The Stromberg WW is a wonderful carb, but they do have one design problem - an aluminum throttle body.
Over time, as aluminum oxidizes, it forms......aluminum oxide, which is an excellent abrasive. The aluminum oxide then "sandpapers" the throttle shaft and throttle body, causing a major vacuum leak.
A competent rebuilder will remove the shaft (FIRST REMOVING THE STAKING FROM THE SCREWS), and check both the shaft and throttle body for wear. Bronze bushings will be installed in the throttle body (fixes the issue, as now there is no movement in the area of oxidation); and, if necessary, replace the throttle shaft.
Design clearance is 0.004~0.006 inch.
Once the repair is accomplished, the WW is one of the very best two-barrels ever produced (my opinion, others may differ).
Jon.