I currently have TIF IV ignition on my 84 F150 4.9L 6. I have replaced it twice once at 75,000, once at 150,000 and i now have 200,000 on the truck. I think there is a trend forming here and i am thinking about converting to a duraspark ignition before it leaves me again.
I have studied all the shop manuals and electrical schematics, and it looks like I will have to change the distributer, carborator, and will need the duraspark harness.
The electrical schematic for the 84 4.9 shows both ignition systems and the wiring looks easy. However, there is a question about wether the balast resistor is allready in the harness or if i will have to install one.
How could i check this. ?

 

If you could locate the wire, you could measure the resistence with a good meter. I would use a external ballast resistor. Or better yet, install a msd 6a. You won't need to worry about a ballast.

 

Sail, you won't have a ballast wire/resistor with the TFI ignition (and the E type coil). As Mike says, use an external one with the DuraSpark.

In my opinion however, it's not worth the swap. I would just change the TFI module every 75K as regular maintence. Or better yet, find a way to keep it cooler or change it's location.

The Duraspark modules also go bad on a fairly regular basis. I always carry a spare in my center console.......

 

Some good info here....

https://www.ford-trucks.com/2_8Duraspark.html

Although it is for a conversion of a 2.8Litre engine in a BroncoII/Ranger the principles are the same.

 

Thanks Guys Maybe I will just put a spare module in the glove Box.

 

Mike W, OK, will you please explain what a "msd 6a" is, and where do you get one.