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Tip: Swapping the ?Flat? on the Van?s Fuel Valve

Ironflight

VAF Moderator / Line Boy
Mentor
One of the outcomes of our little ?Valve Handle? problem on the RV -3 was a post from a member (I beleive it was "Gasman")that said ?if the handle is on the wrong way, it can be easily fixed by taking the valve apart, driving out a pin that holds the nylon valve seat to the shaft, reversing it 180 degrees, and putting the pin back in.? This was so simple and elegant of a solution, I just had to take our spare valve apart and have a look. Sure enough ? it?s THAT simple! This trick allows you to use the stock handle, or the aftermarket handle with a ?D-Shaped? hole if you wish, and orient the pointer the way you want it. Yolu don?t even have to change the valve body in the airplane ? just the stem assembly (once you drain the tanks down low).

Here?s the body in the vice ? just put a wrench on the big nut to open it up. Keep the parts in the correct orientation and order as it comes apart:

IMG_6193.JPG



Here?s the stem with the nylon ?ball? seat on the end:

IMG_6194.JPG



Just drive out the little pin, turn the seat 180 degrees on the shaft, put the pin back in?and the ?flat" on the shaft is where you want it:

IMG_6200.JPG



Reassemble your valve, taking care with the O-rings, and you?re done.


Paul
 
Well in some cases you can also file a new flat

I needed to put the valves in a console and keep it narrow for leg comfort. I mounted the valves (2 of them - one for the tip tanks) at 45 deg from the aircraft centerline and determined the orientation of the handle to give the pilot intuitive tank selection and filed a new flat on one shaft to accomodate the need. The other one was OK as is. Both valves in the console have have 4 input ports and the one which I will call the front one is what I will call 1 is the 0 deg input port and the others in clockwise standard position are 2=90 deg, 3=180 deg and 4 =270 deg. When I rotated both valves 45 deg with respect to the aircraft centerline 1=315 deg, 2=45 deg, 3=135, and 4=225. That is still functional for the fuel system but the pilot (me) might get confused. I'm going to customize the port numbers a little more by adding the letter M for the rear valve (as in Main) and T for the forward valve (as in tip). The plumbing connections are T1 = left tip tank, T2 = right tip tank, T3 = plug, T4 = plug, (T3 & T4 cannot be selected because the console design prevents handle rotation to those ports), T output = M1, M2 = right main tank, M3 = Plug, M4 = left main tank and M output supplies fuel to the engine. So the pilot looks at the forward valve and it can only point to 315 or 45 degrees as the only selectable positions and since 315 is left of centerline and 45 is right of centerline and he knows the left of center is the left tip tank and right of center is the right tip tank automatically IF he is flying on the tip tanks. The Main valve (the aft one) needs to point to the tip valve straight in front of it if he wants to fly on the tips but there is no selectable "detented" position because the valve is turned 45 degrees to the left. The solution is to file a new flat on the shaft 45 deg. clockwise fron the production flat and reinstall the handle indexed by the new flat. Now the pilot sees two fuel selectors that are intuitively operated: Main forward tip valve controls tank selection and the tip valve is either left or right of center and fuel flows from the left or right tip tank respectively. Main right isolates the tip valve and fuel flows from the right main tank. Main left isolates the tip valve and fuel flows from the left main tank. Main aft turns off all fuel supply.

M T Fuel
F L Left Tip
F R Right Tip
R R Right Main
R L Right Main
L R Left Main
L L Left Main
A R Fuel Off
A L Fuel Off

Where: F = forward, R = Right, L = Left, A = Aft (Rear)


Bob Axsom
 
Last edited:
Paul, try this you might really like it.......

One of the outcomes of our little “Valve Handle” problem on the RV -3 was a post from a member (I beleive it was "Gasman")that said “if the handle is on the wrong way, it can be easily fixed by taking the valve apart, driving out a pin that holds the nylon valve seat to the shaft, reversing it 180 degrees, and putting the pin back in.” This was so simple and elegant of a solution, I just had to take our spare valve apart and have a look. Sure enough – it’s THAT simple! This trick allows you to use the stock handle, or the aftermarket handle with a “D-Shaped” hole if you wish, and orient the pointer the way you want it. Yolu don’t even have to change the valve body in the airplane – just the stem assembly (once you drain the tanks down low).

Here’s the body in the vice – just put a wrench on the big nut to open it up. Keep the parts in the correct orientation and order as it comes apart:

IMG_6193.JPG



Here’s the stem with the nylon “ball” seat on the end:

IMG_6194.JPG



Just drive out the little pin, turn the seat 180 degrees on the shaft, put the pin back in…and the “flat" on the shaft is where you want it:

IMG_6200.JPG



Reassemble your valve, taking care with the O-rings, and you’re done.


Paul


And if you do this in the start before you plumb the valve in, you won't have to cross the fuel lines at the valve. Makes it much cleaner.

The other thing that I did when I had the valve apart was to replace the spring with a much softer one from Ace Hardware bag #148U compression spring 1-5/32 Lgth, 3/8 Out Dia. .028 Wire Gauge. Cut this 3/8" tall and bend flat. The original spring forces the cone to seat with too much pressure and over time, the valve gets harder to turn.

Installing this spring will make this fuel valve operate with ease and still be positive. This valve IS SO SIMPLE and altered with this spring, I would put it up against any Andair valve for function, safety, value and least amount of parts.

GASMAN
 
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And if you do this in the start before you plumb the valve in, you won't have to cross the fuel lines at the valve. Makes it much cleaner.

The other thing that I did when I had the valve apart was to replace the spring with a much softer one from Ace Hardware bag #148U compression spring 1-5/32 Lgth, 3/8 Out Dia. .028 Wire Gauge. Cut this 3/8" tall and bend flat. The original spring forces the cone to seat with too much pressure and over time, the valve gets harder to turn.

Installing this spring will make this fuel valve operate with ease and still be positive. This valve IS SO SIMPLE and altered with this spring, I would put it up against any Andair valve for function, safety, value and least amount of parts.

GASMAN

I did the short version of this - clipping off a little, then stretching the spring back to length. Your version is much more elegant - great to have it for the archives!
 
And if you do this in the start before you plumb the valve in, you won't have to cross the fuel lines at the valve. Makes it much cleaner.
GASMAN

Great tip! I'm going to go back and modify mine before closing the area
 
But Where do they go?

Good tip Paul.

There have been a number of good tips posted recently, this one included. When I post a tip I usually put "Tip" as the first word of the title in order to help anyone using the search engine. However, I seem to remember you mentioning a "Tip" section which seems to be very hard to find. I cannot recall where it is now on VAF. When I looked at Tip section last week when I could remember where it was, there did not seem to be many of the latest tips deposited there.

Is Doug or any of the mods going to address this issue?
 
Good tip Paul.

There have been a number of good tips posted recently, this one included. When I post a tip I usually put "Tip" as the first word of the title in order to help anyone using the search engine. However, I seem to remember you mentioning a "Tip" section which seems to be very hard to find. I cannot recall where it is now on VAF. When I looked at Tip section last week when I could remember where it was, there did not seem to be many of the latest tips deposited there.

Is Doug or any of the mods going to address this issue?

Uhh....scroll to the top of this page - the Fourm is "RV Building Tips/Techniques".

When you open any of the forums, the default is to show you the last month of posts. Change that to "from the beginning", and you'll see everthing that has been contributed.

i sure HOPE Doug hasn't cleared them out!:eek:
 
Springs & Fond Memories

Cutting a portion of a coil spring increases its spring rate and increases the stress on the wire in the spring.

So I am +1 for Gasman's idea.

Now the fond memory part (non-engineers can ignore):

For mechanical engineers, refer to Mechanical Engineering Design, by Joseph Shigley for coil spring design. I discovered younger engineers who reported to me had used this book in their ME design classes too, so it was nearly ubiquitous 25 -40 years ago.

Through a stroke of very good fortune, I took the class from Professor Shigley himself during the summer semester of 1969. He was wanting to publish a new revision to the text, had course material he wanted to try out, but wasn't keen to grade lots of papers. The class schedule listed the course instructor as "staff" so the enrollment wouldn't swell. I was too much of a country bumpkin to realize for a while how privileged I was to be taught by such an acclaimed individual. BTW, he was an incredible instructor. Normally, since we are talking about the U of Michigan, he only interacted with graduate students. At the end of the semester, Prof Shigley told us that we were the best undergraduate class he had ever taught!

LarryT
 
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