Name that part !!

Came across this at the Thirlby boat shop . for a shiny new dime , Name that part ?

Diaphragm shutter, the carb takes a photo of the driver's big fanny as he drives. Where's my dime?

More seriously, it looks maybe like a real early experiment in cobbling together a sort of constant-velocity carburetor, with that shutter ganged to the butterfly. I gotta look some more to see if that makes any sense. The intake trumpet is cute.

Well now wait, maybe it's ganged to a choke? Why?

Come on, when are the smart tech guys going to weigh in here?

I'm waiting to Smitty. Since its at the Thirlby shop and I think Eddie ran at one time the PR eons ago or I think he did maybe something off one of those motors. No clue here though