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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. <br>
<br>
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.<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 3/18/2023 9:49 AM, Simon Lachlan via
Healeys wrote:<br>
</div>
<blockquote type="cite"
cite="mid:000001d959b9$ad626970$08273c50$@alexarevel.plus.com">
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<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif">Here’s a can of worms that we haven’t
delved into for a while….<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif">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.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif"><o:p> </o:p></span></p>
<ol style="margin-top:0cm" type="1" start="1">
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l0 level1 lfo1"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif">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??<o:p></o:p></span></li>
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l0 level1 lfo1"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif">And which plug? Seemed to be mostly
between NGK’s BP6ES & BP5ES. Was a hold-out for their
B8EGV 5627</span><span style="font-size:12.0pt"> but that</span><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif"> was dismissed fairly vigorously by
Jeremy Welch as being way OTT for normal road use.<o:p></o:p></span></li>
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l0 level1 lfo1"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif">And, I have 12,000 miles+++ as plug
replacement mileage so long as they still look and perform
OK. Any thoughts?<o:p></o:p></span></li>
</ol>
<p class="MsoListParagraph"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif"><o:p> </o:p></span></p>
<p class="MsoListParagraph"><span
style="font-size:12.0pt;font-family:"Times New
Roman",serif">Thanks, Simon<o:p></o:p></span></p>
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