fuel/air needle valve question (rough running tractor)

I have a 1951 Farmall Super C, new carb, but after the tractor warms up the tractor will start to loop. Meaning, the lever behind the carb starts asking for fuel, then more air, then fuel, then more air. Basically; it runs fine, then runs rough because it has to little air/ then runs fine, all within seconds. I jump off the tractor readjust the air/fuel needle valve and the tractor runs like a champ for a few minutes, but the needle valve keeps backing out to the wrong setting. THe valve will not back out totally, but enough to cause the rough running. What can I do to stop the backing out? I thought about lock tight or finger nail polish on the threads, but is there something else I should do? Thank you all.... the tractor has new plugs (gapped correctly), new wires, new rotor, new distributor cap, starter, coil, new fuel, fuel tank is cleaned out, fuel line is cleaned out, sediment bowl is clean...

Does that valve have the spring that should be in it?? If yes it may need to be pull out more so it hold the needle in place

I can tell when my Farmall C is calling for more fuel and gets it because it revs back up. How does it tell you it needs more air?

The air adjustment needle is for the idle circuit.
After you are above idle it is out of the circuit and you are now running on the power jet.
I would guess you have an adjustment problem with the governor to carburetor linkage rather than a air adjustment. You could also have some binding keeping the linkage from working freely.

On the idle needle you adjust air into the fuel to have a mixture to cause the engine to run smooth at the desired slow idle RPM's. The power jet is the opposite with the vacuum cause by the turning of the engine drawing air up thru the venturi that needs the proper fuel mixed in with that air to run smooth above slow idle or at fast idle. This is metered with the power jet to get the proper fuel mixed into that air for a proper mixture for higher RPM's and pulling power.

Get the tractor running smooth at slow idle and then forget that needle exists. You can run the tractor wide open and remove that needle, place it in your pocket and the tractor will not know it until you slow to a slow idle.
You could have something in or around the power jet causing your problem also.

I believe the tractor is telling me it needs more air and/or fuel because of the, "it runs, it runs rough, it runs, off and on." Much like when I mix the fuel to air mixture when I fly an airplane. As I make the mixture to lean I can kill the engine, or to rich she runs a little rough.

I attached a picture, the needle that I"m pointing to, is that the air adjustment needle? If so, I adjusted the tractor at idle, ran smooth. Then I re-adjusted the tractor at full idle, because when I went up a slight incline, and had a load on the back (water tank) the engine bogged down. So I jumped off and adjusted the screw, the one I"m pointing to 1/4 turn, after a couple of times getting off and on. It appears the tractor is running correctly.

So is this needle the air adjustment needle, and the idle needle is the screw right behind the fuel line, to the right of this screw?

That is the main jet adjusting screw. CCW gives it more gas.

Thank you Teddy52food.

I turned it CCW 1/2 turn, so that gave it more gas as I was headed up hill. I'm assuming it was, "running out of gas" when we were headed up hill and pulling a load?

Sometimes if I applied choke I could get some power but not fully, running correctly like it should.

What is the screw to the right, behind the fuel line?

Idle adjusting. In is richer & out gives it more air. Engine has to be at a slow idle when adjusting.

Over to the right is the air adjustment for the idle. Get the idle smooth then open it up wide open with the hand throttle and adjust the one you circled to the fastest RPM and then turn it back in until you just get it to slightly slow the RPM's and you should be good to go. When adjusting the idle have the power needle turned out a coupla turns.