1950 Farmall Cub

Have a 1950 Farmall Cub with Carb flooding problems.
Have worked on old carb with no luck.
Fuel runs right thru the needle and seat. Replaced the needle and seat. Fuel runs right thru the needle and seat. Ordered a NEW replacement carb and it has same problem.
With only 2 gallons of gas in tank, fuel overrides the needle and seat even on the new carb. A friend who has run into the same problem says I need to find a solid needle and seat with no neoprene tip.
All carb kits I can find have neoprene tip on the needle
Anyone have any other ideas as to this problem?
Thanks for any tips.
James

Resetting the float height on a new carb seems to be required these days. Maybe they get bent in shipping. Check it.

Float height is also critical but another consideration needs to be addressed. The Cub carburetor is quite small and there is very little clearance between the float and the side of the bowl. They are prone to touch the side of the bowl. Also you may want to check to assure that the gasket between the bowl and body does not cover a vent.

I adjusted it several times. I can set the float tight enough to completely shut off the fuel. If I let the float set where the needle can open any at all then fuel just runs right thru.
Brass float on new carb or old carb has no problems going up and down. With top off carb holding needle closed with float assy works. I can blow on fuel line with no leak in pressure.
As soon as I put top back on carb and open gas valve fuel then runs right thru. I either have full flooding or no fuel at all.
James

Same thing happened on a carb for our John Deere D. The bowl vent was plugged.

Those rubber tipped needles need to have a set put in them to seal off like they should. They will set on there oven over time but work better if you put a set in them when you install them. To put a set In the tip one takes the needle and has it In the seat and then taps on the needle with something. Then you pull the needle out and look at the rubber tip. You should see a ring set In the rubber tip that is what is called a set

One of the most common causes of flooding is trash in the fuel stream getting under the needle/seat. It only takes a microscopic trace to hold it open.

Take a fuel sample from the line in a clean jar, see what you catch. I'm not a fan of inline filters on gravity systems, be sure the sediment bowl screen is in place. Another solution is a short stand pipe inside the tank to keep from drawing fuel off the bottom. But the best solution is a clean, rust free tank.

Back to the carb, I like to do the "suck test" before final assembly. Set the float level, hold the upper assembly upside down, suck on the fitting, hold your tongue over the end of the fitting, see if it will hold vacuum. If it won't, it is leaking somewhere. Be sure the seat is tightening down on the gasket. Look at the needle and seat with a magnifying glass. Any imperfection, nick, cut will cause it to not seat. If the seat is damaged, a Qtip in a drill with valve lapping compound will polish it up. Be sure the float tang is pushing straight down on the needle and not resting on the rim of the seat.

As others said, be sure the float doesn't touch the sides of the bowl.

When I do the final connection of the fuel line, I'll turn on the fuel first to flush the line, then connect it while it's running fuel. That way no trash can get in. Especially if the area is dirty around the connection and difficult to get to.

i had the problem on one of my cubs, [ i got rid of all them, for what i was doing with them, i was just asking too much from the tractor] but there are several things that can cause that . first you didn't mention when the gas runs thru, is is while its running or when the engine is shut off, gravity feed tractors when off must have the fuel turned off at the sediment bowl or shut off valve if its made that way on all my cubs, fords and allis Chalmers which were 7 tractors, only one could be trusted not to leak fuel......so far. next cubs float level is very touchy, the adjustment must be followed exactly, if you go much less, the engine will run out of gas if your asking a lot of the tractor, ie; mowing plowing ect, if its too much the engine will flood, also the needle and seat as mentioned must have a set put in it, i put the needle in the seat with the float out and just LIGHTLY tap it a couple times with a LIGHT hammer, dont over do it , it seems to help. also make sure your sediment bowl is actualy turning the fuel flow completely off, many new ones today wont and need to be worked on until they do, all but one of me cubs were using tractors, i mowed and plowed gardens with them, all of them had extensive work done to them in order to make them basically a new tractor so they could be reliable, some of the jobs i did were 60 miles away, not the place for a touchy tractor, but the last one you had to turn the fuel off anytime the engine was shut down, i had put on numerous carbs, and sediment bowls on the thing and it never changed, i still have a carb in a box on my truck lol

Thanks everyone for suggestions.
I have butted heads with this enough for now.
I will start over Wednesday.
Hope everyone has a Merry Christmas.
James

I had a wd allis doing that. After several times ,found the bowl gasket was missing the bowl vent hole.

In addition to the suggestions below, I installed an in-line shut off valve so that you don't have to mess with that valve on the sediment bowl. It's a plastic ball valve. They
sell them at most auto parts stores. Carb on my Cub leaks as well.

Take the bowl off carb and use a clear container to act like a
bowl. Turn the gas on and you will be able to see your problem.
I had a problematic carb. The needle wasn't the problem. It was
leaking where the valve seat seat screwed into the carb. I had
to sand the rust and pits off carb so seat would make a tight
fit.

Several years ago I had a few Cubs, one kept leaking from the carb. Someone on this website had posted a Briggs and Stratton part number for a needle and seat that would fit and it stopped leaking. Sadly I have forgotten that part number :-( Maybe someone here remembers what it was.

http://www.external_link/new/fl/5183fp.htm tm tractor parts sells the all steel needlesand seats