ION-related IGN Comments & Coil Quest

[Clare Snyder]

Shannen Durphey wrote:
> 
> steve ravet wrote:
> >
> > kenkelly at lucent.com wrote:
> > >
> > > garfield at pilgrimhouse.com wrote:
> > > >
> > > > On Wed, 27 May 1998 20:25:43 -0400, "Bruce Plecan" <nacelp at bright.net>
> > > > wrote:
> > > >
> > > > >All the General Motors Distributorless Coils are four terminal.
> > >
> > > GM HEI coils are also four terminal, so we can probably say
> > > that all GM coils since 1975 are transformers, not
> > > autotransformers. The HEI coils have all four terminals
> > > already in place, of course it implies using the HEI
> > > distributer for easy mounting.
> > >
> > >                 Ken
> >
> > How about a five terminal coil?  I just looked at my motor (from a '91 Caprice, TBI 350), and it has the small cap HEI w/external coil.  The coil has 4 regular wires (two white, one pink, one large
> > gauge pink) on two weatherpak plugs, plus the high tension lead to the distributor.  What's up with that?
> >
> > As far as coil-per-plug, I had compiled a list of them at one time on the EFI reference document I was maintaining.  You can find a copy of it on the vettenet,
> >
> > --steve
> >
> > --
> > Steve Ravet
> > steve at imes.com
> > International Meta Systems
> > www.imes.com
> 
> Okay.  Here's what you got from the GM HEI coils. The IN CAP
> style have 5 wire terminals .  The BAT and C+ are connected
> to the primary positive side.  BAT is power in, C+ carries
> voltage to the module.  TACH and C- are connected to the
> primary negative side, and C- is switched by the module.
> GND is connected to the iron frame of the coil and is the
> ground for the secondary.  Spark, of course, travels through
> the exposed metal portion which aligns with the carbon brush
> in the center of the cap.
> 
> EXTERNAL style coils are very similar.  There are two
> connectors, each with two wires. In each connector one wire
> is pink and one is white.  Although they are not labeled,
> the  wires in the grey connector are BAT (large pink) and
> TACH(small, white, and often terminates close to the coil,
> taped back to the harness).  The wires in the black
> connector are C+(pink) and C-(white) and are part of a small
> harness which connects to the ignition module.  The design
> and function of these is similar to the above description.
> There is no GND wire as the coil is bolted directly to the
> manifold.
> 
> Although they are probably difficult to find in the wrecking
> yards, the coils for the newer Vortec pickups and (if my
> memory is correct) LT1 type engines are electrically
> similar, but physically smaller.  The secondary terminal is
> somewhat recessed, and provides better coil wire retention.
> Wire colors are different (and much smaller gauge, a sign of
> what?), but same function.
> 
> And now a brief question, found only by those who bother to
> read an entire post.  Will someone please give me a brief
> description of the difference between a transformer and an
> autotransformer?  (We could say that all transformers in
> cars are Auto transformers ; )
> 
> Shannen
An autotransformer is basically one coil of wire, wrapped around a core,
with a center tap. An ignition coil falls into this catagory, as does a
Variac. A transformer has 2 or more separate windings, physically and
electrically separated.
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