Just had a look under the bonnet of my mid 80`s Mog and there are two wires connected as the coil + which would seem to indicate that there may be a ballast resistor in the circuit. I could not see a ballast resistor similar to those I have in times past, however I guess it could be built into the base block onto which the coil is mounted..?
No sign of a radio suppression capacitor similar to the one L. posted, but in my Haynes manual covering the Rover SD1 V8 from 76-87, there is a wiring diagram on page 220 the wiring diagram for V8 S models identifies item 102 as being a ballast resistor 103 being the ign coil, and 105 alongside being identified as a radio capacitor... Might be best to draw your own conclusions.
As RichardV6 determines the correct coil to operate with a Ballast resistor is 9 volts, then I have every confidence that is what it will be... as opposed to the circa 6 volts I suggested it might be, I just remembered it was a lower voltage coil... Thanks Richard.
My mid 80`s +8 has no EFI and has an alloy bodied Lucas coil with a white top....
L. I don`t quite understand the pic of the capacitor/condenser these are designed to reduce spikes on circuits with fluctuating voltages by flattening out the peaks in a voltage graph measured over short periods of time as in the switching such as an ign a coil on and off in rapid succession to fire the spark plugs, which is an entirely different function from that of a ballast resistor that is designed to drop the voltage arriving at the ign coil..
While my Mog has no visible capacitor visible alongside the coil, that the Mog was rebuilt it may have been discarded at that time.... I have never tried to listen to the radio while driving, though it does not suffer any interference from the pulsing of the ign coil or plugs, though i suspect while driving the radio would be difficult to hear over the sound of my Mog`s somewhat untamed exhaust note... (-:
