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Original elektrick ignition

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2021 at 7:09pm
Going from memory you need to see 10.5v to the coil or it's very likely the ignition module is failing.
Old school is take them off, grind a groove in the resin to casing at the back, bake in an oven at 140 degrees F for an hour, refill the groove with epoxy, cool and try it. Separation and moisture were the biggest failures. The problem with baking is that a weak capacitor could fail and your done.
Baring this, a replacement module or move on to a new ignition system.
Lots of threads on HEI, Duraspark/MSD box and other replacements that are more reliable then the original factory Prestolite. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mark09 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2021 at 8:54pm
Back when these were newer and we had this problem at the dealership a TSB came out about the  fine wires could break by the connectors and cause ignition failures.  Suggested repair was cut off connectors and solder / seal to repair.
Easy fix, but if YOU didn't want to remove connectors, while engine runs try to wiggle wires at connectors to find what side has the broken wire/wires and replace only that side of connection. AND CARRY A SPARE MODULE. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Aug/02/2021 at 1:57am
Prestolite ignition does not have a resistor wire between the ignition switch and the ignition coil positive terminal. The ignition coil receives the full battery voltage. 

The voltage measured at the negative terminal of the ignition coil depends on the switching action of the control module. Most of the time with the engine not running it will measure at the same voltage seen at the positive terminal because the circuit is open. When a tooth of the trigger wheel passes the sensor inside the distributor it will trigger the control module to ground the negative terminal of the coil, making it's voltage momentarily go to 0v for just a split second before it returns to battery voltage. A typical handheld voltmeter like is often used for automotive electrical diagnostics won't show this 0v reading because it cannot respond fast enough. It's reading will just drop momentarily and return to battery voltage or it'll average to some reading below battery voltage. In either case, a spark should come from the ignition coil at the same time as this momentary drop in negative terminal voltage, indicating that the Prestolite system  is operating correctly. 

A failure of the Prestolite system to spark is most often caused by a faulty ignition module, though I have seen many fail to spark from ignorant mechanics ruining the wiring. I got paid a handsome amount of money one time for fixing one that somebody had horribly cross-wired. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jesper Quote  Post ReplyReply Direct Link To This Post Posted: Aug/05/2021 at 5:30pm
Thank you guys for your replysThumbs Up
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