SELECTING SPARK PLUGS.

New Zealand Herald, Volume LXVII, Issue 20620, 19 July 1930, Page 14 (Supplement)

SELECTING SPARK PLUGS.

CORHECT TYPE ESSENTIAL. There are many factors which have a bearing on tho proper fnnctioning of a spark ping, which may not bo understood by tho majority of motorists. It is a mistaken idea to suppose that one plug, if only of a good make, will function equally well in all engines. Mechanical strength and electrical efficiency will -not of themselves ensure the satisfactory functioning of a plug in service. In itself, a plug may bo perfect, yet according to engine conditions it has to meet, it may either oil or soot up, or give rise to pre-ignition. If the correct sparking plug is selected it will seldom cause trouble. When a plug soots up and a dry black deposit'of soot forms on the insulator, tho cause is usually with the mixture, which is too rich, choke-tube too small, too little air, or unsuitable fuel. The remedy is to clean tho plugs, correct tho carburettor setting, and, if necessary, uso plugs with a lower heat resistance. When the plug has fouled with cril, and a wet oily deposit of soot is found inside the plug, the cause may bo attributed to leaky ! piston ring*, too much oil in the crankcaso or plugs unsuitable. In this case, after tho engine has been put right, it is advisable to use a foul-proof plug. If the body of a plug becomes coloured by heat, it indicates that the -plug is not tightened up enough and probably no packing ring on the plug seating. Any of tho above troubles will cause bad engine starting, misfiring when running slowly on top gear, and a loss of power. Leading spark-plug manufacturers make their plugs in various patterns, graded on the scientific principle of heat resistance, Which is a guide to users in choosing tho right sort of plug for their engines. Many makes of efficient and dependable plugs are marketed in Auckland, nnd in most instances in a wide range of types to suit various engine conditions. This enables those motorists who experience plug troubles, to select the make and type of plug that ensures satisfactory results.

" BLAOKING-OTJT " DANGER. There is in some quarters an entirely mistaken idea that it is courteous and a sign of " good driving" to extinguish one's headlights at the approach of another vehicle, it being hoped that the other driver will respond in like manner. This practice, which is known as " blacking out," has been condemned as exceedingly dangerous by every motoring organisation and by almost every experienced car driver. When the head lamps are suddenly extinguished, the driver's eyes do not "respond quickly to the sudden contrast between a well-lit road ahead and a faintly illuminated surface, dimly outlined in the feeble rays of the side/lamps. The result is that cyclists or pedestrians ahead of the car are not observed, and in not a few instances they have been run down by an overtaking vehicle. TWO USEFUL HINTS. Many motorists to-day take a keen interest in matters mechanical, and, in consequence, repeatedly discover that there are numerous small yet unimportant details which can be attended to by themselves without on all occasions seeking professional help. Naturally, the more serious repair or adjustment jobs should be left to those who specialise, but more often than not, with the aid of useful and practical hints and tips, the lesser running adjustments can be done quite readily in one's own garage. For example, a source of ignition trouble can bo a sticky rocker arm. Oil should not be used. After removing the rockor and cleaning the rocker-arm bearing, effective lubrication can best be obtained with the aid of a lead pencil, the lead, or graphite, serving as a dry lubricant. Another useful hint to help detach an obstinate wheel is to attach a suitable strap to the wheel spokes, and insert a jack in the loop between the end of the axle and the strap; then operate the jack in the ordinary way, and the stickiest wheel will noon respond.

NO RUNNING BOARDS. Some of the smartest-looking motor-cars on English and French roads to-day have no running boards. The same tendency was noticed at the recent Melbourne Motor Exhibition, where two of the finest and most expensive cars were minus the usual running boards, these being replaced by disappearing folding steps, that dropped into position when the doors were opened. Judging by the complimentary remarks made by many motorists who inspected these two cars, their appearance was considerably enhanced by the absence of the customary running boards. From a utility point of view the running boards on many family cars do good service as carriers for luggage, and in this connection are a great convenience to many owners of cars making long trips. For the family cars and specially those used in the country, the running board has a definite utility value, although luggage on tho running boards may not improvo tho look of a car from an aesthetic standpoint.