Originally Posted by 79cherokee
Can someone inform me a little more on the extra ground wires that are being talked about on the module and the distributor? (on motocraft set up on an 84 cj7) I had a post earlier and replaced my pick up coil and it ran fine, but the more I read this I think it was a ground problem. I don't want to take any chances on loosing fire again!
Virtually the ONLY way to kill a factory coil is by loosing electrical 'Ground' to the engine head(s).
When the head(s) don't get ground, the circuit isn't completed, so the high voltage electrical discharged will jump to ground INTERNALLY, inside it's own coil....
Burning the crap out of the wires in there when it does.
If you add a DEDICATED GROUND WIRE from the battery negative terminal or negative binding post, to the engine head(s) the secondary, or high voltage discharge, will have somewhere to go...
And the bonus is your plugs will fire like they are supposed to!
Use about a 12 Ga. common wire from the battery or binding post.
Clean off the connection point on the head with sandpaper, get down to clean metal before attachment.
Use an Internal Star Washer (Gripper teeth on the inside of the hole) so the contact point STAYS connected.
Use some 'Copper' or 'Gold Colored' 'Anti-Seize' compound on the joint.
The copper base is conductive, so you keep an electrical connection, and the grease helps seal out moisture and dirt.
Run the ground wire on over to the ignition module.
I usually connect it to the 'Black' module wire HARNESS SIDE.
If you connect to the module wire it's self instead of the harness, your warranty might be void on the module,
You will have to reconnect each time you change modules.
Just trace the 'Back' module wire across it's connector, and splice the ground in on the 'Harness' side of the connector.
The reason for this is the entire Primary side of the ignition system grounds through the module.
Ignition coil and module BOTH get ground through the module...
The distributor is supposed to supply ground to the 'Black' wire, but after 22+ years of corrosion, rust, loose bolts and oil reside, very few ground connections are reliable.