Proofing an HT coil on a 1988 Vet

[Estam]

Suspect the HT coil that sits top of the distributor. It's removed, benched and dis'assyed.
Can I strike 12 volts across the coil and connect an alligator to the center electrode then to the plug?
Would this create a spark to proof the coil?
Any suggestions please....

 

[dougelam]

You will need the proper ground path

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[Estam]

You will need the proper ground path



The transformer's lamination's are grounded to the secondary and the plug is sitting on them.
Grounding isn't a problem.

So do you know then if I can flash 12v quickly across the primary of the tranni and produce a spark?

 

[dougelam]

Why do you suspect the coil as being bad?

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[Estam]

Why do you suspect the coil as being bad?

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Yes, good question .....I suppose I have to start somewhere and I have a no spark situation and my rotor had black marks all over it so I replaced it to no avail. I took the distributor cap off and wanted to proof the coil before I start with the HEI module which can be a bit of a pain.

Where in Michigan?

 

[dougelam]

Grand Rapids,
I am going to assume that you have a 12 volt test light.
Without unplugging the distributor cap turn the 4 hold downs and lift it off.

KOEO (key on, engine off)
With the test light connected to ground, back probe the connector w/12 gauge wire-it should light
If it does back probe the next cavity over, if it lights your coil is good (the windings anyways)
Now with an alligator clip type jumper wire to ground clip the other end over the discharge in the center in the cap (the pin that touches the rotor)
Move the clamp of the test light to the positive side of the battery, rapidly touch the white wire going to your ignition module if your module and coil is any good you will get the spark that you are asking for. If not module time of so check the resistance of your pick up coil - open, bad continuity good

Hope this is a good start, never tried to control an ignition coil any other way my self

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[Estam]

Thanks for the information.... My distributor was benched and found the ht coil secondary was shorted. New coil and all running perfectly.

 

[LLC5]

Thanks for the information.... My distributor was benched and found the ht coil secondary was shorted. New coil and all running perfectly.

FYI, the only proper way to check and HEI coil out of the distributor cap is with and ohmmeter, looking for spec's, opens or shorts. The HEI coil has enough energy in to kill a human being if you tried to load test it out of the distributer, never try to do it.