There is no open or closed position. In the normal position (where yours is sitting with no spring)exhaust is deflected toward the bottom of the intake manifold. In normal operation the spring heats and moves the flapper to send the exhaust directly out the pipe. Both positions are open as far as exhaust flow is concerned.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.