I am swapping out my 44idfs for a set of 40idfs.

My 44idfs have this little I-don't-know-what on them. See the red circle in the pic.

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Below are the 40s. Notice that they don't have that little I-don't-know-what on them.

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Do I need to transfer the I-don't-know-what from the 44s to the 40s?

TIA

just checked, my 40's don have that thing in red on them. I would'nt worry about them.

The "I don't know what it is"...part on your carburators is the breather for the float bowl.....Your carburator tops/ or the carburators themselves are not common. I suspect they are of an early manufacture, and for a specific application/or engine.....check to ensure that they actually Vented the float bowl.(the side holes are drilled and open). Another application might be for a supercharger application which pressurizes the air cleaner-carburator. The float bowl breather(" the i don't know what it is") is designed so it can have an extension tube extending OUTSIDE the pressurized air cleaner to provide proper/accurate /normal pressure for the float bowl. It is not necessary to transfer that part..It would be difficult anyway, as the carburator TOPs are different. You could swap tops., but the smart move is to keep original tops with original carbs.