Farmall 400 Throttle Adjustment

pmarkel · Jul 15, 2016

I recently bought a Farmall 400 gas tractor. It runs real well but seems to be running at low RPM (working load should be about 1450 I think). What is the easiest way to check what RPM it is running at at fast idle with a digital tachometer and how do I adjust this? As the tractor has power steering, there is a bracket obstructing my access to what I believe is the governor housing which I was told contains an adjustment screw (only had Deere's before so I am not too acquainted with the IHs yet). Thank you for your time,

Sincerely,

Peter Markel

fastfarmall · Jul 15, 2016

Have you got a old combine cylinder speed checker, where you hold it on the center of the shaft, you can use the same thing on the end of the PTO shaft. Too speed up the engine take the cover off the govenor and tighten up the one spring, Y0u should have 610 rpm on the pto, I think .

fastfarmall · Jul 15, 2016

The govenor plate,and yes it is behind that power steering pump, It aint that hard to loosen it up, and move it to the side.

Janicholson · Jul 15, 2016

Make sure the threttle lever is moving the governor aremto its full travel.. They wear along the pivot points and twist in the rods. fix that first so it is
fully open in the next to last notch of the notch plate. Jim

Bob in wc Ia. · Jul 16, 2016

I found that a piece of a small mirror, about a 3/4" circle, stuck to the crankshaft pulley with 2-sided sticky tape, works good to get a reading with a digital tach. I found these mirrors at Hobby Lobby. I guess on your 400 it would be put on the power steering drive pulley. No-load speed for a 400 is 1600 rpm. Maybe back out the adjustment bolt about 2 turns to start. If you can't get it up to speed by adjusting the adjustment bolt, it might be a weak spring. Another thing to check is the length of the vertical linkage rod that extends up on top of the governor housing, and connects to the throttle shaft with a clevis and pin. To check this setting, remove the breather tube cover screws and turn it away to get clearence. Dont let it hit the fan. You may have to loosen the nut where the tube connects to the head to be able to turn the tube. To adjust, remove the clevis pin, then, with the throttle lever wide open, and the lever on the throttle shaft held to the top of its movement, the pin should just fit freely. If it doesn't, adjust the clevis to fit. Hope this helps. Bob

pete 23 · Jul 16, 2016

About 99 chances out of a hundred, the linkage is not moving lever at the governor to stop. You can easily get in behind and check that. Those throttle linkages wear at many different points and the worse one is the pin and hole right at the control lever and rod right there by steering wheel. Most have been pulled beyond the last notch and hooked off end of quadrant for years.

Janicholson · Jul 16, 2016

Sounds familiar! Jim

56 Fan 400 · Jul 18, 2016

(quoted from post at 11:20:12 07/16/16) Sounds familiar! Jim

That it does. Thanks Jim.

pmarkel · Aug 15, 2016

Thank you for the advice. I did notice that there was a lot of slop in that speed control linkage by the steering wheel. Once you pull the lever 2/3 of the way down the quadrant, it was so worn on the rod and the pin hole that it wasnt moving the remainder of the throttle linkages to governor. I fixed that (temporarily) with some bushings but I still couldn't reach the rated RPM. I did as Bob suggested and removed the breather tube to check that the vertical linkage which connects to the throttle shaft was adjusted properly and I believe that it is. So I am going to replace the spring next and see if that makes a difference. Thank you for your help.

Peter Markel

Farmall 400 Throttle Adjustment

pmarkel

Member

fastfarmall

Well-known Member

fastfarmall

Well-known Member

Janicholson

Well-known Member

Bob in wc Ia.

Member

pete 23

Well-known Member

Janicholson

Well-known Member

56 Fan 400

Member

pmarkel

Member

Similar threads