Upon closer inspection there are three presets or half drilled holes in the manifold side: closed, half open/closed (depending on your view of the world) and full open flapper.
Applied heat to the set screw, turned it out, and replaced the rusted in nut.
Not sure I see the performance benefits to this set and forget flapper other than one less part in the field. Otto, the flapper locks in once the set screw is in place. I dont believe this military design used a spring.
This is another great mystery that will haunt me until I exhaust my last breath.
Last edited by tom moore; 10/16/2024 8:37 PM.
