SPARK PLUGS.

Press, Volume LXI, Issue 18400, 5 June 1925, Page 5

SPARK PLUGS.

YEARLY CHANGE DESIRABLE. Long time experiments by motor-car manufacturers have proved that it is actual waste and unfair to a motor-ear to run it more than a year with the same set of spark plugs. Thousauds of motorists have found that a new set of plugs after from 8000 to 10,000 miles not only makes better performance certain but actually saves enough in oil aud gas to 1 pay for the new spark plugs.

Other thousands, when they prepare their cars for another season of driviug, will install a complete set of new spark plugs. Why it is real economy to do this is easily understood when the part that spark plugs play in engine operation is known definitely. In the engines usod in motor-cars to-day the charge is fired in each cylinder at every o.ther revolution of the crank shaft. This means that the spark plugs are called on to deliver the firing spark from COO to 1500 times per minute, according to the speed of the engine. '>

The temperature around the firing points runs from 600 degrees up to 1800 degrees Fahrenheit, the average being around 1300. In most motors oil continuously is being splashed on and burned off the spark plug. This tremendous heat and stress, due to tho rapidly alternating compression and firing strokes, gradually affects tho efficiency of tho spark plug, no matter how well made it may be. The spark plug will continue to fire and ignite tho cylinder mixtures, but combustion is not nearly so complete. The products of combustion gradually adhere to the surface of the core and eventually induce surface leakage, which weakens the spark after a long period of 'service. _ The electrodes aro pitted and oxidised by the terrific heat and the incessant sparking. This materially increases the electrical resistance. As the spark loses intensity at the firing points the operate of the 1 , engine seriously is affected, i all power is not securedfrom the gasoline consumed. The engine becomes sluggish. Acceleration is slower. It lacks pull on the hills. The unconsumed gasoline seeps by the pistons and dilutes the oil in the crank case, affecting lubrication and many times causing serious injury to the working parts. This process is so slow n that the motorist rarely notices it. But the operation actually is about the same as driving with a partially-retarded spark or too rich a mixture. The installation of a new set of spark plugs is a revelation to tho motorists. x

The difference in engine operation is so marked as to bo unmistakable. Power and pickup are better. There is more speed. Engine., operation is improved in every way. And the motorist actually saves the cost of the new spark plugs in oil and gasoline.

The annual report of the Iloyal Automobile Olub of Victoria Ltd. states that at a conference held at Adelaide in October a Federal body was formed, the name of which was decided on afl "The Commonwealth Association ox Automobile Organisations," the following being the bodies recorded as foundation members:—Autooar Olub of Tasmania, Automobile Association of South Australia, National Roads and Motor-' ists' Association, New South Wales, Royal Automobile Club of Australia.;, Iloyal Automobile Club of Queensland, Hoval Automobile Club, of V ictona and Roval Auto. Club of Western Australia.