Farmall M RPMs

Sounds to me like his governor bearings may be rusted up. Take the cover off the side of the governor and see if there is rust in there, if so sometimes you can take the bearings out and spray them with penetrating oil to loosen them back up. When you put it back together put some silicone or a new gasket on the cover.
 
the governor spring most likely is broken. you dont just loose that much rpm from adjustment when not touched. there is adjustment screws inside of cover though.
 

Try 1450, not 1800 as rated RPM. I suppose many have been "turned up" over the years, but they are not a high winding engine from the factory.
 
Well more then likely your problem is the fact that everything is wore out , from sloppy linkage to the bushing missing in the linkage inside the gov. The two arms that hold the gov. spring is suppose to have BUSHINGS now huge holes that let the spring flop around in the holes . Just about everyone that i have been in the bushings are long gone . When done correctly it will make a new tractor out of it.
 
1450/1595 makes my point even easier... It's not turning that many RPMs normally.

If you're judging RPMs by ear, and saying it's not getting up to full RPMs because it's not "screaming," then there may not be anything wrong.
 
Full rpm on a Farmall M is a couple hundred less rpm than full rpm on a Farmall h is. In short, an m does not scream like an h will.

If you happen to have a friction type handheld tachometer handy: Then it is not so easy to use it on the engine itself due to clearance issues, but it is very easy to use a handheld friction tach on the PTO shaft with it engaged. At full rpm you should be seeing somewhere around 600 rpm on the pto shaft at wide open throttle and no load.

FWIW: I have some investigating/adjustments/pin slop/spring tweeks to do on an ole m that I am fixing up for myself as it is only seeing about 500 rpm on the PTO shaft at WOT. My h is spot on at 600 pto rpm at WOT at no load. Of course this 600 rpm drops some under a load and then gets you in the neighborhood of the proper SAE spec of 540 rpm that equipment operates at under load.
 
(quoted from post at 23:39:35 08/25/13) Low idle: Engine - 425; PTO - 158
Rated speed: 1450; 540
High idle: 1595; 594

Owen - Excellent spec post. Your specs further confirm the WOT info in my post. My dial type tach does not have the resolution to tell between 594 and 600 though -LOL

Thanks for posting the idle PTO rpms as I never knew those. That will be beneficial information for me anyway.
 

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