MOTORS AND MOTORING

Dominion, Volume 23, Issue 79, 27 December 1929, Page 7

MOTORS AND MOTORING

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CARBURETOR DEVELOPMENT, DOWN DRAUGHT SYSTEM More attention Is now being given to carburetion and manifold systems than for some time past, judging from a study of the 1930 car announcements that have appeared up to date. In the effort to wring every ounce of power possible out of each cubic inch of piston displacement it is natural that the carburetor should come in for some refinement. Probably the most radical departure from past practice is the down-draught type of carburetor that has already been announced on one model and which will be found on others before long, according to reports now current. The down-draught manifold has been with us for a little while. In this type the manifold leads down into the intake parts of the engine. In the downdraught carburetor, however, the carburetor is actually mounted above the intake manifold and the charge is drawn downward into the manifold from the carburetor.

The reasons given by the engineering department of the concern using the first of the downdraft carburetors in automobile practice are interesting. They state the purpose behind the move is to increase the volumetric efficiency of (he engine. In other words, they mean that each intake stroke will leave the cylinder more completely filled with combustible mixture with this type of carburetor. They state that this is the case because the engine does not have to pull the mixture up against the force of gravity but down with it, so that at times when the vacuum is the lowest in the intake manifold the velocity of the fuel particles will not fall so low that condensation will take place and a large proportion of the fuel fail to reach the combustion chamber.

These engineers point out that with ordinary carburetors mounted below the intake it is necessary to restrict the throat opening of the carburetor to a great degree so that the velocity of the fuel will be maintained. Naturally the smaller the opening the greater the velocity. With the down draught carburetor it is possible, they state, to use a larger

Here is a good idea for cars with a dickey seat. It | is a cover for the seat and can be of | use when the car is j too hot and there is much dust, and I is of equal use on j cold damp days in 3 winter. So far none j of these have been' a seen on the New I Zealand market, ! but it is safe to : predict that if j they were brought i out here, they : | would have a good 1 sale. The cover 1 shown in the illus- j tration adjusts to, | fit all makes of cars! 1

A feature of it is that there are no screws and bolts that there are no screws and bolts that have to be driven Into the car body and spoil it. Instead there are brackets which clamp onto the seat frame, rods which adjust to the proper size and height, hooks which fasten in back of the top and side straps, all of which are easy to place and fasten

“SPARE WHEEL.”)

throat and consequently not to restrict the breathing capacity of the engine unduly. ... , Anyone who has had a car fitted with the vacuum operated type of windshield wiper will know that there are times when the wiped hardly moves at all because the vacuum force in the intake manifold was so low that it does not have the strength to drive the wiper. This is the same force that is relied upon to draw the charge into the cylinder. The theory advanced is that this weak force working against the force of gravity cannot do as well as if the force of gravity were working with it. Consequently, by placing the carburetor above the intake the force of gravity is added to the action instead of being subtracted from it. The result of the down draught is that a lower vacuum will, do the work in the intake manifold and consequently the throat of the carburetor can be made larger and so can the intake passages, giving the engine increased breathing capacity. This is a big factor in increasing the volumetric efficiency. With the reduced vacuum there is in addition a greatly reduced temperature of the intake. This contributes to the density of the charge. Since the charge is less rarefied with the down-draught carburetor, this is claimed to produce another factor in increasing the volumetric efficiency of the engine. The final claim is that with the reduced tendency toward condensation it is possible to get improved distribution of the gas. In other words, each cylinder is said to be filled not only more completely, but more uniformly. . The new fuel pumps are claimed also to help the filling of the cylinders. Here again it is claimed that the vacuum proves unreliable at times when it is needed and that in order to be sure of a uniform supply of fuel at all times the safest way is to pump it to the carburetor. This follows aeroplane practice where the fuel pump has always been used. The down-draught carburetor and manifold is also a product of aeroplane development. Vacuum is not to be relied upon at all with the aeroplane. When the craft is at high altitudes the difficulty of getting sufficient charge into the cylinder is so great that it is necessary to use superchargers in order to get proper performance.

properly. There is a hookless fastener underneath the top which when pulled folds the top back so that the seat is easy to get into or out of. The metal parts are said to be rust-proof and the top itself waterproof. There are side curtains so that the seat can be entirely closed.

WAVE OF OPTIMISM BRITISH MOTOR INDUSTRY For the nine months ended September the exports of British motor goods exceeded 25 per cent, in value and 40 per cent, in number, the figures for the same period in 1925, showing an expansion in practically every market throughout the world (states an English paper). The Motor Exhibition at Olympia was remarkable for the extraordinary public enthusiasm shown over the range of British motors, while the Press of Great Britain has been full of a note of optimism that at long last the postwar difficulties of the industry have been overcome, and that to-day British manufacturers can offer a range of vehicles at competitive prices which are suitable for every sort of road condition.

Perhaps the most interesting feature of the development of the past months has been the confidence in the industry shown by 'ne of the largest insurance companies in the world, which has become definitely associated with the movement, backed by the British Government, to extend the export market for British motor products.

There are signs to-day that motor agents all over the world are clamouring for good British agencies. With (lit extraordinary development of the British utility car in every part of the civilised world it has been shown that owners are realising that the motor car is a means of transport which costs money and that although such a car may not provide some of the features associated with other types of vehicles it is in the long run the most economical form of modern transport in the eventual profit and loss account. That this is so is testified to by the demand for this form of transport, which has been growing to a remarkable extent over the past twelve months. Even so, it is as yet only in its infancy. It is seldom that maufacturers advertise to tiie world tile fact that motor transport costs money, but British manufacturers a. least realise that it is neither in the interests of themselves nor their customers, nor aids the financial stability of any country, to exploit uneconomical!,v the motor vehicle to create an illusory demand. It is necessary to look at transport in its proper perspective to the welfare of any community. Too easy finance or credit insurance in respect of certain articles has been said by General Hertzog to be a disease menacing to society. Tiie British Industry does not deny that in certain cases the ex-

tension of too easy credit for the purchase of certain types of motor cars has proved dangerous in respect of vehicles which are expensive to run or which have a high rate of depreciation and which, perhaps, do not play their proper sphere in the economic stability of tiie customer. Tiie manufacturers of the utility car which is to-day capturing the imagination of the world believe that they are providing an essential means of expeditious and cheap transport which, by adding to the, economic prosperity of the community and the individual, will provide tiie answer to tiie statement that hire purchase “is an absolute disease and menace to society.” With respect to all ranges of ears and commercial vehicles there is a definite feeling of optimism at home that the greatest opportunity to-day exists for a wise and wide expansion in the export of every type of vehicle.

LUBRICATE UNIVERSAL JOINTS

Remember that a mechanical universal joint needs occasional lubrication, but, unfortunately, owing to the inaccessible location thereof it is usually neglected, with dire results A greasegun nipple is provided and for certain mechanical joints a special lubricant is available, which it is advisable to use. Naturally, a fabric joint does not need any attention in this respect, although when inspecting the chassis it is as well to make sure that nuts and bolts are securely locked.

OUTSTANDING FEATURES AT OLYMPIA

GENERALLY FOR COMFORT AND CONVENIENCE Among the outstanding features of the Olympia Motor Show (England), this year, may be mentioned tiie large number of cars lilted with four-speed gear boxes, and tiie increase over last .year of the use of coil ignition, which, it is stated, is now used on 60 per cent, of the makes of cars on the British market. Up to a year ago American designers regarded four speeds as unnecessary on cars of high horse power, and at Olympia last year there were no American models having more than three gear ratios. This year no fewer than five American car makers are among the converts to the four-speed gear box. Tiie increased popularity of coil ig nition is due partly to tiie fact that modern coil apparatus is now known to be entirely reliable, partly to great efficiency, and also because it is a means of reducing slightly the cost of the complete car. The last-mentioned factor, however, is of small importance compared with reliability, even on the lowest-priced cars, while on cars costing several hundred pounds it cannot be seriously considered. The great increase in the popularity of coil ignition is not really due to any radical altera tion in the design or construction of such items as generators, starting motors, magnetos and coil systems, but

rather to a better appreciation of the advantages of the system for easy starting and slow running. For many years coil ignition has suffered from a prejudice against it handed down from the very early days of motoring when coil, condensers, contact breakers, and distributors suffered from as many defects as did the early chassis themselves, and batteries gave endless trouble, as they were not specially built for the work they were called upon to do. The modern battery has been greatly improved since those days, both as regards mechanical construction and electrical efficiency, but there is now no reason why an ignition system depending upon it should be suspect. With regard to coacliwork, another feature of cars for 1930 is the provision of wide bodies with sides and doors standing downwards outside the frame almost to the running board, and in many cases the valance has been altogether abandoned. This gives a more pleasing outline and more room. In a number of cases steps only are provided for tiie doors. Luggage accommodation, too, has been much improved. Better upholstery is being used in the interiors than in the past, while there is also ar; increase in the number of pneumatic cushions fitted as standard. Crankcase ventilation lias received a good deal of attention, and with a view to preventing fumes from entering the bodywork, many firms have adopted ingenious devices for sucking them out of the bonnet. In general the improvements which have been made in 1930 cars tend towards comfort and convenience.