The wiring is driving me nuts. With my points style ignition including a MSD resistor and MSD Blaster Coil it will pop and bang and misfire when I have the ignition wire plugged into the voltage regulator. It runs great when the ignition wire is unplugged and truck is not charging. Is it possible the points are getting too much voltage? I have the resistor that MSD recommends using when using a points style distributor. It is in line with the ignition wire. I replaced the ignition that normally would be a resistance wire as the covering was literally crumbling apart and dangerous. I replaced with same size wire and put resister inline before coil.
It is funny that I work on late model wiring and diagnostics every day but this one is kicking my back side. I am old enough to have worked on these when fairly new. I guess I just have forgotten a lot of it as it is so different to todays DIS and fuel injection. It is so simple it is hard. I appreciate someone taking the time to remind me what I have forgotten. These is no place to hook up a scanner. LOL

 

COLF-12250-A .. Resistor Wire-Ignition Coil (Motorcraft DY-37) / Obsolete ~ Available from autoparts stores / 1960/70 all FoMoCo vehicles.

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

 

I have an external resistor inline in the ignition wire that is a 1.4 ohm. Does it make that big a difference?

 

I just checked this resistor and it is .8 ohms resistance. No store in town has the wire to replace the original tho it looks like it can be ordered. Standard Motor Products is #RW34T. I can get a 1.4 ballast resistor but would it be better to just get the resistor wire? Does it make a difference? Thanks again

UPDATE I ordered the resistor wire and will have it tomorrow morning. I will pull out the wire I put in along with the ballast resistor and put in the resistor wire. After that will see what happens and report back what happens with the misfiring, ect when it is charging.

 

and pix please
roy

 

The sputter from hell.... this one just won't die.

My guess is component failure at higher voltages. Everything can be suspect to fail at a 13.5 vs. 12 volts when it is old, weak, hot, dirty, almost going to ground, etc

Disconnect the B connection from the alternator where it goes to the battery at the solenoid. Plug in the regulaltor and see what happens. With this battery wire hanging in air, it can not supply over voltage to the system.

If the sputter goes away, you have to find out which component is failing due to the higher voltage which is best done with trading out parts with someone with a working system.

Generally I would be suspicious of the coil first, resistors second, regulator then alternator then wiring.

If the sputter remains.... start by trading out the regulator which must be taking the system to ground somehow, if that does not fix it, look at the alternator wiring and test the alternator.

In '75, I poured a half gallon of gas on a lawn mower for sputtering when hot. I then set it afire. It gave me great satisfaction watching the electron gremlins sizzle and pop.... Just saying...

Good luck.

 

LOL
Well, I do have good news in that I replaced the new wire that I put in going from ignition to ballast resistor to positive side of the coil with a new resistor wire from parts store. It is a Standard Motors Products part# RW34T. And it runs like a champ! Thanks again to you guys for giving me a nudge in the right direction. I might actually take it for a drive this weekend. I still have to put ign switch back in and repair wiring going to steering column that I took apart to track down the last problem.