Ed,
Does your governor look like this one? (48-52, and maybe 1953).
Most likely, your carburetor is like the one at the link above.
Here is the 1954 governor - it looks like the earlier one. The operation of that governor is described in those shop manuals. I do not see a mention of a speed-sensing device in the distributor, but I did not study the Shop Manuals very carefully. It looks to me like the adjustments are made in the governor assembly. The 47-55 GM governors that I have taken off of trucks up to 2-tons are as shown in those Shop Manuals (270 amd 261 engines).
Are you missing the adjusting screw/cap and/or associated parts?
Do you have the carburetor that came with the engine and governor?
