triumphs
[Top] [All Lists]

RE: One Black Plug

To: "john donnelly" <pdonnel1@san.rr.com>, "'triumphmail list'" <triumphs@autox.team.net>
Subject: RE: One Black Plug
From: "Randall Young" <ryoung@navcomtech.com>
Date: Wed, 29 May 2002 22:49:44 -0700
> Here's another curious note. The manuals describe multiple plugs
> (all Lodge
> #'s) depending on the condition of the engine (stock, race
> modified, etc.).
> Are the Bosch, Champion, NGK plugs we've been discussing here covering
> these conditions (or heat ranges?), or is there an equivalent for each of
> the Lodge #'s?

At one time, there were conventional construction Champions available that
would fit, in different heat ranges.  However, to the best of my knowledge
they have been discontinued.

> Or, let me ask a different way. Is there a cross reference chart showing
> hotter/colder plugs, possibly by brand?  Spending $10 or so
> trying to find
> a better plug may be worth the money, but I need to know what
> model numbers
> to go after.

Thing is, if only one plug is black, the plugs are not the problem !

Plug heat range is a fairly confusing topic, at least to me.  For Bosch
plugs, the number determines the heat range (IOW if only the number is
different, the plug will physically fit), and the higher the number the
hotter the plug.  So, if you could find them, a W8BP would be a hotter plug
(the 'R' means resistor and my chart doesn't list a WR8BP), and a W6BP would
be a colder plug.  However, I've been told that all but a few non-resistor
plugs have been discontinued.

For NGK plugs, it's still the number, but they run in opposite order, so a
BP5HS is hotter than a BP6HS (and is listed as the equivalent to the W8BP).
However, I don't find a BP7HS listed, BP6HS is given as the equivalent to
both WR7BP and W6BP.  Of course, manufacturers take a lot of liberty with
equivalence charts !

> One last note. When running the Lucas Sport coil, the spark should be
> hotter (more voltage,  meaning bigger spark). Does that mean you
> can could
> spread the plug gap wider (maybe to .030) to obtain a bigger (better?)
> spark?  It seems like there needs to be a balance between the
> coil and the
> plugs (and wires) based on the condition and tuning of your
> engine. Bigger
> (or hotter) may not be better.

Some people have reported a small improvement from opening the gap to
perhaps .027".  .030" is too large IMO, you'll start having rotor failures
and whatnot.  Personally, I couldn't tell any difference whatsoever, so I'm
still running .025".

The temperature of the spark does not go up, neither does the diameter of
it.  What does go up when you lengthen the gap is the length of the spark.
If you think about this in terms of lighting a candle with two matches
instead of one, you can see why it doesn't make a big difference.

Randall

///  triumphs@autox.team.net mailing list
///  To unsubscribe send a plain text message to majordomo@autox.team.net
///  with nothing in it but
///
///     unsubscribe triumphs
///
///  or try  http://www.team.net/cgi-bin/majorcool


<Prev in Thread] Current Thread [Next in Thread>