Carburetor problem or not?

Apologize for the length of this post from the get go.
First some background. 1953 MM BF my dad purchased a few years ago apparently from someone flipping "restored" tractors. When he got it would run okay 10 15 minutes then die sit a few hours same thing again. Long story short time constraints, sickness he never got around to working on it. Since he passed thought I would tackle it as I have been through a few other tractors he had getting them running. Tank had been lined but did not hold. Removed tank, carburetor, tore carb apart it had been reworked not in bad shape but dirty, rusty nothing too bad compared to other tractor carbs. Put an auxiliary tank to reinstalled carb cleaned points started right up but had a miss did not drive as aux tank was stationary.. Checked compression, new plugs, ran fairly good but had some blow by, smoke out oil filler tube. Cleaned tank extensively reinstalled. Started but still a miss. Replaced coil, wires, points, condenser, idles real smooth when first start. Give her a little throttle starts missing almost like a lope or surge. Load her a little smooths out. Took carb apart again in case something from tank had got in. Fairly clean reinstalled. Not knowing what had been done previously but assuming timing okay as it ran okay for 10 15 minutes just thinking that tank lining failure may been cutting of fuel supply causing original issue my dad had with it. At present time I think she is flooding out. I can give a little throttle drive her in 3rd gear running fairly smooth, if I shift to 2nd or changing throttle she starts sputtering and jerking. Throttle down a tad smooths out eventually. I think if load matches throttle runs fair. I put a 6ft flail mower on her mowed in 2nd gear did okay as long as all things remained constant. The carb does not have a high speed adjustment. The air mixture screw makes a tab bit of difference at higher rpm but not much. At idle it will smooth her out. I am thinking it is getting too much fuel if she is running half decent and give her a good amount of throttle at once black smoke. Pulled plugs black and sooty. She starts real easy has been converted to 12 volt. Am I barking up the wrong tree? Could it have the wrong high speed jet in carb? How do you determine that? Can a smaller jet be installed and drilled out to match the engine? She has the Hercules IXB3 engine M&S carb not sure the number need to clean the paint off tag. I would check timing but do not have a light may need to call in some help. I have double checked firing order and wires. Moved wires on distributor one space made everything worse. Thoughts and suggestions appreciated.
 
I did not reset the float it appeared to be new best I remember it was set about 1/4". Something I can check again. Thsnks.
 
I am trying to figure the same thing out on an Avery R, which is pretty much the same tractor/engine but different hydraulics.

Which carburetor is on it? I am thinking a Marvel Schebler TSX400 is the correct carb. Mine got pretty gunked up and had a J-B weld
repair around the inlet needle seat. I know the TSX400 can work: There is one on Mother's BG with the same IXB3 engine.

So far I have had a TSX33 on it (Ford Carburetor, don't know which model: I installed the throttle plate and shaft from the TSX400 so it
would work with the Hercules governor link) and also a TSX455, which I bought off Ebay after determining that it did fit that engine in a
power unit configuration.

Mine did not have any governor response. One thing I discovered today is that the link from the carburetor to the governor arm is way too
short. It was the one that came with the tractor. (I don't know if it was from the different carburetor or from a worn governor, although
everything inside the governor looked pretty good when I took it apart to look at the flyweight assembly.) I made a new link from a piece
of 5/16 rod, measuring with both the governor arm and the throttle shaft at wide open throttle. The governor is working now, but like you
describe there is still a pronounced surge.

All my I/T manual says is to set the distribuitor static timing at TDC. One thing I have noticed on mine is that the timing is varying a
lot. The TDC mark can be seen throught the pipe plug hole in the bell housing just to the rear of the carburetor. When I do have my
advance timing light adjusted close enough to find the mark, the mark is actually jumping all over the place. I don't know if that is due
to the timing light itself or worn bearings in the distribuitor. When I quit the timing dial on my light was reading about 20 degrees. But
it still has a surge.

If you figure something out on your tractor, please post back here what you did. Thanks!
 
A couple things to check:

How is the air cleaner? Most have a wire mesh inside the canister that needs to be removed and cleaned periodically, often over looked. Try a test run with the tube disconnected, see if there is a difference.

Check for vacuum leaks. Spray some flammable type carb cleaner, or use an oil squirt can with some gas. Carefully spray around the gasket areas with the engine idling. Listen for changes in engine speed, sound. Another thing that occasionally shows up, an internally burned through siamese manifold. This is where the exhaust and intake manifolds are cast or bolted together in such a way they can burn through internally and cause exhaust to enter the intake. About the only way to do a for sure diagnosis is to remove the manifold and fill it with water, look for it to transfer from one to the other. (This only applies if your manifold is so designed.)

Have you set the valve clearance? If not, take a look at the entire valve train, look for broken valve springs, bent pushrods, etc. Remote possibility there is a loose valve seat, but let's not go there yet.

Is the thermostat in and working? A 180 or 195 thermostat will help keep the engine cleaner, make it run cleaner, last longer, get better economy.

How is the distributor? Is the shaft bushing/bearing tight? Any side play will let the point gap change at random, do strange things.

If there is any doubt about the points, replace them. Also try a different (preferably an old) condenser. Points and condensers have a terrible reputation now, the quality is just not there. All ignition components are aftermarket. Look closely at everything, compare it with the original, assume nothing!

Is the centrifugal advance free and the springs in place? The timing can be generally set by ear. As long as it isn't kicking back against the starter, clattering under load, backfiring, or loss of power, it is probably close enough, just play with it a bit, you'll know when it's right.

When it was converted to 12v, what was done with the coil? Getting the correct coil or coil/resistor combo is critical. Get it wrong, it will have a weak spark, or overheat the coil and points. It can have either a true 12v coil, or a 6v coil and a resistor.

The best way to know is to check the resistance across the primary coil terminals out of circuit. A 12v coil will have about 3 ohms resistance.

A 6v coil will have about 1 1/2 ohms. A 6v (1 1/2) + a ballast resistor (1 1/2) = 3 ohms. Check the resistance across the - primary terminal to the ign side of the resistor.

Best to test the coil, not rely on what was bought or what the can says. A proper coil will make at least a 3/4" spark at the coil tower, and will run at about the same temperature as the surrounding engine components.

The fuel system:

If the tank is flaking rust or the liner is coming loose, something will have to be done eventually. If a new aftermarket is unavailable, there are universal tanks on Ebay, other solutions.

An easy test for fuel delivery, and this (as is any other test) is best done when it is acting up, with the engine off and the fuel valve open, pull the drain plug in the carb bowl. Be ready to catch the flow in a clean glass. It should have a full flow, not slow to a drip or stop flowing.

Look at what is caught, if it's dirty there is still contamination in the tank. If there is a loose liner, it will continue to produce trash.

If the flow is insufficient, could be a clogged screen inside the tank, in the sediment bowl, or the screen in the carb inlet fitting (if equipped). If there is an inline filter, that can be a problem. They don't work well with gravity systems. If there is a fuel pump, check it's performance.

Jetting the carb:

Adjusting the carb is the last thing on the list to do. Everything else MUST be right, or it's an exercise in futility. Be sure the float level is to spec, the engine oil is clean and not contaminated with gas.

Start with the engine warmed up, air cleaner connected and serviced, clean gas, as said, everything adjusted and in spec.

Adjust the idle mixture first. The engine must be idled down to the 400-500 RPM range. Any faster and it will be off the idle circuit.

Turning the idle mix screw in richens the mix, out leans it. The screw adjusts air bleed, not fuel flow. Turn it out until the engine falters, back in to best idle. The adjustment is minimal, but it should make a difference. If it doesn't, the circuit is clogged or the idle speed it too high.

That the main is not adjustable, not much can be done short of changing the jet or converting it to an adjustable jet. To test the mixture, with the engine at slow idle, fully and suddenly open the throttle. The engine should respond crisply, without hesitation. A single puff of black smoke is desirable. But only a puff, it should not continue to smoke once up to speed. This only applies to black smoke. Blue smoke is oil, another story.

If it continues to black smoke, the area around the tail pipe is black soot, then it may need a smaller jet.

A lot to digest, but do one thing at a time. That way what was done can be undone if it didn't work out. Let us know how it goes...
 
1/4 inch on float should be correct, Steve has given great advice and instruction on this however the fact that this is a flat head engine with the valves in the block make it more
difficult to diagnose or adjust valve related issues.

I say this so you dont tray and take off a valve cover on the head when there isnt one, your access will be behind a plate on the side of the block.

Good luck with your search and i would probably look into relining the tank for no problems with it in the future if you plan on keeping it.
 
I checked the air cleaner yesterday and cleaned the wire mesh screen. It looked fairly clean and had clean oil. Also started it with the cleaner off, no noticeable change. While bushogging this afternoon with a D14 I thought I would try taking the air tube off at carb to see if I might have a restriction In it. That will be my next step. I have noticed oil pressure drops when engine warms oil does not smell of gas but this has been sitting several years. Plan to change oil next time I have a few spare minutes. Thanks for the input.
 
Yep first flat head I have messed with. Hope I do not have to go that far. Going to do another compression test since I have had it running a good bit since first test. Hope this proves valves are okay.
 
Distributor shaft does not have play side to side. Replaced 6 volt coil and resistor with a 12 volt coil. Have good spark.
 
Just a thought , most main jets are removable , and if you inspect it closely
on the side of it, there is a tiny air bleed hole hole make sure it not clogged ,
 
When you say you moved the plug wires one space
and it still run to me says you have a timing issue.
That tells me the rotor in the cap is pointing nearly
half way between the spark terminals to the plug wire
towers of the distributor cap. I would guess that it is
way advanced. Another thing that might explain why it
runs okay for 10 - 15 minutes may be a sticking
centrifugal advance, but is some how loosening up
when the engine warms up. This allows additional
advance to cause it to run poorly. I’m surprised you
are not getting spark detonation when this happens
but those old tractors have a really low compression
ratio. Just my theory.
 
Thanks for thoughts. When moved wires it made things worse. Backfired did not start. Since I have cleaned tank it has not quit I have ran over 30 minutes. I have good fuel flow through carb. From all the suggestions I plan to check my air mixture at idle, pull plugs, do a compression check again comparing to first test, check top dead center on #1 verify distributor alignment, verify spark is strong. If I am having issues with valves or seats a compression test should show that, correct?
 
You seemed to imply it ran when you swapped the wires. My theory was bad from the start. Thinking about it more an engine simply cannot run with the plug wires that far off. Just way to many degrees between the two terminal locations on the distributor cap, especially in a four cylinder, sorry to mislead you. It is still possible that the advance in the distributor is part of your issue.
 
No worries hard to write out every detail. Advance is something I had not thought of some one else mentioned that too. Plan to kind of start from scratch in case I missed something. The more I think about advance of timing at higher rpm it does make sense. That may be what I have overlooked. May look at that first when I get back to it. Uncharted territory for me I assume just need to go deeper in distributor or do I remove the distributor?
 

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