I have a four cavity Lyman mold that when I barely snug down the sprue plate stop bolt, the head of the bolt sits too low and will not let the sprue slide fully into the closed position. When I back the bolt out enough to allow the sprue to close, the threads are so loose that the bolt will loosen further as the sprue plate is opened and closed.
I am reluctant to take any material off the sprue plate's stop notch or the bolt head. So I made a one and a half wraps around the threads with a strip of aluminum foil and that seems to have tightened the threads enough to keep it from backing out on it's own.
My question/concern is whether the dissimilar metals (steel, aluminum, cast iron) when repeatedly subjected to mold temperatures could become an issue over the long term. I'm thinking not, but.........