Terry, I think you mean electrode and not diode. A diode has low resistance
in one direction, and very high resistance in the other. A spark plug has
the same [high] resistance in both directions.
The only advantage I have observed with the Splitfire plugs is that they
might need re-gapping less often. The spark has two paths it can take to
ground from the split electrode and will take the path of least resistance
(the shortest of the two gaps).
The Bosch Platinum plugs I am using only have about 20 miles on them so it
is too soon to tell how they will hold up over time. Platinum is often used
as a catalyst to speed up a chemical reaction without actually entering
into the reaction itself and becoming a by-product. This is high school
chemistry. My hope is that the Bosch engineers have at least been educated
in simple chemistry and know how to successfully use Platinum in this manner
so that we don't have to worry about it burning off after a few hundred
miles.
Reid
'79 Spitfire (original owner)
-----Original Message-----
From: Terry L. Thompson [mailto:tlt@digex.net]
Sent: Friday, May 19, 2000 9:14 AM
To: spitfires@autox.team.net
Subject: Re: Splitfires & another issue
Splitfires don't work in theory because, even though they have a split tip
to ground, the electrical diode is still single point of powere emination.
An arcing spark is likely to jump to one or the other, but not necessarily
both simultaneously (and if it does, the spark voltage will be greatly
reduced). In the instance that you are burning-up plugs (incorrectly
gapped), I suppose the split point will take twice as long to burn away the
ground, but that's not exactly a saving grace.
I have NO idea what Splitfire makes a double core cable, since both wires
would terminate on the same diode. It seems to me that a larger diameter
(7mm-8mm) wire would perform the same duty (and better) because, DC current
travels through the mass of the object (unlike AC which travels over the
surface of a conductive material). And the Splitfire dual cores look like
two 4mm cores, which should be less conductive mass than a 7mm
wire(cylindrical volume =3.14 x (radius x radius) x length) . (384.6 cubic
mm of volume/per linear cm of cable for a 7mm wire compared to 251.2 cubic
mm of volume per linear cm of cable for a dual 4mm wire.)
I hear that there are some plugs that actually have multiple diodes as well
as the multiple ground 'finger's to generate multiple sparks, but they are
not made for our vehicles. You'd probably wind-up burning nice holes in your
piston heads.
Also, from what I understand, the Platinum plugs are good for the first
100-500 miles, that's when the platinum coating has burned-off of the diode,
and you're left with a standard plug.
The other issue is going back to telling the difference between a Jaguar
owner and a Triumph owner...Has anyone else noticed that there are a hell of
a lot of engineering types that own Triumphs (specifically Spitfires)?
The only commonality I have seen to Jaguar owners is that they have more
dollars then sense (though I've heard tales of people that actually do more
than change the oil themselves in their jaguars!).
-Terry L. Thompson
'76 Spit 1500
Maryland
> I just saw a notice in the parts store that either the U.S. or state of
> California (I forget which) won some kind of lawsuit against the
> manufacturers of the
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