First I have very little auto electrical knowledge so please be very specific if you don't mind. Laymen talk.
Hello my truck is 1987 F-250 XL 4x4 351w auto 4 barrel carburetor.
Here's my issue engine went TU. Picked up a good used engine. A friend talked me into going to the HEI system to which I am. I have the Dura Spark system now. My new dissy calls for a run/start wire only. Will that be before the module or after and what wire is it. (color)

Question 2 In the process we lost the voltage reg. Are they vehicle specific. You look at parts stores on the web so many different choices (which one). I've looked at a few wiring diagrams that show the wiring from the alternator to the reg. Very confusing they give you so many different choices.

 

Ford had many different alternator setups. You need to identify which one you have. Since you have a 87, I would be suprised if you had the regulator that mounted on the inner fender, by then they were usually built on or in the alternator itself. How do you know you have a regulator problem?

To properly wire the HEI, none of the factory wires will really do. The HEI likes at least a 12 gauge wire, and you can run a new one in through the firewall and hook it to a spot in the fuse box that has power with the key in start and run. Some people also power the HEI from the battery through a foglamp type relay and then to the HEI. They use the old Ford ignition wire to power the relay. The Ford ignition wire is the white/lightblue strip wire going to one side of the coil.

 

Thank You Franklin 2, I will run a new wire to the fuse box. One other wiring question. The wire that goes to the water temp sensor is no where to be found. From what I've read it should be red/ white stripe. I would think it would be loose somewhere just can't find. I'm wondering if it was powered from the old coil. David

 

No, no connection to the coil. It's a single wire just like the oil pressure sensor below it. A lot of times Ford bundled the oil pressure and the water temp gauge wires together, one being white/red and the other being red/white. On most engines the temps sensor was at the top front of the engine on the intake, so that wire would drop out of the harness and then the harness continued down as a single wire to the driver's side front where the oil pressure sensor is on the small v8's near the oil filter.

You should have it somewhere, keep looking.

 

Could it be a production run change? My 3/87 has a fender mount reg that looks every bit 28 years old. Got two 2g alts that I'd love to get rid of for a 3g. Still have the factory wire harness for it.

 

My 89 diesel has the 100 amp alternator with the external regulator also. I guess it would be considered a 1G version. All the 2G's had the built in or on regulator correct?

It seems the downfall to the 2G is the output connections where they used the slide connectors that can overheat. They had the same problem with the headlight switch connectors also. Otherwise it's a good alternator. My ranger had a 2G and when it went bad, I looked they where expensive to replace. And with the reputation it had, I had a GM alternator off a ss monte carlo sitting there, so with a little modifications to the brackets I am using it and it's still working.