Updated: Aug 24, 2021
regarding our Edelbrock kickdown conversion switch, i Get asked a lot about wiring the 64 and later 400/300 kick down switch on stock cars. Since i Was drawing out a simple diagram for a customer, I figured I might as well share it on here too.
Whats confusing to most people is whether they should remove all the old wiring with the old switch. at first glance, the late kickdown switch has 5 wires coming out of it. 64 is one year only with no variable pitch 2 speed converter. So if you have a 64 trans, ignore the VP part. I always prefer to not butcher up the stock wiring. That way if the customer or future buyer of the car, wants to put it all back stock again, they have the option to. Simply remove the kickdown switch and the lead to the trans and set aside. On vp cars, I now tie up the pig tail lead up to the wiring harness already clamped to the firewall. I use new male spades to plug into factory female pig tails, and then tape it off with electrical tape. Run a 3 wire pigtail off original kickdown power source (2 if not running electric choke). Originally the VP was wired to activate at partial throttle and when foot is off throttle completely, so it takes less pedal effort to hold the car back at traffic lights, when you change converter stall. You will be losing the mid throttle feature, (which doesn't really make the car perform better.) You can run it to a toggle switch, just the same (which is what I do on my cars) so you can have it on all the time when you choose. Very helpful with big camshafts. Another option is run it off the brake light switch.
Don't let transmission shops talk you into removing the VP feature. It's a nice one to have. Is the 64 transmission bad? Of course not. It's a one year only case and valve body. The 65/66 300/400 transmission has the VP and 2 physical low gears, and is a better option if you're looking for one.