Topic: Jets -

[jwc66k]

The picture shows two secondary jets for an Autolite 4100 carburetor, the "down" or "inside the carburetor" are shown up (note the holes). Both are size 58, but the one on the left is a new, replacement size 58, and the one on the right is the original Ford size 58F. Note the "cup" on the original Ford jet leading to the hole, and lack of the "cup" on the reproduction. The original primary jets have the same "cup" feature. I assume the Autolite 2100 carburetor primaries have "cups".
My question are:
What is the purpose of the "cup"?
What difference does the lack of the "cup" vs the use of the "cup" make in performance?
Jim

[preaction]

I would think it has to do with flow dynamics and performance as simple as the shapes may appear the tooling for the ford jet was likely more costly and specific where as the newer part simply "cheaper" to produce.

[tim_morrison82]

One is engineered, the other is made roughly the same size and has a hole drilled in it...