A Successful Amateur Venture

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A. N. L. Maclachlan developed a fairly ordinary sports Austin Seven into one of the most successful sprint Austin Sevens ever. His car eventually clocked 20.23 sec. at Lewes and climbed Shelsley Walsh in 44.4 sec., while it would reach 72 m.p.h. in second gear and accelerate from rest to 100 m.p.h. in approximately 25 sec. Such performance from an amateur-built 750-c.c. car is little short of amazing, and we are deeply indebted to Maclachlan for this interesting account of “how it was done.” — Ed.

The history of my sprint Austin Seven began in 1926, when R. M. Papelian took a Gordon-England “Brooklands” Austin Seven to America and ran it successfully in a number of races against much larger cars. So tickled were the Americans that they described it as a ” Pint Size Auto with Speed to Burn,” and the following note appeared under a photograph of it in an American periodical:

“This amazing little auto makes 80 miles to the hour and 40 to a gallon of gas.”

Anyway, after suitably impressing America, the car was shipped home, and I heard of it through an advertisement in the Motor Press. This was some time before the Inter-Varsity Speed Trial, and, as Oxford were badly in need of fast cars, I sold my old “Chummy,” which had been considerably ” hotted-Up,” and purchased it.

This was my first real racing car and I was naturally thrilled by what to me was the amazing performance it put up. With the wings off and the aero screens down, it would do a genuine 80 m.p.h. and would run up to 5,700 r.p.m. in second — about 55 m.p.h.

After using it for a short time, we began to get ready for the Speed Trial, and decoked the engine very carefully, polishing the head and ports. All unnecessary weight was taken off the car and, after testing to get the best ignition and carburetter settings, all was set. Our efforts were successful, as in the trial the “Tiddler” made fastest time in the 1,100-c.c. class, with a time of 51.8 sec. up Ewelme Down, against a fastest-timeof-the-day of about 45 sec.

In my youthful enthusiasm I had never heard of such things as rev. limits, and it was not long before I broke the crankshaft. Fortunately, it broke in the middle of No. 2 big-end journal, and the only damage was that the white metal in the big-end was torn up. A visit to Laystalls produced a new crankshaft and strict instructions not to exceed 5,000 r.p.m. I had learnt my first lesson and I have never broken another shaft on the Austin. Apart from one or two trials, I did no other competition work, as, leaving Oxford, I became a pupil at Thornycroft’s Basingstoke works and could not get time off. However, in 1928 a friend and I ran through the London-Land’s End Trial and got a Gold Medal — I remember simply romping up Beggar’s Roost at maximum revs. in bottom gear.

By now the car had done about 23,000 miles and the bores were getting worn, so the engine was dismantled and completely overhauled, with new main and big-end bearings, hardened liners to the bores and standard-size Specialloid pistons. During this period the Austin was my only means of transport and was driven very hard on all occasions. About this time I had several experimental cylinder heads made, and also tried out a number of proprietary aluminium heads, eventually fitting a Ricardo-design head with a compression ratio of 6.5 to 1. This gave considerably more power, and on a test lap at Brooklands without screens or wings the car achieved a lap of 79 m.p.h. So well streamlined was the body that putting on the very small aero screens and wings took 8 to 10 m.p.h. off the maximum speed.

By the autumn of 1928 the body had got very spent and the chassis was also a bit dicky, so the body was completely removed and the front axle, brakes and steering were overhauled, the body being scrapped. I had by then become the proud possessor of a “Hyper Sports” Supercharged Lea-Francis 4-seater, and was WM toying with the idea of making the Austin into a genuine sprint car. After much cogitation a rough design was got out and, with the aid of one of the body shop carpenters, a new body frame was built and covered in Rexine fabric. This made a very light construction. At the same time the seating was lowered, a new petrol tank fitted where the passenger seat used to be, and the radiator lowered and sloped back, the original bonnet being cut down to suit. As a result of this the performance on hills, and acceleration, became really brisk and on getaway I could hold all but the fastest motor-cycles. The general appearance is shown in photograph No. 1.

During the winter of 1928 the car went up to Austin’s for a series of bench tests with various cylinder heads, and the table below gives a summary of the results :—

The Ricardo head gave a flatter power curve with higher peak revolutions. At that period the standard touring Austin Seven gave approximately 13 b.h.p. at 2,800 r.p.m., and for the time the performance was good, as ordinary No. 1 petrol was used for the tests, with a Solex carburetter having 23-mm. choke and 110 main jet.

The first sprint event I entered for was the Lewes Speed Trial in March, 1929, and the performance was good enough to get a first in the 1,100-c.c. class with a time of 26.4 sec. The next event was a dirt-track race near Portsmouth, organised by the Portsmouth and Southsea Club – the field consisted of two Salmsons, an Amilcar, a Morgan and the Austin. After a rather slow getaway, due to wheel spin, a tremendous “dice” ensued, and on the last lap I managed to snatch the lead in a cloud of dust and cinders, to win by a length amid loud cheers. Although very exciting I felt that this particular form of entertainment was very hard on the car and have never tried it again.

Later in the year I ran in the October Brooklands Meeting and got a third in a Mountain race at 58.2 m.p.h..

In December, 1929, I sailed for South Africa on business, so the Austin was put away, and it was not until I came home in June, 1931, that I saw her again. By this time the blown “Ulster” Austin had appeared, and one of these was owned by J. C. Elwes, a friend of mine, at Basingstoke. Elwes had already done well at Brooklands, and together we were to race with our Austins; and later with his J.4 M.G. and Aston-Martins in a good many events. It was Elwes who fired my enthusiasm to make the “Tiddler” really fast, and we decided to convert the engine to the “Ulster” type. Accordingly, an “Ulster” crankcase, crank, timing case, blower drive and No. 4 Cozette supercharger with Solex carburetter were obtained and the engine rebuilt, using an Alta aluminium head with a compression ratio of 6 to 1. The bodywork was improved, heavier brake cables fitted, and the car had its first try out at Lewes in the spring of 1982, where it won the 1,100-c.c. class with a time of 24.8 sec. Then came Shelsley Walsh and a tie for first place with E. R. Hall’s M.G., the time being. 49.2 see. I should also mention that when “Ulsterising” the engine, cast-iron clutch plates, stronger clutch springs and close-ratio, constant-mesh gearbox pinions were fitted. These raised first and second gears, so that, with the 4.9 axle ratio, second was 7.07 to 1 and first 12.5 to 1.

The next event was the September Brooklands Meting, and I gained first place in the Senior Mountain Handicap at 62.86,m.p.h. The Autocar report said: “Maclachlan’s Austin travelled with such vim that it speedily took command of the situation, though its victory was as near as no matter snatched away by Shuttleworth’s Bugatti.” This last-named car shot past me just after I crossed the line, and I had seen it out of the corner of my eye coming up the finishing straight very fast, and was in a fever of apprehension whether I would cross the line in time to win the race.

During the 1933-34 seasons the car ran virtually unchanged, apart from a few detailed improvements, but increasing knowledge of the various courses enabled me to put up improved performances at most events.

The 1933 Whit Monday Meeting at Brooklands produced a second round the Mountain at 63.8 m.p.h., and the June Shelsley Meeting a first in the 850-c.c. racing class in 49.4 sec. in pouring rain, whilst the Brighton Speed Trial also gave us a win in the 850-c.c. class, with J. C. Elwes driving.

The best performances in 1934 were 23.8 sec. at Lewes and second in the 850-c.c. class at Brighton at 61.6 m.p.h.

By now I was really beginning to know my way up Shelsley and round the “Mountain,” and in May, 1935, got up the former in 45.6 sec., being third in the 850-c.c. class, whilst at the Whit Monday Brooklands Meeting I got a second in a Mountain race at 65.4 m.p.h., with a fastest lap of 67.5 m.p.h.; these were both great advances on previous best efforts. However, I felt that the limit had been reached with the existing boost of 9 lb./sq. in., so it was decided to make the car really potent. My ambition was to get up Shelsley in under 45 sec. and Lewes in about 20 sec., and possibly get round the “Mountain” at about 70 m.p.h. So during the summer the car was completely stripped and a design for the new layout drawn up. In order to reduce the major alterations to the minimum possible the general idea was to make a genuine single-seater with a light streamlined body, with the driver seated over the rear of the propeller shaft and well back — this would throw the weight well back when accelerating and reduce wheel spin.

A Centric supercharger displacing 800 c.c. per revolution was driven off the front of the existing blower-drive, which was fitted back to front in the timing case. This gave about 17 lb./sq. in. boost and necessitated mounting the radiator rather far forward on an extension of the frame. A new induction system was built up out of steel tube, the clutch pedal moved to the near side, and a new, remote gear change fitted. The rear springs were mounted over instead of under the frame, lowering the rear of the car about 2 1/2 in., and a brand new “Ulster” dropped front axle assembly and spring was installed. The castor angle was increased and the steering box mounted over the gearbox, with a long fore and aft rod. The larger “Ulster”-size brake drums and shoes were also fitted and an entirely new, direct-acting cable brake system, with heavier cables, made up; new rear wheels with 17 in. by 4.25 in. tyres completed the chassis alterations.

By this time Shelsley was looming up and I decided to run the car as a chassis to get some idea of what was going to happen. A few preliminary runs to get ignition and carburetter settings about right showed that there was tremendous urge, and we set off full of hope.

The first practice run was very fast, but on the second, near to the top, water started shooting out of the side of the engine and loud noises came from inside. The head was taken off and disclosed that the gasket had gone, and also that one of the cylinder liners had collapsed and damaged a piston. As I had been entered in the Austin Works Team something had to be done, so we rushed the car to Longbridge and worked all night, fitting a new block, head and pistons; these were of the standard “Ulster” pattern. We got through by about 9 a.m. and went straight back to Shelsley very tired and dirty. On the hill all went well and, in spite of feeling somewhat insecure, perched on the open chassis, I managed to put up a time of 45.4 sec. (Photograph No. 2.)

It was obvious by now that we were on to a good thing, but that the “Ulster” block and head were not going to be good enough for the high boost — so Austin’s were approached and produced a new block, head and crankcase with extra holding-down studs; the head had 25 3/8-in. studs and was of aluminium, whilst the block had ten 3/8-in, studs holding it on to the crankcase. The gasket is made of copper-foil, .008 in. thick. When rebuilding the engine the opportunity was taken to put in a new “Ulster” crank and rods, also Austin’s produced some very beautiful slipper pistons with two 1/16-in. rings.

The next job was the bodywork, and here Harrington’s, of Hove, co-operated most successfully, making a lovely little single-seater in aluminium on a framing of 1/2-in. steel angle, a new tank holding about 4 1/2 gallons being fitted in the tail. The general appearance is shown in the photograph taken at Poole Speed Trials in 1936 (No. 3). The rather long nose was shortened in a later modification with great improvement.

This work took place during the winter, and by the spring of 1936 all was ready for a try out. Several long runs with soft plugs, mudguards and petrol-benzol mixture served to run-in the engine, and a further series of full-power runs on a quiet stretch of road enabled the best ignition and carburetter settings to be arrived at. Unfortunately, some trouble with the fuel feed occurred at the May Lewes Speed Trials, and the best time I could achieve was 22.4 sec., the engine cutting out several times up the course. However, the performance showed that when properly going we should be able to get down to nearly the hoped-for 20 sec.

At the next Lewes Meeting all went well and the Austin made fastest time in the 1,100-c.c. class and was third in the 1,500-c.c. class, with times of 20.38 and 20.23 sec.; the latter time I have never succeeded in improving on. After this came the Shelsley Walsh hill climb with a time of 44.4 sec. on a showery day, when the road was far from dry. This was probably the best show the “Tiddler” has put up, as it was the fourth fastest time of the day, Raymond Mays’s E.R.A. making the fastest time in 41.4 sec. Walter Baurner and Charlie Goodacre made phenomenal climbs in 42.6 and 43.2 sec. in the Works Austins, but I had the satisfaction of beating Charlie Dodson on the other o.h.v. Austin and the redoubtable Hans Stuck on the Auto-Union.

The next event was Poole Speed Trial in August, 1986; this was one of the most enjoyable in which I have ever had the pleasure of competing. Not only was the course most interesting but the organisation was excellent and the day and surroundings lovely. There was quite a lot of “dicing,” as the “S” bend near the finish was really most exciting, and Sydney Cummings on the Vauxhall-Villiers finished up in the bushes after a terrific skid. This was a most successful day for me, with wins in the 750-c.c. and 1,100-c.c. classes and a third in the 1,500-c.c. class. The best time was 23.42 sec., which compared favourably with the fastest-time-of-the-day of 22.82 sec, put up by George Hartwell on the ex-E. R. Hall M.G. Magnette with Zoller supercharger.

At the last Lewes Meeting, after a tremendous tussle with Hadley on the works’ s.v. Austin, we eventually emerged victorious by the narrow margin of 0.03 of a see., with a time of 20.53 sec. On this occasion Waddy’s very clever four-wheel-drive, two-engined “Fuzzi” won the class with a time of 20 sec. dead.

During the following winter the radiator, which was rather too far forward, was cut down in size and set back over the front axle, and a new cowling made for the front of the car, greatly improving its looks. The object was to reduce the weight on the front wheels and improve the handling. At the same time new rear wheels with 16-in. by 5.25-in. low-pressure tyres were fitted, the previous rear wheels being put on the front. These large tyres enabled me to use a very low pressure, 15 lb. front and 10 lb. rear, which improved the cornering and grip, and also made the car a good deal more comfortable; it is very difficult to make the tail slide and there is remarkably little wheel spin when getting off the mark — the car appears to shoot forward the moment the clutch takes up.

During 1937, 1938 and 1939 the only events in which the car ran were the Lewes and Brighton Speed Trials, as I found it impossible to get away to more distant meetings. At nearly all these meetings Dennis Evans, on his very rapid “Montlhèry” M.G., and the Austin had a tremendous series of ding-dong battles, first one and then the other winning. The outstanding duel and performance took place at Brighton in September, 1937. The Austin started off with 25.91 see, in the 850-c.c. class, Hadley taking 26.47 sec. on the works o.h.v. car and Evans 26.59 sec. In the 1,100-c.c. class Hadley broke the record with 25.7 sec., Evans did 25.8 sec. and I took 25.94 sec. In the 1,500-c.c. class I got a really good start and broke the record with 25.56 sec., which is 70.42 m.p.h. for the standing-start half-mile, with Evans doing 26 sec. and Hadley 26.02 sec. On the last run the Austin crossed the finishing line at 6,400 r.p.rn. in top gear, which was just over 100 m.p.h.

The last event in which I ran was the Lewes Speed Trial in May, 1939; this gave me another win at 21 sec. dead in the 1,100-c.c. class and a second in the 1,500-c.c. class, with a time of 20.5 sec.

I am afraid this has been rather a catalogue of speeds and times, and so to conclude I propose to add a few details about the car. The chassis is the original “Brooklands” model, with the addition of the “Ulster” front axle assembly, larger brakes and improved brake cable system. The gearbox is also original, as is the entire rear axle, with the exception of the crown wheel and pinion; these latter are standard “Chummy” ones, using the 4.9 to 1 ratio. I have also used the 5.25 to 1 “Van” ratio and the 4.45 to 1 “Brooklands” ratio, but find the 4.9 best, as I get quicker acceleration than with the 4.44 and can also run up to 40 m.p.h. on first and 72 m.p.h. on second at 6,500 r.p.m., which I never exceed — this, of course, is with the close-ratio constant-mesh pinions in the gearbox.

The engine has been pretty well described earlier in this article and is somewhat of a mongrel, but it retains the original “Brooklands” high-lift camshaft, the compression ratio is 5.8 to 1 and the maximum boost about 17 lb./sq. in. The all-up weight of the car with the driver on board is about 900 lb., and I have calculated that the maximum b.h.p. is in the neighbourhood of 60, though the engine has not been bench-tested in its present form. Calculations show that on the level it should reach 80 m.p.h. in about 15 to 16 sec. and 100 m.p.h. in about 25 sec., and cover a standing half-mile in about 26 sec. This was strikingly confirmed at Brighton, when the best time for the standing half-mile was 25.56 sec. and the maximum speed at the finish just over 100 m.p.h.

With the Centric supercharger, the carburetter used is a 40-mm. Solex, and ignition is by the original Blic magneto, which has never missed a beat all its life. Since 1935 I have always run the car on Anglo M.G. 2 fuel, which is not tricky and keeps well. The engine is very easy on plugs. For warming-up and road-testing, K.L.G. L.B.1s are ideal and never oil up, but, of course, will not stand up to full throttle – -in actual events Champion N.A. 14 long-reach plugs are the most successful, but their life is short, as the porcelains crack after a few runs. Probably a harder plug would be better — on the other hand, I am certain of the N.A. 14s not misbehaving or wetting-up on the line. It is a great relief to be absolutely sure the engine will start up and remain on four cylinders, as in sprint events there is often no second chance if you miss your start. This applies particularly to Shelsley, where if you fail to start properly you are not allowed another run.

The Austin is at present all vaselined-up and carefully stored, but I hope the day is not far distant when she will be out again and, after suitable preparation, should be as good as ever. Her present appearance is well shown in the very fine photograph taken by Klemantaski at the Poole Speed Trial in 1937 (No. 4).

Cylinder Head Comp. – Peak Ratio – R.P.M. – B.H.P. – Max. B.M.E.P.
Austin “Brooklands” Head (C.I.) – 5.45 to 1 – 4,400 – 23 – 100 lb. sq. in
Ricardo Head (Al.) – 5.5 to 1 – 4,500 – 23 – 94lb. sq. in
Ricardo Head (Al.) – 6.8 to 1 – 4,700 – 28 – 108 lb. sq. in