> > For negative ground, the "-" or "SW" terminal of the coil should be
> > connected to the distributor, the other to the wiring
> harness. For
> > positive
> > ground, the "+" or "CB" terminal goes to the distributor.
>
> Randall, are I you sure this is necessary?
It's not absolutely necessary. But most sources will tell you to do it, and
the OP was wanting to know what to look for, so I mentioned it.
In theory, the spark plugs are easier to fire with the proper polarity
(somewhat the same effect as a vacuum tube diode). Thus, changing the coil
polarity should reduce the chances of having a misfire under conditions
where the spark is marginal (low voltage, eroded points, high rpm, etc).
But in practice, the difference is too small to notice, at least if the
engine has had a tune-up in recent history.
> Electronically, I don't
> see how it makes any difference.
Here's a rather more lengthy article on the subject, along with some test
methods:
http://mgaguru.com/mgtech/ignition/ig104.htm
> Is there something I am missing or
> that could ultimately be harmful?
Running with the polarity backwards won't damage anything directly. In
fact, some engines fire the plugs backwards on purpose. (I had an old Honda
motorcycle that fired one plug backwards.) Worst case, the engine might
need a tune-up a bit more often (or waste more fuel when it needs one).
> Although not related to the Lucas coil's polarity, the only
> thing I
> wondered about was if the capacitor (condenser) across the
> points was
> polarized, but I didn't see any evidence of that.
No, the condenser is a non-polarized type (typically paper). It has to be,
because the kickback from the coil (when the points open) is opposite to the
battery polarity (thus the condenser sees voltage in both directions).
Randall
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