Over the 40+ years I’ve been doing this stuff three times after rain races cars gave problems. In each case the problem was electrical. Two bum ignition switches and one master switch got soaked. Check those out and make sure you have a spare with you. Another time I stupidly put away a car for the season after a rain race. Next season the carb was a mess, the intake manifold rusted inside to the point that it needed tossing and worst of all the wheel lugs rusted in place.

So do what you need to do to prevent the DNF at the Glen.