Reply to "Ballast Resistor"

The e-core coils were not originally used with ballast resistance BUT the TFI ignition modules the coils were paired with utilized dynamic dwell to prevent over-charging or under-charging. Your Pantera's Duraspark II module does not provide dynamic dwell.

Since they were not used with a ballast resistance there is no precise answer regarding how much ballast resistance to use. The real question is, can you use the e-core coil without ballast resistance AND without dynamic dwell? A coil that over charges will run hot and will fail more quickly than normal. I don't know how robust those coils are. Give it a try and see what happens. You might want to keep a spare coil in the car ... just in case. If you want to install some ballast resistance, installing a resistor with approximately the same resistance as the primary resistance of the coil will get you in the ballpark.

Unless you've installed a separate supply for ignition power, a section of the original wire that supplied power to the coil had ballast resistance built into it (Pantera L). So your coil power may have ballast resistance. Unfortunately if that same wire is used to provide power to the ignition module it shall have ballast resistance too; the module supply is not supposed to have ballast resistance. The power for that wire passes through the ignition switch, and there's usually some resistance associated with the ignition switch too. I would suggest you bypass that entire circuit so you can control exactly how much resistance is in the coil circuit.

Make sure the ignition is performing up to spec before you install the e-core coil, this way you can make a valid before and after comparison. Check to make sure the ignition module and coil are wired properly. Install a new distributor cap & rotor, install a new Duraspark II "oil can" coil, replace the central plug wire and gap the plugs properly.

Unfortunately the performance of a Duraspark II ignition is not much better than a breaker point ignition, the main benefit being there's no points to adjust. No argument the e-core coil is a better coil, but you're triggering that excellent coil with a low-performance fixed-dwell, sine-wave pulse triggered ignition.

Ford has built some excellent performing ignitions over the years:

(1) Crank trigger, EDIS-8 module & EDIS coil packs (dynamic dwell, precision trigger, electronic timing)
(2) TFI-IV distributor, TFI-IV module & e-core coil (dynamic dwell, Hall-effect trigger, electronic timing)
(3) MSD distributor, Duraspark I module & Duraspark I coil (dynamic dwell, breakerless trigger, mechanical timing)

Dynamic dwell means the coils are properly charged from idle to high rpm, never over-charged or under-charged. All ignitions with fixed dwell over-charge the coils at low rpm and under-charge the coils at high rpm. An over-charged coil runs hot and its life is shortened by the heat, an under-charged coil has reduced spark energy.

There's one caveat with the TFI-IV system ... use a late model remote mount TFI module and put it in the passenger compartment away from the heat of the engine compartment. There was a massive class-action law suit regarding the TFI ignitions with modules mounted to the sides of the distributors. The TFI modules failed due to engine heat.