Coil Not Getting Full 12V

When I installed the Pertronix Flame-Thrower ignition coil last weekend, I discovered that the coil was not receiving the full 12 volts required for optimum performance (I was reading only 10V on my volt-meter). The installation literature suggests that there is a resistor somewhere in the circuit that needs to be removed in order to get the full 12 volts. Well, first of all I don't even know what a resistor looks like, and a close inspection of the wiring schematic didn't reveal any resistors leading to the positive terminal of the coil. Here's a link to a nice wiring diagram in PDF format that you can zoom in on for a 1972 1800E (should be the same for a 1971 1800E ... I think?!!) Of course, me reading an electrical schematic is like a 3 year old reading the Wall Street Journal.

So, either there really is a resistor, or there's a voltage bleed somewhere somewhere in the circuit leading to the positive terminal of the coil. From what I can tell, the 2 brown wires feeding into the positive terminal of the coil are from the main fuel injection relay and from the horn relay via fuse #6 in the fusebox. In this 1st photo, the twin brown wires are shown connected to the positive (top) terminal of the coil. Red wire from negative terminal of coil goes to the tach. Figuring out the wire colors was a task all by itself since all my wires are black ... they're either spray-painted black by some previous owner or black from years of grease and dirt fusing to the wire jackets! Only with some 1-on-1 time with the rotary tool did I manage to coax the wires to reveal their "true colors".

Fuel Injection Relay - Before:

Fuel Injection Relay - After:

A volt-meter test on the battery showed a full 12 volts, so I decided to trace the source of the voltage drop by removing the main fuel injection relay, cleaning up all connections with the rotary tool and some electronic contact cleaner, reattaching all connections, and ensure proper grounding. The only thing missing is I need to get my hands on some anti-corrosive zinc paste that I read about in this excellent article about electrical connections in our old Volvos. This guy is almost fanatical about the stuff, needless to say, I found new religion. I also extended the session with the rotary tool to include the restoration of the relay housing pictured in the before-and-after photos above. First, a rotary paper sanding bit was used to remove surface impurities, followed by the stainless steel rotary brush to get that brushed steel finish.

Of course, after hooking everything back up and in my haste to test the voltage, I mistakenly set the multi-meter to test resistance and completely fried the unit! I probably just blew the fuse in it. In any case, I wouldn't know the results of my efforts until I have the fuse replaced and my multi-meter working again ... story of my life.