This is a quick rundown on how to set up the governor on a Farmall H or McCormick W4 tractor.
Before we set the governor up you are going to want to make sure that your timing is set, spark plugs are gapped correctly and in good working order, ignition system is working well, valve lash is correct, carburetor is clean and adjusted properly (you may have to adjust some carb settings when setting the governor but it will be easier if it is already pretty close), Inspect inside governor housing for items with excessive wear or broken springs. if you suspect there is an issue or observe excessive blow by or blue smoke when engine is running check the compression, lastly check your oil bath filter is filled to the correct level and take a look at your intake piping, If any of these areas have an issue it is best to fix them first.
The next step is to disconnect the battery
Remove the breather cap on top of the governor housing, this can usually be twisted out of the way without damage, if it does not free up easily you will have to remove the thermostat housing in order to remove the line or use a crows foot socket to loosen
Set the throttle position at WOT
Check that the pin that goes to the governor shaft moves freely and does not have excessive up and down play. If it is tight or binds then you will need to remove and inspect for wear. In order to free up a pin that is binding there are 2 screws on the back of the housing that hold on the governor shaft housing, this housing has slotted holes that allow you to move it up and down in order to set the pin drag. Once set replace the pin, cotter pin and reinstall the vent cap. This has now set WOT on the throttle to WOT in relation to the butterfly valve in the carb.
Run the tractor and get the engine warm, once warm set the idle RPM to 450. I am using a multi meter with inductive clamp, if you do not have one there are strobe light tachometer apps available for the smart phone, handheld tachometers etc.
Once RPM is set, shut off tractor, disconnect battery and remove governor cover, you will see a lever with 2 set screws, the set screw at the top will set the low idle RPM. Now that you have set the Idle adjustment on the carburetor you can adjust the set screw on the top so that at Idle on the throttle lever it is in contact with the housing. Once set replace the governor housing cover with a couple of bolts. Run engine and confirm that the idle RPM is still 450.
Run the engine and set the throttle to WOT, check the engine RPM, rated maximum RPM for this engine is 1650. Turn off tractor and remove governor cover, you can now adjust the lower set screw to set the WOT Maximum RPM, you want the set screw to be touching the housing at 1650 RPM and WOT on the throttle lever. You may need to move the adjuster screw in and out in order to set the RPM correctly, this may take several attempts starting and running the tractor at WOT in order to dial it in. Once you have set the WOT RPM replace the governor housing cover and gasket if needed.
Please use your head and work safe.