C4 MSD Installation

The wiring is straightforward, but finding a place to mount
the sucker can be a problem. At the suggestion of many forum members, I
mounted mine in the front passenger side area where the horn is located.
The trick to this install is buying some aluminum strap, 1” x .20” by
3ft. I got mine at Sears Hardware for about $3.
The first thing I
needed to do was relocate the horn to make room for the MSD box. You can
either bend the factory horn bracket or fabricate a new one. I made a new
one so that the horn sits lower, and closer towards the
engine.
Here’s how I mounted the MSD box. You’ll need to make
a bracket that runs from the black plastic ”bulkhead” at the very
front of the compartment down to the bolts that attach the lower skirt
(the black skirt under the nose of the car) to the bumper cover. If you
look down into the compartment, you’ll notice that the bolts come from
below, and stick up into the compartment. Using a vice, I bent the
aluminum strap into a ”Z”-type pattern so that one end would rest on
the black plastic bulkhead at the front of the compartment, then turn down
towards the ground for 2 inches, then towards the rear of the car for 9
inches, another bend pointing down, and a final 1” bend towards the
back. Drill a hole in the rearmost ”tab” of aluminum, and drill
another hole in the front tab. Sounds like a lot, but it’s really easy
to do.
Now, line up the rearmost hole in the bracket with one of
the bolts sticking up into the compartment that holds the lower skirt on.
Get under the front of the car, remove that bolt, and replace it with a
longer machine screw. Run that screw up into the hole, through the
bracket, and tighten. For the front part of the bracket, I drilled a small
hole in the black plastic bulkhead, and used a self-tapping sheetmetal
screw to hold it down.
Finally, to mount the MSD to the bracket
you’ve made. You’ll use the rest of the aluminum strap to fabricate
two small brackets to hold the MSD to the ”Z” bracket. These brackets
will go across the short sides of the box (top to bottom, as you look at
the box). Cut two lengths of strap the proper width, drill holes to match
the mounting holes in the box, and set them aside.
Assembly: Put
the MSD box lengthwise onto the bracket. Flip it upside down, and center
the bracket onto the back of the box. Take the short lenghts of strap and
place them on top of the ”Z” bracket you made, line up the holes, and
use machine screws and lock nuts to tighten down. Leave them loose enough
so that you can still move the box around a little. Put the box/bracket
combo into the compartment, line up the mounting holes in the aluminum
mounting bracket, and line up the MSD box so that it doesn’t interfere
with anything. Take it out, tighten up the short lengths of strap. Put the
box back into the compartment, and screw down the bolts that hold the
”Z” bracket. Run your wires. I soldered and shrink-wrapped all
mine.
Although there’s only one length of aluminum strap holding
it down, it’s in there rock solid. If you have trouble picturing what
the ”Z” bracket should look like, you’re only trying to have a
horizontal surface to mount the MSD box. The forward mounting point is
higher than the rear mounting point, so you have to bend the aluminum
strap a few times to lower the box into the compartment, otherwise your
headlight will hit it.
That’s it. If anyone has trouble, I can
mail a template to you.