WC Won't Start

My rebuilt 1948 WC won't start after a rain.  It is housed in a garage all the time and is mainly a show tractor.  It has a new distributor cap, plug wires, coil, etc. but won't start until a day or two after the rain.  Is this typical or what might be the problem?  Thanks for any help.

J - 1st Check for voltage at the coil. Then check for spark at the coil wire, when you crank over the engine.  If no spark, I would remove the Dist Cap and clean the points.  Don't use a file.  Just clean with a piece of cardboard and some tuner cleaner.  They probably have a thin film on them from sitting for a while.  Retry for spark by moving points open and close and checking spark from coil wire.

Depending on which mag you have there are gaskets under the cap(s), one or two depends on model. If you dont have them you need to get them. Then next time  it isnt raining (if ever?? LOL) or a time of high humidity remove the cap and dry things out good inside with a hair drier. Get it good and warm, you wont hurt it with a hair drier. While the caps are off take a look for carbon tracks inside of the cap, also look at the grommet where the kill wire stud comes through the case and if cracked it needs replaced also. If the grommet and stud has been painted over remove the paint. Then reassemble with the new gaskets.  Have also seen problems with the kill wire or switch with dampness. To check remove the kill wire at the mag and try to start it.  It could also be the new wires or cap are defective unless NOS F-M parts.  China is fully capible of screwing up anything. One last thing is do you know if the mag is putting out as it should be? It is not rare to have one that will barely start an engine under good circimstances and then a little loss here and there from humidity will put it down. It may need to have the magnets charged up.