Early non-HP style 4500 carb where the only tunable part are the main jets.
This is a 3 circuit 1050 #9375.
I added a "high flow" metering block, which is nothing more than a block with a provision for a PV. The stock blocks have none.

Typical fat and blubbery part throttle operation for this style of carb was corrected by installing transfer slot restrictors.
I usually install changeable air bleeds in these old carbs, but on this one I left them alone.

This carb has very nice part throttle manners now.
Maybe not perfect for a lot if street duty, but vastly improved from how it was from Holley.