[Healeys] Plugs

[Bob Spidell]

I've run over 150K miles on Champion plugs with nary an issue (and will 
continue to do so); RN12YC for the BJ8 and whatever the recommended is 
for a 100M (RN10C?). With Pertronix Ignitors in both, I run slightly 
over 'book' value (0.025") at 0.028" and both run very well (I also run 
stranded copper wire secondaries, so the 'R' is important, plus the plug 
caps have a resistor in them as well). My one-time auto shop teacher 
father maintained whatever spark was sufficient to ignite the mixture 
was adequate--mixture and compression took it from there--but a larger 
gap induces a 'hotter' spark which may be beneficial with leaner 
mixtures and at higher engine RPM (but has less margin as the electrode 
erodes). A larger gap requires the coil to produce more secondary 
voltage to jump the gap; a sports coil may be required to produce a 
consistent spark. 12K miles on plugs is fine in my experience--as long 
as the engine is in good nick--and they can be cleaned and re-gapped at 
least once. Sandblasting is a no-no as it will pit the ceramic insulator 
and can cause issues.

I came across a YouTube video by David Vizard where he claims E3 Diamond 
'Split Fire' plugs produced slightly better mileage; yep, E3 makes a 
plug for Big Healeys (6-cyl only, I think). I've heard rumors that 
counterfeit NGK plugs are in the market.



On 3/18/2023 9:49 AM, Simon Lachlan via Healeys wrote:
>
> Here’s a can of worms that we haven’t delved into for a while….
>
> So, I’m trying to get all my ducks in a row for a short run abroad. 
> Car is a MkII BT7 with a DW fast road cam, 3 HD6s, big bore 6 branch 
> and 123Ignition plus a so-called Sports Coil.
>
>  1. I was looking through my library of files on Healey topics and saw
>     that we were all over the place on plug gaps…..all the way up to
>     0.035”. So what’s the opinion there??
>  2. And which plug? Seemed to be mostly between NGK’s BP6ES & BP5ES.
>     Was a hold-out for their B8EGV 5627  but thatwas dismissed fairly
>     vigorously by Jeremy Welch as being way OTT for normal road use.
>  3. And, I have 12,000 miles+++ as plug replacement mileage so long as
>     they still look and perform OK. Any thoughts?
>
> Thanks, Simon
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20230318/d4965e10/attachment.htm>