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...
- Thread starter Stacey246
- Start date
NOT quite sure about your problem analysis/root cause, but if the mixture needle IS actually moving on it"s own, it needs to be snugged up. Likely it either passes through a "packing gland" or a spring.
If it has the brass "gland" tighten the nut up a bit to squeeze the packing tighter, if through a spring, stretch the spring a bit to put more tension against the head of the mixture screw.
If it has the brass "gland" tighten the nut up a bit to squeeze the packing tighter, if through a spring, stretch the spring a bit to put more tension against the head of the mixture screw.
You could drill a hole through the end of needle valve and hook a spring through it and hook the other end of spring to something to hold it in place or maybe 2 or 3 wraps of Teflon tape would work to keep the needle valve from backing out.
Good luck and please update as to what works for you.
Good luck and please update as to what works for you.
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?
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?
SparepartsTN
Member
The screw that you are adjusting is the "Main Adjusting Needle", initial setting is 1 1/8 turn open. "With engine running at governed speed under full load, turn the adjustment needle in until the engine power just begins to drop off. Then, turn the screw out until the power picks up and the engine runs smoothly."
The other needle you asked about is the"Idle Air Adjustment Needle", initial setting is 1 turn out. "Start the engine and turn the idle adjustment needle in until the engine begins to 'roll' from too rich a mixture. Then, back the needle off until the engine runs smoothly."
These instructions are for a MS carb on a ford.
The other needle you asked about is the"Idle Air Adjustment Needle", initial setting is 1 turn out. "Start the engine and turn the idle adjustment needle in until the engine begins to 'roll' from too rich a mixture. Then, back the needle off until the engine runs smoothly."
These instructions are for a MS carb on a ford.
SparepartsTN
Member
Forgot to say, that intake gasket between the carb and manifold looks suspect, believe I would clean the surfaces good and use a new one.
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