Ok: If it has a screw for choked idle speed to be set it will use a "cam" without the steps as if by chance you pulled the choke when carb was on base warm idle it would fight itself trying to run upstairs of the steps so they use a smooth one.
You can see that from who knows who's carb in the pic below. If no such thing is on this carb it was meant to be manual idle speed by foot or a separate throttle cable which is more like a throttle lock - usually pull, twist to lock and it would stay there till you released it.
Not to be funny but manual chokes really suck! Best anti-theft control you could use as you have to get personal with each one to know how it will behave AND how long to leave it on or gradually take it off on a time by time basis.
They also don't use choke pull offs with a diaphragm and usually have either a hole in the plate or made such that it can't shut too tightly choking off all air for a quick flood. Most manual chokes required pumping the gas (automatic ones too) 1-3 or more times depending on how cold it was. Pumping a carb does "squirt" a shot of gas when you push the gas pedal with any tapping, pumping and continues to to change without a hiccup when you suddenly accellerate too.
By "cam" or "eccentric" I mean a thing like drilling a hole in a quarter dollar off center such that if it turned on that hole the distance changes with rotation - same crude idea,
T
Ps: In this pic below - see the rusted cam with the screw with spring such that it doesn't rattle to a new setting or fall out....
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Tom Greenleaf - MetroWest, Boston
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