[Kenth]

One can't help but wonder why Pontiac decided to change to the unvented gasket 7015345, for all 1959-66 end carburetors as noted in service manuals from 1967 onwards?
There must be a reason since engineers do things for a reason.

Still, most, if not all, end carbs left the factory with the vented gasket and who knows how many of these got the unvented gaskets when the car was serviced?

BTW, 1966 Olds and 1959-60 Cadillac did not make this change from the vented 7015106 for their end carburetors.

Olds and Cadillac didn't have the same volumes of these end carburetors so maybe they didn't care about the possible problems with the vented gaskets?