High Road and By-Road

Waikato Times, Volume 108, Issue 18165, 1 November 1930, Page 24 (Supplement)

High Road and By-Road

FUEL CONSUMPTION. FACTORS THAT INCREASE. There are many cases In which a petrol engine is unjustly blamed for consuming too much fuel. There are engines undoubtedly which eat petrol, as the saying is, in spite of carburation being as good as it can be. Such engines are defective either in design or workmanship and nothing that the user can do by adjustment will reduce their appetite for petrol.

This type of engine, however, is rarely met with to-day, and in nine cases out of ten heavy fuel consumption can be reduced to a reasonable quantity by correct adjustments. There are instances in which an engine, in good running condition gradually, or it may be suddenly, develops excessive petrol consumption. The 'causes for this are several, and though there is a tendency to suspect the carburetter at once, it is rarely Nameworthy, and it is advisable when investigating fuel wastage to postpone experimenting with this instrument. The first step is to ensure that the consumption figures obtained are reasonably accurate. It is not sufficient to assume that there are, say, ten gallons of petrol in the tank unless the quantity has bean seen poured in, or knowing the capacity of the tank, actually seeing it full. The next step is to ascertain whether any fuel can escape before reaching tire carburetter by making certain there is no leakage from pipe unions taps, and filters. Test the float chamber feed valve to see that the fuel supply is cut off when the correct level is reached. To do this, cause the needle to admit petrol to the float chamber until the correct level is slightly exceeded. Petrol will then run out'of the jet and drip from the carburetter body. These drips should quickly become less frequent and finally cease, showing that the needle valve has seated. Having carried out these tests and found no leakage it may be assumed that some function of the engine is not being performed correctly if the fuel consumption is higher than it should be.

An engine will go a long way without being cleaned of carbon, but if it is desired to keep the petrol bill as small as possible the valves should be ground to their seats every two or three thousand miles covered. The timing of the opening and closing of the valves affects the quantity of fuel used, therefore the tappets should be inspected to see that there is a gap between the bottom of the valve stem and the tappet head when th,e valve is closed and the engine hot. If there is no gap when the cam is at its lowest position the valve will not seat properly, and, of course, will not be gaslight. The result of both these defective tappet adjustments will be that more petrol will be used to cover a given mileage than would be the case if the valves were in good order. The gap should be between two and three thousandsths of an inch when the engine is hot. Misfiring will cause an increase in petrol consumption. Intermittent misfiring is not always easy to' detect; a defective plug may spark in small throttle opening conditions, but may fail to function when a higher compression is obtained with wide open throttle. Plug points w r ear away slowly, and therefore the gap requires occasional adjustment. The length of the spark gap has some bearing, on fuel consumption. Sometimes the ignition advance and retard lever does not move the contact breaker through its full movement with‘the result that the ignition timing may be late, never being fully advanced. Late ignition will overheat the engine and also he the cause of more fuel than necessary being used. Clutch slip v of cause, will cause fuel eonsumlion to increase. It is not often nowadays that one experiences a slipping clutch, but slip will take place when the lining wears to the extent where the rivets project. Badly adjusted brakes are also a cause of fuel wastage. If the shoes are not clear of the drums when the hand or foot levers are in the off position the vehicle will require a greater effort from the engine to propel it. All the foregoing remarks apply to an engine w'hich has been economical in fuel consumption, but has gradually become extravagant.

VALVE COOLING

NEW METHOD ON TRIAL. One of the difficult problems that automobile engineers have to solve in engine design is the effective cooling of the valves of the “poppet” type. Various ways have been evolved to do this with water cooled heads, by using special metal alloys and other such means.

The latest idea is a salt cooled valve in which the valve stem is made hollow and is half-filled with salt. After the engine becomes warm, when started up for operation, the salt melts and rapid movement of the valves in action circulates this cooling liquid around the stem and underside of tlie head, which is also hollow. This internal cooling, it is stated, carries away the heat from the valve seat. This type of saltcooled valve is now being tried on commercial motor vehicles, such as trucks and buses, marine engines and tractors in U.S.A. Whether the tests will prove satisfactory enough to make private car manufacturers adopt a similar type of valve remains to be seen.

The makers claim for these saltcooled valves, four important advantages. These, they state, are: (1) valves which run “black” under conditions where uncooled (by salt) valves run “red” hot; (2) there Is a lessened tendency towards detonation (or ‘‘pinking") and pre-ignition because of the lower temperature of the operating valves; (3) also this cooling eliminates valve-burning, distortion, pitting and undue wear; (i) they improve the fuel consumption by lessening the tendency for detonation or back-fires with weak mixture. As the firm who are making these salt-cooled valves have specialised .on supply valves to alt the chief U.3.A. motor factories for many years, it is interesting to learn that they are making such a revolutionary change in an important part of the power plant. Slow speed motors are now using it on trial, hut whether the design could si and up lo ils work on a highspeed engine has yet lo lie proved. The result of ils trial under such conditions will no doubt be eagerly awaited by car manufacturers.

A COLUMN FOR' MOTORISTS.

DRIVING POSITIONS. ESSENTIALS OF COMFORT. Many light-car drivers and also a large proportion of large car drivers too, one sees on the road, do not seem to be quite as comfortable in their seat as they might be. Car manufacturers often come in for a good deal of criticism in this matter, but it is only fair to state that they are not entirely to blame, the real trouble being that a large number of motorists do not really know what is the most comfortable position, while those who do will not always take the trouble to modify their cars until the seating position, contrbls and so on are as near being right as they can be. Many of the former class are people who are running their flrist cars and who have never had the opportunity to sample the seating arrangements, and so forth, in other cars; it is not surprising, therefore, that beyond putting the seat a little further forward or a little further back, they leave things much as they were when the car was delivered, and regard any discomfort they may experience at the end of a long run as being largely inseparable from motoring. With the object of helping drivers to obtain the maximum comfort their cars are capable of yielding, it might be well to outline the ideal driving position and general control. It is a matter of fact that any well-de-signed racing car is immeasurably superior to the average mass-pro-duced touring car in these respects. First of all in a racing car the driver usuallv sits so that his back is almost upright, a very slight rearward lean only being given whilst the seat cushion itself will be found to be long and of such a shape that it gives him adequate support almost to the back of his knees. His legs are neither doubled up nor stretched straight out, being at such an angle that when any of the pedals are fully depressed his legs are still not quite straight. The steering column is well raked —if well designed—so that the wheel is far nearer to the vertical than to the horizontal, whilst it- comes well , back, so that when the driver's hands are on each side of the rim, his elbovvs are well into his sides almost, in fact, touching the squab of the seat and when he lets his hand fall naturally from the steering wheel, it will drop almost directly on to the brake and gear levers. This, then, is the position which gives both comfort and confidence when driving and this is the position which every owner should aim at approaching as closely as he is able. Many normal cars fail in the aijgle of the squab, which in some cars is sloped back too greatly, doubtless to pander to the tastes of those motoi Ists —and there are quite a number of them —who imagine a reclining position is best. Actually it is a very bad position. The driver’s arms are too far from the controls or else leg room 1s insufficient. Any driver who cares to go to the trouble of experimenting along the lines Indicated In the racing car wiTl not be likely to regret it unless he happens to be the fortunate possessor of one of those cars where everything is just right.

SPARKS. It Is a fact that all the woodenheaded drivers are not found on golf courses. • # • * It Is stated that there are now nearly 300.000 motor vehicles In Australia' over six years old. Oil cooling systems on motor-car engines are claiming the attention of American parts manufacturers who are now busy with experiments in this direction. * * * * A representative of the Canterbury Automobile Association is placing sisms and colour route bands from Lake Lyndon to Coleridge, Harper River, Rakaia Gorge, Mount Somers, Staveley, and Rangitata and also In the 'Methven district. • * * * From Milan, It has been announced that the Ford Company has completed its purchase of the Isotta-Fraschini motor car factory in that city with the view of beginning the construction of a new low-priced car under the name Ford-Isotta-Fraschini. * * * * The old Idea that ownership of a motor-car of a motor-cycle implies wealth still obsesses an English borough council, which has decided by the casting vote of the chairman against permitting tenants of council houses to erect motor garages in their gardens. * * * • Wife (at busy crossing): “Now, remember. Herbert, the brake is on the left, or is it the right, or, in any case, don’t—” Husband (at the wheel) : “For heaven’s sake stop chattering. Your job is to smile at the policeman." . Canvas signs which, rolled up, can be easily carried by road patrols, have been introduced by the Automobile Association in England in order that guides may notify motorists of alternative emergency routes. They can be fixed or hung on trees immediately a patrol is aware of the trouble on or near his beat. A novel competition was inaugurated by a motor agent in Berlin recently. In the showroom was displayed a new closed car, the doors of which were locked. Then 100,000 keys were distributed throughout the city, only two of which could fit the locks of the car. The car was to be given to the recipient of the key who first, opened the vehicle. Almost every keyholder went to the showroom to try his luck, the prize falling to a lady.