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Old 03-20-2013, 04:45 PM   #1
MurphyJ
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Default Coil test question

When i purchased my 30 pickup there were a number of extra parts that came with it. One of them is a used coil. Is there a way to test a coil on a bench without it not being installed on the vehicle? Thanks again.
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Old 03-20-2013, 05:21 PM   #2
Joe K
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Default Re: Coil test question

Can you rig up a 6v battery (note + to + and - to - on the coil primary connections) and a high tension wire? (start at the top of the coil and bend it around and bring the loose end back against the mounting bracket or exterior surface of the coil)

Sometimes the simple tests are best.

If you momentarily complete the circuit on the primary - you should see the spark jump across a 1/4" gap on the secondary.

Don't hold too long. Momentary contact is best. It's the establishing and removal of the magnetic flux in the coil which makes it work. Constant electric flow means a non-moving magnetic flux which means no secondary current/voltage produced.

I've forgotten what the ohm readings across the primary means for 6v versus 12v. But someone here will fill that in since you may have a 12v coil - and you'll be able to tell with a VOM.

Joe K
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Old 03-20-2013, 09:00 PM   #3
Tom Wesenberg
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Default Re: Coil test question

Also connect a condenser across the two primary terminals, or the spark will be weak.
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Old 03-20-2013, 11:10 PM   #4
walt jones
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Default Re: Coil test question

Joe K and Toms sugestions are great. Set the circuit up as they have suggested, but take one of the wires from the primary side of the coil and wrap it around the tang of a file. Connect another wire to the battery. Draw the wire from the battery along the file inermitantly making connection. Breaking and making the current in this way will cause the field to build and collapse many times as the wire is drawn down the file, similar to the action of points in the distributer. This will cause a lot sparks to be developed across the gap in the secondary. Good luck
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Old 03-21-2013, 06:09 AM   #5
Kevin in NJ
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Default Re: Coil test question

The best way to test a coil is with a coil tester. The tester acts like points and causes a nice arc that you can make adjustable.

The test needs to have a second function where you run current through the coil to heat it up. As most coils seem good until heated. Then the spark will get noticeably weaker.

You can also test the condenser, but if you have a modern burn out proof condenser you should be good to go for a long time.

Here is a link to Tom's low cost homemade coil tester.


Coil Tester
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Old 03-21-2013, 10:13 AM   #6
Purdy Swoft
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Default Re: Coil test question

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Quote:
Originally Posted by Joe K View Post
Can you rig up a 6v battery (note + to + and - to - on the coil primary connections) and a high tension wire? (start at the top of the coil and bend it around and bring the loose end back against the mounting bracket or exterior surface of the coil)

Sometimes the simple tests are best.

If you momentarily complete the circuit on the primary - you should see the spark jump across a 1/4" gap on the secondary.

Don't hold too long. Momentary contact is best. It's the establishing and removal of the magnetic flux in the coil which makes it work. Constant electric flow means a non-moving magnetic flux which means no secondary current/voltage produced.

I've forgotten what the ohm readings across the primary means for 6v versus 12v. But someone here will fill that in since you may have a 12v coil - and you'll be able to tell with a VOM.

Joe K
Just to add to joes good info, the OHM for a six volt coil should be 1.5 and a 12 volt coil should be 3.0 OHM
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Old 03-21-2013, 12:32 PM   #7
Hicktick
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Default Re: Coil test question

The easyiest way is to strap it beside your coil with a wire tie and switch the wires .

See if your engine will run , how long could it take ????

If you dont have a testor , that is .
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