Ford used the resistor wire for DECADES... 60s into the 80s.

Josh

 

Btter reduce volts on Petronix too.
Completly blew mine up over weekend in the crawler.
I mean blew it up...what a mess inside the dizzy....

 

I am having same problem after I replace the points it runs good for a couple of days and then starts to stumble and miss. So checking to see what my bolts are at the negative side of coil and I think it was 12v if that is the case would that mean I need to replace resistor wire? If so where is this located? Also would I need to replace the coil also?
Thank you

 

You are 100% correct fords of that year used a resistance wire. I know because I have a 73 F-250. However as much as there are Points haters out there I like points because they are simple to repair. If electronic goes out when yer out in the boonies yer screwed. If points go out you can clean them and re gap them. I feel simpler is better. And thats what those trucks came with Original. The only thing I changed from original is the Carb and Intake to a Edelbrock intake and 600 CFM carb.

 

Where is the resistance wire located? How would I replace it? Do I need new coil?

 

SO the illness is a "stumble/miss" after replacing the points?

What makes you think it's the ballast resistor circuit?

First off, you would be better served if you started your own thread as this one is 9 years old.
If you read it through, have you replaced the condenser?
Have you set the points with a tach/dwell meter?

If you want to throw parts at her without troubleshooting first, well, that's your call.
But check the ballast resistor circuit first: Key ON engine OFF...measure the voltage from the BAT (+) terminal of the coil to ground, not the TACH TEST (-) side... You want to see ~ 5-8 VDC.....mebbe ~ 6-9VDC.

 

Yes I am new and just realized how old this topic is my bad. Yes I have replaced the condenser
yes I have replaced the condenser also. I did a complete tune up on truck when I first got it and soon after I did it it was slowly starting to stumble at first then became worse as I drove it more. At first I thought that it may have been a bad ground on my condenser as I could not get the screw out that was holding it down so I just removed the old condenser from the strap and reused it with the new one but it that is the ground I definitely would not say that it was a solid ground. So going after the problem that happened after the work I started there. I was able to get hold down screw out and replaced it and a new condenser but still had the stumble miss fire issues so I looked at points and found them to look “ burnt for only having less than 150 miles on them so I replaced them thinking the ungrounded condenser could have burned them up. Installed new points gaped them and timed it and it ran awesome without stumble or hesitation now as I put more miles on truck maybe 50 mikes it is starting to stumble very slightly on acceleration just what it started to do last time so I’m thinking something is burning up my points and at this point I don’t know what so I’m trying to figure it out any help would be awesome I will definitely check coil bolts when I get home to see where I’m at and that should tell me if resistance wire is bad right? Although it did looked cracked in several places on the insulation so I wrapped it with electrical tape maybe I need to take a closer look at that pink wire again?

 

If your coil is messed up, I'd bet lots of money that your resistor wire is bad, was removed/trimmed/etc, something. Check your coil volts, I'd almost guarantee you've got full voltage to it, and you're burning it up, as well as putting too much voltage to your points and burning them, too - at the very least, you should have low voltage to the points, 4-8v, I believe.

Did all Ford trucks this era use a resistor wire? I had it in my head some used an internally resisted coil, so it was 12v in but only 6-8v out to the points? Different brands did it differently, IHC used 6v coils up to electronic ignitions, ballast resistor on the firewall, others used 12v coils straight up and a ballast resistor/resistor wire between the coil and points, and some used resistor coils - I forget who, however. They used to be really popular when switching something over from 6v to 12v.

 

Yes, check the voltage to the coil, key ON, engine OFF.
If that pink resistor wire is brittle as you say it probably crapped the bed. In that case it's putting a full 12 VDC...(or BAT voltage) to the coil.....and probably burning it out and, in turn, the points. These OEM coils weren't made to RUN on BAT voltage, just a few seconds in the START mode.

Take a check of yer coil, too....ohm out the primary and secondary windings... ~1.5 ohms on the primary and mebbe 10K ohms on the secondary - on a points vehicle.

Afterthought: When rechecking yer resistor wire, make sure a PO hadn't tapped into it for a radio, etc. It should be all alone in the wiring world.

I think it's still available from a parts store/Dealer.......(courtesy NumberDummy) C0LF-12250-A .. Resistor Wire-Ignition Coil (Motorcraft DY-37) / Obsolete

61.49" long / Color coded pink / 1.30-1.40 ohms resistance / #20 gauge wire.

1960/73 ALL FoMoCo vehicles. 1974/75 ALL FoMoCo vehicles without DuraSpark electronic ignition.
__________________

 

well to my surprise the volts at the coil is 7.1 with key in on position not running ? I will check resistance on windings when I get home and see what the coil is at ?

 

-i have seen 12v systems where you will measure about 7 volts due to the voltage drop across the coil (because it does have a resistance). If you just replaced your coil you might make sure that you purchased the correct part. They do offer a 6v or 12v version and when you buy them from your local parts store they usually do not have numbers on the part itself(just the box) and of course, they look exactly the same. You mentioned replacing all tune-up items so I would not assume that you were given the correct stuff. It may help to bring your multimeter to the parts store and ask them to pull both versions to ohm test them in comparison to yours. I have had to look up the part for an older model just to obtain the correct one. Unfortunatly, our parts stores computer systems have flaws and most of them have thrown their books in the trash(where the real information is at).

 

i did not replace my coil yet I will test the ohm on mine and see what it reads what would a 12v vs 6v coil read in ohms? I do have a Napa right down from my house who still have all the books and there is a great counter person also so that helps

 

I cannot remember, but I suggest going to your Napa Guy there Im sure he will let you take measurements of coils off-the-shelf so that you have that data on hand. Most manuals just say measure across the coil, which is vague, so it is better to do in person so you know where to put the poky bits to get the reading your looking for. I put points on a 302 project i did like 5 years ago because they are simple and cheaper and went through all of this, got mad and went electronic in the end. I've packed away my books now and not sure where i put them?

Did you have problems before you went to replacing anything???

 

Where are you getting these points and condensers from?

The "classic" and parts store market is saturated with absolute junk ignition parts these days. Even remanufactured distributors are sent out with these **** parts. Only use Motorcraft or NOS points and condenser, or Echlin, Standard, etc from the 50's thru 70s. They aren't tough to find and they don't cost any more than the junk. Used pulls from a junkyard are better than the new stuff. Noticed you said problems surfaced right after replacing condenser.

Probably once every couple weeks here on this forum alone somebody has the same problem. Junk condenser. Probably have more than one problem going on here but, the replacement condensers especially are no good at all. If you have an old original put that back in for now. Once a set of points have been run a fair bit a feeler gauge is about impossible to use, to set them correctly a dwell meter should be used. Also the distributor cam should have a light coat of distributor grease. A brand new set of points, the rubbing block will wear down a bit and point gap should be re-checked after 50 or 100 miles or so. Then the gap or dwell should be good and stable for a long time. El-cheapo points will just continue to wear down to a nub.

The resistance wire is part of the wiring harness, it runs from the ignition switch to the firewall and is pink in color. Unless it's been removed or bypassed it's probably still doing its thing.

 

well no but I did replace everything the day after I brought it home so I did not put many miles on it? And maybe the guy was having issues and replace it all and put up for sale? I’m just ready to drop some money on a HEI dizzy and forget it all ! Lol if I do that will that need a coil also? Or is that the point of electronic ignition is no points and coil?