Just starting a new rebuilt motor and the carb. shot a stream of gas out of the tiny hole above the name plate near the side of the intake. I took it off and set the float because I thought it may be sticking. Re-installed it and turned on the gas valve and the same thing. Gas just pours out the hole. If you look at the enclosed picture you will see a small hole just behind the choke axle hole. Is this supposed to be plugged? Or is it a hole for air to the float bowl? Any advise that can cure this problem would be appreciated. Thanks
If gas is coming out that hole the needle is not seating and shutting off the supply. That hole is not plugged.
Richard: Thanks - what would you recommend I do to cure this?
If the float level is correct and the float is ok, It may be dirt or something keeping the needle from seating. A new needle and seat may be needed if the old needle cannot be made to seat properly. The old manual shows a guy blowing in the inlet opening while moving the float up and down to tell if it is seating properly.
Some of the experts no doubt will have comments that may help when they see this thread.
Sounds like you need to take the bowel and float off and carefully inspect the float valve and seat. Maybe it is defective or could just be some foreign object in the sealing surface. Also make sure that the float floats and that it is adjusted correctly.
I have seen the float be a sinker instead of a float, and it was a brand new float. Take a small cup of gas and see if the float will float or sink.
I often check needle valve seats by blowing into the gas inlet. With the carb right side up air should pass easily into the carb. With the carb upside down its almost impossible to blow air into the inlet.
It has to fail either this test or the "float in gas" test.
It could be the carburetor has been rebuilt using a Grose jet. This is a ball bearing instead of a needle and seat. They don't work well.
i created a thread on this last week too. I hooked up the brand new carb, let it run and as soon as that float fills the engine stumbles and gas pours out the side. I talked to the catalog supplier and they told me to take it apart and inspect or send it back. I took it apart and same problem as soon as it turned on. So I sent it back... my old one ran better!
anybody know if that hole can just be plugged up?
I had a G last year that did that--worked with the bowl off and testing, then leaked when back together. Result was the bracket was either attached to the repro float in the wrong place or the float was too big. It caused the float to rest against the side of the bowl when assembled, so that it couldn't float and cut off the flow. A little sanding on the float cured that.
You cannot plug that hole unless the carburetor is only going to be used for display.
I'm with you on that Grose jet. They just don't work well. I've worked on several Ts that didn't run well at all or were pouring gas out of the carb, and found them to have those blasted things. I'd put in a stock needle and seat, and then all would be well.
Grose jets are junk jets.
This one caused me grief twice until I threw it out.
First time gas was dripping all over the garage floor when I opened the gas shutoff. Removed it, cleaned, had the ball working. Ran for a while...then...second time the T would not start, gas starved, no gas flowing, dang thing stuck closed!
No third chance to mess the carb again, threw away this Grose jet.
Guys: Thanks for all the suggestions. I have the stock jet and have taken apart again. The float works properly in a cup of gas. The neddle jet is clear. It will not pass air when closed and allows air when open. I will install again this afternoon and post results. Thanks
Another possibility is if the wee gasket between the seat and the body is missing or defective, this will show up on the "pass air" test.
I had one once where the base of the seat was machined at an angle so it was impossible to get it to seal.
What Ken T said.
Also. The "problem" with the original type valves is that if the tapered valve has ANY wear or visible ring around it, or if it is uneven in any way, it will leak.
That said. I have been told the proverbial hundred times that you cannot repair that valve yourself. In spite of that, I have, on at least a dozen carburetors, pinched a piece of fine wet-or-dry sandpaper in my fingers over the end of the failed valve and spun it back and forth pinched in that sandpaper with my other hand. ONLY ONCE did I have to go back and redo it for a second time. My carburetors almost never leak (except when some junk got into the valve from the gas tank). I rarely turn the gas off from the gasoline tank. They don't leak. They don't hang up. I never have trouble from them.
Sorry "hundred people". I am going to continue to fix them myself whether you say I can or not.
Drive carefully, and enjoy, W2
Wayne, I do the same thing but spin the needle in a drill press or lathe. The seat can be cleaned with solvent and the hand spinning of a bamboo chopstick sharpened to fit inside.
I had an older gentleman who worked on small engines for many years. He told me to use valve lapping compound on stubborn needle valve and seats.
I went thru the same thing with one of mine, and it was the float.
1 thing I do that may be so taboo I will be banished forever from T world is I use the yellow thread tape on the threads of the seat houseing.Not much,just a round or 2.I was told that the threads could be worn and letting a slow leak happen.Made sense so I am doing that.No troubles so far from that procedure.
I am currently working on a John Deere B carb that filled the crankcase up with gas.
I will start another thread in reference to something I saw on a rebuild video this evening.
No banishment, but isn't that what the gasket under the seat if for?
Yea,that is the correct thought but this dont seem to hurt anything.
1 thing I have often thought about on some of the old cast carbs is there a chance the body of the carb that the seat is threaded into could be cracked and that explain sometimes a carb you just cant make work right?
RESULTS FROM FRED ON INSTALLING AGAIN! Sorry to report nothing seems to work. I took it on and off 3 more times each time adjusting and checking the float. The Blow test works as it should even with the bowl off and hand holding the float - the neddle valve seems to work. CLUE: It did not just leak out the hole - it ran steady stream as if there was no valve at all. I am stumped. Think I must have a bad carburator???
I know you have probably done this but shake the float and listen.Sometimes a half full float will still "float" but not good enough to work.
I allways put a little wieght on a float,say a bolt,then soak it in carb clean fully sumerged with the bolt laying on it.What I found this does is it gets the solder joints below the liquid that would be just above it on a semi working float.
I would say if the float is good,and the level is right,you need a needle and seat.
My dad allways has told me that gas will find a crack or place to leak worse than water.
Thanks Mack. I did put the float in a cup of gas and it stayed up on the side opposite the hinge. Should the whole float stay up or just the side opposite the hinge? I am beginning to think you are correct about the new needle and seat. The thing I don't understand is how it passes the blow test great. The gas runs out like it has a direct line to the hole. It starts as soon as the bowl fills up.
This might get a little messy but did you try hand holding the float with the gas on to check for some path for the gas directly from the gas inlet to the leaking vent?
You said, "it ran steady stream as if there was no valve at all." maybe there is some interior defect??
Hold the entire float under and look for bubbles. If no bubbles and it passes the blow test, check the adjustment and put the bowl on and turn upsidedown and right side up repeatedly as you listen to see if the float is rubbing the bowl. Do the blow test with the bowl on. If air is cut off when the float actuates the needle by hand but not when you turn it upside down fully assembled, then something is interfering with the action of the float. You can "adjust" with needlenose pliers to get the float back into the center of the bowl so it don't rub.
Also, check the surfaces that mate and slide on each other at the butt end of the needle and the flat surface of the float arm. These should be smooth and slick but some have worn enough to have ruts and grab or don't work smoothly. I always polish these areas. Another issue can be a float arm that is bent to an off shape and catches on the needle instead of letting it move properly. The arm surface should be nearly flat and perpendicular to the needle.
I would do what Jim Thode suggested next. Apply fuel to it with the bowl off and your finger holding the float in the full position. It will get messy so prepare. Watch for leaks.
After all is said and done, talk to Russ Potter and have one of his rebuilt carbs in the mail today. You will be amazed at the running of the car with his carb.
I don't see how the gas could be coming out the hole just behind the choke shaft. Out the vent hole under the name tag, yes. Before gas could leak out that vent just behind the choke shaft it would be poring out the mouth of the carb. first. While that vent is below the gas inlet there is no direct connection. The gas has to go in to the bowl first. The needle valve well, vent under the name tag and the bottom of the mouth are all well below that vent.
Are you running a fuel pump?
Unless the vent under the name tag is plugged and the needle valve is closed all the way.
For gas to be "shot a stream of gas out of the tiny hole above the name plate" there would have to be a good sized crack in the casting and under a fair amount of pressure.
The "and" between casting and under should be "or".
If no cracks are seen and you are using a fuel pump, could be the output is overwhelming the floats ability to shut off the gas and the pressure needs to be cut back. Also check to see that the vent under the name tag is open.
Well I just had a duh moment. The vent under the name tag only comes into play when the spray needle is open.
That hole under the nameplate is a vent hole.For the gas to come out there The bowl is full with the float submerged. For this to happen the only way fuel can do this is by way of the needle and seat.
This may sound funny, but are you sure the needle is not in upside down. The rounded end should be riding on the hinge arm and the only only contact point is the needle.
Also check for cracks anywhere in the carburetor body, especially around the float valve.
Check all of the above, and even if you get it to working just fine, always remember to turn off the valve when you park the car. Even a small drip will drain your tank over time, and will also cause a fire hazard.
Any dirt whatsoever in the tank, or rust sediment has a way of working its way to the float valve, so the tank must be completely clean. One of the reasons the gravity flow system is prone to leaks is that a small leak on a car with a down draft carburetor would not be noticed, because the fuel pump stops when the engine stops. But gravity works all the time gas is in the tank whether the car is running or not, and even a small drip will eventually drain the tank.
Fred, in your photo it looks like the bowl vent hole is plugged. This is the hole that is on the right in your pic, just in front of the end of the choke shaft. Take a drill bit and run it through the hole. You'll probably get a lot of old hardened varnish coming out.
I am going to take the carb over to a friend's tomorrow who has dealt with these carbs for 50 years. He says we will find the problem and I will report back. Thanks to everyone for all their suggestions and they are all good advise. The only thing I had not thought of was the vent hole because I did not know it was there. Again, thanks and I will post tomorrow evening. This one has really had me stumped.
R.V., that's the hole, if I read the posting right, is the one the gas is coming out of. "shot a stream of gas out of the tiny hole above the name plate near the side of the intake" & "If you look at the enclosed picture you will see a small hole just behind the choke axle hole." That sounds like it's open.
You could well be right, but I believe he speaks of gas coming out of the hole under the name plate and exiting what looks like a tiny hole just above the plate below the base of the spray nozzle "tower". Gas could exit there from the hole under the plate.
I am not a carb guy and would suggest sending it to Russ Potter. The only thing I can add is you can't just dunk the float into water and look for bubbles but you can bring a pan of water to boil then remove the pan and dunk the float into the hot water with tongs...the heat will expand the air in the float and if the seam isn't intact it will bubble and need repair.
My guess is bad needle and seat or a cracked casting .
a good trick one of my airplane owner buddys told me, a new needle and seat for his old piper cost 200 bucks, ours are, what 15?, anyway, the fancy new seat leaked just like the old one. so, he used a hand held vacume pump, and polished the needle with tooth paste untill it would hold vacume, then it finally stopped leaking. all my model a's leak, the t's seem better
I had the same problem and took apart the carb numerous times before I found the problem. the needle was seating properly but staying closed or seated. It slides inside what looks like a small spring on mine and that was giving me a problem. gas would flow out the overflow hole as well. I removed the small spring and turned it around fixing the problem. it must be tapered differently on one end or some little difference. I still carry a small bolt with me to tap the carb in case it happens again but so far all this summer it has worked fine.
Check out this old thread. It ends by them solving the same problem you are having. www.mtfca.com/discus/messages/50893/72449.html. Jim Patrick
Sorry just not getting back to report on my results. After my OLD T expert/friend tried everything he knew, I then installed the carb. and it still ran gas out the small hole just above to the right of the name plate. The neddle valve seats; the blow test works as supposed to; the float does float in a can of gas; there is no obstruction inside. We are stumped!!! I finally found an old carb in my stash of stuff with a name plate showing "Ford" Model F" and cleaned it up and installed. No leaks - works great. I gave the other carb to my friend to experiment and see what he can find. Thanks for all the suggestions.
Must be an obscure crack in the housing somewhere, or internal corrosion has opened up a passage that shouldn't be there. I have a Carter AVS carb that I bought for my 1971 Plymouth GTX that does the same thing, leaks horribly despite multiple teardown / rebuild attempts. The floats, needles, and seats all check out good.
Here is my procedure for rebuilding T carbs. I will use a NH for example. Take carb completely apart. Sometimes you will need to use a torch and heat up the carb to remove stuborn seats. It will destroy the gaskets but they are cheap. After carb is apart including all choke /throttle plates name tags ect. I heat the carb up slowly with a torch till it is just starting to glow red hot. The lead passage way plugs will melt out but that is OK. Pay attention to where the holes are so you can re plug later. when just turning red throw the carb in a bucket of water. I know that I can hear moans groans screams of Oh My but I have never broken one yet. I may be lucky but after about 30 or more rebuilds not a broken one yet. The purpose of the "shock treatment" is to break the rust loose from the internal passages. These old cast iron carbs are rusty inside. even though you can blow carb cleaner thru all the passages the rust inside the passages has restricted them. carb cleaner will not remove the swelling of the sidewalls of those little passageways. Only heat and a shock treatment will. After the shock treatment clean and inspect all parts. Replace all gaskets, they are cheap. and blow thru the passageways with carb cleaner, wd-40 ect to veryify they are open. I then cut a piece of 1/8 inch brass brazing rod or a brass bolt to aprox 1/4 inch long. You want it to slide into the old holes that were plugged with lead. Make sure the end of the brass rod inserted into the holes is nice and square cut. After inserting into the holes the brass rod can be cut to extend about 1/8 inch outside the hole. Take a small hammer like a tack hammer and slowly peen the protruding brass rod down to form a very small rivet head. The one plug in the intake gasket flange will need to be filed smooth after peening. They will never come out.!! After installing the 3 brass plugs in a NH It is time to reassemble the carb. Re install the choke and throttle plates and shafts Make sure they seat well and the spring returns the choke to open when at rest. Make sure the throttle shafts have little to no wear. Useally a new shaft will take up most wear, but if excessivie you will need to install some kind of bushing in the carb body to take up wear. Check the casket sealing surface for the needle seat body. If good install the needle seat body and gasket. Do not use a gross-jet they are junk. Either use a new needle set or rework a old one with valve grinding compound to make a good seal. Next install the spray nozzle and gasket with new ones unless you are sure your old one is not enlarged. It needs a nice square corner where the spray needle meets it to work well. Next check float for holes by submurging in boiling water for a second or two. Bubbles will form if it is a leaker. If it is OK Install the float needle into the seat and install the float on its pin. Set float height to specs for your particular carb. Holly NH is set by turning carb upside down and bending float ear till it is level and parrelle with the carb bowl gasket sealing area. Next turn carb right side up and blow thru the gas line elbow. You should be able to blow thru it. Next turn carb back upside down. Instead of blowing thru the inlet elbow you will need to Suck. While sucking and creating a vacumn stick your tongue to the elbow and release the suction. Your tongue will stick to the inlet elbow. It needs to stay stuck there till you remove it. If your tongue does not stick to the elbow you have a leaking needle or sometimes a cracked carb casting where the elbow screws into the carb. A crack at the elbow is useally caused by overtighting the elbow. Be carefull when installing the elbow to not break your carb. Next install the spray nozzle adjusting nut into top of carb. Inspect the spray needle for wear at the tip. If there is a groove at tip it can be repointed with a fine file and carefull workmanship or just buy a new one. A smooth running engine is largely due to the spray needle being true and its sealing point in the spray nozzle being a nice sharp edge at point where spray needle contacts it. Next install spray needle and screw down till it is closed. Be carefull and not overtighten it and destroy your spray nozzle. Back it out 1 to 1-1/2 turns. This is a good starting point. All engines are different so you will fine tune it when car is running. Next check drain valve and plug. If OK install a new bowl gasket, bowl, drain valve with new gasket and tighten. The last thing is to re-install the old nameplate (or new one)over the vent hole. For no reason should the vent hole be plugged. At this time you should have a complete restored carb. I think I covered everything but I am not a very good author. With good workmanship you should have a very good running carb. The main reason for all the work is to open those passageways up. Good luck...