Farmall M lack of RPM governor?

Last night I was trying to adjust the hi idle rpm on my M to be 20% over stock. I have been running a 3-4 yr old "magic" or hardware store spring and governor response has been good. I back out the hi idle limit screw and my rpm"s max out at about 1820 rpm with the screw not touching the stop. I removed older spring and compared it to a new spring that I have that looks exactly the same. New spring had noticably more tension so I installed it and it was good for right at 1900 rpm and that was it. Ive checked my external linkage and it is not binding anywhere. Any ideas on what to check next? It seeems these governors should yield more rpm yet mine is still lacking a bit to meet my maximum allowed at a tech inspection. What are you guys thoughts on this?
 
The screw isn't touching the stop. That is because the stock linkage doesn't allow the governor control arm to move through its full range of motion.

There are 3 things to do to improve this.

1 - adjust the length of the rod from the pivot linkage to the governor arm (by bending it, or cutting and welding it) so that the pivot linkage is more "sideways" and less "up and down". This way the pivot linkage moves the rod more through its range of motion.

2 - the long arm of the pivot linkage that the rod to the governor is attached to should be made longer. Cut it, piece in about 1/2" to 3/4" of material, and weld it back together. This again will make the pivot push the rod more with less pivot motion.

3 - drill a new hole in the governor control arm a little shorter than the factory hole. Maybe 1/2" to 3/4" shorter. This way the rod will swing the control arm more.

You still won't have "full" range of motion in the governor, but you should get enough to go from a nice slow idle to 2000 rpm with stock spring.
 
Rust farm, no problem. This site has helped me out over the years, and has given me the phone numbers and email adresses of some very smart people in the pulling world. Glad I can help someone else out. Sometimes it is hard sorting out the good advice from the BS, but that is half the fun. Good luck.
 

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