Actually, it does.
Better electron emission is obtained when the center electrode of the spark
plug is of negative polarity. This is because of the thremonic emission
effect from a cathode (negative electrode).
The output from a coil is a decaying sine wave. That is, alternating
positive and negative pulses with each one smaller than the previous one.
Optimum performance is obtained when the system is polarized such that the
first swing (the largest) is negative on the center electrode of the spark
plug.
This all sounds very esoteric but in actual fact it makes little difference
in actual performance. Modern ignition systems have sufficient voltage that
you will get adequate performance without worrying about polarity. If you
reversed the wires on the coil you most likely would not notice the
difference in performance.
Ignition tends to be binary. That is, it works or it doesn't. If a spark
is hot enough to fire the fuel mixture, a hotter spark does not do it any
better! If your car does not electrically misfire, it is adequate.
Gerry
> -----Original Message-----
> From: LSelz@aol.com [SMTP:LSelz@aol.com]
> Sent: Tuesday, May 04, 1999 11:02 AM
> To: Dave.Vodden@uk.ecitele.com
> Cc: morgans@autox.team.net
> Subject: Re: Positive or Negative Earth
>
>
> Dave copied us from a Mini site as follows:
>
> "....When very early cars were built with negative earths (ie. the
> negative
> terminal of the battery connected to the chassis) it was found to cause
> excessive corrosion of the battery terminals compared to
> positive earth cars. Positive earth cars also required 10% less voltage
> from
> the ignition to produce the same spark. British car manufacturers changed
> to
> the then superior positive earths but European and American manufacturers
> retained negative earths....."
>
> I may be doing dishonor to the institution that granted my MS in Physics,
> but
> I don't yet understand how this can be. I know how a battery generates a
> potential difference between its terminals via a chemical reaction, and
> understand in terms of atomic charges, electrons, and "holes", why
> current
> flows via a conductor from an area of higher potential to lower electrical
>
> potential. I don't understand how the terminology we use ('+' and '-')
> can
> generate a hotter spark in a transformer coil depending on which one we
> define as "ground".
>
> "Won't somebody help that poor man?"
> Lannis
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