The Stovebolt Site Forums The Parking Lot Big Bolts Handy "Vari"spped governor on BB 48 1.5 Ton

Is the only line to the distributor for the vacuum advance? If that is so then it seems to me that the governor would affect the vacuum advance somehow, but that the actual governing is set by an internal spring as the manual describes.

On my '60 IH the distributor actually has lines just for the governing, it uses the rotation of the distributor shaft to affect airflow for the carburetor governor. My truck does not have vacuum advance.

If the governor affects the vacuum advance then installing it incorrectly could very well affect how the truck runs. If I'm understanding the manual correctly, installing it upside down would cause the governor to not function as it relies on airflow(in the correct direction) to close the butterfly. Perhaps the governor was set to kick it at a low enough rpm that a previous owner chose to just disable it to get a higher road speed but did not remove completely.

Tad