I have been searching all over the web for information regarding the Duraspark ignition system. This site kept turning up in my searches so I figured I would post here as it appears many of you all are very familiar with this ignition system. And it turns out I was already a member from several years ago...

But first let me preface this with the fact that I am not an electrical genius so please keep that in mind with suggestions, etc...

The application for the Duraspark is a 302 set up for road racing. The rules dictate that the Duraspark must be used for Fords running a carb. I have yet to purchase any Duraspark components other than the distributor which came from the parts store for an '85 Mustang with the steel gear for the HO roller cam.

I want to make all of the wiring harnesses using Weatherpak connectors as the Duraspark module will be mounted in the interior of the car. I have been unable to find what appears to be accurate information regarding the amp draw of the Duraspark... With that said, what gauge wire should be used to fabricate the wiring harness?

Regarding the coil, by the rules of my class, I can run either an oil filled Ford coil or a Ford TFI. Again, I find all kinds of different information regarding the use of coils as well as a ballast resistor...

The best I can tell is the oil filled coil does require a ballast resistor in the "run" circuit but the oil filled coil may not be the best for a road race application.

Other information indicates the use of a TFI coil with a resistor as the resistor only controls voltage to the coil... Some state without a resistor the use of the TFI coil will "cook" the Durasapark module. Then others state the TFI coil is designed to receive full battery voltage...

Can anyone confirm the successful use of a TFI coil with a "blue strain" Duraspark module?

If a TFI coil was used, did it require the use of the resistor?

With my application being a "race only" car I will be using a push button, or momentary toggle switch, for the starter and a toggle switch for the ignition.

From what I can make out from the diagrams I have studied it would appear the correct way to wire the push button and toggle would be as follows: Duraspark white wire to the "S" on the starter solenoid with the push button in line of the 12V source to the "S" on the starter solenoid.

The Duraspark red wire to the "I" on the solenoid with the toggle switch in line of the 12V source to the "I" on the solenoid.

It would seem that using a push button, or momentary toggle switch, to the starter may result in a slight "overlap" of the 12V source to the white wire and the red wire to the Duraspark unit. For example, the starter button is pushed and the engine fires. If the starter button is released the engine will shut off. If the toggle switch is flipped while the while the starter button is depressed the engine will remain running because 12V is now applied to the red wire to the Duraspark box and the starter button can be released. Am I understanding this correctly? If so, will this present a problem with 12V being applied to the white wire and red wire at the same time?

I guess another option would be to just not use the white wire at all... I could get the engine spinning over with the push button and then flip the toggle switch to activate the red Duraspark wire to fire the engine. Do any of you all see a problem with using this method?

If any of you all have a specific wiring diagram for using a starter push button and toggle switch for the Duraspark I would really appreciate a link or posting it up.

Sorry for the long post and all of the questions.

Thanks again and any and all advice is appreciated...

 

I want to make all of the wiring harnesses using Weatherpak connectors as the Duraspark module will be mounted in the interior of the car. I have been unable to find what appears to be accurate information regarding the amp draw of the Duraspark... With that said, what gauge wire should be used to fabricate the wiring harness?

14 gauge would be plenty normally, but since you are running a longer distance to the inside of the car, just go ahead and use 12 gauge. That will take care of any voltage drop issues you might have.

Regarding the coil, by the rules of my class, I can run either an oil filled Ford coil or a Ford TFI. Again, I find all kinds of different information regarding the use of coils as well as a ballast resistor...

The best I can tell is the oil filled coil does require a ballast resistor in the "run" circuit but the oil filled coil may not be the best for a road race application.

Other information indicates the use of a TFI coil with a resistor as the resistor only controls voltage to the coil... Some state without a resistor the use of the TFI coil will "cook" the Durasapark module. Then others state the TFI coil is designed to receive full battery voltage...

Can anyone confirm the successful use of a TFI coil with a "blue strain" Duraspark module?

If a TFI coil was used, did it require the use of the resistor?

The duraspark II system was designed to run the duraspark II coil. The type of coil along with the resistor sets the current and power that the duraspark ignition box must handle. If you are running a stock setup and longevity is the concern, I always recommend running a duraspark coil, it has the plain prongs on it and requires the horsehoe connector that they sell in the store.

That being said, there are people who run the TFI coil with mixed results. It may give a hotter spark but this will require the ignition module to pass more power as the engine is running, and it may run hotter. If you want a no-nonsense run forever system, run the duraspark coil. If you want to experiment, you can try the TFI coil, but I would get some extra cooling going for it, like mounting it on a large piece of aluminum or mounting it so it gets a little airflow somehow to help keep it cool.

No matter what coil you decide to run, YOU MUST RUN A RESISTOR. This more than anything sets the power the module must handle, and it was designed with this resistor in place. Running without the resistor will make the module fail in a short time. You can rob the resistor from a Ford harness(special wire near the ignition switch wiring) or you can go to the store and buy a large white resistor for a Chrysler vehicle. The original Ford piece of resistance wire will probably be closer to what you need in value, but people run the Chrysler resistor with success also.

From what I can make out from the diagrams I have studied it would appear the correct way to wire the push button and toggle would be as follows: Duraspark white wire to the "S" on the starter solenoid with the push button in line of the 12V source to the "S" on the starter solenoid.
The above is correct. What this does is place 12v on the white wire during cranking only. This will tell the module to retard the timing a set amount so the engine is easier to crank over. This will be very useful for you if you have your "race engine" timing set advance for power, making the engine easier to crank when it's hot.

The Duraspark red wire to the "I" on the solenoid with the toggle switch in line of the 12V source to the "I" on the solenoid.
The above is not correct. The red wire only goes straight to the ignition switch and then the 12v source. Run a wire directly from the COIL + to the solenoid "i" terminal. Then run another wire from the coil + to the resistor, and then the other side of the resistor will go to the ignition switch.
The brain of the module gets a full 12v(red wire to module). The coil + gets about 9v when running through the resistor, but the wire directly from the "i" on the solenoid sends a full 12v to the coil + only when cranking. This gives the engine a hotter spark during cranking, when the voltage is low anyway because the starter is using all the battery power.

It would seem that using a push button, or momentary toggle switch, to the starter may result in a slight "overlap" of the 12V source to the white wire and the red wire to the Duraspark unit. For example, the starter button is pushed and the engine fires. If the starter button is released the engine will shut off. If the toggle switch is flipped while the while the starter button is depressed the engine will remain running because 12V is now applied to the red wire to the Duraspark box and the starter button can be released. Am I understanding this correctly? If so, will this present a problem with 12V being applied to the white wire and red wire at the same time?
Don't worry about the above. You can have 12v on both the red and the white, that is really what you want when starting the engine. The red wire is the brain of the module, the white wire is just a signal to retard the timing a set amount.

 

Dave...

After reading over several of the posts on the board before reactivating my membership I had come across several threads you had responded to regarding the Duraspark. I was hoping you would respond...

I have several things to say to you... THANK YOU, THANK YOU, THANK YOU, THANK YOU!!! Have a safe and happy holiday. And THANK YOU again!!!