I could use a 1974 slant six manifold heat control valve expert!

Does the ceramic coating get backed on? Or some sort of heat proses greater than the heat it sees while operating on the engine? Perhaps the spring wound it’s self and the ceramic coating when cured held it in that position. The butterfly is now in the wrong position do to the counter weight and no spring pressure. Posibly acting as an engine brake giving you the noise. Meybe a new one would do the trick, I don’t know, just throwing it out there