Pertronix and Ignition Coil wiring confusion

[aphaynes]

Looking at the wiring diagrams for the 1000 series in my 1964 GMC maintenance manual, the ignition coil just has one yellow wire going from the positive side of the coil to the starter/starter solenoid. However, under my hood I have the yellow wire, but also a black wire connected to the positive terminal. I have installed the pertronix ignitor and coil and when measuring as instructed, I measuring 7.5v instead of 12V at the positive terminal of the coil. Supposedly this means I have a ballast resistor somewhere that needs to be removed. However, I cannot find it. I assumed this would be mounted on the firewall in the engine compartment somewhere. However, all I see is the two wires (yellow and black) disappearing into a bundle of wires wrapped in tape. So, first, is my wiring correct for a 1000 series truck since it does not agree with the drawing; and , second, where the heck is this resistor, if there even is one? :confused::headscratch:

[BarryGMC]

The wire is a resistance wire. Trace it back to the switch. Add a #12 wire at the switch. Make sure its on the hot-run-start side of the switch and not just hot-run. Barry.

[aphaynes]

The wire is a resistance wire. Trace it back to the switch. Add a #12 wire at the switch. Make sure its on the hot-run-start side of the switch and not just hot-run. Barry.

Thanks Barry! Hope you are doing well. Bar with me here...
Resistance wire? Letting the wire itself act as a ballast resistor? Add #12 from hot-run-start to...?

[BarryGMC]

Hook it to the coil just like original. Cut the old wire open and you will see how its a resistance wire. I am doing as good as I can. My cardiologist wants to pop in a pacer defibrillator . However welding and gas powered tools are a problem. Cardio versions are rough in a controlled situation. So the thought of getting hit when I strike an arc has me bugged. I don't want to give up a few things but I don't want to get a serious trigger flinch either. Things to ponder in the next few months. Barry

[aphaynes]

Dang. Didn't know you had that going on. Prayers are with you.
I'll check it the wire. I guess driving it to town and back right now with 7.5v on the coil would not be a good idea? Wife and daughter were hoping to go to the drive-in in it tonight. Oh well. LOL.

[aphaynes]

Call me a newbie but it just looks like silver stranded wire in a black insulator to me :lolsmack:

[BarryGMC]

I will look at my junk. Most I have seen are solid wire that is tinned. Or a 3 or 4 strand twisted tinned wire., . Thanks for the prayers. My dad died at 48. I got the same condition. The kids seem clear. So hopefully it ends with me. Norske and ojibie Cree seem to be a genetic problem for me. This is a problem for my Yale trained cardiologist. Since I am still more capable than most.

[BarryGMC]

If it runs drive it.

[aphaynes]

LOL! It ran but I had time to run the wire as suggested. So now it has the proper 12v at the coil. And we still made it to the drive in! :D

[bozzhogg]

This may be off topic but I have a '66 GMC with a 305D V6. Am I suppose to use the same sparkplugs as the 305E or am I to use a different plug for the 305D V6????

[aphaynes]

This may be off topic but I have a '66 GMC with a 305D V6. Am I suppose to use the same sparkplugs as the 305E or am I to use a different plug for the 305D V6????

I have no idea. Maybe the pros here can answer that.:goodluck:

[bigblockv6]

You're not off topic at all, The 305D was used from 1961-62 and will have shorter reach plugs over the 305E so it is important to use plugs specific to the 305D. AC-C44-S were the spark plugs used on 305D engines, long discontinued so you will have find out what number cross links with it or replaced it.

[newyorksong]

This entire thing needs more research because I read a post from the HCI guy who seemed to know quite a bit and he pleaded "Please if you use PerTronix use it WITH the ballast resistor wire in the truck!" His point (ha points!) was that it will work fine with the lower voltage and NOT burn out as the PerTronix can do. I am doing this now and wondered about the info from PerTronix about doing away with the ballast resistor wire. Fingers crossed but I did notice that aphaynes WAS able to run to the drive-in WITH the ballast resister (which BTW is what looks like the silver stranded wire looking wire) ... The wire IS the resister! Plus my 65 1000 ran for 3 yrs with the 2 wires on positive of coil. Much more important however is: WHAT MOVIE???