Farmall 300 carb

Still fighting this dang carb. I can get it running great at high idle but smokes at low idle or almost clean at low idle and dies at acceleration. I rebuilt the carb with a kit from MacDonald carb. I soaked the carb in carb cleaner and all passages are open. It was dripping gas and leaving black dots on the hood at startup before I rebuilt the carb. I adjusted the float to 1-5/16" per the instructions. Is this correct? I did disconnect the air intake to rule out the oil breather. If I leave the gas on it will not flood the carb either. When the tractor is running I could hear what sounded almost like gargling or bubbles.
I am thinking that I need to set the float lower (or larger measurement from the throttle body to the bottom of the float when inverted), that the fuel level may be a bit too high yet. The air going through the idle jet (not the needle valve, the open passage that goes from above the butterfly valve to the load jet) is sucking fuel with it. Currently I have to have the idle needle valve screwed all the way in and the position of the load needle affects the low idle performance.
Does this sound like a plausible situation?

If the low idle adjustment screw needs to be all the way in, that carburetor is NOT clean. You have missed a passage somewhere. Check that tiny, brass idle metering jet. THAT passage needs to be open and clean all the way down into the fuel bowl.

That jet I can see through so it is clean. I can spray carb cleaner through all the passages so I am not sure how else to ensure everything is clean. At low idle is it normal to hear the slurping noise from the intake with the air cleaner unhooked?

Is the float in good condition? No holes? Is the float free to float, and not making contact with the fuel bowl? With the carb off the tractor, you should be able to turn it upside down, and then rightside back up, and HEAR the float moving. If you cannot hear it, then the float is hanging up somewhere.

I learned years ago that just because you can spray carb cleaner in and threw the passageways that is still not good enough. One need to use a small wire or as I do I used a torch tip cleaner tool to poke out all the passageways.
Also as Rusty say is the float good. No dents not rattling if you have it out and shake it. Also as he says can you hear the float move when you turn the carb upside down then right side up

With the float off the carb I can shake it with no noise (so the inside of the float is not filling with gas). I could hear the float moving when I turned the carb over. I will try running a tip cleaner down the passages also. Is the slurping noise normal though? My thinking is the idle air is drawn from the load tube ( the one with three holes in it). Is that correct?

Getting to much fuel at idle. If a 361525R92 gasoline carburetor it shuts idle fuel off with idle screw turned all in. If idle speed is set slow the engine should die like that. May be pulling fuel from higher speed side at idle for some reason. Never know if any parts are switched by now. If a different carburetor number what is it?

D Slater, I believe it is that one. I will double check when I get home, but it is the style that controls the fuel not the air with the idle screw.

(quoted from post at 10:52:40 03/15/18) I learned years ago that just because you can spray carb cleaner in and threw the passageways that is still not good enough. One need to use a small wire or as I do I used a torch tip cleaner tool to poke out all the passageways.
Also as Rusty say is the float good. No dents not rattling if you have it out and shake it. Also as he says can you hear the float move when you turn the carb upside down then right side up

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EXACTLY!! Especially that tiny idle metering port.

This is the tag on the carb.

OK, sorry for bugging you all so much on this. Above the butterfly there is two holes. One has the tip of the idle needle sticking through it and the other is right at where the butterfly valve would close on (actually just slightly above the contact spot). Both of them seem connected together and lead down to the idle jet. I am assuming the open one gives a little less than the minimum needed of fuel and the needle makes up the rest. Is this correct? So the only air drawn during idle is the little bit that is leaked around the valve? I checked all passages and they are clean.

I switched the idle needle back to the old one with no change. Getting tired of taking this carb on and off. I did check the passages with a tip cleaner and all were good. I have to be missing something but I can't find a good layout how these carbs are supposed to run to see if a plug got discarded over the years or what.

Run that tip cleaner down through the idle metering jet until you can see it come out throgh a slot down in the fuel bowl. YES, it will go through.

OK, I assume you took out or maybe even replaced the idle jet that screws into lower bowl . It is the jet about half inch long with screwdriver slot . The hole in that jet is extremely small and you would have to be extremely careful of not oversizing it if probing it with a nozzle cleaning tool. It should measure right about .025 hole or number 72 wire gauge drill bit.

If the engine smokes black at idle and you have to control smoke with main jet, you clearly are over fueling at idle. All fuel and air for idle comes through that jet and then through those small ports you described , PLUS, the amount the butterfly is opened with the idle speed adjusting screw.

When you limit the fuel with main adjusting screw it will surely stumble and even die when trying to speed up the engine.

If you idle circuit checks out good, idle jet not over sized, you should look for fuel being delivered through the main metering nozzle that extends up inside the venturi. Nothing should come through main metering nozzle at low idle speed. Requires a sharp eye, mirror and light to actually see any fuel being delivered through that nozzle when running. Can be done though.

Adjust your main load adjusting screw with engine running full throttle. Screw it in until it slows engine, or sputters and then turn out until smooths out and then give it another half turn. If it smokes a little black at that setting, your main jet is over sized and will require screwing it back in to clear it up. If it has proper jet, you can screw it out until the cows come home and it will not take on excess fuel. One never knows what has happened to that jet over the years as it almost never gets replaced but does get drilled out.

I will run the tip cleaner down to the bowl. I also ordered a new idle metering jet to rule out and oversized one or one bored out. I stuck a borescope camera when the engine was running and could not see any fuel coming out the main nozzle.

I also ordered a new float to rule that out. If all else fails I guess I will have to admit defeat and bring it to someone to have them check it out. I will update this thread on the result.

Thanks everyone for your time and knowledge.

Have some questions, Can't make out the carb ID tag ending. R91 or a R92 suffix? Is the air bleed passage open into the discharge nozzle bore? In throat of carburetor at lower hole, does the throttle plate close off most of hole at idle speed setting? Gasket have a good seal between halves?

The tag ends in RS. Makes no sense to me. There is nothing after the s, I double-checked. Yes, the idle air port comes out in the threads of the load nozzle port. And I will check to make sure the plate covers the hole. I think it wouldn't cover it though.

I will triple check it tonight and remove all the paint.

R91 throttle body is the one with yellow marks, R92 is the other. Could be a problem if a 91 and mixed parts.

(quoted from post at 00:45:23 03/20/18) R91 throttle body is the one with yellow marks, R92 is the other. Could be a problem if a 91 and mixed parts.

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It is a R92. I kept scrubbing with carb cleaner and finally could make sense of the markings.

I also had the butterfly valve upside down. When I put the stamped markings up the valve was able to completely cover the hole without the needle.

I got the tractor to purr like a kitten at 300 RPM and bumped it up to 450 RPM where it is supposed to be.

Then all heck broke loose. I gave it a little fuel and it stumbled and died. Then fuel dripped out the bottom. The dripping quit but I was never able to get it to even run on all 4 cylinders. I didn't get a chance to pull the plugs to make sure I didn't screw something up with all the backfiring and stumbling.

I am thinking the float is over filling the bowl. I checked all passages and the air bypass (the un-jetted passage from the throttle body to the bowl) is the one that comes out in the threads of the main jet. It then comes out behind the ventri where it can then re-join the idle fuel. I ran a tip cleaner through everything and watched the tip come out the other ends.

Who would think a simple carb rebuild could cause so many headaches? It always ran rich so who knows when the original problem began.

Ok, so I replaced the float and the idle jet. Started the tractor and it only ran on the #4 cylinder (it was the only one with a bit of warmth). I removed the plugs again and did a compression test. All 145-155 (pretty good I must say for a tractor that hasn't been overhauled since before 1984). I put new plugs and no go. I checked the spark and I was getting some extra flashes when I was on the #2 plug. So I decided to replace the cap. While doing this I notice the connections are not in the greatest shape. Called it a night and will hopefully get to replace the cap and wires tomorrow and update you all.

Replaced the cap and wires and all is good. So it needed a new float, cap, and wires along with the general carb rebuild.

Thanks everyone for your help and time.

(quoted from post at 20:12:44 03/24/18) Replaced the cap and wires and all is good. So it needed a new float, cap, and wires along with the general carb rebuild.

Thanks everyone for your help and time.

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Fuel problems and electrical ignition problems will quite often imitate each other.