Got the cooling fan swap done, sort of.
I am tired of buying third world junk and paying first world prices for it. I had to buy three toggle switches before I got one to work without a failure of some sort. First one mechanically locked up after one use. Second one, the cheap pot metal threaded part stripped upon installation. Going to go to Aircraft Spruce and buy a good one I guess, would have been much cheaper in the long run. Then the temperature sending switch, not sensor, typical GM type aftermarket switch, never worked. Engine got up to 210 then I just grounded out the switch lead and the fan came on. Toggled on the high speed and it worked fine too. If I hadn't of gotten my haircut the other day I would be bald right now, lol. Anyway, the details.
Yesterday I did all the electrical work. Not much to say other than it was a long tedious day of routing wires, cutting to length, crimping, soldering, heat shrinking and wire looming.
Used two relays to control the low and high speed functions of the Derale fan I am running. The instructions for the fan kind of casually mention that the low speed portion needs to be running before you fire up the high speed side. So here's how it's wired, for now.
Low speed relay has switched 12v provided by the wiring harness I put in a while back, this is hooked to one side of the relay COIL. The ground side of the relay COIL is hooked to the aforementioned (failed out of the box) GM temperature switch. If it worked this switch would have grounded the relay coil when the temperature of the coolant hit 185ish. Seems there is some slop in the the actual turn on temp. In my testing I ended up just jumpering the switch wire and the fan came on, I figured if the temperature switch hadn't come on by 210 it was either never coming on or was useless for what I wanted. Once this relay is energized it takes power from the battery side of the remote starter solenoid, thru a fusible link and 10 ga. wire, and sends it to the fan low speed connection. It also sends 12v to one side of the high speed relay COIL connection. This was the easy way to ensure that the high speed side only came on once the low speed side was running. Since the high speed relay will not have power to it's coil till the low speed side was energized it was a fail safe setup.
High speed relay COIL gets it's ground from a toggle switch on the dash, for now. I plan to put a temperature switch on this relay to automate it's activation. But I will probably keep the toggle as an emergency override as well. Output side is similar to the low speed relay, fusible link, 10 ga. wire to relay, outputs to fan high speed connection. It works as expected. Will not turn on if the low speed relay is off, toggle switch cycles it on and off manually.
Near future plans, I have two new Speedmaster switches coming, from Jegs. One is set to turn on at 185, off at 175, this will control the low speed fan. The other is designed to turn on at 200 and off at 185. this will control the high speed fan. In order to install them I have a water outlet spacer with two ports coming as well. Fortunately, the flathead uses the same water outlet setup as the pre 79 Mopars do, so that was easy, lol. Otherwise I would be doing it myself. The low speed temperature switch will work just like I have it wired right now, on the high speed side I will wire the higher rated temperature switch in parallel to the toggle switch so that either can turn on the high speed side.
The relays were mounted so as to not drill new holes in the core support.
