Governor/Engine surging

Mon Apr 15, 2013 10:39 am

I have a 1956 Farmall Cub and after running for 5 minutes or so, the engine begins to surge. THis occurs at low and high speeds.
Is the governor sticking?
What controls the governor?
The sediment bowl is clear with fresh gas.

Re: Governor/Engine surging

Mon Apr 15, 2013 11:59 am

Has your carburetor been removed or adjusted recently?

First I would remove and clean the main jet on the lower side of your carburetor (I am assuming you have an IH style). Clean it out with smooth brass wire and blow out with compressed air.

Then I would follow the procedures laid out in the following links from the service manual courtesy of Rudi to make sure the carb is set to your governor.

http://www.cleancomputes.com/Cub/Blue%2 ... -02-18.jpg
http://www.cleancomputes.com/Cub/Blue%2 ... -02-19.jpg

You may also have to make adjustments to the bumper spring on the governor body itself, described here:

http://www.cleancomputes.com/Cub/Blue%2 ... -02-20.jpg

Locations of the bumper spring shown here:

http://www.cleancomputes.com/Cub/Blue%2 ... -02-19.jpg

Re: Governor/Engine surging

Mon Apr 15, 2013 12:33 pm

My first thought is the fuel flow is partially restricted, almost but not fully keeping up with engine consumption. Could be external to the carburetor or internal. If the surging is fuel flow related it should be considerably more pronounced at higher rpms.

Next thought is the linkage adjustments indicated by Brian.

Re: Governor/Engine surging

Mon Apr 15, 2013 8:18 pm

Also, something easy to check is to see if the linkage from the governor to the carburetor is rubbing against the engine block, or if crud has built up in there causing it to rub. I've seen this on MANY cubs, even ones that have recently been re-painted and the carburetor re-installed. It's really easy to get that little rod bent towards the block and not even realize that it's rubbing. On the cub I did a few years ago, I think I bent the rod when I went to re-install it onto the carb. Did the exact same thing as you're describing. Saw where it was touching the block, grabbed it with both hands and gave it a little bend outward, problem solved!

Re: Governor/Engine surging

Tue Apr 16, 2013 9:46 am

Lubricate and make sure that all the linkages move freely - see breakdown :

Image