MOTORS AND MOTORING

Dominion, Volume 11, Issue 51, 23 November 1917, Page 9

MOTORS AND MOTORING

IBy Cmjtoh.] x

Sparking Plugs. Sparking p]« ES are known to have been m constant use for many thousands of miles, without showing any perceptible deterioration; the only attention bestowed upon them being that they are periodically cleaned and the points adjusted. ■ So long as these latter not worn out, the plug should bi> serviceable, and provided the insulation is of a durable nature, there is practically -little or nothing to deteriorate. Frequently, however, plugs show signs of being unreliable after very lone service, and close examination in suoli cases will probably show it to be due to the interior being fouled up with carbon rather than from any structural defect. After a thorough cleansing and adjustment of points, if needed, they are generally restored to their original good condition. Some motorists, however, cling to the belief that sparking pliißs tire after much use, and periodically chnngo them, sometimes with good effect. Such a result, however, may be duo to unsuitable plugs being used in the first instance, for they vary in several ways. That there- is something in plugs being "tired" or exhausted*was instanced in a case irlioro a large touring car failed lamentably in tho running. The chauffeur tried everything his ingenuity could devise- to obtain better results, but without success, when ho was advised to change the plugs; and on this being done tho effect was most gratifying. The engine responded quickly to the throttle, while tho petrol consumption was much more- satisfactory. It may bo said hero that many motorcyclists, change the plugs every few thousand miles.

Where the Carburreitors Fail. If the speed of ■ the cugine never varied we should always have a correct mixture, once the size of the- jet- and the opening of the air intake were determined. As the variations of the engine speed nre rapid and irregular, the mixture has to be corrected automatically by the carburettor itself. The pre-sent-day carburrettor supplier too weak a mixturo at low speeds and too rich a charge at high' speeds. In order to .get a- fairly efficient charge over a wide range of speeds, various devices have been resorted to —variable.'jets., variable choke-tubes, etc. Hot-water jackets and hot-air devices are sometimes added to mako more certain that •tho -mixture, when _it arrives at-the appointed place, is in a gaseous state, and considerable attention is being given to the question of more thorough vaporisation of the fuel since attention was focussed.upon tho use.-of paraffin and.heavy hydrocarbons. The ideal carburettor, will vaporise tho liquid fuel before tho suction of the...engine acts upon it. With the accretion of. knowledge experiment and everyday use of the motor, it is now. seen that the ordinary carburettor is hut a measuring instrument for the fuel, and, not even a perfect.yaporiser, much less a device lor supplying p.ure gas to tho engine. It is recognised that tho carburettor of the future will need to ho an instrument that will supply the engine with a mixture composed of tho absolutely correct proportions of petrol vapour and air at all speeds, and bv the time the mixturo is drawn into the combustion chamber it must be in a perfectly gaseous state. At present tho available carburettors givo ;i mixturo ■which varies, considerably according to the engine speed. This is due to tho fact that petrol, being of a different density to air, is affected differently by the constantly changing, suction of tho engine., As the number of revolutions drops or increases, so does the proportion of petrol chance iii relation to the air in the mixturo.

Tyre Hints. - When replacing an inner tube after "a puncture, iun the- hand round tho insido of tho cover to be assured uo nail or other foreign substance is cmbedded —after removing tho cause of the last mishap, of course. It frequently happens that a small nail or tack, or even a pin,.may havo penetrated the cover and even reached the tube, without actually puncturing it; but on removing tho old cover the tack or pin may be drawn farther through the cover, when the new tube will assuredly be punctured. This, has been demonstrated many times. Similarly, when repairing a'puncture or changing a tube, clean out tho cover, even of road grit/which s.oraetimcs accumulates, for motor tyre tubes are easily ruined by allowing any kind of foreign substance to remain in tbeVover. When inflated, the pressure of the tube

against the cover is considerable; hence, to allow any hard matter to remain means that it will eventually be forced into the comparatively soft tube, which it will either puncture or badly abrade and render porous.. Here and There. Bβ careful when adjusting the brakes that they do not drag. Jack, up both' rear wheels and adjust brakes as usual so. that when lever or pedal is applied they show an even resistance on each wheel when tried by hand. To make sure that the outside band does not drag, look between it and the brake drum. It should show daylight all around. The only way you can tell if the inside brake is frco is to spin the wheel with both brakes off. There are many ways of filling grease cups. The first thing to do is to wipe off all dirt that may be present boforo removing tho cups from the car. This is to prevent grit getting into tbo grease, which it will do otherwise.

Don't forget to look at the battery at least onc ( o a week in hot weather when the car'is being driven daily. Tho more you drive the more distilled water is required to keep tlio plates covered. Also this water evaporates more rapidly in summer than in winter.

The water in the radiator will evaporate much more readily on hot days, and so it should be watched very carefully. Whenever the radiator steams a certain quantity of water is lost, so that tho supply note low before you realise it. It will be well to get in the habit of filling the radiator every day, and then you are safe.

A spare float does not take up much room on the car, but it is a useful detail to have with you. It. should be packed carefullv in a small box to -prevent damage. There are so many types in use that ifc is not always possible to obtain 0110 locally at short notice. It sometimes happens that tho- wear on the needle chafes a hole in tho centro tube, which it would be an impossibility to repair with the usual soldering iron; tlio only remedy would b 0 a new float.

Lighting-np time: To-day, 6.58 p.m Noxt Friday, 7.6 p.m.