|Not too hot, not too cold
Question : MY 1973 Ford Escort 1.3GL requires new spark plugs but I am now
unable to buy the make and grade of Motorcraft plugs recommended by the engine manufacturer.
My local spare parts supplier recommends a copper type with a
wide heat range. While it will physically fit the vehicle, I am worried that using a plug of incorrect heat range will result in engine
damage, and would be grateful if you could suggest any alternatives.
Answer : IT is important that spark plugs of the correct heat
grade are fitted to your engine.
Too hot a grade will result in pre-ignition (detonation) that will
eventually result in engine damage, while too cold a grade will result in
carbon (soot) deposits forming on the plug. The latter means higher exhaust
pollutant levels, loss in engine power and increased fuel consumption.
Graded spark plugs have not been available for some years. The use of
copper, platinum and iridium has resulted in spark plugs with wide heat
Modern plugs are less susceptible to overheating which means the chance
of engine damage from detonation is reduced.
Moreover, modern plugs exhibit excellent durability and wear characteristics, and often spark plugs are now renewed at 100,000km