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

Not a good idea to coat the spring, it is thermostatic so is temperature sensitive. It will "windup" or "unwind" according to the temperature. If I understand your description it seems to be working but is coiled one turn too loose or is installed backward. Cold at rest the butterfly should be closed and the spring against the stop and tensioned. When heated the spring should relax and allow the butterfly to freely open.