OK, let’s give it one more shot. Refer to the parts blowup below. There are two things that open the carburetor butterfly shaft, the roller on the front and the fuel saver rod on the side. They are two separate issues. I am going to try to explain the fuel save rod.
The vertical throttle shaft on the side of the motor moves the brass link #6 in the picture. #6 is attached to the armature plate by a spring, #1.
as you move the throttle control, the link rotates the armature plate until it bangs up against the boss on top of the cylinder. When that happens, it is at Cruise Throttle position and the collar/rod has not yet opened the carburetor—but should be ready to.
Further movement of the throttle control and link compresses the spring #6 and it snaps over center (what I called cammed, probably not the best choice of words). As it snaps over center the collar and rod kicks the carburetor to horizontal position. THAT is wide open throttle position, and seems to be what is confusing you.
So, it is very simple. With the control at cruise throttle position the pivot pin #8 should be just touching, but not pushing on the collar #9-10. Further movement of the control makes it snap over center and pushes the rod & carb to WOT position.
I may not be the best with words, but that’s about the best I can say it.
