Pertronix Ignitor 2 on my '66 Imp

The above two paragraphs explain why I don't like the idea of putting in a higher resistance coil and removing the ballast resistor: You may actually develop a hard-start condition after doing this.

I just did what Tech told me to do, replace the coil with the system, said I didn't need to touch the BR and could be wired directly to the coil. Said and done!

Voltage in the coil secondary winding will only increase until it overcomes the resistance of the air gap at the spark plug. If your old ignition system was able to do that, the replacement components will behave identically in practice. If you really want a hotter spark, increase the spark plug gaps as well.

I set mine to .45 and noticed a small difference, more so in the reliability of the system then having to fiddle fart around with points.
 
Thank you. That needed to be explained in more detail than I have done.



I never thought about this... It makes perfect sense that it would be designed like that.



This is what I've understood as the difference in the two systems.



Bingo!!
Ultimately burning up a coil is not about voltage but power, specifically how much power the primary windings can handle without overheating. P=V*V/R or Power (Watts) equals voltage squared divided by resistance. If you have a ballast resistor in series, that adds to the total resistance, limiting the power to protect the coil.

On a standard Mopar ignition, the ballast resistor is bypassed while cranking. During cranking, the system voltage droops because the starter draws more current than the battery and wiring can supply. Bypassing the ballast resistor compensates for this. If you remove the ballast resistor by swapping-in a coil with higher internal resistance, obviously you can't bypass that resistance.

Also note that the actual resistance of the ballast resistor varies with temperature, increasing when underhood temperature is hot. The system is designed to increase coil power when the engine (and coil) is cold because the coil is able to handle more power and the added power may be required to ignite the fuel, and decreasing coil power when the engine (and coil) is hot. I've never seen it written anywhere that the internal resistance in a coil varies with temp the way a ballast resistor does.

The above two paragraphs explain why I don't like the idea of putting in a higher resistance coil and removing the ballast resistor: You may actually develop a hard-start condition after doing this.

The Ignitor-1 is much like the Mopar electronic ignition system, a points replacement which works pretty much the same, so the above description would be applicable.

However, from what I've read before, the Ignitor-2 has a current regulator similar to a GM HEI system. HEI systems do not have nor need a ballast resistor by design because they internally limit the current. A more applicable equation would be P=I*I*R or Power (Watts) equals current (Amps) squared multiplied by resistance. The Ignitor-2 should have a built-in upper limit on current output so that max power doesn't exceed some reasonable threshold, which would eliminate the need for the ballast resistor.

Note that the whole idea of swapping in a performance coil or electronic ignition won't provide much benefit for a street car with an ignition system already in good condition. Voltage in the coil secondary winding will only increase until it overcomes the resistance of the air gap at the spark plug. If your old ignition system was able to do that, the replacement components will behave identically in practice. If you really want a hotter spark, increase the spark plug gaps as well.

I don't think I could a better explanation anywhere!
 
So, leaving my stock Echlin12 in place WITH ballast resistor: good.
Replacing said coil with lower resistance unit and leaving BR in place: bad.
Using recommended coil from Pertronix and gutting BR: good.
Is there a significant benefit to be had by switching to the hotter coil/recommended setup?
 
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