HOT PLUGS FOR COLD ENGINES

Evening Post, Volume CXXIII, Issue 19, 23 January 1937, Page 26

HOT PLUGS FOR COLD ENGINES

One of the most misunderstood motoring . phrases is that which describes plugs as "hot" or "cold." This is the position as explained by the Lodge Company. A few years ago, in racing circles, plugs were divided broadly into two categories— "hot-stuff" plugs and "slave" plugs. The former were used for racing, the latter for light running before and after the event. The term "hot-stuff" became contracted to "hot" and, conversely "slave" plugs were often known as "cool" or "cold" -plugs. Actually, of course, a "hot-stuff" plug is one which will keep cool under racing conditions, whereas a "slave" plug is one which easily heats up and so burns off the oil which reaches the points when the engine is running light The leading plug manufacturers have therefore reversed the old racing nicknames and now define plugs in accordance with. their properties. In future, a "hot" plug is one which gets hot quickly and is used in a cool or oily engine, whilst a "cold" plug is the erstwhile "hot-stuff" model—one which keeps cool under conditions of extreme heat and is therefore used in racing or other high-compression engines.