Duraspark II which wire to delete? HARNESS AND NEW BOX DONE

I found out I do not need to run a ballast resistor, with my MSD Blaster ss coil. I can run full 12 volts .I'm in the process of changing my ignition to the blue grommet box, so I'm going to make or buy a new harness, so in this diagram, which wirers would I delete if any or just eliminate the ballast resistor.

The wire coming off the "I" terminal sends 12 volts to the coil when the ignition is in the start position.
It just bypasses the resistor, so it s not needed. And yes, just eliminate the resistor in that diagram
and that will send 12V to coil.

Erase the resistor from the drawing and draw in a straight line on that red-green wire. Then you can erase the brown wire too. Everything else stays.

I forget which harness you have savage, but if it's still stock, that resistor wire is entirely under the dash, between the ignition switch and firewall pass-through. Depending on the year of the Bronco, it might actually be a separate thing you can unplug and replace with standard wire.
Or you can just run a new one from the switch to the firewall connector and leave the old one in place if you want. Up to you.

If it's an aftermarket harness, then you don't have a resistor wire. Only a stand-alone ballast resistor which is a bunch of coiled up wire on a ceramic base thingy bolted to the body or engine somewhere.

Paul

I'm sure this modification will work. Having an unmodified Duraspark II work flawlessly for 40 yrs. makes me ask what shortcoming of the stock system is remedied by doing this. Have any of you seen a specific flaw?

DirtDonk said:

I forget which harness you have savage, but if it's still stock, that resistor wire is entirely under the dash, between the ignition switch and firewall pass-through. Depending on the year of the Bronco, it might actually be a separate thing you can unplug and replace with standard wire.
Or you can just run a new one from the switch to the firewall connector and leave the old one in place if you want. Up to you.

If it's an aftermarket harness, then you don't have a resistor wire. Only a stand-alone ballast resistor which is a bunch of coiled up wire on a ceramic base thingy bolted to the body or engine somewhere.

Paul

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Hey Paul ,its a centech wiring harness and I think it just has the ballast resistor. Thanks viper and every one else, I kind of thought it work that way ,but wasn't sure. Dave

I pick up the connectors and the blue module, I need to pick up the wires and start building this harness, of course it 80 degrees and nice out, and the bronco's down.

jckkys said:

...Have any of you seen a specific flaw?

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The only "flaw" that gets the most discussion that I can remember is the more complicated wiring as most see it. While it's not that big of a deal for anyone with some moderate wiring understanding and patience, many look at it and cringe. And when you add multiple choices of modules and connector layout to the mix, the cringes get deeper and more mind-numbing.
To the point that they just go with the supposedly simpler fixes of things like Ignitors, all the "ready to run" stuff out there, and even HEI distributors. The number of people using HEI's in fact, kind of bears out my assumption that the only real fault anyone finds with Durasparks are the wiring.
When doing a conversion from points, a Duraspark is really the only one that requires you source/build a separate ignition harness to control the distributor and separate module and ignition coil. This alone is enough to sway some in the direction of one of the other choices.

Yes, there were some here over the many years that did have some module failures. For whatever reason, they had a few burned out Duraspark boxes. I even had three failures, but I concluded that it was the cheap $18 knockoffs I was buying. Bought two different types for about 100 bucks each and never had an issue after that. Those two are still good and up for sale in fact. Probably why finding an OE original in the junkyard is not such a bad solution.

Funny though, that in all the discussions of "what's better" nobody seems to remember the legions of complaining GM vehicle owners in the '70's and '80's that could not keep a GM HEI alive very long either. But things change...

Even savage here started the discussion, if I remember correctly, because there were different wiring configurations, his had been modified anyway, and which way to go to keep it Duraspark. Or something to that effect. So even here that aspect did cause some drama. But in his case at least he's sticking with the Duraspark.

I always grin when I see some aftermarket setup, such as an MSD or Mallory distributor, that is utilizing the magnetic trigger design from the Duraspark distributors in their versions. Whether controlled by an internal or external module, the pickup and stator/reluctor(?) are the Ford design.
That part at least must be well thought of in some minds then.

Paul

I would double check the info about not needing a resistor for the blaster coil with a duraspark setup. To my knowledge blaster coils dont require a resistor with a MSD or other CD type igintion. But with any other type you MUST have a resistor. The Duraspark doesnt send power to the coil like a CD igintion does. The coil on the duraspark has voltage all the time.

If you look at this link and go to the instructions you'll see that you do need the factory resistor wire or a added balast resistor if it has been removed for a duraspark application. All the blaster coils have the same specs just different housings so even if you dont have the duraspark specific coil the resistor is needed.. http://www.msdperformance.com/Produ..._-_Blaster_2_Coil,_Ford_High-Performance.aspx

Part of the reason that MSD really only says that its needed with points systems is because the electronic systems tend to have the resistor built into the wiring and a lot of the older points setups had a ballast resistor mounted on the firewall or the coil bracket. Some coils like a pertronix have the resistor built in and can take 12v but most other coils wont leave the key on to long with the engine off and the coil may blow up or burn up usually they will blow apart slightly due to the oil expanding and start leaking everywhere. Of course it may not but you'll be taking a chance without one.

Post up the specific part number for your coil if you know it.

Paul

Hey Paul, The coil is Blaster SS Coil, PN 8207, I called MSD and talk to a tech,and he said it can run on 12volts and said I don't need a resistor. So is he blowing smoke up my ****,OR WILL IT WORK? I just got all MY STUFF FOR THE HARNESS ,SO I'm READY TO GET THIS STARED. broncnaz ,I looked at that coil and its not what I have, my instructions are different, http://www.msdignition.com/uploadedFiles/MSDIgnitioncom/Products/Coils/8207_instructions.pdf

broncnaz is not incorrect in what he was saying, and the inter-relationship (heat-wise) between a coil and trigger is sometimes a mystery. But frankly, if MSD said it would be OK (and assuming they knew that you were not running a CD box) then either it's good to go, or they owe you a new coil when yours fries!

That said, I'd run it on 12v too. I've run many of my coils that way on purpose, ever since I bought my first Jacobs coil (stated to run on 12v specifically) and my very first Blaster coil (private labeled Ford Motorsport) coil with my Duraspark blue box.
So that's points, Ignitor I and II, and Duraspark triggers, all with the full 12v to my coils.

That's why I differentiate that what broncnaz said is absolutely true, but that it also sounds like your coil is good to go.
If if fries, I'll send you one of my Jacobs coils to use.
(and now I'm going to go read up on the #8207 anyway!!!;D)

Paul

Hey Paul, I'm just going to run it with out the resistor hoping the tech's right. Here's a tech answer on the MSD forum , that it should work with out a resistor, on the duraspark II ignition.http://www.msdignition.com/forum/showthread.php?t=21008

broncnaz said:

Duraspark doesn't send power to the coil like a CD ignition does. The coil on the duraspark has voltage all the time.

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Note from 8207 instructions:
Note:
If installing the Blaster SS Coil to a points distributor or a non-current limiting ignition system without
an MSD Ignition, a 0.8 ohm ballast resistor is required (MSD PN 8214). The resistor should wire in
series along with any factory resistors on the positive coil wire.

So is the Duraspark a non-current limiting ignition system? If so broncnaz might be on to something.
But the "tech" says you'll be okay, so like Paul says, if your coil fries, they owe you a new one...

Kind of a piss poor answer from a supposed tech. Answer is "not really"
I dont believe the tech knows that much. Any vehicle that came from the factory with duraspark will have the resistor wire. So basically the tech's answer is correct he doesnt need the extra .8 ohm resistor because the system has a 1.2 already. Probably why they have run it for years without issue.

While your instructions may differ the note right at the top says it all. "If installing the Blaster SS Coil to a points distributor or a non-current limiting ignition system without an MSD Ignition, a 0.8 ohm ballast resistor is required (MSD PN 8214). The resistor should wire in series along with any factory resistors on the positive coil wire."
The duraspark system doesnt limit current to the coil as when you turn the key on the coil will have power. Basically they are even saying to add the extra resistor even if you have factory ones already??
Lots of confusion with MSD. Probably why they have a lot of issues with there stuff. Its up to you on what direction to take listen to the tech or follow the instructions. Either way you may never have a issue. Just dont leave your key on with the engine off. As that will kill a coil fast especailly if it should have a resistor.

Im a little slow there. you found the note.

I'm not sure what module is being portrayed in savage's diagram; post #1. A Duraspark II has a 2 wire connector with red and white wires, not blue and red/blue.
As I said, circumventing the resistance wire/ ballast resister will work to supply 12 volts to the coil. What I'm asking is, if a reduced voltage coil functions perfectly well, why rework the wiring to facilitate a 12 volt coil? I don't know of any shortcoming that this would fix. I've seen no failure to fire even lean mixtures with the specified plug gap of 0.44'-0.50". Ford tried a high voltage Duraspark I system in '77 Cal. applications. These had larger 0.60" plug gaps. The Duraspark I was dropped after '79. So I guess Ford couldn't see a reason to continue it. In contrast, Duraspark II was used at least through '97.
A friend and UPS mechanic told me the Duraspark II in hundreds of thousands of their trucks, was the most trouble free ignition they used. I did learn that the orange and purple wires from pickup coil to the module carry only a fraction of a volt so the connections and wires have to be solid to assure continuity.
The Painless and American Autowire harnesses are surprisingly expensive but not complicated. The OE points resistance wire should work with Duraspark. The coil, module, and distributor are easy to find and for less $ than after market types.

jckkys said:

I'm not sure what module is being portrayed in savage's diagram; post #1. A Duraspark II has a 2 wire connector with red and white wires, not blue and red/blue.

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Apparently you need a lesson in '76-'77 Bronco wire colors. That is one of my diagrams and it is correct.

I think the modules with a blue wire are duraspark 1 modules no big differenace. Although the duraspark 1 or solid state igintion does limit current to the coil. So he may be able to bypass the resistor although the stock setup still uses a resistor not sure if it will harm the module if removed. Ive heard the blue wire is basically a fuseable link to protect the module. Although Im not real sure on that as it seems to get power from the resistor wire going to the coil so that doesnt seem correct for a fuseable link when the voltage is already reduced.
Some of the replacement modules can have a blue blue gromment but work on DS1 or DSII systems.
In reality no matter what the specs say coils only put out what power is needed to jump the spark plug gap. Usually only on high performance ie high compression, boosted engines, or ones used for racing really see benefits with hipo coils. The way I see it some of these coils are not as good as stock ones. Especailly for a engine thats stock or mild and doesnt see high RPM use. You may get a hotter spark but for less overall time. Some engines have poor combustion chambers or run very lean and the mixture may "flame out" with a short spark where a longer duration spark will keep it ignited. So in some cases a stock coil with a longer spark duration is better along those lines thats where some of the multi spark ignitions help.
Some specs are misleading as most stock coils will put out 40,000 volts just like the aftermarket ones.
Dont get me wrong Im not against aftermarket coils but I think they should be researched carefully. I run aftermarket coils on some of my vehicles.

Just getting back and reading the instructions. Thanks for posting that.
I'm going to have to agree with broncnaz and gr6scott on this one savage. It's pretty clear in the instructions that, unless somehow the Duraspark is a "current limiting" ignition system (which I don't think it is and the others have stated), you DO need the resistor.
A .8 ohm version is not much, and the one you have from Centech may be the higher 1.2 or 1.5 ohm type? Not sure, but that's another thing to check.

I did not check to see what the listing was for the internal resistance to that coil, but the instructions are what I'd go by.

Granted, the e-core type coils that this is, as opposed to the oil-filled cans that the more stock-looking type coils, can handle more heat and abuse, but it says what it says. Maybe it's trying to keep any damage from happening to the Duraspark module, rather than the coil itself? Not sure, but the others can probably answer that.

So by "current limiting" I'm guessing they're referring to the Capacitive Discharge (CD) type ignitions?

Good luck. Very nice coil, but again, go with what the instructions say, or call the tech back and find out exactly why he says it'll work with 12v and a Duraspark.
There's still a chance it might, but get a confirmation.

Paul

By the way... Not being up on my ohm's law stuff, what voltage do you end up with when using an .8 ohm resistor in a 12v system?

Thanks

paul