Dura Spark II

From a 12.6 volt base how much voltage drop should there be on the resisted wire going to a Dura Spark II two box?

I have a old F350 dump truck that is getting the coil smoking hot and losing ignition fire, After checking I am getting full battery voltage on the white momentary retard wire and the red resistive continuous normal run.

I am just going to buy a ballast resistor and add to the circuit instead of standing on my head looking for the pink resistive wire under the dash.

Blake,I'm not much on electrical but,I got boxes and such if you need them. U got my #.

Thanks Rick, I appreciate it but I put a 1.83 ohm resistor in the red line and fixed the problem. I just don't understand why it lost resistive voltage and went full voltage.

Glad to see you fixed it Blake.
I never had much luck with the Duraspark boxes.

I use a 4 pin HEI module on the ol' 84 crew cab now. (25 bucks) If you want I can send a wiring diagram for it.

It makes more power than the MSD 6a system I had on it.

IDT-572 wrote:Thanks Rick, I appreciate it but I put a 1.83 ohm resistor in the red line and fixed the problem. I just don't understand why it lost resistive voltage and went full voltage.

I have seen this very thing on older vehicles where the wiring to the ignition switch has been screwed with or the ignition switch has been changed to a different application switch.
The un-resisted start part gets connected somehow to the run part.

I ran the Dura spark II  on my 68 Torino and 72 Ford F100 for years with no problems at all. Both were daily drivers ! Must be something  way wrong some where else .  I just used my hot  side or coil wire and ran it two the  red wire on the module. kind of like the below diagram.


http://www.michellesfords.com/Wiring_harness2.jpg

whitefield wrote:I ran the Dura spark II  on my 68 Torino and 72 Ford F100 for years with no problems at all. Both were daily drivers ! Must be something  way wrong some where else .  I just used my hot  side or coil wire and ran it two the  red wire on the module. kind of like the below diagram.


http://www.michellesfords.com/Wiring_harness2.jpg

That is the way have my 69 wired but I think I have 2 red wires in the harness and have them wired together then to the hot wire.

Blake as others have wrote, my applications with the Ford Duraspark Ignition system have give quality performance and great service too. When installing those units on my older cars, I incorporate the full Duraspark system, ignition control box, coil, distributor and wiring. My voltage is 12 volts to the ignition control box from the starter solenoid's ignition terminal.

Good luck,
Dave.

rmcomprandy wrote:

IDT-572 wrote:Thanks Rick, I appreciate it but I put a 1.83 ohm resistor in the red line and fixed the problem. I just don't understand why it lost resistive voltage and went full voltage.

I have seen this very thing on older vehicles where the wiring to the ignition switch has been screwed with or the ignition switch has been changed to a different application switch.
The un-resisted start part gets connected somehow to the run part.

That is what was going on with this dump truck............. Resistive circuit was gone.

whitefield wrote:I ran the Dura spark II  on my 68 Torino and 72 Ford F100 for years with no problems at all. Both were daily drivers ! Must be something  way wrong some where else .  I just used my hot  side or coil wire and ran it two the  red wire on the module. kind of like the below diagram.


http://www.michellesfords.com/Wiring_harness2.jpg

This wiring diagram is wrong, in that it does not show the box red wire to have resistive voltage to it.

This truck ran for a good while before the box started acting up from the red wire having full charged voltage on it.

I have seen this before and all that happened was the coil got warm to the touch.

The white wire goes to the starter solenoid for full voltage during cranking and also retards the timing during start up to help with cranking.

I just added the resistor and so far so good..............

Funny I ran mine just like that diagram and didn't even hook up the white wire ! And for the record I just used it as an example . I think I stated Kind of like not as a matter of fact ! Just trying to help !

There were 4 different Dura-spark II ignition systems. The California, (RED connector box), was even an MSD unit in disguise with Ford connectors and Box size.

MOST only have a resistance wire going to the coil, not to the box itself.

whitefield wrote:Funny I ran mine just like that diagram  and didn't even hook up the white wire !  And for the record I just used it as an example  . I think I stated Kind of like not as a matter of fact ! Just trying to help !

I'm sorry Mr. Whitefield It seems I questioned your knowledge and upset you.............. I was just stating what I also have seen and done. Now, with that on the record, we can be friends again................ 

rmcomprandy wrote:There were 4 different Dura-spark II ignition systems. The California, (RED connector box), was even an MSD unit in disguise with Ford connectors and Box size.

MOST only have a resistance wire going to the coil, not to the box itself.

This is the one I have............  I will have to check , but I know it's a blue grommet module and I think it is a 74-78 year.

Some of the diagrams show the ign switch wire but don't show the resistor or resistor wire.

If you put full voltage on this box it will not run long and soon after quit altogether.

I think the 84 ford trucks used TFI ign.

IDT-572 wrote:I think the 84 ford trucks used TFI ign.

The BLUE and the GREY are the most common.  I believe the GREY doesn't have the start retard feature.
BOTH run with full voltage to the box just NOT full voltage to the coil during normal running; (unless the coil is replaced with a high primary resistance coil ... over about 2.4 ohms). Probably some kind of race coil with low primary resistance which is manufactured to run that way, might work with straight current.