I received two rebuilt carburetors for my 1973 Plymouth Valiant. One is a champion that I bought from AutoZone , the other from a shop that my dad had sitting on a shelf for many years.

Either carburetor will start and run the engine cold until the choke starts to open then the engine will stall. I have to hold the plate nearly closed to keep the engine running.

I already have a working carburetor on the engine so the only difference is the carburetors.

Any thoughts?

Sounds like you have a 3rd carb. that works fine on the engine and two others that will not idle down, right?

Are the ones that don't idle down Holley 1920's?
DD

Yes, the third carb works fine. They are all the Holley 1920.

I already know Doc is hinting at a "plugged up" sealed metering block with the Holley 1920 (i have 2 of these that have the same problem)...

With the choke plate closed it seems to run (this causes a rich condition-more fuel than air), how far did you adjust the idle fuel metering screw at the base of the carb (valve cover side), also have you checked for vaccuum leaks to see if the intake mating surface or carb base is letting in more air?

-D.Idiot