If you're talking about a late Midget, the rectangular ballast bolted
underneath the fender lip where the hood closes on the driver side, that
ballast is not the coil ballast. The coil ballast (at least on my '78) is a
resistance wire, a long one that runs way up front along the grill bundle --
kind of furry looking. It is bypassed when you crank the starter, and is in
the coil primary circuit in run mode. You can test its resistance with an
ohmeter - just unhook the coil lead and test between the end of the lead and an
ignition-on wire (I think that's a white wire - I don't have a diagram in front
of me, something else I lost in the recent OKC tornado!). Anyway, unhook the
battery before you do the test and look at a wire diagram to be sure. It
should be about an ohm or two.
The rectangular "Chrysler" resistor was part of the logic for the original
equipment electronic ignition, and if memory serves I think it's a higher value
(about 10 ohms?). It's unlikely you will have a use for it, unless you're
installing an original type ignition, or another electronic ignition that just
happens to call for that same value. It's way too high a value to use as a coil
ballast....
You can abandon the furry one in place and wire in an new one if you like from
an ignition-on source. The long wire types were used for heat dissipation and
low radio interference, but a discrete Chrysler-type usually works OK too. The
value you use depends on the coil primary impedance, and what you're trying to
do. Even if you're not doing the "hot-start" trick, a resistor in the primary
helps points life on a standard ignition. A very low value resistor in the
primary acts a pad to lower voltage a little, and in concert with the condenser
eases arcing across the points. When doing the "hot start" trick with a 6V
coil like the late Midget, they matched the ballast-wire value to the coil's
primary impedence. This effectively dropped the primary voltage in half (about
6V nominal in run mode), but when bypassed during start the coil sees twice
that across its primary.
If your new coil is already ballasted internally there's no way to wire the
hot-start trick; just bypass any existing ballasts and wire your coil directly
to an ignition-on source.
--- Nory P <nory_midget@yahoo.com> wrote:
> Does that mean that if I use the sport coil, I can
> remove that stupid looking Chrysler ballast doing the
> job under the hood at the moment?
> ===
>
===
Michael B. Dietsche, P.E.
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