Valuable Features in a New Plug
Page 58
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SUCCESSFUL results are, we learn, being obtained by the Massa Sparking Plug Co., Ltd., 1711, High Street, Teddington, Middlesex, with its new M.S.T.-type sparking plug. This interesting device embodies an outer wrapping of thin copper foil around the mica insulation, with the object of preventing the deterioration of the insulating material, and of adding to the performance and life of the plug.
An interesting feature of the plug is the use of the maker's patent thermic washer, which divides the gas Spaces and safeguards the insulation against the effects of heat and oil. Being a good conductor, the washer rapidly conveys excessive heat to the body of the plug, and thence to the cooling water. Oil is side-tracked to the outside of the washer and, in tern, 'is burnt oil and carried out of the exhaust in the form of carbon dust.
Under extreme conditions, such as _might obtain in an engine with badly worn cylinders or stuck-up piston rings, oil is said to be deposited on the outer surface of the copper baffle instead of forming a film upon the internal insulator and thus shortcircuiting the spark gap.
Another function of the washer is to prevent moisture from creeping on to the insulation. A further point is that the central electrode is made in one piece of a special type of heat-resisting steel.