Here is a good webpage that I use when playing with the Zenith carbs.
https://www.carburetor-parts.com/Zenith-_c_38.html
https://www.carburetor-parts.com/28228_c_218.html
http://www.carburetor-blog.com/manua...ild_manual.pdf
My rule re governors, whether on the Dodge M37, the M135, or the carriers, is leave them the **** alone. Clean or re-kit the carbs for sure....but stay out of the governors unless there is something terribly wrong with them.
All that said, I do look after carriers that are running the Holley 94 carbs without issue. Perhaps, when not under live fire conditions, one does not accelerate as much.