How to test ignition voltage

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Old April 1st, 2019, 05:21 PM
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How to test ignition voltage

My '68 442 has a '70 455 with HEI. Rebuilt 455 running E85 going in soon with electronic ignition (MSD ready to run) and was told need to be sure it has upgraded ignition wires that provide 12V to coil/distributor as most pre '70 cars has a resistor wire. Car runs hella rich now so I wouldn't be shocked if it had inadequate spark. How do I confirm what wires it currently has? I do have a voltmeter but don't know where to begin.
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Old April 1st, 2019, 06:42 PM
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Who installed the HEI? It requires full battery voltage also. The resistance wire is stiffer than your standard wire. You can measure the voltage with the car running on the Bat+ terminal in the HEI cap.
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Old April 1st, 2019, 07:51 PM
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Car came with HEI already. Is there an easy way to get a lead on the Batt contact? I assume cap stays on. Those HEIs are jammed against the firewall pretty good.

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Old April 2nd, 2019, 02:19 AM
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You can buy the special connector body with a series 56 terminal that will plug in and lock into the distributor cap, or cut one from a donor car. The best place to pick up the proper 12 bolt power source would be to remove the bulkhead connector from the fuse box, pick out the series 56 male terminal with resistance wire from the bulkhead connector, and reinstall the proper wire (14 gauge would be good). If that’s too much work, another option would be to tap into the pink wire at the ignition switch.
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Old April 2nd, 2019, 06:18 AM
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Thanks Matt. I guess I need to remove the cap and see exactly what the Batt connector looks like. I was thinking/hoping I could place a voltmeter lead on there quickly as I really just need to confirm if I am getting the full 12v to the coil or not but it’s so buried back there. The ‘68 hoods don’t give you much help either.
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Old April 2nd, 2019, 06:51 AM
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Its a simple 1/4'' male spade. You'll need its female companion to connect it.
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Old April 2nd, 2019, 07:14 AM
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Go to the autoparts store and get one of these, connect your power wire to one side and the test wire to the other.
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Old April 2nd, 2019, 08:04 PM
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Not sure why I need spade connectors unless I did it incorrectly. I removed the dust cover, which was held on by three screws, and the Batt connector was right there. 12.4V in “key on” position; 11.4V at idle. Only hit my head on the hood 4 times which is a personal record for me.

I'd say your good to go. Feel your pain on the hood..
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Old April 2nd, 2019, 10:11 PM
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My 67 is running a little rich I didn't know about this. I have mine set up as the pink wire is cut and then running straight into the dis from the back of the ignition I'd this fine to do to get 12 volts?
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