Normally, the ballast resistor is bypassed while cranking the engine, delivering a full 12v to the ignition. When the key is released from the start position to the run position, that bypass is opened, and the ignition is then fed through the ballast resistor only, at the reduced voltage. The reduced voltage is supposed to make the points last longer. Whether or not 8.9 is good, I don't know. My memory wants to say something more like 9.5, but I have a feeling that's not your problem.

Pulling the coil wire loose a little way is an old trick to actually create a hotter spark and get it to jump some other bad spot. Something tells me you've got some bad plug wire(s) or bad plugs(s).