File this one under 'weird moments of clarity'.
I must have looked at the ignition coil a thousand times. And noted the presence of a ballast resistor a thousand times. Yet it's only the last couple of days that I've wondered 'why does it have a ballast resistor?'...
Turns out that the factory-installed coils before 1970 didn't have one. This is a '68 reg, '69 model year car. It's also a Lucas 'Super' coil in there right now, which has a lower primary circuit resistance than stock (1.5 ohms versus 3). Presumably whoever got the car running before we bought it had that coil and ballast, and threw it on.
I've disconnected the ballast resistor and that's immediately made a positive difference (engine fires off easier, seems to have dialled out a slight miss that we had). But I'm going to replace the coil, partly to get one of the correct spec in and partly because the one in the car has the mark of Lucas, The Prince of Darkness™ on it
I must have looked at the ignition coil a thousand times. And noted the presence of a ballast resistor a thousand times. Yet it's only the last couple of days that I've wondered 'why does it have a ballast resistor?'...
Turns out that the factory-installed coils before 1970 didn't have one. This is a '68 reg, '69 model year car. It's also a Lucas 'Super' coil in there right now, which has a lower primary circuit resistance than stock (1.5 ohms versus 3). Presumably whoever got the car running before we bought it had that coil and ballast, and threw it on.
I've disconnected the ballast resistor and that's immediately made a positive difference (engine fires off easier, seems to have dialled out a slight miss that we had). But I'm going to replace the coil, partly to get one of the correct spec in and partly because the one in the car has the mark of Lucas, The Prince of Darkness™ on it