I have no experience with these carbs, but have read they can be hard to tune. With no power valve , these would be my last choice for carbs. But given a little know how most things can be resolved.
This is a must read for you, and GTO Geoff ( since edelbrock comes up ) It explains your problem, how to cure it , and the history of these carbs , particularly the first 3 pages.
https://www.tapatalk.com/groups/racingf ... -t872.html