Re: off idle stumble
 

Rebuilt by who? There are a lot of these old carbs, some of them just plain worn out, that get passed around for decades, and often messed with by people who have no idea what they're doing.

Is it even worth trying to save- are the throttle shafts nice and tight?

Re: off idle stumble
 

throttle shafts were tight . replaced the accelerator pump and adjusted linkage , needle under squirter was missing . will update after we run the car .
Thanks to everyone that tried to help.

Re: off idle stumble
 

The accelerator squirter needle will cause that problem. Might not be a bad time to just go over the basic's, like making sure the throttle plate gasket is good and the phillips screws are tight. Had a customer with a new Holley carb and a "bent" accelerator pump lever (out of the box) that caused a similar stumble. Also just recheck ignition timing and if you still use the mechanical advance in the distributor, make sure its not sticking and it moves freely. MSD installs some very heavy advance springs ( MSD distributor) and that has caused stumbles and sluggish performance.
Accelerator pump discharge hole dia. should be last thing on list to tune.
Get your basic's squared away and you should be good to go!

Respectfully,
Henry Kunz 1534 H/SA