Main Adjustment Needle

[ranba]

Trying to figure out why my 2N runs perfectly smooth when the Main Adjustment Needle is pulled all the way out. As soon as i put it back in it starts missing out real bad. I don"t even have to screw it in, i can put my finger over the hole where it goes and it will start missing.
Any help at all would be great!

 

[old]

Float bowl air vent is clogged up so you need to do a carb rebuild and soak it for 24 hours in a good carb cleaner like berry-mans Chem dip and then use a small wire and compressed air to blow out all passage ways. Yep BTDT and have seen it more then once. Also if you go to the N forum below There is a guy in there that does carb rebuilds . GB from MT

 

[ranba]

Thats funny,,just got the Carb from this web site about 8 or 9 months ago.

 

[rustyfarmall]

(quoted from post at 18:34:21 04/13/10) Trying to figure out why my 2N runs perfectly smooth when the Main Adjustment Needle is pulled all the way out. As soon as i put it back in it starts missing out real bad. I don"t even have to screw it in, i can put my finger over the hole where it goes and it will start missing.
Any help at all would be great!

The air cleaner might be plugged up, causing an over-rich condition, and removing the adjustment needle allows just enough MORE air into the carb to compensate for that over-rich condition. Might also have an issue with either the carburetor float or the needle valve and seat.

 

[JMOR]

Removing the Main Power adjust needle essentially vents the bowl to the atmosphere which is a higher pressure than it normally runs, therefore, it makes the mixture richer. This means that you are normally too lean. Why? Could be a restriction in one of the 3 screens or trash clogging an internal passage, float level, or even an air leak at manifold gasket, etc. First, remove the drain pug from the bottom of the bowl and see if it will flow at least a pint in 2 minutes. If not investigate filter screens.

 

[Dick L]

Pull the main jet out and see what size hole is in it. It sounds to me like some how a non adjustable jet got installed. Or find a plug to screw in the top and run it the way it is.
Vacuum caused by the venturi pulling air thru the running engine pulls the fuel into the air stream from the main jet up the feeder tube.
The only way it could run proper is with the fuel being metered correctly going into the air stream. The adjustable jet would have a hole large enough to flood out the engine with more fuel than needed.
I would not think you could get a hunk of crap stuck in the jet that would meter the fuel correctly. The older little Allis Chalmers tractors has non adjustable jets that were sized for the tractor engine.

 

[rustyfarmall]

(quoted from post at 11:49:15 04/14/10) Pull the main jet out and see what size hole is in it. It sounds to me like some how a non adjustable jet got installed. Or find a plug to screw in the top and run it the way it is.
Vacuum caused by the venturi pulling air thru the running engine pulls the fuel into the air stream from the main jet up the feeder tube.
The only way it could run proper is with the fuel being metered correctly going into the air stream. The adjustable jet would have a hole large enough to flood out the engine with more fuel than needed.
I would not think you could get a hunk of crap stuck in the jet that would meter the fuel correctly. The older little Allis Chalmers tractors has non adjustable jets that were sized for the tractor engine.

The Marvel-Schebler TSX33 carburetor on the 9n Ford is a little different animal from the Zenith carb used on the Allis tractors, and the later Allis tractors did have an adjustable main jet.

 

[Dick L]

Probly looks something like this.

I cleaned this one up a few years back and had it back on a shelf. You are correct on the jet not being able to be a small run as is sized jet.
Seems strange the the fuel would be metered that close from a chunk caught in it or under the feeder tube. That would be where I would look. Cleaning under the feeder tube is often overlooked.

The Zenith adjustable jet for the B's and C's will interchange with a sized jet. I have changed them at a tractor pull to see what change I could get.