coil resistor wire?

[marsjess]

So I just started on my first rover and I seem to be playing the parts game to fix problems. I just replaced the coil with one from napa and it says on the coil "use external resistor". My series iii doesn't have one. Do I need one or do I have to buy a special rover coil? Have I burned up my points?

[Nium]

You can buy 12V coils that don't require a ballast resistor. The theory behind ballast resistor coils is that voltage fluctuations in the electrical system are minimized by dropping the voltage the coil runs off of from 12V to something like 9V. To obtain the 9V (or whatever the coil is rated for) the supply voltage is run through a ballast resistor which unlike a normal resistor, that would allow the reduced voltage from the resistor to fluctuate with the voltage of the electrical system, the ballast resistor compensates for fluctuations of the electrical system to deliver a more consistent reduced voltage to the coil.

If you want to keep the coil then you need to get a ballast resistor for it. Napa should have 'em.

Otherwise get a coil designed to run off of straight 12V.

Since coils rarely fail though why are you replacing the coil?

Welcome aboard

[marsjess]

Now that you mention it I don't think replacing a coil has ever solved any ignition problems in the past. Thanks for the info. Do you think I can run the rover a few days without the ballast resistor? Could this cause some of the poor performance during acceleration? We have set the timing, points, adjusted the vaves, rebuilt the carb, replaced the fuel pump, alternator, battery,fuel filter, and she idles perfect but when you put your foot into it she blows back and drops off.

[SafeAirOne]

See this thread for a good explanation (http://www.roversnorth.com/forums/showthread.php?t=6542) of what a ballast resistor does and why.

What do you mean by "she blows back..."?

Without knowing exactly what the symptoms are that you describe, I'd be looking at mechanical and vacuum timing advances or fuel supply.

[kevkon]

Lucas distributors have their share of problems. One major one is that the mechanical advance system is below the contact plate and out of sight. It's not uncommon for dirt and corrosion to hinder or completely stop the advance weights from working. You can set the timing correctly, but the advance can either be frozen or erratic. Check the mech. advance operation by trying to turn the distributor shaft. It should move freely and return. You can also use a timing light and increase the engine revs. You should see the timing advance.

[gudjeon]

The point (pardon the pun) of a resistor, be it internal or external, is to reduce the voltage handled by the points so they last longer. Running without the ballast will not likely cause harm for the short term. Long term, it will have the points handling full 12v when originally made to handle, say around the previously mentioned 9v. Long term use at 12v will likely result in premature wear due to heating and arcing. I rewired my system with a new aftermarket coil and ballast made for electronic ignition. I ran this set up with points and now a pertronix unit. Seems to work and the spark will jump around an inch gap. I'm happy with that:thumb-up:

I second the checking of the distributor's innards. I popped it off the motor for a full inspection. The centrifugal weights were corroded in place and any advance would not happen. Once freed, cleaned and lubed, it was like new again, giving new life to the motor.

[marsjess]

Thanks for your help. We hooked a timing light and watched as the timing jumped all over. It would advace and then retard. Sometimes it would even run great. We set the points only to find the next time we checked they were different. The plate where the point atached wobled all over the place. I ordered a new distributer this evening.

[Terrys]

While it isn't an absolute necessity, when running an external resistor in the coil's primary circuit, it is commonplace to use a different solenoid. There are solenoids which have a 4th terminal, which is only energized when cranking, and a bypass wire is run from this terminal to the terminal of the resistor going TO the coil. When you engage the starter, the resistor is bypassed to give full 'system' voltage, to offset the voltage drop caused by the starter load, when you let off the key from the starter position, the bypass circuit is disconnected, so that primary coil voltage goes through the dropping resistor.
Rather than using a coil without an internal resistor, and changing the solenoid, just use the recommended coil with internal resistor.

[PeterK]

A neat trick I do is use an externally ballasted coil and run an extra wire from the + side of the coil to a switch on the dash so I can send a full 12 volts to the coil which only expects 6 or 8.
It will literally boost your spark and help cold starts and wet water crossings.
Don't run it too long or it will be tough on your coil.

Peter Knowles

[Terrys]

A neat trick I do is use an externally ballasted coil and run an extra wire from the + side of the coil to a switch on the dash so I can send a full 12 volts to the coil which only expects 6 or 8.
It will literally boost your spark and help cold starts and wet water crossings.
Don't run it too long or it will be tough on your coil.

Peter Knowles

Thats what the extra terminal on the solenoid does when you're cranking, but I don't think I would be wanting to increase the intensity of the spark during water crossings, simply because that will double your likelyhood of tracking, arcing etc. The dielectric properties of the ignition wires, cap and rotor are sufficient for a 40,000 volt spark coil, but when you get up into the 55k volt (high intensity range) there is insufficient dielectric to prevent random shorts. This is why it's so common for people to have to replace their ignition wires shortly after going to an aftermarket coil such as the MSD and many others.
Phenolics used for distributor caps on series trucks are alwayss black, and it isn't a fashion statement that there are blue and red caps on the V8s. Blue phenolic has a much higher dielectric rating than black, and Red is higher than blue.
Once you develope a tracking line on surfaces like the distributor cap, it will evetually burn in carbon line and permananly give a path to ground.