Hi all, My Holley NH leaks profusely when I turn on the fuel valve out of a hole on the label side of the air intake. It has progressively gotten worse until now it happens constantly and my 1925 motor stalls. It has run fine for 4 months several times a week. The leak would stop on its own or by whacking the label with a piece of wood but now it does not. I took off the bowl, took the pin out. It has the rubber tip on the pin. The bowl had only a small amount of residue in it. I wiped it and put it back in but it still happens. What could be wrong and how can I fix it?
Mine does that too. I have one of those ball type
Needle valves I forget what it is called I am going to put in a regular needle valve. What is happening is raw gas is getting sucked into the engine.
The all metal needle seems to work best. A search using a search engine (google, yahoo) "float needle mtfca.com" should give you some answers.
Seems like i should take the seat out and check it before ordering a new needle and seat?
1 Float set too high. Unlikely if the carb was OK and now isn't.
2 Grose jet.
3 Needle not seating. Most likely. You may need to put it in a drill and turn it against fine emery paper for a smooth tip, then gently tap it in with a small hammer to seat it. Or, there could be a piece of debris caught in the valve.
4. Fuel leaking around the valve seat. Sometimes the bottom of the hole behind the seat gets boogered up so it's not completely flat, and won't seal. Turn a small facing reamer against it, and make a new gasket. The last I heard, the gaskets currently sold for this are too hard and don't seal well.
I had this when I initially installed my Ford marked NH carburetor. I had cleaned out all the various channels and plugged them ... and cleaned up the needle. It leaked ... took it off and readjusted the float ... fixed the leak.
If you haven't got a tank like on a 26 or 27, forget using a Grosse Jet (that ball valve)...you haven't got enough fuel pressure with an under the seat tank to make one work...I tried it on my 22 and the Kingston L-4 leaked like a sieve. I tried it because it worked great in my Model A...again Model A has a gas tank in the cowl like the 26-27 Model T...I think the only way to get one to work in a under the seat tank would be to also have a fuel pump, the gravity feed just doesn't have enough oomph to close the damn thing with an under the seat tank.
Steve, Striking the needle with a hammer won't work with his needle, it is rubber tipped. Now if he gets an all steel needle, then yes.
Ooops! I missed the rubber tip. I replaced mine with an original because it was sticking shut. I believe a pretty good reproduction of the original is now available, but it may need the emery paper treatment for a smooth surface. Stan showed one that was pretty rough, but I don't know if that was one if the current ones.
Make yourself a float measuring gauge and use it to reset the float across from the hinge. Be sure to measure from the machined flange. Good luck. Jim Patrick
Thanks, so I have to take the whole carb off, flip it over and if the float stays parallel to the flange it is more or less good?
Ignacio, I had the exact same problem - sometimes when I turned on the fuel, it would run out of the intake all over the floor, until I whacked the carb with something.
I figured the problem was the float sticking in some way, and not able to rise up and shut the needle valve.
Taking the carb apart (I didn't even take it off), I saw that the float was bent a bit at the hinge, and it could hit the side of the bowl and jam there.
It was a simple fix, once I saw the problem - just a little 'coaxing' of the float into the correct position.
It hasn't happened since.
Best of luck!
I took it apart. There doesn't seem to be anything wrong that I can see. The seat is clean and smooth, the pin with the rubber tip seems fine see picture. The float looks like it is at the right angle. I could not find any debris. I put it back together: no change still spews gas out of the hole on the label side. How can I tell if the float is bad? Weird that this worked for months, now it doesn't.
Your float is JUNK !!!
Put a small pot of water on the stove and just before it comes to a rolling boil, hold the float under with a wooden spoon & watch the for the bubbles !
As an experiment, lower the float level and try it again, even though the float position looked ok when you took the carb apart.
With that amount of solder on it, the float is definitely suspect ! Kinda wonder how it can float with that much lead plastered on it.
It "Looks like it is at the right angle"...? There's your problem. Do not adjust the float by sight. Make a gauge and measure it 15/64" from the flange as instructed by Ford. 1/64" is not much, but if this measurement is off by 1/64" you could have a problem. If the precise measurement was not important, Ford would not have made such a big deal about it in the repair manuals and Bulletins.
Also, I agree with others that you need to get a new float. With so much heavy solder on it, your float is almost certainly riding low in the bowl, basically keeping your needle valve open and allowing too much gas in. Jim Patrick
Ya, you may have a heavy float. OK. Shirley has been a decent runner for some time as it is. We know this IF we'll pay attention. :-)
Is that float finally full of gas? I wonder about the 18 out here too. Shake it to see/feel or "watch for the bubbles." like Steve T. suggests.
My rule of thumb? Let's test the needle and seat plus the gasket underneath.
This may sound gross/weird. Just do it, suck on the gas inlet elbow (YUCK) on that carb when it's upside-down. Tasty gasoline. :-(
When providing negative pressure (vacuum) to the inlet elbow on the carb, we can generate much vacuum. Slide your tongue over the inlet port's elbow and feel if that valve is holding or if it's leaking like a pig. It's gross but an easy-peasey check. :-)
I'm sure this mightn't help and yet maybe? I hope so. OR. When was the last time you saw the word Mightn't? The dictionary in my browser actually knew that word.
The bad part of a leaking float in your beautiful home garage is gas fumes flow down next to the floor----I neglected to shut my gas off every time my T was used-----fortunately one morning I smelled gas in my garage-----my large catch pan with two inch sides had about four gallons of gas in it-----that's why any pilot light from an appliance should be raised at least 18 inches off the floor-----mine were in the attic or another room. Close call!!!!!!
I disassembled it again. Shook the float, it has liquid in it. I tried the submerge it in almost boiling water and look for bubbles: nothing. I was hoping to find a hole so I could fix it as a new float is a week away. I would love to drive my T to church tomorrow again.
Due to the extra weight of liquid and solder, your float is going to be somewhat sunk at any level of fuel, thus the standard clearance measurement will be meaningless. This is your entire problem in a nut-shell.
If you must drive this week, you will have to experiment with where and how the float sits when it's "floating". You will necessarily have to have a much larger "gap" when closed than the book states, to make up for the "sunk" position of the float when the fuel is at the proper level. The 1/4" gap you have been advised will never close the float valve as you have found. By the time that float is essentially parallel to the casting, the level of fuel is well past any vent or throat of the carb. It will take some fiddling to find the correct angle/gap, but it can be done. BE SURE to have a fuel cutoff and USE IT for this next week any time you're parked.
I swapped the float for a Kingston L4 I have. The hinge is deeper than a Holley NH float. I drove around the neighborhood of flood damaged houses and it seems good enough. Not leaking, car runs. I've ordered the correct one.
Good job! If it works, leave it in there.
Remember the famous quote,
"There is nothing more permanent than a temporary fix that works".
Made it to church and back, no problem. :-)
Hehehe! I figured it'd be fine. :-)
I've never even seen an L4 and here you use the float from one in the NH...
So I purchased the correct Holley NH float from Lang's and put it on today. Did the gap. Leaks profusely again. :-( I am wondering if I need to bend the tab forward some so that it is in the middle of the pin?
There may be a casting crack that's causing the seepage ???
Had the same trouble with a early straight thru NH. crack at the carb fuel inlet
Weigh the correct float when it arrives and then weigh your old float.
The extra weight is important to the level the float will sit in the fuel.
If the air vent on top of the bowl chamber is plugged, the air bubble will also hold the fuel level lower and keep the float from being able to shut off the flow.
Some of those vent holes are hidden under the NH Tag and over-looked.
If I understand correctly, it does NOT leak with the L4 float, but does with the correct NH, even a new one?
I don't understand why a casting crack or plugged vent would not cause a problem with either float.
Can someone explain that?
Works with a L4 float, does not work with new correct NH.
Try lowering the float level. The new floats are not as high as the older ones and might float lower in the fuel. Lower it about 1/16 inch and try again. If still leaks do another 1/16 inch. The problem is that you cannot see exactly how high the fuel is when everything is together so you need to do a bit of experimenting.
Way to much solder on the float and float is set wrong. Replace the float and set angle at about five to ten degrees opposite the hinge.
Send your carb to Russ Potter. If he can't fix it, nobody can.
Look for a plugged bowl vent.
I tried the new Holley NH float again bent the tab some more to give it a bigger push. Still leaked. I put the Kingston L4 float back on and it works. I photographed the two side by side. The L4 one is much thicker and hangs lower in the bowl. Check out the photo. Not sure what to do because the 'correct' one doesn't work so well.
The tip may have gotten hard and the extra lift from the L4 float may be enough to seal the valve.
Did you check for a plugged bowl vent?
How do you check for a plugged bowl vent?
Tom, read the first post. He states fuel is coming out from behind the label. So, the vent isn't plugged if fuel is escaping from there.
There is an insane height difference between those two floats. Problem corrects itself with the "wrong" float eliminating any cracked housing or plugged port solutions. You have a height problem as in the tab isn't shutting off the fuel when the float is fully raised (floating) in a full fuel bowl. Your needle & seat are OK as in they operate correctly with the wrong float in place. Your problem is the needle is not cutting off the fuel with the correct float.
The hole under the label is not the vent. The hole by the choke lever is the vent. I plugged bowl vent will cause an NH to leak profusely. I have seen it many times.
What REALLY bothers me about this is you state it started by itself and appeared to get progressively worse. Your photo's don't show any apparent problems with the carb body hinge or the float hinge ether. I only state the above because it seems to be something you didn't do yourself to cause the problem but you're probably missing something in re assembly with the new correct float. By the way I now think your original float was OK & not the cause of the leak.
Original float had liquid in it so probably bad. It was however thick like the Kingston L4 float.
Is that new info or did I miss it?
Ok, so I'll bite. What is the hole under the riveted on NH tag? Always thought that was the vent.
Charlie, see my above post Saturday, September 02 saying the original had liquid in it.
Can you bend the tab up on the new float like the tab on the Kingston float?
I've mostly removed the "deeper" type Holley floats out of Vaporizers.
A leaking float is a heavy float. A heavy float will not shut off the fuel flow.
Replace it. Chances are slim that you can stop the leaking for any length of time. If you stop it, the leak will return. If you get too much solder on it you are adding weight making a heaver float heavier.
VF arrived today, has an excellent tech report on this problem, jb
that is a vent within the low speed tube labyrinth. This can be plugged and will dork up idle and low-throttle conditions but will not "flood" fuel out the carb. This isn't particularly common, as that passageway is pretty generous in size. The vent that Tom C. is asking about is the vent that allows air to escape from the top of the fuel chamber (bowl). If that is plugged, as he stated, fuel will really flood out...in fact I have seen it "chug" out as the air compresses and pukes out fuel, refills, compresses air, and pukes, and...and...and...you get the idea. The bowl vent is very commonly plugged with rust or in some cases, blasting media, and like the idle passages, is often overlooked by amateur rebuilders. This vent is a hole just beyond the cross hole for the choke shaft and can be found located on the same cast boss on the carb body. It is a very shallow hole that makes a hard 90 degree turn into the top of the float chamber.
Here is a post that has a picture of bowl vent. Scroll down a ways.
James, what is VF?
There is a very good article about the float adjustment in the September-October Vintage Ford.
This article by Mike Vaughn on page 38 describes the same symptoms you describe and how to fix the problem.