I have an industrial 331 that came from the New Orleans airport. It was used to power aircraft sitting on the tarmac waiting to take off. It has the governor system you refer to as well. The motor had not been run in many years. After a bit of tinkering i was able to crank it up. The governor was still connected and I had closed off the small valves that enable the adjustment of the engine speed in relation to the load demands. When I cracked the throttle by hand, the governor snatched the linkage out of my hand and slammed it shut! I had adjusted it to a low idle setting and indeed it worked. This system is a remarkable piece of engineering and is totally mechanical with no electrical or vacuum involved. I have not disassemble the unit as of yet as I was hoping to find someone who might want to restore the motor and preserve the unit as it is. So far no one has shown any interest.