Yup, you don't want to toss Iridium plugs in to do some chops. For that you
use BP7HS or BP7HC (half a heat range colder) and toss 'em after. Iridiums
are for when you think your engine is going to stay the same way for a long
time (and your piston isn't going to hit them). They last and last. Ordinary
plugs need a fairly big wire (about 2-3 mm) to conduct heat away, and the
edge of the center electrode rounds out as the combustion gasses torch away
at it. The wire size of an iridium plug is .6 mm. They melt at 4500 degrees.
If anything in your engine reaches that temp it will all be slag. So the
electrode stays sharp and that means the spark will jump easily, so you can
use a slightly bigger gap with everything else the same. No silver bullet,
no decrease in lap times. Just nice parts that work really well for a very
long time.
-----Original Message-----
From: Jack W. Drews [mailto:vinttr4@geneseo.net]
Sent: Monday, July 12, 2004 3:27 PM
To: Bill Babcock; T.R. Scratchings; Charly Mitchel
Cc: friends of triumph
Subject: RE: TR4 spark plugs
>Ah, yes. Iridium spark plugs. The good and bad of it:
The NGK guys at the PRI show in Indianapolis showed me a videotape of the
spark action on a regular plug and a fine wire Iridium. Terriffic
difference. This was good.
Bought a set of NGK iridums -- price four times higher. This was bad.
Admired them, put them in, felt great about having the latest technology.
This was good.
Went to the track -- didn't run any faster -- this was bad.
Plus, they don't last worth a hoot when a rod breaks and the piston bounces
off the plug and breaks the insulator. That means my big blowup will cost
$5 more because I have to replace a spark plug too. This is doubly bad.
I keep trying all these things that come along, looking for the silver
bullet. Space age ignition wires, goofy ignition systems to light the fires,
a whole shelf-full of camshafts, roller rockers that are really pretty but
don't seem to do anything. No silver bullets. This is bad.
I'm going back to my NGK el cheapos that have worked just fine all these
years, and my conscience won't bother me when I decide to "throw a new set
of plugs in 'er". This is good.
Plus, I get to entertain my FOT friends with this drivel. This may be good
or bad, depending on your point of view.
uncle jack
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