Leaky Carb

rosenkranswa

rosenkranswa

Senior Member
Just cleaned two carburetors. One went back on fine and is working beautifully, the other now has a bad gas leak both with the engine running and not. Leaking from underneath and from the intake port. Checked all the connections for tightness.

Guessing that the float valve is stuck fully open either because of dirt or possibly a sunk float. Would it continue to leak from the intake with the engine running though, even with a stuck float valve?
 
Sure it can. There is a lot more fuel coming into the bowl than your engine can use. Check the gaskets under the jets. I bet one is missing.
 
Didn't remove the jets to clean, just blew carb cleaner through everything so all gaskets on the jets should still be there.

Just pulled at apart again and blew some cleaner around the float valve and float, checked for obvious crud, and put an a fresh gasket. No joy I'm afraid still leaking badly.
 
Sounds like needle and seat or float is sticking .
It's overtopping the cap and main jets which is why it's coming out the throat

Check float action and needle and seat
Hopefully easily resolved
Larry
 
rosenkranswa said:
Didn't remove the jets to clean, just blew carb cleaner through everything so all gaskets on the jets should still be there.

Just pulled at apart again and blew some cleaner around the float valve and float, checked for obvious crud, and put an a fresh gasket. No joy I'm afraid still leaking badly.
Click to expand...

Mine was doing same thing and I took apart and checked the float, then I added another washer to the float valve and it stopped.
 
Hello Wayne: Boy can I relate to your leaky carb problem. Took my carb off -and on - three times each time blowing out, using carb cleaner, setting the float height, taking out the float valve each time and throughly cleaning, cleaning the filters, and the carb still leaks. Maybe I'm stubborn but I still think the problem is with the float valve. So I ordered the "modern" valve from Bratton's, the one with the Viton tip and will install that in another day or two, then see what happens.

Or I just may get to meet you at Mikes in Aston for a carb party, which is always a good thing anyway.
 
The latest - Took carb off and on several times; 1st time to repeat all cleaning steps, still leaking badly; 2nd time took float valve out (newer ball bearing type) examined with a magnifier but couldn't see anything so thoroughly cleaned and reassembled, still leaking badly; 3rd time (after seeing Mike at Hershey) put another gasket under the float valve, took a lot longer but did finally start to leak. Started the engine and the leak stopped, adjusted the GAV, idle RPM and idle mixture to spec. and everything is running beautifully. Turned the gas off and let it die, will check again tomorrow.

So the extra gasket did something, but not a complete cure. All the cleaning certainly had a major effect on the poor running I was seeing though. Like Merrbarb, starting to wonder if a new float valve of the original design (viton tipped) might be indicated.
 
Also might do a test on the float. Could be the float starting to loose buoyancy. The contact point between the float valve and float can also create a wear point on the float that can cause the float valve to stick.
Bob
 
Checked the float when I had it off and it seemed OK, that is to say floated fine in a jar of gasoline overnight. Also checked the height which checks at 5/8. Its just about got to be something slightly off with the float valve. At least its driving very well again, and I usually turn the gas off when I stop anyway.
 
To check a float; bring a pan of water just up to before the boiling point. Submerge the float and look for bubbles escaping from it. Just floating in a jar of gas isn't going to tell you if it leaks.
The extra gasket moves the gas level in the bowl down. You are setting the gas level for the jet at or just below the tip where the surface tension will keep it from weeping over and out the jet.
 
Found this in my notes from past fordbarn threads:
to avoid weeping when engine is stopped:
the top of the main jet should be 3/64" - 1/8" above the top of the cap jet.
look for improper length: main jet (#20) 1 15/32" from tip to head(gasket face),
cap jet (#21) 1 5/32" from tip to gasket face.
Also look in the casting to remove any extra gaskets lurking.
Bob
 
rosenkranswa said:
The latest - Took carb off and on several times; 1st time to repeat all cleaning steps, still leaking badly; 2nd time took float valve out (newer ball bearing type) Like Merrbarb, starting to wonder if a new float valve of the original design (viton tipped) might be indicated.
Click to expand...


The original is a ball bearing style, and the viton is newer style invented in the late 50s I believe. There is another newer style with two balls and a o ring seat.
Guess I'm lucky as the original ball style works great for me.
If you haven't checked yet, look at where the float rubs on the valve. Wear will cause a hang up.
 
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