Replacing points distributor in 66 C20

[MrK5]

This weekend I swapped out the points distributor for an MSD. The previous owner had the truck since 69 and kept almost all the receipts. I looked like the last time he'd done a tune up was in '90 when the motor was rebuilt 12,000 miles ago.

I found a few interesting things I wondered if they were completely unusual.

First, the 12V feed to the coil was a full 12V verified by multimeter. The wire did not look like the resistance wire descriptions I've read. Also what first tipped me off was the wire to the starter was not present; just the 1 wire. It looked pretty factory, not home-brew like the other wiring examples I've seen from the previous owner. Unfortunately this is the best image I have of it. The taped wiring harness looks pretty original too.



So I was curious if any of these trucks came factory with full 12V to the coil? Or was this something people used to do to "hop-up" the points ignition?

The other thing I found was the coil wired backwards. The 12V feed was on the negative post and the distributor wire and tach were on the positive post. I did some reading and found wiring it this way will reduce the output voltage by 15%.

The truck sure idles a lot better with the new distributor. I just wish I'd thought to order a black coil instead of the bright red.



In case anyone is worried, I didn't trust that small guage 12V wire for the coil so I'm using it to trigger a relay with coil power being pulled straight off the battery.