Alpha 1 5.7L '86 Thunder bolt ignition - I replaced the ignition sensor in three months ago, cleaned cap and sprayed inside with WD40 and put a new gasket on the cap base. Yesterday took boat out to run in my new SE106 upper drive, have done 6 hrs over the last 2 weeks, so I have been using it. Motor ran good for 10 minutes then started to miss and run rough. Took cap off and found corrosion on terminals inside cap. Cleaned it and away she went, like a rocket.
My question is, why do they need a gasket when the distributor cap has a drain plug in the side that lets moisture in?
Previous to the ignition sensor fault, I had not had the cap off for 5 years, without any problems.
Just wondering why all of a sudden its corroding?