Holley/Demon Carb stumble

Mattax said

If that 650 is old school tune, its pretty tempting to suggest racing that as test.
If it does the same thing, then the odds are good that the emulsion/MAB etc is not the primary culprit. You can come back and play with those things, but it may not be something that can be fixed with carburation alone (or injection for that matter).

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It's old school!
bought it well used in the late 90's was told it was a 750 and when i found out it was a 600 i threw it in the corner and forgot about it.
When i go frustrated with my vacuum secondary not giving me consistent enough ets, i pull the the 600 out. cut the chock tower off of it and lightly cleaned out the venuri as well as the seam in side the boosters. remove the standard butterfly screws for the round headed ones and ground on the throttle shafts for more airflow. This carb when on my 340 and ran for many a years.
When the 408 was built, it when on because it was a know good carb to break the motor in. Ran it for several years that way. Before the MITTY DEMON DARKEN MY HALLWAYS :D