Main fuel shutoff valve

[Jerrytex]

Looking for suggestions on the main fuel shut off valve. I am putting the fuel system back in my KF 4 and when I got to the shutoff valve, it was very difficult to turn on and off. I had to get pliers to manipulate it. I took it apart and cleaned it real good. Suprisingly it was not that dirty to begin with. I put it back together and it is still real hard to turn. It appears that the valve block and the seat is a tapered fit and seems like it gets bound up as the retention spring pushes on it. I am thinking about just replacing the whole unit with a ball valve since I moving the valve from the throttle mount to the console anyway. Any other suggestions? I am assuming that any 1/4" brass ball valve will work? Harbor freight has a 1/4" valve with teflon seals so I believe that will handle gas. Probably use these for the wing tanks as well?

[szicree]

Having not built a Kitfox, I have no familiarity with this particular valve. However, since a very large number of homebuilt accidents are fuel system related, I would think carefully about using a valve of unknown quality from a store like Harbor Freight. I certainly buy stuff there, but usually stuff that has no cutting edges, moving parts, etc.
(my electric fly-swatter comes to mind). I remember a set of wrenches that wouldn't even fit the intended size of bolt. If these crappy Chinese factories can't even make a 1/2 inch wrench, can they be trusted to make a critical component like a fuel valve? I would suggest at least finding a high quality American made valve, if not an aviation-specific part.

[Jerrytex]

Thanks. I agree about not buying crap when it matters. I am sure I could go to a plumbing supply and get a higher quality valve. I did find a similar valve to the one that came with the Kitfox at our local Marine supply. Might go with it if I can't get the one I have to work more freely.

[Dave S]

Jerry,

Not all that infrequently, a little coating of corrosion or crud can be responsible for changing a smooth working valve to an inoperative valve - doesn't even have to be enough to see - just enough to increase the friction - not that dirty can still be be dirty enough to muck it up. Pretty hard to repair a tapered seat valve if any corrosion is present - usually go for a replacement.

The main fuel valve on our kitfox has worked smoothly from day one and continues to do so without a leak. I would recommend one from the factory - they do a pretty darn good job of getting second party parts that work well with a kitfox without costing all that much - experience is worth something.

One habit I have gotten into with airplanes is always turning off the main valve at shutdown and opening it up at startup (obviously!) The cycling helps keep the valve from getting so it doesn't work.

Get a good one.....not one of dubious lineage.....:)

Sincerely,

Dave S
KF7 Trigear

[jtpitkin06]

http://www.aircraftspruce.com/menus/ep/fuelvalve.html

You can find a large selection here.

[t j]

Here's my fuel valve story. About two months after I received my Classic 4 old Skystar sent me a service bulletin to replace the fuel valve because they had been leaking. The part number in that service bulletin was different than mine so I didn't replace it.

Fast foreword 13 years. My kitfox had been completed for six years but been in storage unflown for those six years. I got it ready and started flying...keeping an eye on that fuel valve because it just didn't seem right for some reason. About a month after that first flight sure enough the valve started leaking when I shut it off after a flight.

I took it apart and the O rings were hard and cracked. Probably from all those years sitting dry with no use.

I replaced it with one of those little 3/8 brass ball teflon WOG...water, oil, gas...valves from the hardware store. It cost less than $3, looks just like the J3 Cub valve from ACS for $125 and now has given me 4 years and over 100 hours flawless service.

I had to cut about a quarter inch off the handle to fit it into the model 4 fuel valve bracket. A couple screw clamps, a couple screws and a little short piece of aluminum angle hold it to the stock model 4 mounting bracket.

[Jerrytex]

Thanks for the pics. That is exactly what I was thinking about doing. The marine valve that I found is built like the one that I have already so it probably would end up doing the same thing (getting bound up). The ball valves are alot easier to turn and most have teflon seals so they are impervious to gas/ethanol. I checked aircraft spruce as recommended and I too saw the J-3 cub valve for $137. While I know not to short myself on quality parts in an airplane, I do think this is a little high for a simple ball valve. Thanks for all the advice.

[t j]

I shut off the fuel because I trailer my Kitfox. Bouncing down the road can cause the carb needles to "Jig" letting fuel flow into the crankcase of my two stroke engine.

[DesertFox4]

I use 3 of the brass ball valve type TJ shows in his photos. They've worked flawlessly for over 7 years.
I am in a hangar so I seldom shut them off ( couple times a year) except to work on fuel system i.e. replacing inline fuel filters, working on carbs., replacing fuel lines and the like.
Not apposed to it, just don't.
Maybe someday my fuel system will spring a leak while I'm away and flood the hangar with fuel. NOT a good thing to have happen at my airport.