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Coil Wiring

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timsgolf

timsgolf

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1967 AH 3000 BJ8 MKIII
Modified with chevy 327 v8 engine & 4 speed muncie transmission.

The car died while driving today. Stone cold dead. No response at all when turning the key. Lights work.

Popped the hood & saw one coil wire had come loose & fallen down onto the exhaust manifold, where it had melted & welded itself there. Note that the wire is still attached to the coil - it's the other end that is disconnected. (See pics)

I pulled it off the manifold, but can't locate the proper attachment point. Can anyone advise?

Thanks, Tim

p.s..., I saw another thread very similar to this one, but it dealt with attaching wires properly to the coil. Plus, it was an original Healey, not a modified version.
 

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That's a Chevy coil bracket and I'm guessing a Chevy coil and a negative earth car. One coil terminal says "+" or "BAT" if Lucas, and this wire should go to the ignition switch. So with this unknown wire disconnected, turn on the ignition switch and see if you have 12V between the coil + terminal and the chassis, and also check if this loose wire has +12V to the chassis. If the wire has +12V and the coil terminal doesn't, then that's where it goes.

The other coil terminal is marked "-" or "CB" if Lucas (for Contact Breaker), and goes to the distributor points. That should be easy to see since your coil and distributor are so close together. Plus this wire is suspiciously red (as in USA car positive) and longer than needed to reach the distributor, so there's a good chance it's an ignition positive wire.
 
AHS said:
That's a Chevy coil bracket and I'm guessing a Chevy coil and a negative earth car. One coil terminal says "+" or "BAT" if Lucas, and this wire should go to the ignition switch. So with this unknown wire disconnected, turn on the ignition switch and see if you have 12V between the coil + terminal and the chassis, and also check if this loose wire has +12V to the chassis. If the wire has +12V and the coil terminal doesn't, then that's where it goes.

The other coil terminal is marked "-" or "CB" if Lucas (for Contact Breaker), and goes to the distributor points. That should be easy to see since your coil and distributor are so close together. Plus this wire is suspiciously red (as in USA car positive) and longer than needed to reach the distributor, so there's a good chance it's an ignition positive wire.
Click to expand...
Thanks AHS - it's the ignition system that's dead for sure - along with the electric fuel pump. I don't have a volt meter. Is there any way to check without one?

I wondered if maybe there was supposed to be a wire from the coil to the starter solenoid? The starter & solenoid are down below on that side of the car. But I'll need to jack it up to get any view/access to see if something looks obviously missing.

Tim
 
A 12v light bulb will do if you don't have a voltmeter.
On a Chevy starter solenoid, there is a connection to provide full battery voltage to the coil while the car is cranking and bypassing the ballast resistor, so you might have that. If your car fires when you are engaging the starter but then won't run when you stop cranking, then it's definitely disconnected ignition wire to the key. The loose wire would go to the same coil terminal as the one that goes to the solenoid.
 
Note the type of connector - the flat female style and not the screw hole style. I have looked everywhere I can think of and don't see a flat male style anywhere that it would have come loose from.
 

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I don't know what style connectors are on your coil. Where does the other end of this wire go?
 
It is connected to the + side of the coil. I'll try and get a better pic of the top of the coil.
 

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The top of the coil in this view is the + side. There are 3 wires connected. The one on the right -with the yellow band at the connection point, is the one we are discussing. I flopped it around where you could see the whole thing. I stretched it down toward the starter solenoid to see if it would reach and It isn't long enough to reach down there.
 
You can try connecting this loose wire to a source of battery power (or a wire straight back to the battery +) and then the car should run. But that's not really where it should go, it should go to some source of power that's active only when the ignition key is on, and if it's a chevy type coil it should probably come from a ballast resistor. Lucas coils didn't require a ballast resistor and I don't know what you've got in this custom installation.

A source of ignition on power can be found at the flasher, overdrive switch, wiper motor, fuel pump, heat blower switch, or tachometer. Most of those are under the dash, and you probably don't have the overdrive switch, so maybe it went to the flasher?
 
Sounds good AHS.

The OverDrive switch is now the fuel pump (don't have OverDrive). I don't think I have a flasher. The other dash panel switches are for Panel (gauge) lights, Wipers, & Parking/Headlights. One toggle switch was added under the dash for an electric engine fan.

The only things working are the Parking/Headlights & the Panel/Gauge lights. Wipers, electric engine fan, fuel pump, and ignition are all dead.
I wanted to get it running before tomorrow afternoon - have an appointment set with my mechanic to install some front end/steering parts that just came in. If I can't get it started by then, I'll just have it towed to his shop & he can fix the wiring issue as well as the other stuff.

Tim
 
Sorry, that was wrong, it doesn't go to the flasher, it goes to the turn signal control switch first. But the ignition wires also go to the fuesbox, what type does the car have now? As originally wired, one of the fuses had a lot of white wires(ignition) connected to one side and a lot of green wires (accessories) connected to the other. The ignition is the white side.
 
Here's a pic of the "fusebox". Looks like a royal mess to me! Haha... There are alot of white wires on one side though - as you suggested.
 

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None of the stock wiring appears to remain there. But one of those fuses must have a wire leading back to the ignition switch, and that is where the + side of the coil needs to go. Possibly through a ballast resistor, depending on the coil type. I don't see a ballast resistor anywhere so far. Maybe it's a Lucas coil.
 
Do you have any under the hood pictures from before the failure? You might see the wire and get a better sense of where it was heading.
 
Legal Bill said:
Do you have any under the hood pictures from before the failure? You might see the wire and get a better sense of where it was heading.
Click to expand...
Great idea Bill!

I just checked through my roll of pics and didn't see anything clearly. However, in one of those it looks like the wire dives downward from the coil - very tight to the coil. That direction, combined with the flat style terminal end on the wire, makes me think perhaps it attached to the starter down below. The issue there is, the wire seems slightly too short to get there - plus it would have had to have fallen upward to end up on the exhaust manifold.

This failure happened right at dusk on Saturday evening. I was trying to get it figured out before Monday afternoon when I had an appointment with the mechanic to install some front end parts that had recently come in from England. Since I didn't get the ignition/coil wiring issue sorted in time, I towed the car to the shop yesterday. As soon as I'm able to talk to the shop I'll post the solution on here.

Thanks all, Tim
 
I'm a little late getting to this. However, I might be able to offer some insight here.

On a typical Chevrolet small block from the 1960s and 1970s, the "run" position of the key switch provided coil power through a ballast resistor or ballast wire. There was also a connection from the coil "batt" terminal to the starter solenoid that was a direct connection with no ballast or resistance. Generally this is a terminal marked "R" or maybe "I" on the starter solenoid, separate from the solenoid power from the key switch on the purple wire. Typically the coil power form the solenoid is a yellow wire. This gave the coil full power while the engine was cranking on the starter (when battery voltage was likely lower than 12V). So it's normal for there to be two wires connected to the "batt" terminal on the coil.

The ground (earth) connection is made through the points in the distributor.

EDIT: Added details about the wire and the terminal it connects to on the starter solenoid.
 
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All,

I talked to my mechanic today and now have a partial answer. As posted above I had the car towed to the shop. Their first concern was getting it cranked so they could pull it inside and get it up on a lift to do the planned front end parts replacement. Within minutes they determined it was a BLOWN IGNITION CIRCUIT FUSE. They have installed the front end parts and the car is now at the alignment shop. When it returns they will track down the loose wire attachment point.

My theory now is this:
Where-ever the wire shook loose from (I'm leaning toward the latest add-on - the engine cooling fan), it fell down onto the hot exhaust manifold where it shorted the ignition circuit and blew a fuse. No damage to the coil or other electrical parts.
 
Just a thought on this, is there any electrical connections on the carb, maybe for an electronic choke,
this would require an ignition feed wire also,
Not knowing the engine in question, just a guese
 
Thanks mezy! I'm not sure about the choke. I replaced the carb a few weeks ago with a Williams Custom carb.

The final opinion is that this is truly a mystery wire! Seriously, the mechanics never found where it was supposed to have been attached. Consensus is that it was not attached anywhere on the other end - just lying up in there and eventually vibrated its way free, shorting on the manifold and blowing a fuse. Don't ask me why the terminal end was still connected to the coil!

The wiring in general, but especially under the dash and fusebox, is a total mess. Apparently when the engine swap was done years ago, they didn't replace the old fusebox, they added a second one! Wires are going everywhere - jumping from one to the other, etc... It was highly recommended that we go ahead with new wiring. I agreed to it. The new wiring harness was placed on order today and should be ready in 5-6 weeks. I knew this was coming, but wasn't thinking I would do it this quickly. What I wanted to do is replace the dashboard, center panel, glovebox, and trim, etc... at the same time we did the new wiring.

The only dashboard replacement options I've seen (ahspares & moss) are the woodgrain. Does anyone know if there are any other options out there? Maybe somebody does custom work in this area?

Thanks again for all the responses,
Tim
 
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