Farmall Cub Forum -- Questions and answers to all of your Cub related issues.
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Hello I'm new this site. My 9 year old son purchased a 1949 cub that sat for 5 years, after getting it to run noticed threre was no throtle range(first notch idle 2nd notch wide open). Also had a miss. We rebuilt the motor installed another govenor but still the same trouble no throtle range. After many checks and conversations with other mechanics and collectors still coming up stumped. Tried many adjustments still nothing. I noticed the throtle lever will not go back to the first notch without alot of pressure, the arm on the govenor goes down and pinches the spring on the housing. I've looked at other cubs and this doesn't happen. thinking I have a linkage problem but not sure. I have inspected three different govenors I have and can't find anything different in them thats why I'm leaning towards a linkage problem but its driving me nuts. Thanks for any help.
with it started, can you stand on the left side and pull on the carb linkage and get it to slow down? once slow, can you rev it up.
When you push or pull on the throttle, with someone watching, does the rocker lever on the gov. relax and stretch the spring? does this rocker arm move smoothly and easily?
Is there ANY play in the linkage from the gov. to the carb?
Does the long rod from the throttle to the gov have any or a lot of flex to it? Is it in the bracket that is mounted to the head?
Any, and all of these could cause your issues.
Congrats to your son on acquiring his very 1st Cub and good show to Dad for helping him with his new toy One heck of a way to get some quality father and son time.
In the diagram below, suggest you lubricate all the connecting points with a good penetrating oil. Not WD-40 but something like Nut Buster, PB Blaster, Kroil, Solvo-Rust etc., Let it soak in and reapply as required. Patience is the key to unfreezing the governor rod assembly. Dirt, crud and corrosion can freeze it up pretty tight. That should solve the problem.
One of the first things I recommend to new Cub owners is to read the Owner's Manual - click on this link McCormick Farmall Cub Operator's Manual 5-1-49. Suggest reading it and then familiarizing what you read with the real thing.
We have lots of resources for our members and might I suggest that you also follow the links below. Tons of info on Cubs and solving problems as well as other good stuff
Have you adjusted the governor linkage to the carburetor?
From Rudi's manuals:
http://www.cleancomputes.com/Cub/Blue%2 ... -02-18.jpg
http://www.cleancomputes.com/Cub/Blue%2 ... -02-19.jpg
Thanks for the sugestions, all the linkage is free and lubricated. I had bushings made to take up the play in areas that I could. With it running I can slow it down by pulling it back, when I let it go it springs back wide open. I used the manuals on Rudis page to adjust the linkage, but with the throtle lever not going all the way back I don't know if i'm starting at the right spot when it says to set the throtle half way then adjust the yoke on the carb shaft. Thanks again.
The problem suggests that the governor weights are not operating or the rockshaft is binding. When the throttle is opened, the throttle rockshaft on the top of the governor pivots and puts tension on the throttle spring, which is attached to the governor rockshaft. This tension on the rockshaft swings the fork inside the governor that is attached to the rockshaft back against the thrust bearing. Since the carburetor throttle plate is now fully open and the engine is increasing in RPM, the rotating weights inside the governor are propelled outward. This action pushes forward against the thrust bearing inside the governor, which pivots the rockshaft in the direction to close the carburetor throttle plate. The engine high idle is established by adjusting the throttle spring tension to provide just enough resistance against the rotating weights to prevent the weights from closing the carburetor throttle plate beyond a set high idle point. Unless you know that the governor you put on the tractor was working properly, you may still not have a good governor. Condensation in the crankcase is an issue with Cubs when the engines are not regularly brought up to operating temperature. This moisture can settle on the governor innards, causing rust and gum to accumulate when the engine sits idle for a long time. If your linkage seems loose and free, I would pull the governor, separate it, and examine the innards to make sure everything moves freely and is free of rust or gum.
there is a stop-screw for the butterfly at the top of the carburetor near where the governor linkage attaches to the carburetor that I've had to adjust. The governor linkage into the carburetor is tricky in my opinion and it doesn't take much turning to change the idle and full throttle settings for the engine.
For what it's worth, my Cub has had an issuue with some slop in between the shaft and the rockshaft spring lever (items 4 and 8 in Rudis schematic). The woodruff key has "wollered out" the spring lever so that the govenor reaction is minimized. i.e. the govenor rolls the shaft to speed up or slow down the engine but the thottle doesn't respond, or at least doesn't respond as it should, having some lag time and when it does react it tends to jump the rpm's. The reason I mention it is because it's in an area that wouldn't normally be observed and not something one would immediatly suspect.
As Dale said it could be any or all these things, I wanted to point this out as a less obvious possibilty.
Read this - Lurker Carl's Cub Governor Rebuild. It might be helpful.
Much has been written about the back and forth play that can develop between the woodruff key and the keyway that connects the extension to the governor rockshaft. On my first Cub, there was a small allen head set screw in the hub of the governor rockshaft. At this point, I do not recall if it was positioned directly over the woodruff key, as I think it should have been, but once the extension shaft with the woodruff key was inserted into the hub and the set screw turned down, it locked the two shafts together nicely. I do not know if this set screw arrangement was factory original in some years or it was a unique modification by the previous owner. I have two other Cubs and neither have the set screw. Regardless, it would be a rather simple modification to prevent the develpment of play at the coupling.
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