Hi folks, finally got the Cub back together and it starts and runs but not getting Throttle response and it idles too fast. Zenith carb was thoroughly cleaned and when reinstalled couple months ago, engine purred like a kitten when test started. Have not touched the governor as know nothing about them. Any adjustments there? In the interim, just fluid maintenance and parts replacement. Thanks for all counsel
Throttle governor issue
- Thread starter Swede
- Start date
Bill V in Md
501 Club
Could be control rod/linkage binding somewhere. With engine off, move engine throttle lever back and forth and confirm that you see a corresponding movement at the carburetor throttle.
staninlowerAL
501 Club
Whn
One of the causes of no throttle response is the control lever on the governor shaft is frozen up. When you are checking the linkage for movement pay close attention to the lever part reference #11 to see if it moves freely on the shaft ref #12. It should not have any restriction of movement and needs to be lubricated occasionally. If it is not moving, disconnect the throttle rod from the lever and lubricate it with your favorite penetrating oil and tap it LIGHTLY in both directions. The lever is cast and will not withstand aggressive treatment. BTDT! In extreme situations the lever might have to be removed an cleaned/lubricated. JMHO Stan
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staninlowerAL
501 Club
If you remove the cotter pin from the rod that connects back to the lever at the operators station and the rod from the lever #11 should move freely. If it is stiff or won't move continue there. Also there should be a stabilizing clamp under a stud at the rt rear side head bolt that helps to keep the long rod from flexing in the middle. It's right above the oil filter cover in the picture. Stan
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staninlowerAL
501 Club
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The rod should have a clip to hold it near the right rear of the engine head. They have said on here it is needed to prevent the long rod from flexing.
There is a 5/16" short bolt there for it.
Below are pictures of it at TM Tractor Parts.
control_rodclip - Page: 1 of 1
TM Tractor Parts has a new clip, it looks like it should be flatter, like the pictures of the one above are.
You can bend the rod, if needed, so it stays naturally in the position it should be in to be in the clip.
Sometimes the rod can be bent wrong, so it is springing away from the clip.
Bend the rod over a long length, if needed.
Hold it near the front, so you don't put force on the governor arm.
Bend the clip closed some so the rod can't come out of it.
Be sure the rod slides easily in the clip.
There is a 5/16" short bolt there for it.
Below are pictures of it at TM Tractor Parts.
control_rodclip - Page: 1 of 1
TM Tractor Parts has a new clip, it looks like it should be flatter, like the pictures of the one above are.
You can bend the rod, if needed, so it stays naturally in the position it should be in to be in the clip.
Sometimes the rod can be bent wrong, so it is springing away from the clip.
Bend the rod over a long length, if needed.
Hold it near the front, so you don't put force on the governor arm.
Bend the clip closed some so the rod can't come out of it.
Be sure the rod slides easily in the clip.
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If the spring at the governor is broken or gone, you can move the throttle lever to any position and the engine will just run at slow idle, as I remember.
Below is a picture from TM Tractor Parts of the governor cover and the spring.
TM Tractor Parts has a new spring.
Oil the throttle arm where the cotter key is in the picture. Work oil into the arm pivot there.
The IH and the Zenith carburetors have a slow idle speed adjustment screw near the top of the carb, on the engine side of the carb.
The 2nd picture below shows the screw on the Zenith carb.
I sent you a message.
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When you say "back together," did you split the tractor and take the linkage off between the throttle and governor? That linkage can go in either way, and if it is backwards, it can bind and limit throttle response.
The other members commented on the rocker arm on the governor with the spring. Getting that free is very important.
There is also a procedure in the manual to adjust the linkage between the governor and the carb. That is also important for throttle response.
I would also look for long cotter pins in the linkages. They can catch and bind.
Very rarely are the issues inside the governor itself. I would try a lot of other things before even thinking about removing the governor.
The other members commented on the rocker arm on the governor with the spring. Getting that free is very important.
There is also a procedure in the manual to adjust the linkage between the governor and the carb. That is also important for throttle response.
I would also look for long cotter pins in the linkages. They can catch and bind.
Very rarely are the issues inside the governor itself. I would try a lot of other things before even thinking about removing the governor.
