A few questions : the circuit that goes from ign. sw. to coil plus terminal 1978 f600 (389xd) is in series with this "filter" Is that correct ?
second: I have installed a Pertronix breakerless unit, should I eliminate this "filter" ?
third: will a voltage reading with a digital multimeter on the plus terminal reveal to me if there is built in resistance in the ign. circuit ?
the Pertronix installation instructions wants the unit to receive a full 12 volts to its red wire & I am hoping I wont have to run a new dedicated wire from ign. sw. to red wire !

THANKS in advance!

 

The schematic shows the filter in parallel with the coil not in series. It is connected to the Ignition switch side of the coil.
I tried to paste a copy of the schematic but got an error message " to many characters".
I'll mess around little and try again.

 

PDF image attached

 

The filter is a capacitor (also known as a condensor from the days of yore). The idea is that the capacitor will pass through certain frequencies to ground, thereby canceling them out. This removes high frequencies from the +12V circuit that the radio runs on.

AM radios, and FM to a lesser extent, had a REALLY hard time with ignition noise.

The above also goes for the condensor inside the distributor. It is meant to help stop arcing as the points open.

 

You have a FORD DURASPARK on the truck and you are going to PERTRONIX? Wondering why?

What PERTRONIX is saying is that it's module wants to see 12V (also consult directions for coil voltage). Depending on the model year of the DURASPARK, voltage can vary. V was increased year-by-year (through a resistor) as the DS produced a hotter spark.

Does the instruction sheet specify 12V or full BAT VOLT? There is a difference.

That capacitor has nothing to do with the VOLT. It is only a radio interference filter so you can enjoy your RAP MUSIC.

 

1978/79 600 and larger series trucks have the DuraSpark II blue module, introduced on damn near everything else in 1976.

I listed the capacitor part number (D5AZ-18832-A) and applications in another of the OP's posts.

 

my truck has points & condensor, I bought it at a local estate sale & know nothing of it's history. I have learned to question everything when following other mechanics !!!!!
To be more specific: the instructions said to put red wire before a ballast resistor so I assume that would also apply to resistance wire, therefore how do I determine it has R with a voltage reading ?