cub coil

[Mike in Ohio]

'48 cub sputters and quits after about 45 minutes or an hour of mowing, leave it sit for an hour or so and she starts right up and runs great for a while longer. Previous owner converted it to coil from magneto. I rebuilt the engine 2 years ago after dad let it run out of oil, never had this problem before the rebuild. When putting things back together I over tightened the nut on one of the coil wires breaking the stud off. Replaced it with one from Napa it worked great for a short time then started acting up. New coil fixed it for a short time. So either I am missing something else electrical, or I need a better quality coil.

Can you guys help me either with what I am missing or with a better quality coil.

Thanks

 

[mattofvinings]

I would check the "power" or "hot" wire that goes to the ignition. If there is a break in the wire or bad terminal it could be your issue. It wouldn't take long to run a new temporary wire outside of the normal harness and tape over the existing ring terminal(s) to see if that helps.

I seem to get 3 years out of a Napa coil for my Super A on 6v.

 

[gene bender]

Why only 3yrs

 

[BarnyardEngineering]

Is the tractor 6V or 12V?

If it is 12V, is there a ballast resistor between the ignition switch and coil?

What kind of coil did you buy? Specifically what did it say on the package?

If you connect a 6V coil to a 12V system without a ballast resistor, it will run great for a while but the coil will run extremely hot. The coil will quickly degrade and fail, which sounds like what is going on here.

There are also two types of 12V coils, one that needs a ballast resistor, and one that does not. So, you can't just "slap a coil on it." Some thought must be put into the process.

 

[jsfarmall]

I buy internally resisted coil for all my tractors. You might have accidentally got a coil that's not internally resisted. Definitely sounds like and electrical problem and not an internal engine problem.

 

[mattofvinings]

(quoted from post at 10:15:25 05/25/17) Why only 3yrs

Probably something I did wrong. I had another brand of coil and it also lasted 3 years...out of being tired of working on it, I was driven to 12v negative ground and solved my problems another way.

 

[old]

NO coil have an internal resister they are just made for 12 volts by being wound different

 

[John T]

jsfarmall and others,

FYI Being a used tractor dealer and farmer for years and having owned literally hundreds of tractors, I NEVER SAW ANY OLD FARM TRACTOR COILS WITH DISCRETE STAND ALONE RESISTORS TUCKED AWAY INSIDE THE CAN, even though many may refer to them as "internally ballasted"

A typical true 12 volt coil simply has more winding length and/or resistance per unit length to get its 2.5 to 4 ohms of LV primary winding resistance NOT BY HAVING A RESISTOR INSIDE THE CAN

HOWEVER as J DeMaris was kind enough to post these pictures once wayyyyyyy back when THERE ARE INDEED COILS WITH INTERNAL RESISTORS best I can tell a very few old cars used them.

Take care yall n God Bless

John T

 

[Mike in Ohio]

It is still 6v positive ground. The coil came from either Napa or tractor supply, bought it last summer, I don't have the box any more. I will take it out this weekend and get it hot then check for power at various places to try to diagnose properly.

Thanks for the replies.

 

[old]

If you got it at NAPA it is likely to be good still but if you got it at TSC well it is China junk so who knows if it is good bad or somewhere between