ive always wondered what this ground wire doeswh
 

What does the ground wire where the coil bolts to go to? It just goes way back into the wiring and I always wknder what it goes to. This is on my 82 SC. Same place the spark plug wires ground.

On a '79, the other end goes to the CDI.

Both A & B coil wires go to the CDI box. See where the B wire travels to the CDI box at terminal 31/1 then to ground. Not sure why it goes to the box but it definitely ends up grounding to the same place the spark plug wires ground to - the chassis.

The entire 82 electrical diagram is in the tech info center. Here is the page with the coil.

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part1-2.jpg

I assumed that you were talking about ground that has the ring on it that mounts to the bracket that holds the coil. If you were, then in the pic Bob provided, it is the brown wire that is connected to CDI 31/1 and goes to point 22. This is the same stud that the spark plug shields ground to. It ties to the B coil wire at the connector that plugs into the CDI.

Great detail supplement. I am now not sure where my brown wire "grounds" to. I will check in the AM and get a picture. Yes, it all grounds to the chassis but Kerthunk I think is reading the OP's request better than me.

Sorry for my vague description. I tend to ponder things as I am tired, then post them only to realize later my explanation or descriptions are bad haha. Yes, I meant the ground wire with a ring that mounts to the same stud that the spark plug shields ground to.