Coil ? Points ? Other ?

[christophe]

Just measure the current at the coil. If you get full 12V, you need an internally ballasted coil. Around 9V and you need to add an external resistance to a non ballasted coil. To differentiate the coils, you need to measure their primary resistance with an ohmmeter. Around 1 ohm means that your coil needs an external resistance. In the other case, you'll get a resistance between 3 and 4 ohms.
IHTH.

[jackb]

where do I take these coil voltage measurement(s) ?

[Jeffry Cassel]

Could be bad condenser. Yrs ago I wanted in the Air Force hobby shop and didn't have all the time in the world. These airhead airmen needed to get out of my way! They "tuned up" their car and it would not run. They rebuffed my suggestion that they had a bad condenser so I drove off base, bought a new condeser went back and replaced it, set point gap and they were out of my way. An old coil can test and work fine cold but when it warms up the old insulation breaks down and no spark. Now I lean heavily toward Pertronix!

[jackb]

Report: Installed new condenser. Pulled the coil to find it was a 6 Volt ! I have both types of coils. I guess to measure I just power up the coil with 12 volts and measure across the coil terminals to determine whether it has internal resistance....? Battery on charge .........

[TWChamp]

Just measure the ohms of the 2 primary terminals, and it should be about 1 1/2 ohms.
If it's a 12 volt coil with built in resistance, then it should read about 3 ohms.

Or just connect a 6 volt battery charger across the primary terminals, and the meter should read about 4 amps for a 6 volt coil.
If it's a 12 volt coil (with built in resistance) and the battery charger is set on 6 volts, then the meter should only read about 2 amps.

[jackb]

just measured the primary terminals on my 12 V coil = 4.9 ohms. Internal.

[christophe]

Sorry for the late reply.
The current to the coil is measured between the + post of the coil and a good ground, with the ignition on.
You don't need power to the coil to measure its resistance. The values given in the pic are for a ballasted coil.

[jackb]

OK now. What should I replace the 6 Volt coil with ? All electrics are Delco...

[Mrs K Corbin]

Depends. What battery do you have in there? 12V battery gets a 12V coil and a GOOD 12V condensor. Some 12V coils need a ballast resistor, some don't.
6V battery gets a 6 Volt setup.

I changed my system over to 12V some years ago, but that's not always the answer, as it was a lot of work for what was essentially wrong at the time (too small battery cables and bad grounds caused the original problem)
I ended up changing way more than that. Bulbs, coil, condensor, (entire charging system)

[jackb]

OK-as a point of reference, the truck was converted nicely before I got it, ... less a few items. It has the original distributor , but transplanted generator and regulator. I might be guilty of trying to learn more than I need to know......but specifically: can I put "any" Delco , internally resisted coil in this truck ? I see in the book specs different ohm readings for different vehicles, distributors, makes, as relates to coils....etc.....Is any of that information critical to my new replacement coil choice ?

[jackb]

Maybe / finally / Success ?!...... Swapped in NOS condenser & Delco coil (Internal resistance) that I had in stash from 59' wagon tune up kit . So far, so good.

[Mrs K Corbin]

YAAAAY! Good to hear

[christophe]

Glad to hear about that.
About your coil, it is always best to fit the original coil with the original distributor, but, as long the resistances are in the same ballpark, you should be OK even if its brand is not the same. In 1959, Studebaker used Delco coil # 1115122. More details here: http://www.studebaker-info.org/Tech/...Tuneupcht.html.
If your new coil suits the truck, I would record its resistance values for future reference. You'll get different values with another brand or an high-perf coil. The most important thing being not using a internally ballasted coil with a external resistor or using a non ballasted coil without a resistor.
Nice day to all.

[Mrs K Corbin]

OK dumb question. How do you tell the difference between internally and externally ballasted?

[TWChamp]

OK dumb question. How do you tell the difference between internally and externally ballasted?

Externally can be a ceramic block resistor or a resistance wire built into the wiring harness. With the key ON and the points closed (or the points terminal of the coil grounded), you can measure the voltage at the feed terminal on the coil. If it's about half to 2/3 of battery voltage, then you must have external resistance.

I wonder if I misunderstood your question. I'll bet you are asking how to tell if the coil is internally ballasted, and not the car's wiring.
If that's the case, then just measure the ohms between the 2 primary coil terminals (out of the circuit). If it has about 1 1/2 ohms, then it must not have internal ballast. I'd guess about 3 ohms for an interal ballast coil.