Carburetor Problems - Farmall H, have to run at half choke

I am having carburetor trouble with my H, I have rebuilt it twice in the last couple years and cleaned it several times. Problem is no matter what I do the tractor will not run right unless the choke is half on. Does anyone have an idea what to do to solve this?

Still has to be fuel starvation. Two things ofter overlooked are
the tank outlet and the brass screen in the float bowl inlet and any filters inbetween. Next check float bowl fuel level, then blow out all passages and jets. Doubt it could be mis-assembly it is a pretty simple carb.

Sure.
First, the fact that the choke is able to make it continue to run (if not perfect) means it is getting fuel in sufficient quantities to the carb. If it were supply it would perk up at first then die.
Second, the choke richens the mixture by restricting the air supply, forcing greater vacuum to be applied to the fuel jets in the carb. Richer is usually adjustable with a load screw located at the bottom of the carb at an angle. If this screw provides no change in richness, or not enough, there are three possible issues:
A partially plugged main jet. They need to be spotless, and can take several cleanings to be correct.

A Low float level.

A manifold leak internal to intake/exhaust system at the heat chamber, or external at the manifold to block, or manifold to carb gaskets.

I would start in order to assess the issue.
An internal leak must be tested by removing the manifold and plugging the carb connection with a rubber plug, then filling the manifold with water with the intake ports pointing up, but flat to the world. Leaks show by flow out the exhaust. Jim

Open that main jet screw at the bottom of the carburetor as this will enrich the fuel mixture. Even garden tractors and big rotary mowers have that same feature. Hal

When you rebuilt the carb, did it run well or did you still need to run choked? If you still had to run choked I would say you have a fuel flow problem. Keep in mind the H has a gravity fuel feed system. Any blockage will hamper the amount of fuel getting to the carb. Check the fuel flow path from tank exit to carb bowl, including float level. If that is all well I would check for intake leak, i.e. loose manifold or carb. Vacuum leak someplace.

What is this carb from?

did you install an in line fuel filter by chance? if so, remove it. most in lines are for a pressure system and will not flow enough fuel thru.

It will fit my Toro Whirlwind rotary mower. It may also fit my Wards tractor with a 14hp B&S engine. Here's the mower and tractor. Hal

Have you drained all the gas out of the tank and checked for crud? Have you cleaned the strainer at the input to the carb?

Water in the gas or crud in the tank would explain cleaning several times and getting the same issue.

Some good advice here, any of the above could cause a lack of fuel problem.
With the gas turned on at the tank, remove the pipe plug at the bottome of the fuel bowl on the carb, have a catch can ready, a lot of fuel will come out at first until it has drained the bowl on the carb, give it a minute or two, and then see how much fuel is coming out of it, if the fuel line, sediment bowl , float & needle and tank are in good working order fuel should continue to come out faster than the plug hole can keep up, shut the fuel off at the sediment bowl on the tank, & fuel should continue to run out of the carb bowl for 10 seconds or so. If not, you have to isolate the flow problem, start at the tank, drain it, and check the tank for trash, rust or any obstruction where the sediment bowl screws in, check the sediment bowl while you have it off for any obstructions, re-install the sediment bowl, set a coffe can under it, fill the tank enough to cover the sediment bowl stand pipe and turn the fuel on, turn it back off, re-install the sediment glass bowl & replace the screen, leave the glass loose, turn the fuel on, & it should fill up quickly, turn it back off, install the fuel line, leave the carb end off, turn the gas on, fuel should flow freely at the carb end, coffe can should be about full by now, the only thing left is the needle & seat.
Remove the carb bowl to check the needle & seat on the float, you may have trash in the seat or possibly a needle with a rubber tip, check to see if your needle is completely metal with no rubber tip, the rubber ones are notorius for sticking. Check the pin that the float actually hinges on, make sure it operates freely, with hardly no side play, and no binding or sticking thorugh it's amount of travel.
Attach the fuel line to the carb. Now have your wife turn the gas on the sediment bowl, fuel should flow freely through the needle & seat, now that we are sure the gravity part of the system is functional, re-install the carb bowl with a new gasket.
Loosen the packing nut ( 7/16 wrench) one turn on the main jet needle valve, turn the spring & screw counter clockwise until it is in your hand, suirt a shot or two of carb cleaner into the jet hole, squirt the main jet needle & spring you have in your hand & wipe with a rag, DO NOT use any abasive to clean the tip, only carb cleaner & a rag. Have you wife turn the gas on again and in a minute or two gas will come out of the main jet hole have her turn it back off, re-install the needle & spring into the carb, turn it by hand until it bottoms out, DO NOT overtighten just until it quits turning clockwise, back it out 3 and 1/2 turns, tighten your packing nut snug not tight. When plowing for instance that same needle should be out 4 to 5 turns, this controls the fuel mixture under load.
Another one that I learned the hard way, is remove the fuel line where it attaches to the carb, and remove the fine screen, replace it with a new one, it hardly takes anything to slow the flow of fuel through it. To test to see if that is one of the problem you can remove it & then test run your engine to see if that's the problem.