Tom.....I am speaking from my "Recent" experience with my 39 Merc so not sure IF my experience is different than what year you are working on.....Obviously you have to start One wire at a time, and by that I took the longest wire and fit it into the cap straight on......then I slid the cover on to the cap and bent that ONE wire how I needed it AND by that I looked at where that longest wire needed to exit the cover and go into the wire loom. Then looked at the best route inside the cover for that one wire to exit the cap where I needed it!!! It takes some constant bending and re-bending and I also installed the cover as it would be when finished IE with the rubber o-ring to make sure the cover fit tightly!!! Then the same for the next longest wire. Pull the cover back off the one wire, then straight on with the next longest wire, then slide the cover back on, then orient the 2nd wire around (or above) the center post of the cap and bend and orient it the same as the first re-bending and manipulating it as needed. Again install the cover as it would be once installed and make sure the two wires fit in the cover and the cover fits the cap!!! Then move on to the third wire etc etc!!! I tried to do a "quick" drawing to "maybe" help explain the way I oriented my wires......again I pulled the tube off the car, once I got the wires in the cap and bent how best they fit the cover and how the routed around or above the center post, I slide on my cover gasket, then re=installed the cover with how they were best fit, then pressed the cover on and install the O-ring, then slid on the rubber boot on the wires to the cover opening, then ran the wire into the tube and re-installed the tube and then snapped the cap/wires into the distributor.
I have wondered the same thing myself. They must have had enough people assembling the caps, wires, and loom units in a different part of the factory so that the assemblies were available at the right time on the assembly line.
