Glenn, you have received an assortment of carburetor advice in your previous posting. It goes with the territory.

The Carter YF can be a replacement carburetor (example for Rochester B). In that situation you use what was used before (as it came from the factory).
Around 1966, Chevrolet and GMC began installing the Carter YF on truck engines. In this situation you use the Carter flange gasket 1A-31.
There are internal carburetor air passages that need openings to engine vacuum and this is the reason for the slots in the gasket.
https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=895997

Which model Carter YF do you plan to use?
Attachments
1A-31.jpg (88.12 KB, 91 downloads)

Last edited by buoymaker; 10/16/2022 3:55 AM.
"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."