cub running bad

[Jack]

Well I played around with the carb today , and I think I'm going to need a carb . The long brass tube that goes through the center of the carb is broken off, and gas started filling the breather tube up, I did have it not surging like it did yesterday,
I thing the carb was my whole issue from the start

[Glen]

Hi,
The carburetor is probably repairable, if it is not in bad condition.
They have said on here before that the broken end of the Idle tube can be removed using a left hand drill bit, by hand, no electric drill. Put a vise grip pliers on the drill bit to hold it, maybe.
The idle tube screws into the top half of the carburetor.

Below is a listing for a new one at TM Tractor.

http://www.tmtractor.com/new/fl/384fp.htm

If the carb leaks or drips out the front on the ground, it may have dirt in the needle and seat.
Or it might need the float level and float drop set correctly, to the specs in the Cub service manual.

The needle and seat wear after years of use, and don't seal anymore, then they need replacing.
TM Tractor has a new needle and seat.

Another thing to look at about the condition of it is the wear in the throttle shaft, at the top of the carb, if it moves side to side, at the linkage where the rod connects, then it needs improving so it is not loose, and probably the shaft replaced.

We bored one out and put in small bushings for the shaft. It was not loose after that.
The engine can take in air at the shaft if there is much wear there, that affects the way the engine runs at slow speeds.
A new shaft used to come in some of the carb kits.

[Jack]

Thank you Glen

[Bob McCarty]

Another thing to look at about the condition of it is the wear in the throttle shaft, at the top of the carb, if it moves side to side, at the linkage where the rod connects, then it needs the bushings and shaft replaced.
Some of the carbs might not have bushings there, the shaft just runs in the cast metal. That makes it harder to repair, it has to be bored out and little bushings put in to tighten the shaft.

The Cub IH carb has felt shaft seals that are easily replaceable. There aren't any bushings to replace. The threads on the idle tube are 4/48, the calibrated orifice is in the threaded end (in the carb top). Your Cub should still run with the broken idle tube, although the idle may not be as good as it could be.

[Eugene]

Have you considered that a failing coil can cause surging?

[Jack]

I ordered a new carburetor.
I was thinking back, when I took the plugs out. N
#2 & #3 plugs were pretty carboned up

[Jack]

I'm waiting for a new carb to arrive from TM
I will post the results after I install it.
Thanks everyone for your replies

[outdoors4evr]

The new carb will likely need to have the float adjusted. Probably easier to do that before it is installed.

[Jack]

Thank you

[Jack]

The carb arrived today, I installed it, and she purrs like a kitten now
Thank you everyone

[Bob McCarty]

Save the old carb and have it rebuilt at a Cubfest to keep as a spare.

[Jack]

I do plan on keeping it,
Thank you