Zenith carburetor modification question

[Joop]

Zenith carburetor modification question

A friend of mine found this in his collection.
Air hole was closed and area opened up around the secondary well.
We are wondering why it was modified and how does it work.

Thanks

 

[1931 flamingo]

To air balance if running air cleaner??
Paul

 

[Tom Wesenberg]

I don't see how it would work since you want the balance tube to end before the choke plate.
Also I don't see any opening for this passageway.

 

[Kurt in NJ]

perhaps it is part of a failed experiment, an attempt at balancing ---maybe a groove was cut in a different venturi

 

[Grampy]

I have one exactly like that!
I didn`t make much sense to me; I just thought someone was trying something unusual, so I dismissed it and it`s been sitting on the shelf since then. The body is a Zenith 1.

The only other difference I noticed is that there is not a weep hole in the bottom of the air intake at the choke.

It seems unlikely there would be two of these so far apart if it was just somebody messing around.

 

[Grampy]

I tried pursuing Vince`s suggestions. I was unable find the material or I didn`t have access.
Is someone able to tell JOOP and me what it is about those Zenith Carburetors?