, and the Clayton-Amilcar in March, 1947; he also bought a spare engine and was able to rebuild both cars to his own specifications. The ex-Humphreys car remained substaintially unaltered, the secret of its performance being pluperfect fitting. That may be the reason for these two Amilcars being the only examples running successfully in this country; they definitely do not respond to ham-fisted assembly. Finch fitted an aluminium screen before the dumb-iron oil tank owing to the great difficulty experienced in getting the oil to attain, and maintain, a decent working temperature. He ran this car at Gransden, where it finished third in the 1,100-c.c. racing-car class, at Prescott, at Brighton and at Great Auclum in 1946, and at one 1947 Prescott meeting. The car weighed 15 cwt. with oil and water.
The Clayton-Amilcar is of great interest. Its carburetter is a Solex with barrel throttle, now rarely seen, but having the advantage of an unobstructed choke at full bore; it is of 40-mm. size, with a 35-mm. choke. Whereas the ex-Humphreys car retains the 20-gallon tail tank, the Clayton car has a smaller 17-gallon rear tank, and Finch has fitted another 7-gallon tank beside the driver; he also grouped the instruments on a smaller dashboard in front of the driver, and made a beautifully-neat windscreen of perspex in an aluminium frame spring-mounted to the scuttle. Everywhere one looks on this car one observes the same meticulous care in preparation; the detail work is a joy to behold. The weight of the Clayton car is now down to 14 cwt. It uses the aluminium bonnet from the other car, but the remainder of the bodywork is steel and the chassis is very weighty; it may be that a lighter chassis will be produced for it in due course; the engine certainly deserves it.
One thing that surprised Clayton, when he called on Finch to see his old car, was that it had been standing with the radiator full. In 1933 we found it so difficult to retain gasket sealing that these engines were always drained of water whenever they were to be left standing any length of time; this points to the excellent fitting referred to before.
Clayton was also astonished to see the car start on the first pull-up, tick over, and go up to peak revs., clean, and on the same Lodge plugs.
Now for a few points of general interest regarding these two Amilcars.
The special camshafts for the blown engine give timing as follows:
I.O.: 12 degrees before t.d.c.
I.C.: 47 degrees after b.d.c.
E.O.: 43 degrees before b.d.c.
E.C.: 15 degrees after t.d.c.
Ignition: Fully advanced 60 degrees before t.d.c.
Tappet clearances: .018 in. exhaust; .014 in. inlet.
Finch uses two axle ratios, 4.5 to 1 and 5.1 to 1, and the Clayton engine with Villiers blower would appear to peak at 7,500 r.p.m. The wheels have been rebuilt, with 16-in, rims at the rear and 18-in, at the front, and these are used with 6.00 and 4.75 tyres, respectively.
As I have said, only Clayton’s car was fitted with a special front axle, the ex-Humphreys car retaining the standard Amilcar axle. No further trouble has been experienced with the apparently weak beam, but both cars have been fitted with brake-reaction cables to save the beams from torsional stresses.
Last season Finch took the Clayton car to Ulster for the handicap event, with the engine from the ex-Humphreys car as a spare. The Clayton engine had a compression ratio of 8 to 1 and the Villiers blower, giving 16 lb./sq. in., proved too much for the cylinder block, the whole top, complete with studs, erupting. Before this happened the car was going extremely well, although a rapidly increasing oil-leak caused Finch some anxiety.
On arriving in the Isle of Man the ex-Humphreys engine was fitted to the Clayton car. This engine has the standard Amilcar-Roots blower, blowing at 12 lbs., and a compression ratio of 6.64 to 1. On the first day’s practice the blower casing cracked and the Villiers blower was substituted. Although the car, in this condition, was running well, it showed signs of a rich mixture and an oil-leak also developed, so Finch withdrew the car in order to save the engine for further development work. I nearly forgot to mention that both of these cars are using stouter than standard connecting-rods, the standard Amilcar issue being unsafe over 5,500 r.p.m.
After returning to England correct jets were made and the car ran, completely trouble-free, at two Prescotts, Brighton and Merston. At Brighton, out of 15 starters in the 1,100-c.c. racing class, Finch was third, at 72.8 m.p.h. for the standing kilometre, and he was sixth in the 1-1/2-litre category. At the V.S.C.C. meeting at Prescott he was first in the 1,100-c.c. racing class in 54.95 sec., a time which he had bettered in practice, with 53.25 sec. Down at Merston he was second in the 1,100-c.c. racing class and fourth in the 1,500-c.c. racing class. I consider that the Amilcar’s showing in the 1,500-c.c. racing classes is very praiseworthy, as it is in this class that there is most competition.
Finch thinks, and I agree with him, that, for a production of the mid nineteen-twenties, using suspension which is now deemed primitive and a chassis assembly that weighs the world, he has coaxed the Amilcar Six into giving a performance which is, to say the least for it, very satisfactory. — H. L. B. / W. B.