Rubber Fitting for Small Block Water Pump

Steven190 said
Put grease on the tap and clean after a few turns and re-apply the grease.
Measure the hole to see what is the closest tap size. Do you have a caliper?

Dicer said
Pack your tap with grease, it will catch most of the metal chips.....

Any special kind of grease? I have calipers at home. I believe someone else told me 3/8" NPT.