Some details of the methods employed to obtain extra speed for racing

By Felix Sciven

From the outset I wish to make plain that the car of which I am writing, although exceptionally fast, is made up of standard touring model parts.
In order to allow any engine to deliver the utmost power, however, in general refining process of small details has to be undertaken., and this, in the main, is what I have done. For example, in the beginning the standard connecting rods and pistons were most carefully balanced by means of filing and scraping, each unit was brought to exactly the same weight as its fellows. A copper induction pipe of rather bigger bore and easier sweep was made to replace the standard induction pipe of aluminium, and a larger size Claudell-Hobson carburetter was fitted. The opening and closing of the valves remains just the same as in the standard touring car, but there is sufficient “ nose” on the cam to give a slightly higher lift of the valve itself, while, to make the tappets follow the contour of the cam more closely, stronger valve springs are used.
Initial Tests and Speed
At first I took the car with a rough test body containing one or two sandbags on to the track at Brooklands, and tried it at speed. The engine proved to be a very willing one, and after first of all trying various grades of spirit, I selected Aviation as giving the best all-round results. Although the rough test body and dash were the very reverse of streamline shape, I was able, after minor adjustments to carburetter, tappet clearance, etc, to lap at approximately 75 MPH. I have found that the best clearance between the end of the valve stem and adjustable tappet to be six-thousandths of an inch, and the main jet that I have selected in the Claudel carburtetter, when running on Aviation spirit , is one hundred and twenty five
The ordinary extra air control, as fitted to the standard model, is also utilized, and has proved to be extremely useful even for racing purposes, for after a lap has been covered and the engine really warm to its work, a fair amount of extra air can be given to advantage. I find that on my car no fan is needed on Brooklands, as the natural draught created when running all out, which is in the neighbourhood of 80 MPH, is amply sufficient to cool the radiator. Incidentally, Castrol R engine oil appreciably increased my speed when used instead of ordinary touring oil.
The Running Improving
From preliminary tests on Brooklands I was satisfied that the car had distinct possibilities, but I had a outer jacket put round the T portion of the copper inlet, as I found that the inlet pipe , owing to the evaporation of petrol, became stone cold when the car was in motion, and this state of affairs did not lend itself to good acceleration.
To all intents and purposes, I have left well alone and the seal which the Brooklands authorities put around the engine and attached to the frame after verification of cylinder bore and stroke, etc, remains still intact., the car however has gradually become faster as is parts have become run in.
One of the earlier difficulties which presented itself was that of getting the car to hold on the road. This was done by the fitting both rear and front Derihon shock absorbers, and by selecting rather weaker spring leaves for the rear suspension, as with a two seater body these latter had rather too much camber in them. In addition, the springs were core-bound. This makes the springs stiffer and rather less comfortable over really bad surfaces at low speeds, but for high speeds it is absolutely right, and as a test I have found that both hands can easily be removed from the steering wheel at 70 MPH.. The fitting of a sports body of a shape more nearly approaching to the steamline renders the car much more comfortable to ride in at high speeds, for with the ungainly test body the wind pressures and eddies while going down the Railway straight in the teeth of half a gale had to be felt to be believed.
Furthermore the streamline body which was fitted, increased the speed of the car by fully 5MPH beyond that attained with the rough test body. I have since carried out one or two little ideas in a way of streamlining axles and dumb irons, all of which contribute to pace and I was told that at the Whitsun Meeting, I have been clocked to cover a lap at 87 MPH.( I hope Mr. Ebblewhite will not read this, although I do not suppose he has missed much in this direction that will serve to aid him in fixing his handicaps)
Although I have found this sporting model of the Austin “ Twenty” car an ideal fast touring machine, out of which one can extract a great deal of fun in competitions.