New ignition coil, hot negative battery cable?

[LuckyLightning]

I just installed on my 1962 235 a new ignition coil that had several good reviews.

I went to start it up and she fired up right away. Idle was rough so I figured it just needed to warm up, so I kept the choke pulled out and I let it go for about a minute and as I exited the cab it finally stalled out.

Okay, no problem. I go to fire it up again...

Nope. Engine turns and turns and turns, but it's like there's no spark.

As I'm taking a look at the coil under the hood, my arm happens to graze the (exposed) negative cable where it attaches to the battery terminal, and it was hot! I touched the positive and it was fine to the touch. Both battery terminals were also fine. I grabbed the coated section of the negative cable to remove it from the battery, and it was pretty warm also.

Anyone see this before? Could the coil be bad straight from the store? Or is it the wrong coil for my truck (even though the store website says it's the right fit)? Why on earth would the negative cable be hot?

One thing to mention: when installing the coil, as I was tightening the nuts on the terminals of the coil, the top "lid" rotated a little due to the torque of applied to the nut (which was not much more than a good-solid-tightening-up). Not sure if that does anything to the coil, but wanted to mention it just in case.

Also, not sure if this matters: I removed the original generator and upgraded to an internally regulated alternator.

[T and S]

You have a wire crossed some where causing a short. That is the only reason the negative would get that hot.

[LuckyLightning]

I kinda thought so too, but I reconnected everything the same as it was before. Odd.

[nsb29]

I would think your problem is probably in the alternator wiring

[LuckyLightning]

Wouldn't I be having other symptoms with my truck if that were the case?

I went out to the truck this morning to check the ohm readings on the new coil. I took the coil tower cable off for the secondary ohm reading (this is the only thing I did to the coil).

Ohm readings were fine so I reconnected the battery cables (I left them disconnected overnight). I went to start the truck and it fired right up. I was more diligent with the choke and slowly let it out as the truck warmed up. Idle stayed consistent, and both battery terminals were normal to the touch.

At this point, everything seems fine. My only guess is the cable to the coil tower needed to be reseated.

[wildearp]

If your battery cables were getting hot, it was probably from the starter.

As far as coil issues, are you running a ballast resistor?

[JJLT1]

Engine turns and turns and turns,

running the starter for a long time,, that will heat up the battery cables..

[Irishbleueyes]

Wildearp is correct, running the starter prolonged period will heat up the cable/s. Unrelated to your ignition trouble. However you should clean all the ground connections in the engine bay.

[LuckyLightning]

Good to know, thanks guys.

I don't think I have a ballast on my engine. Should I be concerned about that?

[LuckyLightning]

I just posted a video of my engine running. Kind of a rough idle. I could smell some gas when I lifted off the valve cover.

[vin63]

Just in case...was the terminal of the negative battery cable tight to the battery post and the ground point on the other end of the cable (as in not loose)?

[LuckyLightning]

No, neither cables are tightened down at the battery. I often need to remove the cables from the battery, so I have them only tight enough for a decent connection to run, but easy enough to slip off by hand when necessary. They've always been like this (for the last few months of idling in my driveway periodically) and I never had the issue (hot negative cable) before.

But like I said, it's not an issue any more.

Or are you thinking this is related to the rough idle issue?

[vin63]

Originally Posted by LuckyLightning

No, neither cables are tightened down at the battery. I often need to remove the cables from the battery, so I have them only tight enough for a decent connection to run, but easy enough to slip off by hand when necessary. They've always been like this (for the last few months of idling in my driveway periodically) and I never had the issue (hot negative cable) before.

But like I said, it's not an issue any more.

Or are you thinking this is related to the rough idle issue?

The reason I brought that up is that if the connection is loose, an intermittent ground path can cause enough resistance to heat the cable and create other electrical issues with ignition, etc. The intermittent positive path has it's own issues, too. There's a reason the terminals have hardware to tighten to the battery posts.

[LuckyLightning]

Anyone?

[Irishbleueyes]

Not related to rough idle issue, however we assume that everything in your mechanics is performing correctly. But I'm sure theres something going on somewhere. I would start with a compression check. You could damage the coil by tightening the post to much. Borrow another coil from someone and test that one.