Farmall Cub

I purchased a Cub a few months ago. It runs great when I can get it started. Ever since the weather got cold it is impossible to start. I tried yesterday for about 1/2 hour, but could not get it going. It is stored inside a barn and not in the elements. I am wondering if I should shut off the fuel rather than leaving it on. Any help would be apppreciated

Cover the basic items first - as mentioned in several other threads do a complete tune-up. Most hard starting issues are related to the lack of proper routine maintenance and a regular tune-up is part of that.
While cranking the engine over check the spark quality. A weak spark at the plugs is often a cause of hard starting.
As to whether or not to turn off the gas - many do that as a routine procedure since a lot of cubs suffer from a slightly leaky float valve. If you do not see evidence of fuel drips from your cub just setting around then it is probably not necessary to shut the fuel off.
If a tune-up does not correct your hard starting problem I would suggest a compression test to get some idea of the condition of your engine.

The cub has a new coil, points and condenser and the spark is good. I didn't check the spark plugs and they might be a possible problem. I did not see any evidence of a fuel leak or drip, I just thought this might be the issue. I have a friend who is a mechanic and he said, " Cubs are all hard to start when its cold". I not sure that everyone who ownes a cub can't get it started in cold weather. I will check the plugs and go from there

One thing not mentioned yet is the battery. Make sure the fluid is topped off and it is fully charged. Unless you have put a new battery in the tractor, you may want to get the battery load tested.

Also - can you tell us how you are applying the choke? Most cubs need a little choke in cold weather. Most of mine take full choke for a couple of turns of the starter until it fires and then about half choke for about 45 seconds to a minute or so before it will smooth out.
Too much choke for too long will cause flooding and not enough choke seems to be too lean to start.

I do pull out the choke for just a couple of turns and push it in immediately. Sometimes the it will start, only run for a few seconds, there doesn't seem to be anything I can do to keep it running. I did notice if I choke it for too long, it floods very easy

How fresh is the fuel. Summer fuel doesn't vaporize enough in cold weather. Stale fuel, is even worse. Ed

I find in cold weather it is usually necessary to feather the choke off slowly to keep the engine running.

All good advise. I will go one step further. Have you checked the compression? It has been my experionce over the years that cub engines that have less than 90 lbs of compression will be hard to start in cold weather. Especially below 20 deg. I have 6 cubs here with all top notch rebuilt engines in them. They all start easy in zero deg weather. 3 are 6 volt. 3 are 12 volt. Have to feather the choke some too.

You did say that you changed the points. Just be sure you set them for distributor 20 or magneto 13 (i think) I have seen some look in the book and use the wrong setting.