coil to ground voltage - Chevelle Tech
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post #1 of 8 (permalink) Old Oct 14th, 13, 6:08 PM Thread Starter
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Ron
 
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coil to ground voltage

On my 66 ss with stock ignition system, what should the voltage be when measuring from the positive terminal of the coil to ground, with all wiring connected and ignition switch on? I am getting about 6 volts. I am getting full battery voltage when the wires are disconnected from the coil, which is 12.5 volts.

Any help will be greatly appreciated.

Ron Bidwell
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post #2 of 8 (permalink) Old Oct 14th, 13, 6:11 PM
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Joe
 
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Re: coil to ground voltage

That sounds normal.

If the points in the distributor are closed, you cause a voltage drop (because remember there is a resistance wire feeding the coil's (+) that limits current. Therefore you will read less than battery voltage. If the points are open in the distributor, the circuit is open, thus no current and no voltage drop and you'll read battery voltage on the coil's (+).


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post #3 of 8 (permalink) Old Oct 14th, 13, 6:14 PM
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Re: coil to ground voltage

Depends if the points are closed or not. I can't remember ever checking it myself but I've always heard around 9 volts (under load)
Checking with wires not connected or with points open doesn't really mean a lot.

{EDIT} oops, didn't see Joe's post.

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post #4 of 8 (permalink) Old Oct 14th, 13, 7:54 PM Thread Starter
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Ron
 
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Re: coil to ground voltage

Thanks guys.
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post #5 of 8 (permalink) Old Oct 14th, 13, 8:16 PM
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Re: coil to ground voltage

What are both the coil + to engine ground voltage at IDLE and 2,000 RPM's, and + post to - post BATTERY readings, at both those RPM levels?

Engine running load will tell the real tale. Static readings, no real info.
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post #6 of 8 (permalink) Old Oct 14th, 13, 8:21 PM Thread Starter
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Ron
 
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Re: coil to ground voltage

Good point. If I ever get this thing to run I will check those readings.
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post #7 of 8 (permalink) Old Oct 15th, 13, 3:30 PM Thread Starter
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Ron
 
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Re: coil to ground voltage

At 2000 rpm I am getting a little over 14 volts when hooked to the positive terminal of the coil and to the ground. When hooked up to the negative side I am getting about 6.5 volts.
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post #8 of 8 (permalink) Old Oct 15th, 13, 11:44 PM
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Re: coil to ground voltage

Don't really care about negative term on the coil to ground, doesn't make any diff. Positive on coil to ground, that is important, along with across battery at same rpm's. You outlined findings in the other topic. Please post there what alternator/regulator combo.
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