Hey guys,

I am new to this forum and do not have a truck. However i have a 1975 302 out of a maverick. I have put this engine into my Rx7. its been quite the project. Educational and interesting. However i am having trouble with the dreaded duraspark...

It is duraspark 1 from what i understand. Its the one with the 7 wires. Anyway i used this (https://www.ford-trucks.com/forums/8...-module-3.html) to wire it up. At the bottom there is a diagram. I used my existing ignition relay (used to power coils and fuel pump when key is on) to power the RUN position wires. For START i have a 30amp switch wired up to the battery since my ignition switch is worn out.

When i have the key on to the RUN position, if i leave it for awhile maybe 5 minutes, the 1.3 OHM resistor i bought gets very hot. Too hot to touch. Hot enough that it starts melting the electrical tape around the terminals. To me, this means resistance. Now i have got the engine to run in the car. by connecting the S terminal to the battery brieflly (this starter solenoid does not have the I terminal). It fires up and runs. Great.

So ive connected the 30 amp switch, to the S on the starter solenoid, effectively replacing the START on the ignition switch. And joined the blue wire from the duraspark module, and the wire from the coil together and connected them to the S also. The blue wire also splits and goes into the resistor before joining the coil wire. Just as it says in the diagram. I flick the switch and it turns on, but when i turn the switch off, the engine dies.....

Now i know something is wrong because i don't think the resistor should be getting as hot as it does. Also, when i turn the starter off via the 30 amp switch, the engine should not die. Is this happening because druaspark is garbage? Or is it because the two wires are not supposed to be connected on the same S terminal... I think they are due to what the diagram says.

I know duraspark has issues.. And i am contemplating doing the HEI swap, since i have 3 HEI modules from when i did direct fire ignition on my RX7. I wired in the direct ignition on the RX7 and did not have problems, so this is not my first time with ignition wiring.

Any help would be greatly appreciated, i can go over the wires again if they are not clear enough.

Thanks for your time,

Nathan

 

You should not leave an ignition system powered up with the engine off. For the factory setup, this would mean a 4 amp load to ground, which can eventually drain the battery. However, this shouldn't melt electrical tape. This sounds like there is a short somewhere, or something is wired incorrectly (like the ballast resistor going to ground instead of to the coil primary winding).

I'm also assuming your ballast resistor is an automotive grade power resistor and not from Radio Shack.

Where do you have the RED and WHITE wires to the module going?

Just because you haven't gotten it to work does not mean Duraspark is garbage. The quality of your work and the pros and cons of Duraspark are not related.

Duraspark does not have issues so much as the replacement modules from off-brand manufacturers. If you stick with Ford stuff, this is a reliable and trouble-free system. I will say that if you're going through the trouble of retrofitting Duraspark into something, I would go with 6-wire Duraspark II ('76 and beyond) because the modules are much more readily available.

 

Hey,

Thanks for the reply,

I am aware of not leaving the ignition on, i just had to get some gas to pour in the carb. that being said, it should not be getting so hot i cant touch the resistor without burning my finger.

The BLUE wire comes from the module, Splits into 2, one goes into the correct ballast resistor i got from the auto store. The other end of the ballast resistor goes to the ignition relay output. The second part of the blue wire before the resistor connects to the red coil wire. The coil wire/blue wire then connect to one wire which connects to the starter solenoid S terminal along with the 30 AMP switch i am using to power the starter siolenoid.

The RED wire goes to the + on the battery. This was the part i was confused about because on the diagram it shows it going to the R above the switch. Which is kinda strange because if it did that it would be no different than the white wire....

The WHITE wire goes to the ignition relays output. Just as one end of the BLUE wire after the resistor does.

basically im getting the R from the ignition relay which used to power the previous coils and fuel pump when the key was turned to the RUN position.

The START has been swapped for a 30 AMP switch since the ignition switch will no longer work for the START position.

Maybe what is wrong is with the RED wire being connected to the battery? If that is the case, where would it go? Seems logical you have three wires, one to constant power, one to switched power, and one to power when cranking the engine over.

Thanks,

Nathan

 

No part of the ignition module should go directly to the battery (like a radio memory would). Only hot-in-RUN and hot-in-START power.

I share your same confusion about the diagram showing both RED and WHITE wires going to hot-in-RUN power. This leads me to believe that there may be a drafting error in the diagram. Duraspark I was used in 1975 only. Wiring diagrams for it are few and far between, so I have no way of checking it. My books only show 1974, or 1976 and beyond. The same is true for the factory wiring diagrams available on the internet.

As far as the resistor getting hot, you can verify that there are no shorts to ground downstream of the resistor. If not, perhaps the module is bad, and is grounding out the BLUE wire internally.

My advice, while possibly not very helpful, would be to use a Duraspark II module (76 and later) with a BLUE grommet. These are available all over, and are easy to hook up. The pickup module inside the distributor of your '75 can be reused. Sorry - if I could find more literature I could be more helpful.

 

Hello,

It took me hours to the the wiring diagram for the 1975 only to find it was wrong haha.

I managed to get ahold of a 1985 ford duraspark with the blue grommet for $20. Will this hook up the the dizzy i have in the 75?

Thanks,

Nathan

 

I understand that to be the case.

 

Excellent! thanks for your help.

Nathan

 

All right, well i got the duraspark two. Hooked it up using this diagram.

Duraspark II Conversion Basics

I am still having the hot ballast resister problem. My question is...

After looking at that diagram, there are two S positions. Are they both the same? The way i have it wired they are both getting power from the starter solenoid, (the I or S terminal, the solenoid that has only three prongs of which two are for the actual starter and the other to tell it to turn on). So my ignition switch sends power to the third terminal, the starter engages and the other wire that is attached to the same prong as my ignition switch output splits into two and follows this diagram.

Is there something wrong with that wiring? I cant understand what i am doing wrong

Thanks for the help,

Nathan

 

Yes, the two 'S' positions must be different. The 'S' position that feeds the start bypass circuit must be on its own dedicated circuit with no other loads - otherwise the ballast resistor will back-feed this circuit with the key in RUN. The two 'S' positions are meant to be electrically isolated once the switch opens, and therefore are drawn as two separate poles in the diagram you posted.

You can accomplish this with an ignition switch with two hot-in-START poles, or an ignition switch with one hot-in-START pole AND a 4-terminal starter solenoid with an 'I' terminal. If your ignition switch only has one hot-in-START terminal, then you must use a 4-terminal starter solenoid. A 4-terminal starter solenoid means that it has one heavy lug for the positive battery cable, one heavy lug for the starter cable, one small terminal labeled 'S' (hot-in-START from the ignition switch to engage the solenoid), and one small terminal labeled 'I' (dedicated hot-in-START from the solenoid that is electrically isolated once the solenoid disengages).

If your ignition switch has only one hot-in-START pole, then use the starter solenoid I mentioned above, and wire it as follows:



If your ignition switch has two separate hot-in-START poles, then use the wiring diagram you posted. In this case you may use a 3-terminal starter solenoid (which lacks an 'I' terminal), or a 4-terminal starter solenoid and leave the 'I' terminal disconnected. I'm not familiar with what the Mazda solenoid would look like, assuming that's what you're using. But you should be able to translate it based on what I've described.

The hot-in-START signal that goes to the ignition module is shared with the hot-in-START signal from the ignition switch that goes to the 'S' post of the starter solenoid. Do not share the hot-in-START "start bypass" signal to the ignition coil with any other circuits.

 

Ignition module used in 1974 is 1974 only / Ignition module used in 1975 is 1975 only.