Hi Everyone. So I have a 1966 Mustang, 289, 2bbl Holley that runs great for about 10-15 minutes, until it warms up and starts intermittently sputtering, at idle or while driving. The sputtering happens maybe every minute or two, and it's quick, maybe for a few seconds, until it runs normal again. When driving, the car does great, but then will be sputtering like crazy for about a minute or so, be sputtering at a stop, then will start running normal for a little bit at idle until the cycle repeats.

The car had been sitting for awhile, and had some issues misfiring and just not running. After setting the timing, readjusting the carb, replacing the vacuum advance, the car ran great, until I discovered this intermittent problem.

At idle, the car would just die. No sputtering, just idling normally then.. off. I cleaned the points (they were dirty, but made good contact and didn't seem to be an issue visually). That seemed to fix the problem with it dying, but the intermittent sputtering remained. Decided to rebuild the carb since it was a bit dirty anyway. Still having the same problem.

I checked the voltage at the coil and saw that the positive side was getting 9V at idle, and up to 12+ volts over 1,000 RPM. This was confirmed with analog and digital meters. Just in case it's asked, the alternator is putting out a consistent 13.9V.

I replaced the points, set the dwell, and it ran great... until the cycle started again.

I took the cap and rotor off again and noticed the points were a bit dirty. Not sure how normal they should look after a couple of miles of driving and maybe a total of 20 mins idling.

I pulled the dash out (I have to test some gauge issues), and decided to pull apart the ignition switch and clean the contacts. I also measured the resistance on the resistor wire from the white connector (that goes to the ignition switch) to the 8-pin connector at the firewall. I'm getting 0.6ohms, sometimes 0.3-0ohms with the meter. This is a red flag, right? Shouldn't I see something like 1.5 ohms on that wire?

Other items I tested:

- I tested the condenser and it ramped up in resistance until "O.L."
- I tested the resistance on the coil. Primary resistance is 1.7ohms, and secondary resistance is 7.97 k ohms.

Before I put the dash back together, I want to see if the resistor wire is in fact bad, or if I might be missing something (I know I didn't cover in here that the carb could just be bad or maybe even bad gas).

Ford says the voltage to the coil should be 4.5-6.6V, and anything outside that, to replace the resistor wire. Before I just start replacing every part (or converting the ignition), I wanted to see what I may be missing.

Any thoughts?

Thank you!

 

I think RPM variable voltage to the coil topping off at 12v is going to be bad for a condenser/point set. If I were faced with replacing the ballast resistor wire, and I had the resources, I would upgrade to Pertronix electronic ignition. Also, even removing the ballast resistor wire from the system for that upgrade is a real pain. With the dash already apart it would be an opportune time. Is there any chance you could post a video clip that captures the sputtering? Typically, a carb/gas problem wouldn't be so predictably intermittent, I would lean toward ignition. You could take a clip lead and provide 12v to the coil (hot wire) to see if the symptoms resolve - understanding 12v at the points will significantly reduce its life.

 

Hello Ive got a 66 straight 6/200 that im restoring. Today im focusing on the distributor side of things. Mine runs amazing for 15 min or so then dies and I have to pull of the road to clean the coil wire and the switcher. Any reason that it’s doing that?

 

Four things come to mind. The first would be moister in the bottom of the distributor that, after the engine gets warm, evaporates and gathers in the distributor cap. If you think that is possible, you can dry out the distributer with a heat gun. Second would be the parts in the distributer are beyond their service life and just need to be replaced with new quality components. Third, and it kinda goes with the second, the condenser has failed and is no longer performing its function which is causing failure of the other components, and Fourth, which I don't think likely for a six cylinder car, someone has removed the ballast resistor wire and the coil is getting 12v all the time the key is in start and run. You could check this with a multi-meter if you have one (get one). The coil should be getting 4.5 - 6.5 volts with the key in run. From the original post, it looks like it would be a good idea to check that at idle and at around 1000 RPM.