Explain this coil question

[Don]

Little 36 quit again,thought I would change out coil,this is a 8 ba engine,running on 12 volts. old coll read about 4 ohms pri current draw should be about 3 amps thru points. But measurement is only 1 amp,
Put new coil a accell 12 volt coil /1.5 ohms primary,added a ballast res to bring up res to about 4 ohms,measure current at about 1.5 amps,should have been about 3,,,remove ballast res,now just coil res of 1.5 ohms and have current of 3.5 amps thru points,starts and runs great!dont know about on road it’s raining put
According to paper current not draw would be about 8 amps??????

[JSeery]

Are you sure you are measuring correctly with good equipment?

[Don]

Very good Fluke dvm and a analog meter measuring current ,all appear to be in good working order,I did zero out meter leads when measuring ohms

[JSeery]

Guess if your happy with it run it and see if the points hold up. The numbers are way off.

[flatheadmurre]

Take a jumper wire from battery to coil if the amps measure as calculated you got resistance in the wires/switch feeding the coil.
If it´s still the same check wires/ground to distributor.
Do you have full voltage to the ballast resistor ?
I would have thought a voltage drop before the coil was needed to get readings in that range...

[Mart]

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Here's what I know, I can't work out if it is relevant to your situation, or not, you decide.

If you run a coil that is meant to run with a ballast resistor without one, it WILL start fine. It will run great.

For a while.

After driving for a while it will falter and then break down and the car will stop.

After cooling down (providing it is not permanently damaged) it will start up and run just fine. Until it overheats again and you conk out. Until it cools down.

Repeat as necessary.

Mart.

[JM 35 Sedan]

My 35 fordor sedan has been running very reliably, for the last 30k+ miles, on a stock helmet distributor that I rebuilt myself, using an original style coil rewound by Skip Haney, a good quality set of points, original style capacitor/condenser checked for the correct mfd value, quality set of inner caps and rotor, set to correct gap, and still using a 6V system. I feel confident I can go out to the garage, start the engine, and drive anywhere I want to go without worrying about distributor problems.

[George/Maine]

Have you noticed the size of wire on 12 volts cars for ignition very small.
The best way to check amps with a resister ,first ohm out the resister 1.5 ohms.
Then with the volt scale measure across the resister.
Being you know the valve of resister voltage div by 1.5 ohms should be about 3 volts
That is running leaves about 9 Volts to coil.
8 amps will burn up soon.
12 volts coils some very few don't need resister, but most do. 1.5 ohm.

[flatheadmurre]

And it´s not that the points are bad having resistance ??
Or connection between breaker plate to coil being bad.
If the amp readings are correct you have unwanted resistance somewhere....

[19Fordy]

Don, Slowly read through below thread completely.
Keep in mind that some folks are using points, some are not. Still helpful.
https://www.fordbarn.com/forum/showt...+coil+readings