# Help with ballast resistor wire replacement on '67 GTO



## redgoat67 (Sep 23, 2011)

My 67 GTO started to idle rough and then stall. After a restart it would run rough and stall when put into gear. Just 2 days before I checked the dwell, timing, idle mixture screws, and idle. Also recently, I replaced the fuel pump, fuel filter and had the carb rebuilt.
My mechanic did several tests and finally determined that the problem was a white w/ orange resistance wire that goes from positive side of coil to ignition block. He determined this by discovering that I was only getting 6 volts to the positive side of the coil instead of 12 volts.
My question is what do I do now? Can I just replace just this one wire with a special ignition wire? Or do I have to get a whole new harness? Page 12-3 in my '67 Pontiac service manual shows a schematic. What do I do to get 12 volts back to the plus side of the coil so my plugs will fire and the car will start. I know nothing in this area has ever been replaced since I have owned this car since new. Thus the wiring is 47 years old.


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## 05GTO (Oct 6, 2004)

The purpose of the ballast (resistor) wire is to lower the voltage from 12-13.8 volts down to 8-10 volts to prevent the ignition system from burning the points. Here is an option,

Replace the points with an electronic ignition like the Crane Cams XR-I (750-1720) that can run 12-13.8 volts, then short the IGN#1 to the IGN#2 connections at the switch.

Now you will supply full voltage to the coil when you start the car as well as when the car is running thru the black w/yellow stripe wire. There is no need to remove the resistor wire so you can keep the original appearance under the hood.


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## redgoat67 (Sep 23, 2011)

Thanks for your reply and suggestion. I would prefer to just replace the bad wire. What gauge wire would I use and couldn't I just cut the old wire at the block and connect/splice the new wire to the old wire stub? I know this sounds like shade tree mechanics but I just want to get the old Goat running as easily and quickly as possible.


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## PontiacJim (Dec 29, 2012)

If you still have points, then that may be about right. That is exactly what the resistance wire is supposed to do (I now have to question your mechanic for not knowing this). 12 volts will burn your points. 12volts only if you have an electronic distributor or did an electronic conversion to eliminate your points. Just for fun, you can use a jumper wire with some alligator clips fitted to each end and hook one side to your coil and the other directly to your battery. Will give you 12volts and shouldn't really hurt anything for the short test you are to perform. If it works, then you know there IS a problem. If not, then it is something else. Pull the wire off to shut the car off with the key because you have just "hot-wired" your car. HaHaHa.

If it starts and runs, then it almost sounds like a carb problem. Provide more info please.

This will sound silly, but bad gas? The gas today with its 10% alcohol can be problematic. Not good to let your car sit as it can absorb water/moisture just from sitting around. The gas also goes bad very quickly. I use the StaBil additive you can get at WalMart which seems to make a difference in my 1997 Toyota which is not really designed for this "modern" fuel. The alcohol in the gas also makes the car run leaner.

Automatic or manual trans?
What is your idle set at when in neutral?
If you give the car a little more gas to bring up the idle a couple hundred more RPM's and then drop it in gear at this higher idle does it stall?
Does this happen when cold or when warmed up?
Is your choke working? If set too tight this stall can happen. If fully open when cold it will stall.
Has a vacuum gauge been put on the intake/carb to check for fluctuations or bad vacuum lines? What is your vacuum at idle? A Vacuum leak will do this.
Did they use the correct carb to manifold gasket for your car? There are different gaskets, some with cut-outs and some without, depending on year.
What are you setting the timing at the crank?
Carb idle screws - turn them in gently until they stop, don't cinche down on them. Back them out 2 1/2 turns which should be about right.

Being original owner, how many miles? Have you ever replaced the factory timing chain and gears? These are notorious for stretching, especially with the factory nylon gears, and will cause gross timing fluctuations. You set the timing using the balancer, but your timing will be way off due to chain stretch, worn gears, or both. Simple test, requires 2 people - pull your distributor cap and put a socket/ratchet on the harmonic balancer bolt to move the crank back and forth. Start rotation in one direction and watch the rotor in the distributor. As soon as it moves, stop. Now rotate the crank in the opposite direction and note how far the balancer on the crank rotates before the rotor in the distributor moves again. Repeat one more time. You should not get much rotation (a few degrees) at the crank before the rotor moves if the chain is good and tight. If you can move the crank balancer a fair amount before the distributor rotor moves, you need a new chain and timing gears. My experience is that 70,000 miles is about it on factory chain and timing gears, sometimes less.

As you can see, many things to check to narrow your situation down and hopefully find the problem so you can enjoy driving the '67.


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## the65gto (Oct 9, 2008)

As an option, you can replace the resistance wire with regular wire and mount a ballast resister on your firewall near the coil. Makes for easy troubleshooting. At present, mine is wired that way.


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## pjw1967 (Mar 10, 2014)

the65gto said:


> As an option, you can replace the resistance wire with regular wire and mount a ballast resister on your firewall near the coil. Makes for easy troubleshooting. At present, mine is wired that way.


In my misspent youth I drove a tow truck at night for spending money. We had a box of them behind the front seat. Always replacing them on Chrysler products.


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## redgoat67 (Sep 23, 2011)

I have pretty much determined that my resistance wire from the firewall harness to the plus side of coil is at fault. This wire is identified on schematic as WHT. ORN. & PPL.CR.TR" Have no idea what PPL.CR.TR mean.
I would like to first try and replace this wire with a similar resistance wire (i.e. w/o adding an aftermarket ballast resistor) Who sells this type of resistor wire?
What would I ask for? Do they come on a spool? I only need about 3.5-4 feet. Also, how is the wire to be connected at firewall at harness?


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## the65gto (Oct 9, 2008)

YMMV, but here is what my 65 resistance wire looks like(yellow, right front) as well as the pins used to connect it to the bulkhead connector. I unwrapped the original black electrical tape, replaced the wire and then re-wrapped with electrical tape.

Additional info. This is a calibrated resistance wire. Meaning that it has a specified length in order to present the correct resistance. The wire has so much resistance per foot and therefore you must have the correct length to achieve the correct resistance (voltage drop) . According to my 65 shop manual, 5-7 volts is normal, greater than 7 volts, the wire resister has too little resistance, less than 5 volts, it has too much resistance. (according to the book), my "run" volts usually run in the ~9 volt range. I think the calculations with this is assuming the battery is 12 volts, when in fact the normal volts is ~13.5 volts or so and cause the readings to be higher ?? I.E. supplied voltage (start) = 13.5, "run" voltage = 9 then the resistance wire must drop 4.5 volts.


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## redgoat67 (Sep 23, 2011)

the65gto said:


> As an option, you can replace the resistance wire with regular wire and mount a ballast resister on your firewall near the coil. Makes for easy troubleshooting. At present, mine is wired that way.


I will probably end up buying and using a ballast resistor like your set up. How do I know what ballast resistor to get. A local parts store has ballast resistors from $10 to $309!


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## the65gto (Oct 9, 2008)

Without "hacking" up the wiring with jumpers etc, (not my preference) what I had to do was remove the firewall connector, dig out the tar/sealant around the pin, extract the pin, solder a new non resistance wire to a new pin and reinsert. Run that wire to a spot on the firewall or some out of normal view area, mount the ballast, connect the wire to one side, the other side run to the coil. Its not really that bad after it is done, maybe daunting before you start, but that's the fun part of the hobby??  If you are still in the troubleshooting mode, disconnect the resistance wire at the coil, run a wire from the battery thru a ballast resister and (with the points closed) see what voltage you have before you start taking apart your harness or your mechanic should be able to just run a jumper wire from the battery to the + side of the coil and see if it starts and continues to run. This should be a short duration test such that you will not over heat the coil and/or burn the points.


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## redgoat67 (Sep 23, 2011)

Just a quick question. Right before I had this problem, I hooked up my dwell meter (engine performance analyzer) improperly to my coil. Instead of attaching my red clip to the negative side of the coil I attached it to the positive side of the coil. The black clip was attached to an engine ground. I started the car and quickly noticed that the specs I was looking for were way off. I then discovered that I had the red clip on the wrong side of the coil. I switched it to the negative side and continued with my tests. Everything seemed to check out. However, could I have damaged the coil with this brief incorrect connection and as a result be a cause of my rough running and hard to start condition?


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## rickm (Feb 8, 2012)

standard ignition co. makes two ballast resistors. RU-11 is two terminal, RU-12 is four for Chrysler products. I think you need an RU-11.


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## ALKYGTO (Mar 29, 2010)

Rick, back in the day with my 65 Dart GT convertible I would run the four prong ballast resistor, when I burnt one up I would just plug into the other one and be on my merry way. I also kept a spare in the glove box.

RedGoat, I don't know if you have a good schematic for your car but I bought one of these cool laminated ones for my '69 years ago and they are great. Here's a link - Classic Car Wiring . Com : Home of the original color laminated classic car wiring diagram :seeya:


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## pjw1967 (Mar 10, 2014)

ALKYGTO said:


> Rick, back in the day with my 65 Dart GT convertible I would run the four prong ballast resistor, when I burnt one up I would just plug into the other one and be on my merry way. I also kept a spare in the glove box.
> 
> RedGoat, I don't know if you have a good schematic for your car but I bought one of these cool laminated ones for my '69 years ago and they are great. Here's a link - Classic Car Wiring . Com : Home of the original color laminated classic car wiring diagram :seeya:


Eons ago I drove a tow truck nights and weekends. We had a box of Chrysler ballast resistors in the truck. Occasionally we would forget to check if the box had any in it. If we had say a Dodge with a bad resistor but it had a double, we would swap like you said. Of course we had to tell the car owner that their windshield wipers would not work.......


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## redgoat67 (Sep 23, 2011)

redgoat67 said:


> Just a quick question. Right before I had this problem, I hooked up my dwell meter (engine performance analyzer) improperly to my coil. Instead of attaching my red clip to the negative side of the coil I attached it to the positive side of the coil. The black clip was attached to an engine ground. I started the car and quickly noticed that the specs I was looking for were way off. I then discovered that I had the red clip on the wrong side of the coil. I switched it to the negative side and continued with my tests. Everything seemed to check out. However, could I have damaged the coil with this brief incorrect connection and as a result be a cause of my rough running and hard to start condition?


FINAL UPDATE
Spoke with a seasoned mechanic about by problem and mentioned what I indicated above and he said it sounds like you may need a new condenser. I thought what do I have to lose. I bought one for $8, installed it myself and after 2 weeks of stewing about this THE OLD GOAT STARTED RIGHT UP!! It purred like it used to and really made my day. :yesnod:
Thanks to all who responded.


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