Turn the knob off fully, remove the bowl & carefully check the groove in the top of the assembly for dirt/crud/old gasket material. Most leaks on a new gasket are caused by:
1. An incorrectly seated gasket.
2. An incorrectly seated screen.
3. A screen just slightly too big . (get out the scissors)
4. Using gasket sealer
5. Incorrect assembly of the screen/gasket
Don't forget to check the bowl rim for chips; if it's chipped, you will never get it to stop leaking. Clean or replace the screen. You can get both the cork gasket & the screen from TSC; p/n 0237144. A cork gasket will work if you soak it first in gas, but I like rubber. Check out tip # 10 at the link below for the correct NAPA part number. However, the newer ones aren't as thick as the old ones and the price is now $4 each. I've got the new ones to work, but it takes a few tries. And, at $4 for a thinner gasket, I'm not planning on using the NAPA gaskets anymore.
Pay careful attention to what JMOR said: see the groove in the lip? That's for the screen. Put it in there & make sure it does not extend over the lip. If it does, trim it, but not too much or it will fall in the bowl. See the square hole in the screen? That because it needs it fit around the square fuel port in the top of the bowl when you assemble it. The gasket goes on next, on the lip of the bowl. Once you get it assembled on the tractor, hand tighten the thumb screw. (if it make you feel better, turn it about 1/8 turn w/ channel lock; no more, or you will distort the bail) Turn the gas on & look at the bowl.
If it starts to fill the bowl, turn the gas off & start over; it has a leak. You will know it's sealed when gas does not flow into the bowl w/ the engine off. It won't fill with the bowl securely on because the float has closed the needle valve in the carb and there is nowhere for the air in the bowl to escape. (assuming the carb bowl is full) When the engine is started the needle valve will open and the trapped air will escape through the carb vent. If you loosen the bowl, it will fill.....and leak.
Do not open the valve more than 2 or 3 turns. All the way open gets you the 1 gallon reserve & that port is usually clogged.
Tightening the knob may fix the leak there. If not, go to the hardware store, plumbing counter & get some graphite packing thread (not teflon) Pack it like a faucet.
All of the above assumes you have an OEM sediment bowl. If not, I'd get one because a lot of the off-shore replacements never work right & the gaskets are odd-sized.
I've got quite a collection of junk sediment bowls around here that were on the N's when I bought them. Nearly every type of leak on the OEM Ford sediment bowl can be repaired. My guess is the previous owners didn't know how or , as is way to often the case with these old tractors., "fixed it" by buying a piece of off-shore junk. It all depends on your supplier; I've never got a bad one from nnalert's. The stems can be replaced. (on an oem style bowl) . But, cross-threading a steel fuel fitting into an aluminum sediment bowl is fatal. Always, always finger-tighten the lines at both the carb and sediment bowl. And then use a flare or line wrench to tighten the fittings. ( see tip # 56). Bottom line: buy parts from reputable dealers & pay attention to what you are doing.
If you get the bowl to seat on a used cork gasket, go buy a Lottery ticket because it's your lucky day. Usually, but not always, you can re-use a rubber gasket.
75 Tips
