Aug 2005
62 Hawk Ignition setup
Look at the (+) side of your coil.  If there is a pink wire there -
then the correct coil is one with internal rsistance. 62 GT's came this
way.   If there is NO pink wire and it has been modified with a  wire
directly from the switch - through an external resistor - then you have
to purchase one for an external resistor.  BTW the external resistor is
mounted just about anywhere.  Mine is located on the intake manifold.
Some are mounted directly to the coil bracket. It is made of ceramic
and is about 3" long and is thumb sized.

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Ref above, the pink wire is a (thermo?) wire that increases resistance internally while voltage is applied.  It will pass 12 volts immediately, but choke down to 4 - 6 (+/- 1) in a minute or so.  The lower voltage is required to prevent points from burning up.  The coil also has an internal resistor to further reduce the voltage applied to the promary circuit, to an optimum 4 volts.

 The condenser inside the distributor will buffer the arcing at the pointw and prevent pitting and burnout

 The coil in this situation is noted to be 'with internal resistor'

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 On a NON-resistive wire ignition, there is a ballast resistor between the ign switch and coil.  This is a large ceramic unit, 3 inches or so and has a metal mount.  It can be mounted anywhere and is not grounded.  The ballast resistor gets very hot in operation and connects the IGN switch to the coil.  The coil in this situation is note to be one 'with external resistor'.

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 When the coil deteriorates in operation, the performance of the car gets erratic at speed or climbing a hill.  It feels like there's not enough power, or fuel is being restricted.  backfiring can result...  At low speed or starting it appears normal.
The points function as a switch to 'make and break' the coil current and provide a spark for every cylinder.  When the points function, there's a small arc when they open as the current is  interrupted.  This small arc is no problem for most of the point lifetiime, but every arc takes a bit of metal away from one side, oxidizes it and deposits on the other side.  This arcing is buffered by the condenser.  When the condenser fails, the arcing quickly destroys the points.  It's always a good idea to change the condenser when replacing the points.
 If you install the wrong type coil during replacement, the internal resistor type on a non internal requirement will choke down the voltage to the coil enough to cause a low power problem.  The external type in an internal application will allow too much voltage to the points and cause them to burn up.