Re: [Amc-list] Distributor issues

[Tom Jennings <tomj@xxxxxxx>]

On Fri, 25 Apr 2008, Armand Eshleman wrote:

> factory stock points distributor.
> here's what I'm thinking.........  if a plug is fired multiple times even at
> a low rpm wouldn't that engine become
> more efficient, produce more bhp/torque at that low rpm, and produce better
> mileage??? Maybe the gain wouldn't
> be tremendous but "not needed" just sounds like nothing below 4000 rpm or
> something isn't even worth consideration.
> Wouldn't something like this even benefit let's say a rock crawler??

If the spark is sufficient to light off the mixture, additional
spark will be firing into the hot plasma. It the mixture is very
lean, or spark weak, multiple sparks might help fire it
off. But misfires are misfires, and you can feel 'em, and they
indicate a problem, something needing repair, not a performance
upgrade. Assuming a close-to-stock motor.

The other reason for fancy ignitions is that it takes time
(milliseconds) to charge up a spark coil with energy (in the form
of a fat magnetic field). At high speeds this is an issue, hence
high performance coils (low inductance/lower resistance/higher
currents) and bigger spark-control boxes.

At low speeds, time isn't the issue it is at high
speeds. (High and low both being relative, but if I recall stock
points-and-coil coil charge times are perfect up to 2500 rpm, and
by 4000 rpm coil energy is dropping off, but that's the practical
rev limit of old-fashioned stock motors, so the factory left
it like that.) A plain old oil-filled coil with points charges
up fine and dumps its energy into the plug when the points open.

Below 4000 rpm, even a mediocre performance ignition system is
good repair will fire off a cylinder full of mix reliably.


Too much ignition may be a waste of money, worst case, but will
not otherwise hurt. Not enough spark is far worse!

For the 195.6, OHV or flathead, it's safe to say a Pertronix
and good coil is way more than enough. Rev that motor to 5000
rpm and it likely sheds internal parts!

For a stock (sub-5000 rpm) AMC six or eight a Duraspark TFI or
GM HEI setup is more than enough.

I wouldn't run points 'cept to be kool! Then you could brag
about not having one single transistor in your entire car
(except radio/stereo :-) and survive nuclear EMP bombs :-)

Beyond that ask an expert! We got 'em here on the list.


And no amount of performance goodies will improve a car in a
bad state of tune.
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