In a message dated 7/6/2001 7:06:20 PM Pacific Daylight Time,
gasket.works@gte.net writes:
<< Can you comment on spark plugs and wires? >>
Thanks, Mordy:
I don't have much experience with plugs and wires, other than the following:
The location of the spark in the chamber is sometimes critical. So, plugs
that position the spark and the desired location are preferred. Some people
go so far as to "index" their spark plugs to the the tip at the same point in
each cylinder.
There are lots of claims out there about dual tipped, Y-tipped, quad-tipped,
and NO tipped plugs. Again, it all comes down to, is the spark in the right
place to light the mixture, and keep it lit. Every engine is different, and
the needs within a given engine are different depending on many conditions
(load, rpm, fuel volatility, air/fuel mix, pressure, etc.). Its my feeling
that finding the right spark plug is more of a trial and error process than
anything very scientific. I tried Bosch Platinums in one car I had, thinking
they'd be wonderful. They quickly fouled...I went back to my old standard
plugs and had no problems.
All wires do is get the spark energy to the plug. Solid core copper is the
best electrically (minimum losses), BUT if they radiate so much
electromagnetic energy in the process that they screw up the ignition or fuel
management electronics, then they haven't been effective. Solid core wires
are hard to find as they're technically illegal on production cars from
manufacturers. The manufacturers can't meet FCC mandated EMI emissions with
them. So, "resistor" wires are much more common. The wire has an inherent
resistance that tends to attenuate the higher frequency EMI signals, while
allowing most of the spark energy to get through. There are various
techninques for manufactuirng such wires (edge wound, silicone impregnated,
etc. etc.). I can't comment on what seems to be the best approach for this.
But what is important is keeping the losses to a minimum between the output
of the coil, and the plug. The losses occur in the wires and their
connections, and a big loss in the distributor (if you have one). There are
at least 2 more sparks occuring inside the distributor...one between the
rotating tip of the rotor and the spark tower its passing, and another
smaller one between the center of the rotor and the center coil connection.
And, possibly a third loss through a resistor in the rotor itself on some
engines. For optimum performance some builders "index" the distributor, by
running the engine on a dyno with a "cutaway" distributor cap. By watching
it with a strobe/timing light, this allows them to see precisely how far the
end of the rotor is from the tower it needs to fire. This can be adjusted to
keep that gap minimum, and transmit more spark energy to the plug, and not
lose it inside the distributor (or worse, have it jump to the wrong tower and
misfire). This may mean moving the points, or sensor inside the disbributor
to keep the timing correct, while rotating the outer housing and cap.
Hope that answered your question..
Myles
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