The Stovebolt Site Forums The Parking Lot Big Bolts 348 diagnosis

The big trucks with the combo centrifugal/vacuum governor does not have vacuum advance as noted by wrenchbender. There are several locations within the governor system that could be leaking vacuum. The vacuum for the governor originates in the carburetor and is directed through passages in the casting to the diaphragm, then through a steel tube to the distributor. A leak anywhere along that path could result in a flat spot in acceleration. It does not appear to be a problem with the governor operation but could be a leak. My Rochester 2G with governor has ball bearings on the throttle shaft, after 67 years it still has no slop in the throttle shaft. I suspect the carburetor is in need of internal cleaning.