Mike
That is the ground point for the rear light harness and would make a fine ground point for your Zetec conversion. If you were concerned about engine to body you could run a temp ground from there to the motor. I would call Bostig and see what they suggest. If you haven't already. 

Bill
87 Zetec Turbo

On Nov 19, 2012, at 3:16 PM, Mike South <msouth@GMAIL.COM> wrote:

> Hi,
> 
> I took most stuff out of my engine bay in doing my Bostig conversion.  I
> needed a to ground a wire from the new wiring harness and added a wire to
> this spot.  I'm wondering if I've done Yet Another Stupid Novice Thing and
> connected to something that isn't what I thought it was.
> 
> This is in the engine bay on the driver's side of an '85 westy auto.  The
> triangular opening on the left side of the picture is the box where the ecu
> would live, and the wire bundle running through the picture is the wiring
> that runs to the rear lights.
> 
> I think I saw the wires coming out of that bundle, screwed to the wall, and
> thought "well, there's a ground point".  I still think that's logical but I
> just figured I would give everyone a chance for a good laugh in case I'm
> spectacularly wrong.
> 
> https://docs.google.com/file/d/0Bw4_lQZfcW6PbC1MRnNXb3kzQUk/edit
> 
> I'm having trouble with my alternator putting out too high a voltage and
> trying to make sure all ground points I'm using are good.
> 
> Thanks,
> 
> mike