I somehow burned up the points on my 71 F100 360 motor. Do I need to use a Ballast Resistor on the positive lead to the coil or should I just replace the points and see how long they last? I think the old set was from 1971 because it still had the white push-on type connector for the coil wire.
I've used the Pertronix Ignitors before, But had one fail and caused a "late" ignition that blew up a muffler, so I'd rather go with points. Any suggestions?
Thanks,
Joe

 

You should check the voltage on the resistor wire at the coil, it should at be about 7+-9 volts. The first generation of Pertronix Ignitors would start over heating after one minute. Its was a known problem if ign key was left in the (on) or run position with out the motor running. Many guys it this to just listen to the radios they don't bother to turn it to the left for the ACC= Accessories which bypassed the ign power to the coil no over heating the the Pertronix unit. The Sec. Gen of the Pertronix Ignitors corrected this problem. orich

 

Thanks Orich, I did see that they have a 2nd and 3rd generation Pertronix unit.
When you say "resistor wire" you mean the wire that connects to the positive side of the coil correct? I do not have a resistor on that wire as of yet. Should I? or is it in the wiring before it comes through the firewall to the 3 connector plug(coil,oil,temp)?
Bless you for your service then and now sir.

 

Yes the resistor wire coming to the + coil side, it's built into that wire from the ign switch. So you just hook up a voltmeter. One lead to ground & one on the +side of coil. You can do this even while the motor is running. Also the points disty cam should be cleaned and re-lube to maintain points gap longer. This slows the rubbing block wear by doing this. Also check for any side movement of disty shaft. If play is found then time to replace whole distributor or which is about 50 bucks or go back to Pertronix unit..my 2cent .
orich

 

I'd say they were due for replacement. Make sure to install new condensor at the same time.

 

Well I replaced the points. It turns out that they were only a few thousand miles old. Only the connecting wire from the coil was from 71. I did notice however that the contacts inside the dist. cap were worn on one side. They actually had grooves in them from where the rotor had sliced into them. I'm hoping that the rotor or cap was mis-aligned and it is not the whole dist that is at fault.
I get 12.3 volts at the coil, so I got a ballast resistor that I am going to wire in when I put on the new cap, rotor and condensor. I hope that will do the trick.
Thanks for everyone's help in stopping the shakes.

 

Don't be so quick to do that. Unless it was removed, it is still in place. When points are open, you will read full battery voltage. Only when the points are closed will you be able to see the reduced voltage. You could also just ground the neg side of coil and you should read the reduced voltage.

 

okay- i need some schooling.
why will you see full battery voltage when the points are open, even if the resistor wire is in place?

 

Yes, that is correct. No circuit completion means no current flow, no dropping of voltage by resistive wire.

 

Ok, sorry to bring up an old thread, but I've done a search on this, and while the resistor question has been covered a bazillion times, I haven't seen an answer that will get through my thick skull. I installed a Pertronix Ignitor (first series, I'm guessing, since it didn't have any numbers after it) in my 68 F-100 with a 240, along with an MSD Blaster 2 coil. I didn't find any separate resistor (this was before I knew about the resistor wire), so I hooked the coil up as it was from the factory, and ran the red wire from the Ignitor to the + on the coil, and the black to the – on the coil (as the instructions said). It runs like a champ. Now for my question: is this wired correctly, or is it a problem waiting to happen? I haven’t had a single problem yet, but I don’t want to burn anything up. In fact, it runs so great, I got a kit for my ’68 Galaxie with a 390. I just want to make sure I get it wired correctly. I’ve read the directions, looked at the digrams, searched through the archives, but I haven’t found a post that just tell me what wire to attach where. Any help is greatly appreciated.

 

I've only seen a few of these personally(never done one myself), but pretty sure what you have done it correct. It would likely not run/very well if you did it wrong.

 

I have used the Petronix units in other old Fords and they work great, unless they fail. My guess is that the one I had that failed years after I installed it, was a first generation unit. Just follow the instructions provided.
BTW thanks for all the help, the truck is running fine since the repair.

 

the directions for the first-generation Ignitor are very clear- if your system has a resistor wire, you are supposed to leave it in place.

to check- fire up the truck and check voltage at coil +.

if you get ~9v, you're all set.
if you get full battery voltage, its a problem waiting to happen.

 

Well, they are and they aren't. They say not to remove the ballast resistor. They also include a few diagrams showing wiring options. Not knowing the wire served as a resistor, I followed the diagram for vehicles without a ballast resistor. Knowing now that the wire is the resistor, I have a diagram showing the wire to the ignition switch, as well as the red wire from the ignitor going into the ballast resistor, and then a wire going from the resistor to the + terminal to the coil. It would seem to me that if I spliced the red wire into the ignition wire, it wouldn't really be that much different than them both meeting at the coil. Or would it? At any rate, I ran the check you suggested and got ~10 volts. Battery voltage while running is a little over 12.5 v. So am I running too high of a voltage?

 

The problem with the first-generation Ignitor is if you leave the ign. key turned on while the engine is not running for a few minutes, as it will load up and over heat and cook itself. Some guys her had the unit even melt the plastic some. The 2nd & 3rd generation ones have a built in shut off.. I've used all 3 of the drop in Ignitor unit. Liked the 3rd the best..orich