Duraspark II conversion Ignition Coil vs Stock

[Mike Armstrong]

This is the ignition coil recommend by The Ranger Station in they’re Duraspark II Conversion article.

https://www.napaonline.com/en/p/MPEIC21SB

http://www.therangerstation.com/how-to/ignition-charging-computers/2-8l-duraspark-conversion/

I noticed on the front of it is written ‘Use with Electronic Ignition’ (ie Duraspark II, I assume).

1) What type of proper electrical connector is supposed to be used on those terminals? Or do you simple wrap exposed wires around the posts?

2) Does this coil require an external ballast resistor?

This is the stock 1985 Bronco II coil I’m currently using, with an external ballast resistor.

https://www.autozone.com/ignition-t...ignition-coil/duralast-ignition-coil/112052_0

I can’t find the output specs on either coil.

1) Is this stock coil any better/worse than the one above?

 

[260Alpine]

Mike, Either coil is fine. The other style coil would use ring terminals. If the Duraspark box ever goes out you can run the distributor with a 4 pin GM HEI with no external ballast resistor.

 

[260Alpine]

GM early 90's pickup coil and bracket with 75-80 4 pin module.

 

[Mike Armstrong]

Mike, Either coil is fine. The other style coil would use ring terminals. If the Duraspark box ever goes out you can run the distributor with a 4 pin GM HEI with no external ballast resistor.

Like these Jim? They look like a spade connector would work, unless those terminal unscrew or something?

http://www.wiringdepot.com/store/p/...kfX3c__3i1kDgh7UUFQ2NstAkWyZN1-waAki2EALw_wcB

 

[260Alpine]

Those connectors shown are what I would use. 14 gauge wire to coil terminals. You do use external ballast with the Duraspark. The older style coil should be for 78 Mustang II for the right internal resistance. The newer style probably has more voltage.

 

[260Alpine]

Most Electronic ignition coils have .5 to 1.5 internal resistance. The Duraspark also uses a resister wire to drop voltage to approximately 8 volts in stock applications. It also has a bypass wire for starting with 12 volts. The HEI uses a full 12 volts. Duraspark is wired very similar to points ignition. You notice in my diagram above for HEI the resistor wire is cut.

 

[260Alpine]

Another issue, some have added the external ballast resistor with the 3 ohm internal resistor points coil or added the external ballast resistor in addition to the resistor wire. Then, because of voltage drop, it causes difficult cold starting. The HEI conversion with low internal resistance coil does away with those problems.

https://www.powerperformancenews.co...onvert-a-ford-or-mopar-distributor-to-gm-hei/

 

[Mike Armstrong]

Those connectors shown are what I would use. 14 gauge wire to coil terminals. You do use external ballast with the Duraspark. The older style coil should be for 78 Mustang II for the right internal resistance. The newer style probably has more voltage.

Thanks for all the info Jim.

Sorry, which is considered the old vs new coil?

I didn’t use the TRS article recommended coil just because I wasn’t satisfied with using those terminals, I didn’t have a male to male ignition wire on hand and I already had a newer stock Duralast coil on hand.

 

[260Alpine]

Mike, The old style is the tin can 78 Mustang II the Ranger article recommends. Your 85 Bronco II coil is the newer style.

 

[260Alpine]

Mike, I remember your hard starting when cold issue. Do you have the bypass wire from the solenoid "I" terminal to the "+" side of the ballast resistor? Also your coil is meant for TFI and has .3 ohm internal resistance. The Mustang II coil has 1.2 ohm internal resistance.

 

[Mike Armstrong]

Hmmmm, without using a continuity light to trace them, it looks like I have a hot wire from the solenoid to the + side of the coil. The ballast resistor has a hot wire from ‘I think’ the ignition, and I don’t remember off hand if that’s Start or Run. The other side of the ballast is also connected to the + side of the coil. The negative side of the coil has only one wire and that is the green wire from the module.

Is that TFI Coil meant to only be used with the TFI Module, and not alone with a ballast resistor like it is now? Hmmmm, I just might be using that can coil with a ballast after all.

 

[260Alpine]

Mike, I've used GM E core (similar) coils with HEI but they were meant for 12 volts. I don't know if it would be an issue with the Duraspark.

 

[260Alpine]

Here is the Duraspark II diagram showing the ballast resistor. I think you are running 12v all the time and not going through the resistor.

 

[Mike Armstrong]

Here is the Duraspark II diagram showing the ballast resistor. I think you are running 12v all the time and not going through the resistor.

Could be Jim. So, 12v initially during cranking from the solenoid, then 12v from the RUN terminal of the ignition but THRU the ballast resistor first.

 

[260Alpine]

Mike, This link may help:

https://www.mgexp.com/phorum/read.php?40,2622505

 

[Charles Johns]

Jim, THANKS for the link to the ignition guy! He explains why a good points system with the best available components, can run a motor just fine in most cases. Reading all the things Detroit does to stop sparks from hurting electronics, one can see why I like old-school points. He does not say that directly, but one can figure out my reasoning from his info. A coil will NOT produce more spark once the arc is made at the plug. If the plug arcs at 18,000 volts the coil does not go higher. Combustion finishes the process, not more spark. Matching spark amount with plug gap, wire resistance and the best available points/cap/rotor/condenser, along with dwell time and proper timing, and one has as good as it gets for the street. PerTronix is better for consistent accuracy and less maintenance, but only slightly. As a factory ignition guy he just explains it far better than I can.