WTB Stewart Vacuum Fuel Tank Flapper Valve (Inner Tank)

[Kfigel]

Anyone know if someone is reproducing flapper valves for the inner tank of a 1920's era Stewart Vacuum Fuel Tank?  The couple of used ones I have leak ever so slightly.  

Edited March 18 by Kfigel (see edit history)

[JFranklin]

That is a simple valve. Have you thought of running both sides over sandpaper on a piece of glass to smooth, and ensure the mating surfaces are flat?

[Kfigel]

11 hours ago, JFranklin said:

That is a simple valve. Have you thought of running both sides over sandpaper on a piece of glass to smooth, and ensure the mating surfaces are flat?

Right, it's just two metal surfaces mating to each other.  I did do a very light sanding with 320 paper over both surfaces and I still get some water into the inner tank.  The surface on the valve body seems to be flat.  The surface on the flapper looks to have a raised round lip that, I guess, is to seal against, or nest into, the flat surface on the body.  A little surprised that this was intended to form a tight seal, but it is 1920's technology.  Asking if these are reproduced was a shot in the dark.  Am thinking to have someone who refurbishes these, like Tim Long in PA, to just take it and see if he could improve it.  Thanks 

[Stude Light]

5 hours ago, Kfigel said:

I still get some water into the inner tank

Wait! What??!

 

If you are getting water in, you have some other problems. All my tanks, and others I've rebuilt, use a micarta flapper valve. Whether micarta or brass, they aren't expected to make a perfect seal but just enough to allow the engine vacuum to draw fuel from the tank.

[Linus Tremaine]

I find that all the ones I have worked on leak a little and I run them without any issue. Its not a perfect sealing system. 

 

 

[Kfigel]

6 minutes ago, Linus Tremaine said:

I find that all the ones I have worked on leak a little and I run them without any issue. Its not a perfect sealing system. 

 

 

Thanks, that was my gut feeling but wasn't sure never having rebuilt one.  I guess I just wanted that input from others that had some experience.  

[Kfigel]

1 hour ago, Stude Light said:

Wait! What??!

 

If you are getting water in, you have some other problems. All my tanks, and others I've rebuilt, use a micarta flapper valve. Whether micarta or brass, they aren't expected to make a perfect seal but just enough to allow the engine vacuum to draw fuel from the tank.

Ich bin ein dummkopf.  The H2O I referred to was how I "tested" my inner tank.  Cleaned the tank thoroughly, then set it up so it sat in a small pot of water to see if any leaked into the tank through the valve/flapper (no vacuum applied).  Did have some after a while but not a lot; wasn't sure if any was acceptable.  I think I'm ok.  

[Linus Tremaine]

That sounds like it will be fine. I learned to test them by putting the whole chamber over my mouth and sucking air in. It doesnt work very well if you have a beard. As long as it closes and creates an ok seal it will be ok

[Stude Light]

7 hours ago, Kfigel said:

Ich bin ein dummkopf.  The H2O I referred to was how I "tested" my inner tank.  Cleaned the tank thoroughly, then set it up so it sat in a small pot of water to see if any leaked into the tank through the valve/flapper (no vacuum applied).  Did have some after a while but not a lot; wasn't sure if any was acceptable.  I think I'm ok.  

Ahh. Okay that makes more sense, however….the inner tank is suspended within the outer tank so the fuel is supposed to drain from the inner tank to the outer until the two fuel levels equal. It is not designed as a check valve to prevent fuel entering from the outer tank as fuel level in the outer will never be higher than the level in the inner. The only thing the flapper valve is designed to do is to flap shut when a vacuum is pulled on the inner tank and  it is submerged in fuel when that happens. With a 5-15 in Hg vacuum applied to the inner tank that flapper valve will suck shut and seal a lot better and the small amount of fuel drawn past is insignificant compared to what flows from the tank. It will be fine.

[Kfigel]

17 hours ago, Stude Light said:

Ahh. Okay that makes more sense, however….the inner tank is suspended within the outer tank so the fuel is supposed to drain from the inner tank to the outer until the two fuel levels equal. It is not designed as a check valve to prevent fuel entering from the outer tank as fuel level in the outer will never be higher than the level in the inner. The only thing the flapper valve is designed to do is to flap shut when a vacuum is pulled on the inner tank and  it is submerged in fuel when that happens. With a 5-15 in Hg vacuum applied to the inner tank that flapper valve will suck shut and seal a lot better and the small amount of fuel drawn past is insignificant compared to what flows from the tank. It will be fine.

Thanks; knew in general how the system worked, but this detail really solidifies it.  Also tells me why I thought this "sealing" point was rather crude in my humble opinion.  Should have the fuel tank back together in a couple of days with good vacuum and fuel delivery!