'70 Ballast Resistor on 440

[bad88t-top]

Hey guys,
I found out at Carlisle that I had the incorrect ballast resistor on my car so I went to "Herbs" and purchased a factory reproduction one.  I'm currently running the Mopar Performance electronic ignition kit on my 440.  I've been running the one that came with the mopar perf kit that was purchased several years ago.  Then, a few weeks before Carlisle I put one on that my dad had assumed was the original but wasn't.
It was discussed that I need to be cautious as to which one I use because the OHM rating on an electronic version is slightly lower than a non electronic ignition ballast resistor.  I ran a meter across the leads and the electronic ignition version read .7 while the factory reproduction one read 1.3.
My question is, can I run the factory replacement ballast resistor with my electronic ignition and orange box?   Can this burn my box up?   Let me know your thougths and thanks...

[Chatt69chgr]

I don't have a definitive answer but the higher resistance ballast will lower the current through the output transistor in the orange box.  That would mean less heat to be dissipated so would be better for the transistor's life.  The current through the coil primary will also be less.  Don't know if that is a problem or not.  Probably wouldn't create at strong a magnetic field in the coil and might produce a lower spark voltage.

[BrianShaughnessy]

Whatever you do... carry spares.   Cause the resistors blow when you least need them to.

Factory repro resistor blew out Sunday morning for Jersey Joe trying to get the B7 Chally R/T to photo shoot with
Hemmings at Carlisle.   

  I've been running a non original looking MSD resistor for years. 

[Just 6T9 CHGR]

The ballast is generally matched to the coil.  If you are running the MP repro coil then the stock repro ballast (1.3 ohm) will be fine.  The higher resistance, the lower output voltage to the coil & the less heat the coil should generate.
I am running an MSD Blaster II coil with the supplied matched .8 ohm ballast.

[BananaDan]

If its matched to the coil, why does the MP EI upgrade kit come with a ballast but not a coil?  That would indicate that different ballasts can work on the same coil and it has more to do with the EI box or the distributor, no?  Also, the ballast for EI is a different OHM rating than the one for points. 

[Just 6T9 CHGR]

I can only assume because since you are "converting" to electronic ignition, you are already running a stock-ish coil with the points system you are replacing?

Absolutely any ballast can work with any coil, but from what Ive read, too high or too low a voltage to the coil can either over heat it or not make it work to its full potential.....dont quote me on any of this though!

Couple of good explanations here but I still dont get all of it!

http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=6707447&page=0&fpart=1&vc=1