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Discussion Starter · #1 ·
I'm going to run a Duraspark II ignition in my '67 Fairlane with a 351W. This will strictly be a cruiser. What's a good choice for a coil on this setup?
 

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Discussion Starter · #2 ·
I've tried to delete this post and rewrite it with no luck. I need some additional information. Yes, I still need to know what coil is best but in researching that I've come across so many posts about wiring a Duraspark II that I'm confused. Some say to eliminate the pink resistance wire feeding the coil but most say leave it in place. I have a full 12V at the coil connection and expected something less due to the resistance wire. So, should I have less than 12V at the coil? Should I bypass the pink resistance wire? What coil should i be using?
 

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I think one of the best modifications is to ditch Duraspark ignition box. Do that with a GM HEI which you could mount to a remote mounted TFI coil heat sink from a later model Mustang or F series pickup or many others. Ford still sells them as well..
Once you have the GM module in place, just use whatever remote mount coil that will work. Solid 12v from a switched source. cut the resistor wire out if it's still there
 

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The whole point of the ballast was to keep that old style oil bath coil from overheating, switching to more powerful modern low resistance E-coil negates that, someone correct me if i'm only half right on that.
 

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The duraspark was OK, but poor components and connections made them unreliable. If your distributor is of that system, use it to drive a 6AL-2 and select a coil with compatible impedance. Or you could do the same with a pertronix digital hp 512. Both are capacitive discharge to give a longer hotter spark, and both have settable rev limiters and switches. Either would be superior to a duraspark.

Just need to keep away from heat sources. I mounted mine on a piece of aluminum with an air gap behind it.

I don't like TFI, there was a lot of problems with modules dying. Strange thing, if you popped off the plastic cover of a TFI, then shine a bright flashlight on the submerged board with the engine running, it would die.
 

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The duraspark was OK, but poor components and connections made them unreliable. If your distributor is of that system, use it to drive a 6AL-2 and select a coil with compatible impedance. Or you could do the same with a pertronix digital hp 512. Both are capacitive discharge to give a longer hotter spark, and both have settable rev limiters and switches. Either would be superior to a duraspark.

Just need to keep away from heat sources. I mounted mine on a piece of aluminum with an air gap behind it.

I don't like TFI, there was a lot of problems with modules dying. Strange thing, if you popped off the plastic cover of a TFI, then shine a bright flashlight on the submerged board with the engine running, it would die.
they overheated. the later models had the module affixed to a heat sink.


I was suggesting only using the heat sink from the later TFI with a GM HEI module.. Duraspark and HEI use functionally identical triggering
 

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Discussion Starter · #7 ·
Thank you all for the advice in reference to the GM modules, the TFI, Pertronix, etc. I've purchased and installed a new Motorcraft DS II blue unit and distributor. I have all the Ford plugs spliced in and connected. So if it's not the ultimate arrangement, so be it. I appreciate you trying to steer me to something that may be better but for now I'm committed to the DS II. What I still need to know is:

1. Should I have less than battery voltage at the coil given that there's a resistor wire in the circuit.
2. Should that resistor wire be bypassed with the DS II system.
3. What's a good coil to run with a DS II.
 

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In that case, I would check the resistance of the primary winding of the matching coil for the ford ds ii system, then look for a similar resistance of aftermarket coil, HP, Ecoil, as long as the resistance matches that of the Oem. If you go with a mallory, accel, or a non-oil filled coil, you should be able to eliminate the resistance wire.
 

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1. Should I have less than battery voltage at the coil given that there's a resistor wire in the circuit.
The resister wire only drops voltage if there is a low resistance load on it... testing the voltage with a high internal resistance VOM doesn't load the wire enough and doesn't show a voltage drop... checking the voltage with the engine running should show lower voltage reading...
 

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Buzz is correct, without a load, the voltage at the coil would appear as battery voltage. The coil resistance would share the voltage drop with the resistance wire or ballast resistor.
 

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Discussion Starter · #11 ·
Car isn't running yet. Voltage was checked with a Fluke VOM and key on but not running. The control module I bought is compatible with a bunch of Ford cars and trucks. So, any coil within those years and models should work?
 

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You may have checked the voltage, but the voltmeter does not present the same load as a coil, therefore the voltage reading would not be the same as it would be with a coil in the circuit.
You can get a battery voltage reading through a bunch of green corrosion, but little or no current will pass through it.
 
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