3600 RPM Falls on Cub Cadet 1450.
 

Cub Cadet 1450 RPM not holding at 3600.

The Tractor has Walbro Carburetor with the original linkage. The issue I am having is the Throttle Control (TC) will not hold at the highest RPM (3600) when pushed all the up on the dash. The TC slowly pulls back down, when running, whereby the engine RPM drops down if I do not hold the TC in place.

I am not sure, if it is the way the linkage is setup or if the TC is the at fault. It seems the Carburetor opens up all the way when the TC is at around ½ way, on the dash. The governor spring is not pulled at that point. Only after, the lever is pushed all the way up on the dash, which allows the Governor Spring to be pulled, allows engine to reach 3600 RPM. The Engine does not reach 3600 RPM unless that governor spring is pulled (I am not sure if that's the way it's supposed to work). If I do not hold the lever in place, the spring pressure pulls the TC back down which lowers the RPM.

Any Help would be appreciated! Bob.

Just wondering how you know it's hitting 3600 rpm?

There should be a screw you can tighten up on the throttle control lever pivot, under the dash, to give it more drag, and stop it from slipping back. If I remember, there is friction washers where the screw goes through the lever assy. and tightening the screw increases the friction, and holds the throttle in place !:beerchug:

Agreed, I would make sure all places that your cable is attached are
tight and there is no way the cable itself is moving. Then start looking
into engine stuff.

Ken

Thank You guys, appreciate your replies. I ruled out the cable itself, at the carburetor it is tight there. When engine isn't running it stays in place. It is only when the governor spring is pulled while running, it moves back down to around the middle of the lever. The vibration and the spring pull seems too much pressure for the lever. I think I going to try to remove it and use a vice with some bolts or punches to see if I can tighten that rivet a little, see what happens. I connected a tachometer to engine, the type that wraps around spark plug wire, not the best but gets me into the ballpark.

Attachment 111086

Attachment 111087

I seriously doubt the Governor Spring has enough pull to overcome the friction in the Throttle Lever. If it does, do you have the right Governor Spring?

:bigthink:

That's the million dollar question! I was led believe that the tractor is all original but since i'm new to working on these tractors, you never know what the PO did to get the best price possible when selling. Attached pic is how it currently looks (a little dirty) it shows how the OP has it set up. It maybe wrong, but I don't know! The only thing I do know, is that the lever does not hold, so the RPM is not where it's supposed to be, if I do not hold it in place at the top of the dash.

I would really like to resolve this RPM issue before winter, where I can run the Snow Thrower I restored.

attached pics of how the linkage is connected. The front cable is the choke ad rear cable is the throttle.

Check your engine mounts! Most likely they have failed and the engine is setting too low. I noticed the cables coming through the firewall have "sawed" their way downward on the firewall. In my experience with these models, this will cause the throttle to continuously back down.

Yes, Thank you, I replaced the engine mounts a few months ago. I have been thinking that it may be the Throttle Control, as it's over 45 years old and been used for a long time where it may have worn out a little. Tightening the rivet may be the cure of the RPM issue. The Throttle is pretty loose, there is hardly any drag at all in it. I'll try to see if I can do something with it in a vice if it works great. If not I just lost a hour or 2 trying to fix it. The other option, I may just need to order a new one, could be time for a replacement and that could be the cure. Thank you all, I'll let everyone know, and I really appreciate all responses, they have been very helpful. `

Bob

Something is not right there where your throttle cable attaches.
The cable should be straight and secured by the set screw that yours has the looped end around. That is where part of your speed control issues stem from. Leads me to think the cable has been replaced.

There is a small hole in what your/that screw threads into (spacer), then the cable goes through that hole and the set screw jams it tight in the hole and the complete ass'y is free to swivel in the lever by means of a small washer.
This washer goes on this small, hex headed & threaded spacer first, before you insert the cable through that hole, then the screw secures it in the hole.

You will need the correct low idle speed set before you adjust this cable.
The way you have it now, with that loop, there is no speed adjustment available. Use the procedure in the manual to set this up including the governor setting for proper operation.

Looks to me there may be slop in that loop when you move the throttle lever.

Also, there should be a "Z" bend in the end of your choke cable so it does not move within the lever when actuated.

See pic's

This is the throttle control ass'y you need.
Part #IH-126465-c2
You can see the tension sdjusting screw on the side and note the straight end on the cable, no loop.

Thank You, finsruskw!

I was not sure what the PO did on this Tractor. I know he made some changes to it. Your photos and explanation are, what I think, I need to fix this issue. I always thought that the cable is not the original one, it was replace before I got the tractor. I think when the PO re-installed the cables he didn't put back together properly, but I had no way of knowing this. I noticed that the spring on mine, is not in the correct position either as in your photo. I will re-work the cables ends so they are correct as you point out & re-set the idle and governor as stated in the manual. The Choke surprisingly, operates with no issue, even though it looks like it is not correct.

The TC you have provided looks like the correct one for the type QL tractor, but there is no way for me to install it unless the PO removed a mounting plate part for that type of TC.

I removed the Throttle Control (TC) with cable and found that the rivet was loose where, the lever moved side to side within the control plates. This looseness within TC was not noticeable when the TC was on the tractor and connected as it was rubbing on the dash slot. It was giving the impression it was working properly and had some drag. I placed it into a bench vice, I found a bolt that was the same size as the rivet on the TC. Squeezed the rivet in the vice, where I was able to measure the amount of force little by little, to increase the amount of drag on the control. It is now working as it should without any side movement with just a little drag. The hardest part was taking out the TC, not much room under that Dash. I will now, re-install the cable and set things properly hoping for proper operation.
Thank you so much.

UPDATE: Re-Install the Throttle Control and setup cables as indicated in the service manual. I have low idle set at 1800 RPM and High Throttle at 3600 RPM. The Throttle Control holds the High Idle without issue. Its running better now, Thank you, all for the assistance. I truly appreciate everyone comments. However, "finsruskw" explanation and photos supplied what I was missing, as I didn't have the information needed to complete the repair. Thank you, FINSRUSKW!

I love a story with a happy ending.:beer2:

Ken