Which way is closed?
And does "closed" mean that zero exhaust heat is directed to the intake?
Might be a good time to review terms of reference and Heat Control Valve orientation.
See Figure 3 in
Manifold Heat Riser and Heat Control Valve. In Figure 3, the left drawing shows the Heat Control Valve "open." The right drawing shows the Heat Control Valve "closed."
Cold Engine. When the Heat Control Valve is
Open, hot exhaust gas is redirected to circulate around the intake manifold and the base of the carburetor before exiting the exhaust manifold and header down pipe.
Engine at Operating Temperature. When the Heat Control Valve is
Closed, hot exhaust gas flows directly to the exhaust manifold and header down pipe; blocked from circulating around the intake manifold and base of the carburetor.
