37 b carb question

Hi,
My father and I use our old b to plant food plots for deer. I've got an odd issue when pulling discs or our cultipacker.
Say when we are going up a slight grade and the load increases the governor opens the throttle and it runs fine, but when reaching the top of the grade and the load lessens, the tractor surges for a bit. The governor is opening and closing the throttle plate causing this issue. If I close the load adjustment a few clicks this gets better, but then the throttle response is terrible and it coughs when opening the throttle. I'm thinking the idle adjustment may be lean. I'm away from the property right now so I can test it right now. Any thoughts?
Thanks

(quoted from post at 06:43:05 09/12/17) Hi,
My father and I use our old b to plant food plots for deer. I've got an odd issue when pulling discs or our cultipacker.
Say when we are going up a slight grade and the load increases the governor opens the throttle and it runs fine, but when reaching the top of the grade and the load lessens, the tractor surges for a bit. The governor is opening and closing the throttle plate causing this issue. If I close the load adjustment a few clicks this gets better, but then the throttle response is terrible and it coughs when opening the throttle. I'm thinking the idle adjustment may be lean. I'm away from the property right now so I can test it right now. Any thoughts?
Thanks

Click to expand...

Why don't you properly rebuild the carb and go from there....

Thanks,
The carb was rebuilt. I am just looking for suggestions on my
settings from someone who may have experienced this issue.
Thanks again

Sometimes if the rod between the governor arm & the carburetor is too short, under the right conditions they'll get jumpy like that & keep surging from wide open to closed to wide open to closed. My guess is if you throttle up it straightens up & flies right? Shifting to a lower gear & throttling up also stops this right?

The length of the rod that operates the throttle plate (when set right) should be 1/2 the diameter of the rod SHORT (to the rear) of dropping into the hole when the carb butterfly is held wide open (engine not running) and the speed selector lever is all the way forward. If that rod is too short they will get jumpy enough to do EXACTLY what you say! The early styled A's were particularly prone to this. Lengthening the rod a bit desensitizes the governor some & may lessen or end this for you. It's a trade off though. Too much & he might not shoulder the load to suit your needs. I'm guessing your rod may be about 3/4 its diameter shy of dropping into the hole. Check that & if that's true, lengthen the rod a turn or maybe two or shift to a lower gear & throttle up.

Also one other thing to check...... since you say the carb was just re-built.... I've seen some kits include a rubber seal that goes 'round the throttle shaft just above the upper shaft bushing. I've seen those seals grab the shaft so hard they cause the governor to be slow and sluggish to respond then crack too far open & surge then have to shut back down. Make sure (with the linkage disconnected) that the shaft turns essentially effortlessly! I've used a small cylindrical stone in a Dremmel to wear those tight rubber seals into a larger diameter so they could no longer grab the shaft so hard. I've also tossed them into the trash. Problem gone.

Hope that's helpful.

Later.

Thanks. Everything you say sounds exactly like what I'm experiencing. I'll check the rod length.
Is there a specific length for the rod from the throttle lever to the governor spring or is that not as important?
The butterfly on the carb moves nice and free.
Thanks for all your help.

To check the adjustment of the rod from governor to carburetor:
Stop the engine.
Remove cotter key from rod where it fits into throttle lever and lift rod out of hole.
Put throttle in full speed forward.
Hold the carburetor butterfly lever in the full open position.
The rod should be ? hole short (⅛ inch) of fitting into the hole on the butterfly lever.
Adjust as necessary. When re-assembling, make sure the cotter key clears the carb casting.

Thanks for all the help.
Is there any special length from the throttle lever to the governor?

No. The length of the rod between the governor lever and the governor spring is not critical. This rod needs only to pull the spring eye back far enough for the spring to make it run up to speed. If the spring is too weak to "get 'er up to speed" then he needs replaced. Adjust the stop bolt/bolts for the throttle lever limits as needed.

Remember, a governor is a system of balanced forces. The spring speeds 'em up & the governor's action slows them down. To compensate for loads the governor lets the spring win opening the throttle. When it's running too fast the governor wins by overloading the spring closing the throttle. Moving the spring's eye just changes the speed at which the "in balance" point takes place!

Make sense?

Makes perfect sense. Thank you for explaining this to me. I appreciate you taking the time to write this.
My grandfather and father bought this tractor in 1960. I'm just trying to make sure it runs the best it can.