High Road and By-Road

Waikato Times, Volume 107, Issue 17976, 22 March 1930, Page 12 (Supplement)

High Road and By-Road

DECEPTIVE SPARK PLUG FAULT. Frequently spark plugs, especially those using mica insulators, are very ■ deceptive in appearance, since shortcircuits which cannot he detected in .daylight are often present. ' By testing the plugs at night, when the spark is plainly visible, each plug being unscrewed in turn and laid on the cylinder block, the path of the high tension current can readily be followed. If the spark jumps between the points, the plug is not defective; but if a number of minute sparks appear to pass between the plug body and the insulator, the plug is faulty. .Often this test can be made in the day-time by merely shading the plug from the light with a dark cloth. In many instances ignition trouble has been traced to the use of the wrong type of plug. The best results are' obtained when the spark is delivered to the cylinder as nearly as possible in the centre of. the explosion chamber. Since engine blocks vary greatly in design* it is perfectly evident that a spark plug that is suitable for one type of engine is entirely unsatisfactory for another. Spark-plug manufacturers have given this .matter considerable thought,. and aim to produce plugs especially designed for use in different types of engines. In some engines the spark plug hole is recessed, permitting of the use of a plug of short body, while others are so constructed that it is necessary to use a longbodied plug. From an engineering standpoint, the highest efficiency from the explosion in a cylinder is obtained if the spark plug points project into the combustion chamber in a manner which will permit of their being entirely surrounded by > cool, fresh gas. If a short-bodied plug is used in an engine which requires a plug of long body, the result is the recessing or pocketing of the poitns. In such instances, dead gas is apt to accumulate, around tile points, and cause combustion to be less rapid than i£ would be if the proper type of plug were used. In other works, the rapid spread, of the ignition flame is better promoted if the points project directly into the combustion chamber than if they are pocketed or recessed away from it. Some engine-builders claim that this recessing of the spark plug is an advantage, in that the points of the plug are less liable to become fouled. This is probably true, but it is the general belief that this advantage is considerably overweighed by the loss of power due to having the poinl of explosion,so far removed from the centre of the combustion chamber.

REPLACING HOSE CONNECTIONS. The quickest method of installing new rubber hose connections to the radiator is- to squeeze the hose flat and then double it over the middle. One end can then be slipped over the radiator pipe easily and the other end will fall back so that the other end worked down over the pippe of the cylinder block.

A COLUMN FOR MOTORISTS.

A USEFUL PAINT SCRAPER. Sometimes it is necessary to scrape paint from a windscreen glass after the car has returned from the paint shop, but it is a matter of some difficulty to find a scraper which will do the work cleanly and with expedition. A scraper which has been found to be very effective in practice consists of an old safety razor blade riveted between two discarded vibrator bridges taken from Ford coil units. These vibrator bridges make the scraper easy to use, and it will be found that the razor blade scrapes away excess paint most successfully. RENEWING WORN VALVE GEAR. It sometimes happens that overhead valve gear of the type embodying push-rod ends may wear into the signs of undue wear, probably owing to lack of adequate lubrication. The push-rob ends may wear into the metal of the rockers, so that it is not only impossible to adjust the clearance, but the irregular shape of the holes makes the operation of the valve g-ear very erratic. To avoid fitting new rockers, the worn hole can be trued out with a specially ground twist drill, and a steel ball as used in ball bearings inserted to a little over half its depth, the surrounding metal being slighly riveted to keep it in place. The ends of the push-rod should then be cupped out and case hardened to keep them in contact with the ball. Replacing the push-rods with new ones having larger cups would probably make a better job.

ALCOHOL FOR POWER. The extent to which petrol is being replaced by alcohol in France is probably not fully appreciated elsewhere, and it will be news to many to learn that the omnibus servloo of Paris, to give an example, is run entirely on what is known as “Carburant National," or National Fuel, which is composed of oqual quantities of alcohol and benzol. This Is made possible by the activo co-operation of tho French Government, with the aim of reducing, so far as possible, the dependence upon imported petroleum products which constituted so grave a danger during tho war. Alcohol, as is well known, can be produced from vegetable matter, and very large quantities are now being obtained from byproducts of the wood-pulp industry, largo factory for the extraction of alcohol from sawdust is in course of erection in France. A carburettor is in use in that country, by which-a fuel mixture containing only 10 per cent, of benzol and 90 per cent, of alcohol gives results similar to those obtained with ordinary petrol. The successful production and use of power alcohol in France brings home the fact that Australia, which undoubtedly has vast possibilities in this direction, has so far made no determined effort to produce power alcohol for automobile use in this country on a commercial scale. It has been pointed out by Mr A. de Bavay, one of the most eminent industrial chemists in the Commonwealth, that sufficient sugar cane could be grown in Queensland to produce huge quantities of power alcohol, that could be used on a 50-50 basis with benzol or benzine. There are, he states, millions of acres in the north of Queensland where sugar cane can be grown, and we have experienced farmers who can grow it. At present Queensland produces more sugar than Australia can use, and a Federal edict prevents more acreage 'being sown with cane. Mr de Bavay is confident, if this restriction is lifted and properly directed efforts made to establish a power alcohol industry in Australia, that not only would many millions of pounds be kept in this country, but that employment would be forthcoming for many thousands of Australian workmen. France has succeeded in establishing her power alcohol industry, and there appears to be no insurmountable reasons why Australia could not do the same.