Hi Jay Quinn and Kevin Sullivan!!
On Thu, 24 Apr 1997, Jay Quinn wrote:
> >A few days ago someone mentioned that they opened their plug gap to
Yup, that was me... using new Bosch PLATINUM plugs + STOCK points ign.
> >something like .040. I'm running totally stock and yesterday tried
Went from stock 0.025" gap up to 0.060" whereupon we experienced
misfiring on a hill, at wot, pulling over 5,000 rpm.
> >opening my plugs up to .035 from .025. Seems to have more power but I'll
According to the dyno tests published in a Mopar magazine, platinum
does have more power than either stock, or Splifire plugs. But ONLY IF
THE PLUG GAP IS OPENED UP SUBSTANTIALLY.
> >have to do some more experimenting. Was the idea to open the plugs until
> >you get high speed miss (coil voltage can't keep up?) and then close them
> >.005? Bigger gap, higher voltage, better burn?
Yes, that's the only way to do it unless you have the use of a chassis
dyno...
> >If the car runs best at .040 why is the spec. .025?
Because the voltage required to fire across a given gap is a lot less
with a new plug with sharp electrode edges and uncontaminated electrode
metal, you can get by with a larger gap than if the plug is used.
In the days of leaded gas, the plug gap used to erode at approximately
0.001" per thousand miles of average driving. So, at about the 10,000
mile mark, you would find it was time for a tune up. File the plug
electrodes to expose pure metal with sharp edges, chip off the
deposits to prevent fouling, reset the gap from 0.035" back down to
0.025" and away you went.
If you had started out with a gap of 0.035", you'd never get to the
10,000 mile mark without a tune-up, more like about 3 to 4 thousand!!
As far as flame front, etc. I don't know enough to spout off. I do know
that at the higher rpm's (over 7,000) the alignment of the plug ground
electrode becomes worthwhile setting by shimming the plug gasket.
TTUL8r, Kirk Cowen
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