Paul Nickalls

12 December 2007 at 21:45 #47029

The confusion with hot and cold is better remmbered as “hot running” or “cold running”. Therefore a hot running plug is needed for a low performance engine (also known as a soft plug) and a cold running plug is needed for a high performance engine (hard plug). A hot plug has a long heat path from the centre electrode to the body and a cold plug a short path so it runs colder in the same engine. Ideally all plugs will actually run at the same electrode temperature under normal running conditions thus different engines require different plugs to achieve this.
Confusingly some manufacturers use a high number to denote a cold plug wheras others use a low number.

bob

12 December 2007 at 22:01 #47030

that’s OK,thanks…
😉
bob

John Hugh

14 December 2007 at 23:10 #47057

Thanks Adrian. I’ll give them a try.

John