I am sure you will have to make a short wire. I get all you guys mixed up, but I looked back through this thread, you are using the Ford Duraspark II system? If so, this tach wire will hook to the coil negative just like it did on the TFI system.

 

Yes I am using the Duraspark II system now. I got the wire harness off a 300. Am I just missing the tach wire because I got the wire harness from a truck without a factory tach? Will experiment with it more tonight.

 

On your duraspark harness you may have a pigtail coming off the coil and ground wire from the dist according to this diagram. Even if you have this, I think your main problem is the wire from the dash was cut during the conversion and is wrapped up in your old harness under the hood somewhere. If you can find that wire, you could easily hook it to the coil negative.

 

I ran a quick test wire from the coil negative to the plug with the light blue wire that I mentioned above and the tach started working. Maybe I will steal the female plug off the old TFI wiring harness to make it a nice clean looking connection instead of cutting the truck wires up. Honestly the wire colors aren't really matching up with the wiring diagrams but if it works I will just go with it ha. The rest of the wiring colors check out, just not the tach.

 

See this post for a photo. Post 5
https://www.ford-trucks.com/forums/1...l#post14455069
Your truck, is a V8, and thus needs a green and black on the engine side of the plug. 2 wires on each side of the plug. The extra black wire on the engine side is a ground which makes the tach read correctly for a V8.
Jim

 

Okay I see what happened now. The duraspark harness I found was missing the 4 pin male connector that goes to ignition module, which I replaced. But I didn't realize there should also be a 2 pin female connector there as well (for tach). So I should be okay if I add in a ground wire and wire to negative side of coil correct?

 

You are correct

 

Hi, I have a new 2100 old school carb for my 85 Bronco II 2.8, and all of the duraspark conversion parts - except distributor.

I'm game to try the locked TFI approach, can you be more specific how I hook up the existing TFI system to lock the timing? Do i leave module and coil all wired as factory, and manually set timing to 25 btdc?

Thank you, Steve

 

Set your duraspark II stuff to the side till you get a distributor, if you ever do.

Have you pulled all the computer wiring out? I would to get it out of the way. You can find the computer behind the pass side kick panel in the interior. Pull it out, and unplug the very large wiring plug. Cut the few wires going to a relay off and tape them. The rest of the remaining wires should go though a large rubber grommet in the firewall. Push this grommet out of the firewall, and then push the large plug with all it's wiring through the large hole and into the engine compartment.

Take the large plug and start gently tugging on it. Anything hooked to it, unplug it and take it out. You will need nothing hooked to this harness.

Once you get the harness out, find the wide plug that went to the original TFI distributor Follow this group of distributor wires as far as you can and cut them. Then unwind them so they are loose going to the old TFI distributor. Cut the top wires coming out of the plug about a inch long, just in case some day you might want to use them for something. Keep the bottom 3 wires long. Wire them up like the diagram below.


I ran these 3 wires in a piece of loom, and ran them over to the driver's side fender. I used the original TFI coil. Over on the driver's side fender in all those wiring plugs you should find a white/lightblue stripe wire. This is your ignition hot. It needs to be tied to the TFI coil + and also the 3rd wire up on the TFI distributor. If you do not still have the TFI plug, you can hunt it down in the harness you pulled out.

The 2nd wire up on the dist goes to the other terminal on the TFI coil.

Originally the TFI coil had a heavy black ground wire bolted to the coil base, and then running over and bolted to the engine block. You need this since the driver's side inner fender is plastic. I used this ground wire for the lower most ground wire on the TFI distributor. That's all you need.

You will have to experiment with the timing. You want it as advanced as possible, but you still want the engine to crank over when it's hot.

 

How kind of you to respond so quickly and completely. I won't need the computer harness that you have described under any of these scenarios, is that correct? A. Fixed timing with existing distributor and coil; B. Duraspark distributor and module; C. Points-type distributor and 12v coil if I can get one for the 2.8.

Thanks again

 

That is correct, you do not need the computer harness, and the whole pass side inner fender can be cleared out except for the starter relay. Anything attached to that computer harness can go. You will be left with a wire to the temp sensor and oil pressure sensor for the gauges, a wire for the evap solenoid near the front of the carb, which you most likely will not use either. There will be a bundle running across the front of the engine for the alternator and the A/C.