MOTOR NOTES

Taranaki Central Press, Volume IV, Issue 338, 20 January 1937, Page 2

MOTOR NOTES

Compiled by “Spark-Plug.”;

IGNITION SYSTEM. A little attention to the ignition system prior to a long run may save delay. See that all terminals are clean and tight, with no loose "wiring or frayed ends. High tension adapters must be free from corrosion or burning and tight in distributor or coil. Contact gap points should be clean and square, and separated to recommended distance, usually .016” to .022.” Spark plugs should be clean and free from internal carbon, with gaps .020” to .025.” Wipe around the distributor head with a petrol-moistened rag, and attend to oiling and greasing at one or more points. A few drops of oil in magneto bearings, and tightening of holding down clamp is suggested. * * * FUEL TROUBLE. Occasionally an engine will develop the habit of stopping, yet starting immediately after. This is usually indicative of dirt in the jet, which falls out as soon as the suction ceases. Misfiring and spitting back also takes place. Remove the base' plug and drain the system (simply shut off) and if convenient clean out the jets. Often by speeding the engine up a fe* times suddenly the obstruction will be dislodged, so this method should be tried first. When the engine cuts out suddenly, with spitting and misfiring, you are out of petrol or there is trouble in the fuel feed. Where unaccompanied by irregular running, look for ignition trouble such as a broken or disconnected wire, a broken breaker spring, or sticking arm. * * * battery care. Examine the battery at least twice a month in summer, and once a month in winter, to see that the electrolyte is kept to correct level, or about iin. above the top plate edges. This is of particular importance in the case of 12-volt batteries, where relatively less solution per cell is used. Avoid the. use of special dopes or patent solutions without" advice as to their suitability. Terminals . should be kept clean - and tight, and a coating of grease tends to prevent corrosion. The earth connection, starter, and switch connections need occasional tightening. Always top up the battery with pure distilled water; never add acid, but leave this to the battery man. * * * FAN BELT TENSION. Fan belt tension should be examined periodically. The proper adjustment is obtained when the fan can be turned by hand with slight effort and without turning the belt. When the belt is worn or grease-soaked, replace it to prevent slip which can cause overheating and low or irregular generator charge rate. * * * REAR AXLE NOISE. Noise in the rear axle need not always be treated as a serious defect. It may be, however, that the oil supply " is depleted, or the oil of insufficient body or interior quality. Look for leakages and have them corrected. Should the noise continue after draining the old oil completely (when hot after a run) and refilling with clean, an expert should be consulted. He will examine the tooth markings of the drive gears, also the bearings as to condition and adjustment, tooth markings, relative clearance and lash at various points. Do not expect a 100 per cent, silent opera ion, especially from an old car or indeed from some of the latest types. Armed with the assurance of a competent mechanic that the gears mark up well under load test, bearings are in good shape and neatly adjusted, ring gear runs true and the

pinion and shaft are free from excess

looseness, there should be no cause for apprehension if the axle tends to hum at critical speeds. Just keep the oil to the correct level, and drain thoroughly at the specified period, usually every 5000 miles or thereabouts. * * * TYRE PRESSURE. It is vitally important that the tyres carry the correct air pressure at all times. Soft tyres are bagged in section, will produce wheel wobble and skidding, and the casings are quickly destroyed. Each tyre carries a certain weight, assuming a fully laden car, and this weight is the basis for calculating the ' correct pressure in relation to its size. The motor-car distributors and tyre companies have full data if any doubt is felt. Excessive pressure, causes hard riding and under-inflation detracts from the best performance. Generally speaking the larger the section, the lower the pressure. * * * FUEL LINE BLOCKAGE. The blockage of the fuel line when white metal die cast carburettors are used, due to the presence of white or red" deposits, was often accredited to the use of leaded fuels, but has definitely been proved by recent research to be due t,o the presence of water in the carburettor bowl. This theory was suggested by the number of complaints received during rainy weather. * * * LOOSENESS. A few points where looseness can cause trouble: Loose radiator supports—result, vibration and eventually core and tank leakages. Usually two bolts at base attaching shell to chassis. On later cars one base centre bolt and brace rods and nuts are to be tightened. Loose hydraulic brake cylinders —result, rattles and grabbing brakes, lack of uniformity all round, and rapid wear of parts. Loose engine mountings—result, vibration, thumping, rocking gear and brake levers, and rapid wear of support bolts and rubber blocks. * * * GREASE CUP. A water leak at pump or impeller shaft is generally caused by neglecting to turn down the grease cup. Or the grease may be unsuitable for that purpose, where . considerable heat is encountered. Avoid overtightening of the packing nut, which would cause binding and excessive wear. Tighten the nut just sufficiently to stop the leakage, with the motor idling. * * -SIBURNING. Burning of the distributor head segments and rotor points is more or 'Kss to be expected due to high voltage of the ignition current. Rapid and excessive burning suggests wear, or that for some reason the distance between the moving and stationary contacts is too great. The distance should be from .010” to .015,” tested by placing beeswax on the distributor head points and turning the- motor over once or twice. The installation of a new rotor is sometimes necessary, or the existing one could be lengthened slightly by flattening or peening the end. The use of a resistance- will remedy a case of high voltage. Dampness can be overcome by drilling a few 3/32in. holes in the side, at an angle- of 45 degrees to the vertical. Existing holes should be cleaned out. The timing of the ignition should also be carefully adjusted. A slack fitting distributor head would unbalance the clearances between rotor and seg ments. Some would be too close, others excessively spaced.