Re: Pertronix Ignitor Inside Info.

[jlandry@domain.elided (John A. Landry)]

In a brilliant stroke of genius, Darrel Kline <darrelk@domain.elided>
blurted out:

>One time I was comparing a couple of different tachometers against a
>quality storage o'scope, and neither one was within 75RPM's of what the
>scope read. It's pretty sad that I needed a $20K scope just to set the idle
>speed accurately.

I wonder if the newer digital hand held engine analysis tools are more
accurate.  A friend has a digital multimeter with automotive functions such
as a tach... I'll have to try it.  We also have an o'scope here at work.
It might be fun sometime at lunch to check his digital tach against the
multimeter.

>If you ever talk to him again it would be interesting to know how the
>Ignitor compares to the GM HEI, and what the peak output current is. 

Forgive my ignorance, but I'm not sure I understand what you mean by "peak
output current."  Do you mean the maximum current (amps) that the Ignitor
can switch on and off?  Or are you talking about the coil?  As far as I
understand things, the peak output of the coil is more a function of *its*
design, the resistance in the secondary circuit (the plug gap for example)
and whether or not the primary field is fully saturated.

>Does Pertronix recommend any particular coil?  There's some really hot
>coils on the market now that will only work with certain ignition modules,
>other modules will burn out.

According to the instructions that came with the Ignitor, any coil which is
compatible with a breaker-point ignition system is acceptable for use with
the Ignitor.  The coil should have a minimum resistance of 1.5 Ohms across
the primary coil terminals.  Pertronix specifically states *not* to use a
GM HEI coil.  Apparently the HEI coil has too little resistance and allows
an excessively high current load through the Ignitor.  This undoubtedly
results in possibly immediate or more likely premature failure.  Like a set
of breaker-points, the Ignitor module can only handle so much current
before it fries.  Taking Pertronix's requirement for at least 1.5 Ohms of
resistance in the coil primary circuit, and further assuming about 14 volts
input to the coil, then the Ignitor is apparently capable of safely
handling (switching) up to about 10 amps of current.

Regards,

John
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