[Healeys] hot/cold plugs

Simon Lachlan simon.lachlan at homecall.co.uk
Fri May 31 09:05:10 MDT 2013

I have a BT7 with 3 HD6s, Denis Welch fast road cam, 6 branch big bore, 123
ignition distributor plus "sports" coil. I asked Jeremy Welch which plugs to
use and he said, words to the effect:

"You gave a "fast road car" and you should use NGK BP6ES plugs".

OK, I'll buy a set of 6 on eBay and gap them at 0.025 per their advice when
I was running a Petronix.

Any comments/advice so far? (He dismissed NGK B8EGV 5627s out of hand as
being "too race orientated". And, for sure, neither car nor I are racers!)


Now, about this hot plug, cold plug thing. Can someone explain it in words
of one syllable? It seems that the hotter the plug, the bigger the bang. The
bigger the bang, the more efficient....within limits of course.

Can someone sort me out with reference to the BP6ESs and the BPR 5ESs which
I am using now. Which is hotter? Which will do what? What difference might I
see/expect? Will plugs - if colder - make the car harder to start? etcetc.

Plus any other tips.....I'm a total ignoramus on this topic. (And on many


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