Farmall Cub Forum -- Questions and answers to all of your Cub related issues.
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I am pretty new to the site having bought a '68 Cub a few months back. It runs well but the throttle only goes slightly more than half way back before stopping or possibly binding. If you pull it farther it springs back. I have had the tank off to do other repairs (head gasket, radiator) and could not see anything physically binding up the linkage. So I wonder if I am losing the top end of the range or bottom. This being my first Cub I have no basis for comparison. It mows ok (I think) but I am getting ready to put it work plowing 3 acres for veg production...ground that hasn't been worked in 30 or more years too. Any suggestions or experience with this would be a great help. BTW, don't know if it could factor in but I put a zenith carb (larger) where there was an IH when I got it.
How does the governor spring look? I just changed one down in Florida for the same reasons as you describe. When the throttle was set all the way forward, the top round of the spring had a bigger gap than the rest of the coils. It had become weak and did not have enough tension to force the governor weights back and allow the carb to open up.
You also mentioned switching over the carburetor type, you might check the governor to carburetor adjustment mentioned here on Rudi's manual server:
http://www.cleancomputes.com/Cub/Blue%2 ... -02-18.jpg
http://www.cleancomputes.com/Cub/Blue%2 ... -02-19.jpg
http://www.cleancomputes.com/Cub/Blue%2 ... -02-20.jpg
http://www.cleancomputes.com/Cub/Blue%2 ... -02-21.jpg
The schematic also shows the spring Raymond is talking about.
You need to check the rpm at full throttle. 'As an experiment I put a governor from a 154 on my cub a few years ago. Due to the lighter weights, etc. it went from idle to full speed at a little over half throttle travel. That is ok if all you do is ride around or mow, but if you do other things that do not require full throttle, it is sometimes hard to pick the right RPM, so I put the original back when I was done. If you are not getting full RPM, check the RPM limit adjustment that is at the top front of the governor assembly. It may be adjusted down too far.
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Thanks to everyone for the quick responses. Looks like rain all day Saturday around here so I guess I will have time to put the advice to work. I will let y'all know if/when I get it figured out. Thanks again
Loosen (not remove) the carburetor from the manifold and check if the throttle plate contacts the gasket or manifold.
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Thanks again to all. I adjusted the linkage arm from Governor to carb nearly an inch. It sure made a difference. I did not have full throttle range at all before. MUCH higher RPM range and the increase in speed and power is remarkable. It did not effect the low end but it sure does seem high at idle (it did before as well). I unhooked the governor link arm to be sure the throttle is backing all the way off and no difference. I adjusted the idle screw down till it seemed to miss and then back up till smooth. Wish I had a tach. Again, this is my first Cub and the only one I have ever heard run so I don't have much of a comparison.
This might solve your lack of a tach problem ...
IH / Farmall Cub / Cub Loboy Tachometer - Replacement New
You will need the drive cable and the mounting brackets -
Check your local auto parts store (O'Reilly, Pep Boys, Autozone, etc.) I picked up a dwell/tach meter for about $15. You just have to remember to reverse the leads to allow for the positive earth.
Eddie - a 1959 International Lo-Boy named after my father in law, who who bought her new.
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