Re: [ihc] Re: Humphrey's Coil Voltage

["Allan Ericson" <lowvolt@xxxxxxxxxxxx>]

----- Original Message ----- 
From: "James Lidberg" <jameslidberg@domain.elided>
> I believe so. That is if you have one.
>
> >
> > If you don't mind. Answering one further question would be helpful in
> > furthering my electrical education. I noticed in the circuit diagrams
one
> > of the wires to the coil was tagged as a resistance wire and had to be
> > exactly 72" long. What is the reason for this?
>
> I believe it is the + feed to the coil and  takes the place of a ballast
resistor. What year Scout is it? I have the
> manual for the later years, and can look it up to give you my opinion.
Page number, circuit number etc would be
> helpful.
>
> - Jim in Mesa
>

The earlier scouts had a resistance wire with a value of "about" 1.8 ohms.
The internal resistance of the coil is about 1.5 ohms, at least every one
I've measured from a stock pickup, travelall, or scout circa 1970. This
gives an approximate run voltage of 6 volts. Naturally, the start curcuit
doubles that voltage, which also doubles the current.

The resistance wire's function is to protect the points, because the extra
current derived from running 12 volts burns them up pretty quickly. Since 6
volts was adequate before the change to 12 volt systems, the auto industry
stayed with 6 volt coils in most vehicles. This was less expensive than
making 12 volt coils.

12 volts does not hurt a 6 volt coil, however. It just makes a bigger spark.
For this reason, you can use a pertronix or even a high powered ignition,
such as an MSD, with a stock coil.

-Allan