High rpm miss
Both ignitions are brand new. So are the wires and plugs. Its funny both ignitions miss at the same exact rpm. Both say they need a full 12v to the distributor which I have verified. I was thinking springs too. But ive broke springs before and was a totally different miss. Can an alternator short out at high rpm? Thanks for the reply. I will try what you suggested.
To be sure, I'd rig up a voltmeter with the lead right at the coil+ feed out in the engine compartment, to make sure that the voltage stays up.... With a good alternator, the voltage on the battery + to - terminals with the engine at a fast idle speed ought to typically be in the 13.8 to 14.5 range. The voltage to the ignition box and coil + should be no less than 1 volt lower.
IIRC the Ford system back then used a
resistance wire to the coil+ terminal, which serves the same purpose as a Mopar ballast; IIRC#2 that wire is in the harness inside the car.
The ignition system 'typically' will draw more current as it rev's up, so that will make sure the voltage is staying up... there might be some resistance in the wiring somewhere.... like that resistance wire mentioned above, or a poor ignition switch contact or firewall connection. Any resistance should show up as a low voltage to the coil+ with the engine running. (It probably will not show a low voltage with the ignition switch 'on' but not running with that Pertronix system.)
Agreed on the springs acting differently. As for an alternator shorting, unlikely it would just do that at a certain RPM range, but anything is possible; monitoring the voltage right at the ignition box would tell you that.
Regardless of the parts being new, 'infant mortality' failures do occur so you gotta check everything IMHO; troubleshooting by 'circumstantial evidence' will bite you in the a**! If the 2 boxes act the same way, then you can likely rule them out, but not something like the plug wires, despite being new. Look for resistance on each spark wire in the 3k to 10k range for most types.
