What exactly is the function of the external exhaust closure that works in conjunction with the carburetor? It's the device that opens the exhaust exit completely when full throttle is employed and closes completely when the carburetor is moved to the idle position.
I have been given one of these engines and the screw that holds this plate against the exhaust is broken off with part of the screw still in the threaded hole. I still have the plate and the linking rod.