MTFCA Forum

My ‘26 roadster with a straight thru Simmonds or NH carburetor failed to start. Diagnostics dictated fuel problem. With the sediment bulb shut off I’m underneath draining the bowl. With that over I removed the bowl and float. Latter didn’t make any noise when shaken but the triangular shaped needle didn’t fall out so I removed it. And it’s rubber tipped so I researched ‘viton’ on past Forums. Then emailed Scott C needing one of his Full Flow Valve sets. But I went to my coffee can of carburetor parts and found this steel needle with a rather blunt or rounded tip. There doesn’t appear to be any circumferential rings around the needle ?…. What’s the groups opinion ??
Use it ? Thanks

It looks like brass. Most metal ones are aluminum. If you dont have the matching seat its probably going to leak. Its not worth bending up your float tang to get the right fuel level. I would buy a new needle and seat and be done.

I have heard of many viton tipped needle valves sticking. I have NOT heard of any viton needles sticking after the following procedure was conducted.

1. Shut off gasoline to the carb.

2, Start engine and let it idle until it dies.

3. Shut everything off, disconnect the battery for long term storage.

The "sticking" problem appears to be based on the float bowl being full, pushing the float up, pushing the needle valve shut continuously. This practice appears to cause the viton to deform and/or fuel evaporating above the viton causing the viton to stick to the seat.

If the needle is NOT contacting the seat, It won't stick in/to the seat.

John, are you saying an NH needle and seat is like crank and cam gears / ring and pinions ? They have to be a mated set ? Steve, I very quickly contacted Scott C trying to buy a Full Flow set but he cordially said more won’t be made until March 2025. Terry, thats a good sequence of events and I heartily concur but it’d be cumbersome at a typical 4 stop tour. …anybody have one of Scott’s Full Flow Valves they’d sell ?

George..... Find yourself a original intake valve, put the triangle shaped valve in a hand drill, and with some crocus cloth apply that to the tip as you spin the valve, .....with the screw in section soak that in carburetor cleaner and use a q-tip with the crocus cloth to dress up the mating surface so the valve will close properly without leakage...... To be sure of your work, set up carburetor on your bench with an elevated fuel supply and check for leakage after an hour or so.

George,

I recommend this procedure at the end of the day or for long term shut down, such as over the winter season. It appears to be the long term pressure from the carb. float pushing up on the viton needle tip, that seems to make the needle stick in the shut position.

Terry ..., if the viton tip inlet needle has such a problem of sticking in the Valve seat, why the heck use it???.... Was it such a problem with the original Ford issued carburetor inlet valve...???.. some time ago there was a gripe among posters regarding the " ball valve setup" not opening and closing properly just like the viton tip controversy.... I've never had a problem with the ball valve sticking closed or open. , and I've never had a problem with the original valve..... if there is a problem, it's probably due to crud that's in the carburetor it's time to do some cleaning.

It seems as though the ball valve type work O.K. on the Improved Ford with the tank in the cowl but it appears that the low head pressure with the frame mounted tanks were the ones having issues.

Robert,

I believe this is a case of "the squeaky wheel gets the grease". NO ONE knows how many viton tipped needles are currently in use. BUT, when one does stick, EVERYONE knows due to the complaints. How many have never had a problem with viton needles?

It is extremely difficult to get a 100% perfect seal with metal to metal contact. That is one of the reasons brass was commonly used, as the brass was somewhat soft enough to deform into a relatively good seal. Steel ball type valves have no deformation characteristics and would have to rely on the seat deforming. The weight of the ball is, often, not considered. As RajoRacer posted, fuel tanks mounted higher, creating more head pressure, had fewer problems with the ball type valves.

All of the problems, I have heard of, with the viton tipped needles, were found after a long term shut down, as in over the winter or during other maintenance procedures where the car was not started or driven. As gasoline evaporates, it often creates a gummy/sticky compound. This compound could be the cause of the valve sticking. Remove the gas before a long term shut down and there will be no gummy compound to cause sticking.

AND to answer your question: Viton tipped needles, having a soft sealing surface, will conform to the seat better, and leak less gas into the passages when not in use. Most of the viton needles have been made by Scott Conger in a "high flow" configuration, with many rave reviews. And, if viton needles were such poor design / operation, why did the auto industry use them so widely, for so many years, in modern cars?

I say: Use what works for YOU and makes YOU happy. If WE are not happy, WE will NOT promote model Ts to the younger public and this hobby will die faster than it already is.

Excellent ideas and thanks to all! Special appreciation goes out to John Tannehill for offering a Conger Full Flow Valve w/ installation tool….What a wonderful neighborhood of Model T hobbiests we have.

Viton needles may depend on fuel pump pressure to function well. Most carburetors in use during the Viton era were/are fed by fuel pumps and they do not have fuel shutoffs, so the Viton is normally kept from drying-out. In any case, a light tap from a screwdriver handle would probably free most any stuck needle in anything but a badly-gummed carburetor. Turn on the (fresh) gasoline, and give the carburetor a tap or two with a hard plastic screwdriver handle, and watch it for a minute in case it floods. If not, choke the engine and give the crank a couple of brisk pulls and see if gasoline drips from the carburetor. If it does, you should be good to go.

I think that Scott's needle/seat would present a larger surface area to the gasoline when closed, which would add (?) to the pressure acting on the needle prior to the needle coming off the seat at any given line pressure.

George, yes they should be a matched set. Different angles may not seal together. For $20.00 new why not.

I tried one twice. Don't know why but it gave me problems. I'm thinking the additives in the California gasoline could be the issue. I finally gave up and put in an original design needle and seat. No more problems, and no more issues.

Larry,

You might try Pure-Gas.org https://www.pure-gas.org/

This web site is pretty good at showing where a guy can find ethanol free gas. The one thing I find concerning, it the sources are updated by YOU and I (users), and some of the postings are OLD as in REALLY OLD. I think I would still check them out if you wanted to go ethanol free.

We use ethanol gas in our modern trucks but all the other engines we have are on ethanol free. It seems to work better for us. Yes, it is more hassle and that is up to you to decide if it's worth it or not.

Good Luck

Hi George,
Sticking to the original question if there is no ring on the tip & the needle centers well in the seat, try taking the seat out setting on a smooth
flat surface put the needle in the seat with a brass or other soft punch give it a firm tap this should form a good ring in the seat for it to seal
on. I test float valves by pulling a vacuum on them with my mouth & sticking my tongue on the end if it sticks to my tongue for a few seconds
it's good. At least till you get a Scott C. valve from John T.
Craig.

Thanks Craig, I shall follow that excellent advice. It’s always been easier for me to remove the intake manifold with the carb attached than the carb by itself. I use the 2 half manifold clamp method. And the original aluminum manifold is already in the vise sandwiched between boards with the carb bottom up. I read about Stan Howes tapping the needle into the seat with a ‘big fella hammer’ and that sounds like your suggestion. And I also test by pulling a vacuum like you suggested and our friend Hugo Richter illustrated in the Carburetor Manual….. Merry Christmas

Tapping on a steel tip needle & seat unit is covered in the service manual.
A lite tap is in order, not a big hammer blow.