Distributor dead - I want to convert to TFI!!

[JohnnyJ]

Well, I just spent some time with my Wagoneer, and it looks like I blew up my nice Mallory Unilite when the ground wire melted against the exhaust manifold. Since I reallly don't want to pop another $300 for a new one, I think I would like to try and convert to the Motorcraft TFI system.

I looked through irbob's TFI upgrade page, and I think I can follow along well enough, but I have a few questions about the rest of the setup since I am converting from a non-Motorcraft setup.

I am converting from a Mallory Unilite that was read by a Jacobs Omni Magnum (also used as the coil). It was set-up very similarly to a points type system and used a ballast resistor. It has been more of a pain and expensive than it is worth, and I want something I can buy parts off the shelf with. So here's my questions:

1) What else do I need besides what is on irbob (http://fsjeep.homestead.com/TFI_Upgade.html)'s site, a distributor, and duraspark box?

2) Does anybody have a wiring diagram for this?

3) I remember that AMC has a different connector pattern than a ford for the duraspark. Would it be worth it to just wire it with the ford connector so I have an easier to find part if it breaks?

4) Am I missing something?

[bchesley]

I would get a new aftermarket distributor if I had it to do over again. I did a TFI and then my distributor went south. I had enough invested to get a MSD billet distributor and blaster coil after I added up the cost of the reman dist. and TFI. Look on Jegs.com or summitracing.com and do some shopping. I think that you wont regret it. The MSD is primo stuff will last forever.

[nograin]

I beleive the Mallory Uni-light is photo or Hall effect type unit, as opposed to a magnetic pick up, so I think you are right, you will need a distributor too.

Before tossing the Mallory stuff, certainly check to be sure its not an easy fix. Melting a ground wire shouldn't have damaged anything beyond the wire if I understand correctly. I don't use Mallory products, but I think they make good stuff and they at least use to have good tech support when I had called them.

[jeepbob]

First lets clear up a couple of misconceptions. The AMC duraspark and the Ford units right down to the wiring harness are the same. I have a Ford box on my Wag. You can even use a Ford harness to wire it in. You must keep the resistor wire between the the power source and the coil weather running a stock coil or the TFI coil(or use a ballast resistor). If you stilll have your stock dist I would use that, if not get one at the bone yard. The wiring harness can come from any duraspark 2 Ford or AMC these would be 76 up to somewhere in the early 80's. The dura spark harness will be wrapped up with the mani engine harness but by slicing a little tape will come out in 1 piece without undoing any plugs except at the starter sol if you unbolt the ign box, dist and coil. You will want to cut the plug off the main engine harness to splice in to your system. The plug to cut will be hooked to the plug on the ign box with the red and white wires. Do not cut off any other plug. It will be simple matter to wire the complete system back in.

[reddog]

I would agree with NG, make sure the the unilite is unrepairable first. Could it be the Jacobs box that fried?

Maybe you could get a reman distributor for a 78 & up and just trade in your old one.

I would assume that the Duraspark box as used in the Jeep is the same box as used by Ford. Why would you use a different box just to move wire posision? I have seen a bunch of the "blue" boxes in a bunch of Ford stuff at the yards but have not traced the wiring on them.

The wiring is easy but I can't help you as I don't have my diagram here. Basically a wire to the coil, the connector to the distributor (3 wires) and two power wires (start and run) for a total 6 wires.

Brad - TFi swap more than a MSD billet & coil?? :confused: A rebuilt distributor was $55 and the TFI stuff with new wires and cap/rotor was under $75. I would only guess the the MSD distributor is more that $130.

Kerry

[JohnnyJ]

I just checked and Summit lists the MSD AMC V8 distributor for $216. I think if I get lucky and find some of the parts at a junkyard, I can do it for cheaper.

I was thinking today that I have not checked the signal from the distributor to the Jacobs box. So I just went out and this is what I am getting, the jacobs box is used as the coil:

brown - ground
green - negative side of coil
red - ignition

positive side of coil shares ignition behind ballast resistor

I noticed that I was getting 12V between brown & green and brown & red. Not sure what this means, is this ok? I have to say, I've never looked at this signal to see what it should be.

I checked and the fuse is not blown for the jacobs box, and it is getting power behind the ballast resistor.

I've thought about picking up a cheap coil and hooking it in to see if it the jacobs box is dead or not. I figure that is the cheapest and easiest part to swap out.

Whadyathink?

[reddog]

Go to the pick-ur-part and get the TFI coil to test it. If you convert to the motorcraft setup you will already have the coil.

Kerry