Following up our remarks last month on the Alexander Engineering engine tuning modifications we were able to drive an appreciable distance in an Austin A40 with Stage One Alexander tuning. This comprises a reshaped head with modified ports and polished combustion spaces, giving a compression-ratio of 8.9 to 1, special valve springs and twin 11/8-in. S.U. semi-downdraught carburetters on ribbed inlet manifolds. A full-flow centre exhaust manifold port adaptor is bolted on to replace the existing siamesed port which is machined off, and an air cleaner is fitted to each carburetter. This conversion costs £37 10s., plus £2 10s. if the exhaust manifold is modified.
The A40 was not only transformed in respect of greatly improved acceleration, as the table shows, and was very fast, the speedometer needle going “off the clock” at over 80 m.p.h. on any reasonably straight road, but it was extremely docile, pulling away smoothly from 20 or even from 15 m.p.h. in top gear. Oil pressure at just under 40 lb./sq. in. and water temperature at just below 80 deg. C. were unaffected and no apparent disadvantages of any sort could be associated with this reasonably-priced conversion. Petrol consumption worked out at 37 m.p.g. on a cross-section of fast and moderate driving, but 100-octane fuel was used, although only a trace of pinking was discernible on normal premium grades. Fitting charges cost £10 10s. including decoke, valve grinding, tuning and road-testing, or £11 10s. if the centre port exhaust manifold conversion is carried out.
As to the Austin A40, which had apparently run 13,500 miles, it proved a very willing go-anywhere vehicle but the stiff steering with much free-movement, worn clutch, body rattles and squeaks, noisy engine, uncomfortable seats, poor road-holding (made possible only by reason of an Alexander anti-roll bar), stiff gear change and crude dash lamp, together with non-self cancelling wipers and time-switch-controlled indicators with awkwardly-placed switch, are unfortunate in a car costing £650 in normal form; perhaps, however, the writer has been spoiled by five years and 78,000 miles of quality small-car ownership! Reverting to the Alexander conversion, the throttle linkage is well carried out, if non-progressive, a genuine 35 m.p.h. in second and over 60 m.p.h. in third gear are attainable, and the brakes, if apt to pull to one side, were entirely adequate for the greatly enhanced performance. The speedometer was found to be 9-9½ per cent. fast and a swinging needle did not help when taking acceleration figures, while clutch slip tended to intrude.
Acceleration / Normal Austin A40 / Alexander Stage 1 Austin A40
0-50 m.p.h. / 21.4 sec. / 15.0 (15.8 sec.)
0-60 m.p.h. / 35.6 sec. / 21.6 sec. (22.6 sec.)
Standing ¼ mile / 24.5 sec. / 21.8 sec. (22.4 sec.)
Figures in parentheses are the mean of runs in both directions.
Engines — From 0.46 c.c. to 15 c.c.
As a change from thinking about motor cars, which is apt to become even more of an obsession than usual at Motor Show time, we present some observations on model i.c. engines. When we were quite young a model petrol engine was a pretty cumbersome piece of machinery, 15 c.c. being considered small and some of these models being not far short of the capacity of the power units which propel present-day autocycles. Moreover, they were expensive and expense didn’t end with buying the engine — carburetter, ignition apparatus and so on were extras.
All that altered ages ago and now you can buy a self-contained model compression-ignition engine which develops maximum b.h.p. at 15,000 r.p.m. and producing quite a lot of power, for as little as 38s. As these little engines work on the diesel principle they really are self-contained and although requiring special fuels they will run for an hour or so on the contents of a 3s. bottle. Normally, of course, these engines would be run for only about a couple of minutes at a time, such as in a model aeroplane, which is ten flights for a shilling. However, they will run for far longer periods, as we were reminded when we called on Electronic Developments (Surrey) Ltd. of W. Molesey — an E.D. engine crossed the English Channel many years ago in a radio-controlled model boat and more recently E.D. have flown a model aeroplane, carrying a gallon of fuel, across the same stretch of water in 44 min., radio-controlled from an accompanying Auster!
This should be sufficient to indicate that these tiny engines are models, not toys. E.D. make a range of eight loop-scavenged engines, from 0.46 c.c. to 7 c.c., which cost from £2 to £8 8s. Most popular is their 1 c.c. “Bee,” an “oversquare” single-cylinder easily lost in the palm of a small hand, weighing 2 ¾ oz., and running at up to 12,000 r.p.m. Over 300,000 have been sold. A new 0.8 c.c. engine is now in hand, to sell for 38s.
Generally speaking all these engines work on the two-stroke cycle and are either air or water-cooled single-cylinders, although E.D. also make the twin-cylinder Taplin for marine work. Cylinders are of case-hardened steel, pistons mostly of fine-grain cast-iron with no piston rings, crankcases of magnesium-alloy or L.M. 2 aluminium alloy to save weight. Con.-rods are forged in R.R. 56 and simple taper-needle spray carburetters are normally used. Overhung crankshafts, reverse-flow scavenging and rotary disc valves in the crankcase figure in the specification.
From the foregoing it will be seen that these “mighty atoms” are real engineering jobs and a walk round the E.D. factory confirmed this in no uncertain fashion. For example, cylinders are machined from the solid, the fins being cut in one “bite” and first ground to an accuracy of 1/5 of a thou. with no minus tolerances, after which they are wet honed to an accuracy of 1/10 of a thou., each one being checked on a Mercer air gauge. This extreme accuracy, again with no plus or minus tolerance, is necessary to ensure good compression hot or cold. Ovality is revealed by this extremely sensitive air gauge and providing this does not exceed (fraction unreadable in scan of original)-thou. it can be corrected by re-honing slightly oversize. (Pistons are honed and individually matched to the cylinders, being hand lapped for ten minutes.) Such methods ensure satisfactory starting and long life and the degree of accuracy demanded is certainly revealing.
In the same way, crankshafts are machined from the solid in EN 202 steel and case-hardened and to ensure that proprietary ball-races are a fit in the tiny crankcases, the journals are machined to a tolerance of 1/8-thou.
E.D. have their own foundry for gravity die-casting, a spacious tool shop where the various machinery operations are carried out on Modern, Herbert 2a, Herbert No. 4, Victoria and other lathes, milling and drilling machines, and a test-room with two test benches in which every engine is run-up on test and rejected if any faults are revealed. Finished engines are dispatched with a test card covering individual carburetter settings, etc.
It is evident that a great deal of research has gone into the “knowhow” which makes these minute engines so efficient — and efficient they are, sports engines giving 80 b.h.p. per litre when fully run in, contest engines being expected to give the equivalent of at least 100 b.h.p. per litre. Some model engines, running on 50 per cent. nitro-methane fuel, have closely approached 200 b.h.p. per litre. That should be enough to make many motor-racing enthusiasts rush out and spend forty bob seeing for themselves how crisply and at what high r.p.m. these E.D. model c.i. engines function . . .