I will bet you cash money that it is going down your distributer shaft if you have an HEI with a vacuum advance. I had this problem and the solution is simple, drill a small hole on the down hill side of the bottom of the distributer so the water drains before it gets to the shaft. The rain runs down the vacum advance into the distributer and when the level gets high enough it goes down the shaft. I am a big time duck hunter and 70% of my running is in bad weather. I have never seen water seep in through the intake bolts on any of the caddy motors I have been around.