Have just rebuilt my governor and now need to get the idle set. I do not have the tach that drives off of the hour meter.
Is there any way to :

A> set the high and low idle without the tach and/or

B> set the idles so that the governor 'works' best

At present I have no idea where the idle(s) are set. I did adjust the low idle till she quit, then I quit, (while eye was ahead)

Looking for the best way to get the governor to that 'knife edge' where increases in load are offset with increases of fuel delivery.
Any suggestions to find that 'spot' ?

There is no correct way to set the idles properly without a tach. The screws are under that small half round cover on top the gov. housing and the low idle is the lower screw and the high idle is the higher screw and both are set with it standing and no load on the engine. You didn,t give a serial number but the book I have covers up to 9U16536 and it,s 550 RPMs for idle and 1535 RPMs high idle.You back the screws off to increase the RPMs and turn them down to lower them.The fuel deliver is governed by the rack setting (travel) but you need the correct tools for that unless you didn,t touch the adjustment when you had it apart.Hope this helps to answer a couple of your questions.

That sweet spot shouldn't have much of anything to do with the high idle and certainly nothing to do with the low idle.

I would guess that the rack setting is the ultimate limit on fuel delivery and power output, so you won't change that by changing the high idle rpm, but you may make it run hot(ter) since in most applications the governor won't stay on the torque spring (max fuel) very much of the time, so when it's not working quite that hard, the high idle rpm (which translates to about 10% lower loaded rpm) sets the fuel delivered and heat produced under normal work.

An easy tach to use is a photo tach that uses a reflective sticker on the crankshaft pulley or the U-joint behind the clutch to bounce it's light off and count rpm's.

Low idle should not cause the engine to die. You should have to push the throttle control fairly hard to make it flip the idle stop over so the governor goes to cutoff.

The rack setting has not been altered during my work. However, I feel that you may have hit on my problem, sounds like I need to get the rack setting right.
Remember reading about the measurement a time or two so I will brush up on it and research some.

Curious though, how would the rack setting become 'out of whack'? Would or could it simply be a factor of time, or just wear and tear? Cause' eye know that this ole' girl has not had much attention since way before I got her coupla' years ago. (She was being push started regular on a farm, till the guy I got her from got the pony going)

thanks for the comments and ideas, sure will help me get this worked out!

The gov rack travel won,t move unless someone has played around with it and then you,ll need the rack setting gauge to re-adjust it. It is a bolt with a jam nut on it so it won,t change unless someone changes it. If you are experiencing low HP or in other words it won,t hang on a push or a pull then it usually is a Gov. spring that,s lost tension. Some guys claim they adjust it by turning it on the factory end adjustment but you don,t have a way of knowing how much to adjust it.o your only guessing so a new spring is the best and only way to go properly and I found the 5F6413 the best spring that the rack setting book calls for with a .215 rack setting.Also with a 5F1941 it calls for a .125 rack setting.I found over the years those big Cat V8s and V12s would work best with that 5F6413 spring.You might want to check the gov. spring # in it now and get that one so the rack is set for that spring.

Good idea for the tach. Shoulda' thought of that myself.
Since the rack setting most likely hasn't changed; it takes us back to the spring as mentioned.
Have been unable to locate a 'replacement' spring for this very late model D6-9U. Perhaps will try adjusting it some and see if she becomes responsive to loading during a push. So far, there has been no additional fuel delivery when the engine loads up.
Fairly confident with the governor rebuild, and if the spring is as worn as the rest of the governor was then that really could be the problem!