I was adjusting timing on my new-to-me 1973 last week. As I turned the distributor by the cap, I brushed the ignition coil case with the back of my hand and got a moderate shock.

Does this mean the coil is bad? Or perhaps not properly grounded? I do not think this should happen normally.

Btw, the car has only 24k original miles, and I think the coil (and spark plug wires) are original.

I am still learning about the car and the mechanics, so any help you can provide would be greatly appreciated. Thanks.

 

Sounds like your coil may have a leak. With it running, use a spray bottle and mist it with water. If it's leaking, you'll see it.

 

Possibly. But 20,000 volts is certainly enough to give you a good jolt. It may have just been coincidentlal that your hand touched the coil at the same time you got the shock. If your hand was on the plug wires, any leakage from one that was firing would do the same thing.

Fire-up the engine in a dark garage at night and see if you have any "fireworks" that show up (ignition leakage). That may give you a clue as to what gave you that shock.

[I try not to make contact with any plug wires when rotating the dizzy on a running engine.]

 

Your hand probably provided a path TO the coil case, not FROM it. As said, it was probably from the spark plug wire through your hand to the coil case.

 

[QUOTE=7T1vette;1589187470]Possibly. But 20,000 volts is certainly enough to give you a good jolt. It may have just been coincidentlal that your hand touched the coil at the same time you got the shock. If your hand was on the plug wires, any leakage from one that was firing would do the same thing.[QUOTE]

Leakage...Especially if the wires are VERY old!!!

 

You've just been introduced into the world of the secondary ignition! We've all heard that electricity tends to seek the path of least resistance. This time, it was you! On a more serious note. If your curious if you have an issue, fire up your beast with the hood popped at night and look for any tell-tale blue arcs of voltage seeking what you became the other day. A path of least resistance. Now, it's time to have some fun with what we've learned. *Here is my one disclaimer. (This got me sent to the principals office in school on more than one occasion 40 years ago or so).
Moving on.... If ya happen to have a spare ignition condenser coil (the tiny little tube with a wire on it by your ignition points). Take the wire end of it and poke it into a spark plug boot after pulling one of the wires of your choice from a spark plug. Then take and ground the metal tube of the capacitor to a good ground of your choice. Then go hit the key and spin it over, then shut it off. CAREFULLY take the wire out of the spark plug boot being CAREFUL to not touch the case and the end of the wire at the same time. you can handle either end safely, just not both which results in completing the circuit. What you now possess is a neat little fully charged capacitor that will stay that way until someone picks it up at touches the case AND the end of the wire at the same time. (Trust me, it's such a curious looking item, I have never NOT had someone pick it up complete the circuit). When this happens, it will discharge a few milliseconds of 20,000-30,000 volts, enough to get a cheap thrill watching your unsuspecting target dribble in their pants...

 

Any chance your hand brushed up against the coil C- terminal? It's not covered/insulated, and that terminal can potentially hit 100-150 volts while the engine is idling.

 

I hadn't thought of that in years- the instructor in my high school auto shop class- if he caught you drifting away he'd toss you a condenser. Natural reaction is to catch it.

 

Nasty trick, if the guy picking it up has a pacemaker...

 

Several years back I had a similar experience. The coil wire on my '69 had a pinhole in it that was grounding to the RFI cover, thus keeping the car from starting. I pulled the RFI lid and the car would start and run normally. Not knowing of the pinhole in the wire, I had my hand near the wire and received quite the jolt.

I had to check and see if my nuts had turned into nightlights.

 

Thanks everyone.

I did a quick check under hood in a dark garage. I did not take the shielding off, but even so could see two flickering orange lights, which appear to be coming from both the negative and positive terminals of the coil. The brighter light was coming from the negative terminal.

I will check again with the shielding removed to see if there is anything else, but the sparking from the coil was certain.

What should I conclude from this, does the coil need to be replaced?

 

Once you get the cover off, do that test again. Either the coil wire is bad or the center tower on the coil is. Basic idea is to PROVE what the problem is-

 

Thanks TimAT, yes I will remove the shielding for a better look.

When you say the coil wire is bad, I assume you mean ignition wire to (+) terminal or wire from (-) terminal to distributor?

When you refer to center tower on the coil, I take that as the coil itself may be bad?

Thanks for clarifying.
Dave

 

If the coil had failed completely, you would not be getting high voltage at all. But, the coil insulator might be cracked and/or leaking.

You could try cleaning off the top of the coil. If contaminants are there, high voltage could be using that as a path to ground. More likely that the center power transfer wire is bad or the coil cap is cracked and leaking. If you find no problems with the coil casing, you could put some [insulating] RTV around the coil terminals so leaking voltage can't reach them. (band-aid fix) Make sure ALL plug wires (including center wire on dizzy) are fully inserted into sockets.

Once you have eliminated the 'fireworks', you should be OK.

 

What he said

 

Thanks guys, very helpful!!
At this point, I am going to replace the coil.

Also, I removed the shielding and had another look while running the car in the dark. There are quite a few flickers on many of my spark plug wires, near the distributor, further down, and also down near the spark plugs. I clearly will need to replace the plug wires, probably spark plugs too.

On that note, what's the easiest way to access the wires, route the new ones, etc? Seems it may be easier from underneath the car?

 

If you want to run the wires per factory intent, you will need to raise the front end. No way to do this from the top side only.

I suggest that you work the process very methodically as there is a lot of work just removing wingnuts/covers, cleaning stuff off, and making sure things don't get mixed up.

1. Work with one plug wire at a time, rather than just ripping stuff off and hoping to get it back together. Only remove those things that need to be removed for THAT plug wire (or that 'pair' of plugs/wires).

2. Once removed, also remove the plug and install the new one at that time (you already have the tools in hand to do that job).

3. Have cleaning rags, solvent, etc. available under the car so you don't have to do the "up & down" thing 100 times.

4. It would help if you had someone topside who could remove each wire from the dizzy as you replace and route it. [Doing it this way eliminates any risk of shifting plug wires in the dizzy.]

5. Look carefully at the routing of wires through the engine mounts, so you can duplicate that setup.

6. IMO, it is better to get a plug wire set that requires you to cut-to-length and assemble the dizzy connector yourself. It is difficult to correctly install a pre-molded and pre-assembled plug wire set in an assembled vehicle. You need the un-finished end to easily route the wires.

Don't get in a hurry, plan each piece of work before executing it...so you don't have to back-track your work. Forget about how much time it might take; just dig in and work the process. Take a short break every hour or so to not burn yourself out.

Lastly, I highly suggest that you purchase irridium plugs for your car. They are much more expensive--but they last an incredibly long time (maybe 100K miles). Hopefully, you will NEVER have to redo plugs and wires again!

 

If you have the stock distributor then you can pick up a set of 9058N plug wires, some dielectric grease and some string.
The easy wires are for plugs 5 7 6 & 8.
The wires for plugs 1 3 2 &4 go through the boomerang.
Pull the # 1 wire off the distributor and remove the wire cap and tie or tape the string to the end of the wire.
Pull off the #1 wire off the plug and pull the wire and the string out from that side.

Match up the length of the new wire (1 2 & 3 are 49 inches) (#4 is 45 inches) and put the dielectric grease just above the new cap at the distributor end and slide the cap up a little and grease the end that goes into the distributor and slide the cap off.
Move the string to the new wire and pull it up to the distributor, put the cap back on and plug it into the cap.

Here's what the boomerang that your trying to get the wires through on 1 & 3



Here's how 2 & 4 look.