How much for the carb float to drop ?

New to me Farmall BN. Had a few instances of gas leaking out the drain hole in
the air intake passage. Got a carb kit and replaced the float valve needle, and gaskets.
Checked float setting before assembly, and fuel level after carb reinstalled.

Still have an occasional instance of gas running out the drain hole. Rapping on the carb bowl
stops it. My ASSUMPTION is that the float is dropping too far and hanging up somewhere.

My "plan" is to adjust the float so it does not drop so far. How far? Seems like just a little would
let enough gas into the carb for this engine.

Comments and advice welcome ...........

There is a specification for float drop. It should be in the carb kit instructions. However, the float drops only when more fuel is needed. If gas is dripping while the tractor is not running, the float LEVEL is suspect, or, that new needle and seat are not doing their job.

Take a little piece of fuel hose and get a barb fitting to gently secrew into the carb. When you take the carb apart blow through that hose with your breath. Now turn the carb over and see if you can blow through the hose. That float should be dead level to the body of the carb. Tickle it a couple of times and see how it is working. Do NOT adjust the float by just pushing on it!!!!! Any float must be adjusted with a tiny pair of pliers because pushing will permanently damage the float valve. The valves with the little rubber tip, just go buy another kit. Gas can get through any microscopic itty bitty path. See what anyone else wants to add.

Sometimes it is normal for gas to run out the drain hole. As in when you release the starter button after 10 seconds of cranking with it choked without it starting

how far? if you don't have the spec. then turn float half upside down and set it level with it sitting on the needle. that's "float level". and the float is be "level" in the carb. if it still leaks you have other problems. you don't set a float up or down.

Some carbs do have a float drop setting.

If there is a secondary tab on the back side of the float that limits the float drop, that is where it is adjusted.

It is not a critical adjustment.

Two things to look for, if there is a bail across the needle that pulls the needle off the seat, the drop needs to be sufficient for that to happen, The purpose of the bail is to pull the needle off the seat in case it gets stuck when it's been stored.

The other purpose for limiting the drop is so the needle can't fall out or drop so far that it gets cocked sideways in the seat pilot hole. If the float were dropping far enough to jamb the needle or float, it would be severely flooding, dumping a large quantity of fuel, not a slight drip.

Setting the drop too high could result in reduced flow, resulting in a lean condition under high power demand if the fuel could not refill the bowl quickly enough.

Some things to consider:

The carb may not actually be flooding. A few drops of fuel following a failed start is normal. It may even drip after a shut down as the unburned fuel drains back down out of the intake.

You can check the actual working float level with a short piece of clear vinyl hose. Replace the carb drain plug with a barb fitting, slip the hose on the fitting, raise the open end above the carb, open the fuel valve. The level inside the hose will be the same as what's in the bowl.

Minor flooding, a slight drip when parked with the fuel valve open, is most commonly caused by trash under the needle valve. It only takes a tiny speck to hold the needle off the seat. Be sure the fuel supply is clean, the sediment bowl is clean, and the screen is in place. I don't like inline filters on a gravity flow system, too restrictive.

If the tank is contaminated or shedding rust flakes, you will continue to have fuel issues.

Once the fuel supply is clean, sometimes the needle valve can be flushed by turning the fuel off, removing the bowl drain plug, or running the engine until the bowl is empty, then open the fuel valve to see if the inrushing fuel will flush out any trash.

Another source of contamination is from getting dirt or grease in the end of the fuel line while making the final connection. I like to open the fuel valve, let the line flush, then let it flow while starting the connection. Remember, it only takes a tiny amount to fowl the needle/seat seal.

Other causes are, a loose seat or missing gasket, a damaged needle or seat sealing surface, the wrong needle, (too short to seat before the float tab hits the seat housing), the float level set too high, a partially sunk float, one pontoon leaking and partially filled with gas (give it the shake test), a bent float hitting the side of the bowl.

A good farmer fix way to test the sealing ability of the needle valve, before assembling the bowl to the top, turn the top upside down, letting the float rest on the needle valve. Suck on the fuel inlet fitting, put your tongue over the hole. It should hold vacuum. If it won't hold vacuum, it won't seal gas, something is leaking somewhere.