Spark Plugs

[rossbraithwaite]

Is there any consensus on which brand or type of spark plugs are best in the 4.2 XK engine?
From Jaguar E Type by Denis Jenkinson:
"Each time it went to the Jaguar factory it came back with Champion sparking plugs fitted and eac time I took them out and replaced them with Autolite AG42s... Jaguar had a contract with Champion to supply plugs for original equipment.... but I did hear from the back door at the factory that a lot of experimental work on the test beds was done on Autolites!"
I think that NGK and probably a few others also make suitable plugs. Does anyone have any opinion?
Thanks,
Ross

[christopher storey]

Most people now use NGK BP5ES or 6ES . I use 6ES and have never had any trouble. I think Heuer knows more about these as I recall his having posted on which is best

[rossbraithwaite]

Thanks Christopher, I did a search of the forum but surprisingly couldn't find any threads on spark plugs. I'm considering a set of the Autolites on Jenks's advice!

[Heuer]

I use NKG BP5ES and they have performed well over 35,000 miles in all sorts of conditions - mostly hot. I did toy with the idea of fitting NKG BP7ES, a cooler plug, to see if they did anything to improve running when very hot but never got round to it. Jenk's had some interesting views on running an E-Type but his comments need to be taken with a pinch of salt as they are 'of their time'. Modern spark plugs have the benefit of more R&D together with the use of modern materials.