Cub LoBoy Coil

I'm fixing up a 1966 IH Cub Lo Boy. Bought a new set of points, plugs, condenser, plug wires, distributor head and coil. (12V)
However--no spark! I have 12V to the distributor plus terminal. Also, checked continuity in the plug wires wherever I could--it's OK. I decided to check the resistance of the coil primary and found it's open (infinity). It is a brand new 12V internally resisted coil.
First question: shouldn't the coil have some resistance, maybe a few ohms?
Second question: If it's bad and I think it is, would it better to get the hotter coil that requires external resistance?
Great forum! Thanks for your help.
Bob

How are you measuring the resistance of the coil secondary... It should show infinity to ground, but is internally connected to the coil primary.

So you need to check resistance from one of the primary terminals to the secondary terminal. Is this what you are doing?

http://www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/FOS-20%20Chapter%206-Ignition%20Circuits/index.html
FOS 20... this may be of help

If you work through my Ignition troubleshooting procedure it can help find the problem. As the points are usually closed if all is well and wired right there's usually no voltage (with respect to ground) on the coils output (to distributor) terminal, see my procedure.

"First question: shouldn't the coil have some resistance, maybe a few ohms?"

YES the coils LV primary between the little + and - terminals should be continuous and have a resistance of around 1.2 to 2 ohms for a 6 volt or 2.5 to 4 ohms for a 12 volt coil.

"Second question: If it's bad and I think it is, would it better to get the hotter coil that requires external resistance?"

While a 6 volt coil would require a series voltage dropping (12 down to 6) ballast resistor if used on a 12 volt tractor, I wouldn't think of that as a HOTTER coil as you asked.

On a 12 volt tractor you can EITHER use a full true 12 volt coil (NO Ballast required) or a 6 volt coil PLUS the ballast. A 12 volt is easier and needs less wiring and no ballast etc. to fool with.

One reason however to use a 6 on a 12 volt tractor is if you have a ballast by pass circuit/system is it can improve starting (hotter spark) in cold weather


Try my Procedure.

John T
John Ts Ignition Troubleshooting