Farmall H running strangely

I have been tinkering on this H for some time now, convinced I have a carb. issue, but now not sure. Seems to start and run good at first, then begins to falter. It runs quite well under load. It will not idle well, it pops and flutters. At any speed with no load it acts the same. I have replaced plugs, points, dist. cap, rotor, condenser, wires. I have tried changing timing. I have rebuilt carb. involving submersion in a great cleaning solution that eats away everything, and have done this to two separate carbs. Both seem to run the same, but today I noticed with one it seems to be freezing on throttle body. This seems to coincide with when it starts to run poorly. It does help having choke closed a bit, indicating lean mixture. I put yet another carb. on today from another H that has not been run in a long time, it looked hideous, but it ran a bit better with this one, although not right yet. I tried spraying around manifold with wd-40 to see if I got any reaction, thinking maybe a manifold leak, but no changed noticed. Anyone have any ideas?
I also noticed today that the H I took last carb from had a completely different manifold. It was wider it base where carb fits.The H and W-4 I had been interchanging carbs from seem to have the same manifolds. Anyone know why a change?
This tractor does run well under load, but I really would like it to run well not under load, and at idle. Any help would be great! Thanks. John

First off go ahead and just tighten the manifold and see what happens. Second, lok at the wide part of the manifold that lets heat surround the intake side. Find what looks like a tiny hole and make sure it isn't plugged up with rust. A bit of baling wire works geat to poke around in there with. The frost is from the fuel vaporizing at the venturi and when liquids evaporate they loose heat hence the freezing. the little hole does 2 things. It give a place for water to drain out should any get in the exhaust pipe and second it lets some exhaust heat flow down and wrap around the intake heating the mixture up so it vaporises properly. Do one of those things at a time and let us know what works.

For starters:
Air leak.
Clogged fuel line
Bad coil or condenser.
mike

Never heard of this hole, never would have thought to look for it. This tractor has sat around a lot. This makes sense. I will investigate further thanks, John

sounds like my m but i have electronic ignition and a new matching pertronix coil.When you figure it out let us know.Mine idles like it has a huge cam in it and when you gas it it responds great,it just idles rough.I have not sprayed anything on the intake yet but i will soon.

Never overlook the distibutor itself, worn bushing, and or worn or incorrect advance. Worn or loose reduction drive gear on distributor. Ideally the spark should occur near tdc at low idle and advance gradually as you speed engine and be fully advanced at rated engine speed of 1450 rpm. Total degree of advance will depend on head, pistons etc it is equipped with, like 22 degrees with fire crater or 30 degrees with flat head aluminum thin wall sleeves and or as much as 40 degrees if it has original size bore. All gas heads figured. Also the spark should not flutter back and forth more than a couple degrees when watching it with a timing light. Excessive camshaft end play can also make spark jump around along with worn gears etc. Some of these old h's still have distillate or kerosene heads on them and comp ratios are so low they run rough on modern fuels.

Just wanted to let you know, I found manifold bolts loose. I also really cleaned carb and now it runs quite well. Thanks for the assistance. John

I found manifold bolts loose.

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I can just see Bob Kerr looking at me with that "Told you so" look on his face. :lol: