1945 Farmall H spitting and sputtering

I would like some help trying to figure out why my Farmall H is spitting and sputtering. So far this year, it's gotten an electrical tune up but I didn't change the condenser. I just installed a new carburetor and filled it with fresh gas. It runs fine for a minute or two before it starts acting up. It runs so bad, I need to keep one hand on the chock to keep it running. The only thing I haven't tried yet is double checking the timing. Any suggestions are greatly appreciated.

Not enough flow from the gas tank.

When I changed the carburetor, I drained the gas tank through the fuel line coming off the filter before I added fresh gas. According to where I got the parts from, the high and low idle screws were preset.

Go shopping for the best made in USA condenser you can find. A NOS IH would be best. Wise old mechanic told me decades ago, "If it acts like ignition problem, it's probably a carb problem, if it acts like a carb problem, it's probably an ignition problem."

Do some simple trouble shooting.
#1 Check that you have a good blue/white spark that will jump a 1/4 inch gap or more a all 4 plug wires and the center wire of the distributor cap. If you have that go to #2
#2 pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in under 3 minutes and yes catch the gas to look for water/dirt etc.

By the way point need to be set at 0.020 and check that it is correct at all 4 lobe of the distributor.
Also when was the last time you serviced the air cleaner and dumped the water and mud out of it

This sounds like a silly question but is the bottom screw the low idle screw?

I may have it figured out well almost. Here's a picture of the carburetor. With the tractor running, I turned the top screw in and it smoothed at high idle. I adjusted the bottom screw at low idle and it's still running rough.

Try checking your manifold for leaks. Both gaskets and possible hole rusted through.

Here's the picture.

Choking sounds like a fuel issue, pull the drain plug on the carburetor and see it it will fill a quart can.

Having to choke it to keep it running is usually a sign of too lean. Could be a vacuum leak, lack of fuel to the carb, float set too low, or clogged carb.

Before blaming the carb, be sure everything else is right. Check the distributor shaft bushing for side play in the shaft. That needs to be very tight or the points won't stay set. Also be sure the centrifugal advance is working. Be sure you have good spark at the plugs, not just at the coil.

Have the valves been adjusted lately? While there, look for broken valve springs, bent pushrods, flat cam, worn rocker assembly.

Back to the carb...

There is a drain plug or valve at the bottom of the bowl. With the engine off, fuel valve open, open the carb drain fully and catch the flow in a clean glass. The flow should start full, then slow as the bowl empties, and continue to trickle. If it slows to a drip, or stops, there is a restriction in the fuel delivery. If there has been an inline filter installed, or the fuel line is kinked, routed wrong, it could be restrictive. Also be sure the screen in the sediment bowl is clean, the valve is not restricted, and the cap is vented.

Look at what was caught in the glass. If there are rust flakes, dirt, or water in the glass, that will also be in the carb. Even though the carb is new, it can still be contaminated. They are simple to open and clean, don't be afraid of it.

Once you establish there is sufficient fuel to the carb, then it can be adjusted. The top screw is the idle mixture screw. With the engine up to operating temperature, choke fully open, air cleaner serviced and connected (be sure the wire mesh above the oil reservoir is also clean, often overlooked), engine running at idle speed, turn the top screw until you get the best idle. Some turn in to lean the mix, some turn out. Just play with it until you get to right, slightly rich is better.

Then adjust the high speed screw, the one on bottom. Turning it in will lean the mix, out will make it richer. To set the high speed, again have the engine fully warm, choke open, air cleaner connected. Set the throttle at full governed speed. Locate the governor linkage, pull the engine down to idle speed, then release the linkage. The engine should go to full throttle as it comes up to speed. Listen to the engine, watch the exhaust. If the engine hesitates and balks, open the main jet (bottom screw) about 1/4 turn, repeat the test. Keep enriching the mix until there is no hesitation. A single puff of black exhaust smoke is ideal. Too much black smoke is too rich, turn the screw back in slightly.

Of course everything works together, if there are other problems, low compression, valve problems, ignition problems, etc., the carb won't adjust. Look everything over carefully!

Thank you everyone for the information. I completed what you suggested and the tractor is running better now.