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How to rebuild a 275 valve

Posted: Mon Jan 05, 2009 1:41 am
by Murff
This info is from Quest Da Turd-Dok:

If you are getting the "A" series valve, no adjustment necessary other than to carefully remove the old schrader valve, clean the F&A tube carefully to rid of the old rubber debris to ensure that the sealing service inside the shrader valve bore is clean, no clogging on the orifice on the other end of the F&A
tube, etc. install the new one and then screw the F&A tube back to the main valve body and that's it!

Of course, you must check to ensure that the valve is functional (try blowing air through while turning the valve between "off" and "on" position to make sure) before you reinstall.

If you are getting the non "A" series (this is the one the comes with "off"--"light"--"on" on the plate), here's what you have to do:

(1) you undo the F&A tube carefully not to strip or cross-thread the F&A tube thread.

(2) you then undo the shrader valve. Chances are, there may be some rubber debris left behind on the inner bore of the F&A tube portion where the old valve used to sit. Carefully, with a jeweller's screwdriver and/or cotton swap soaked in brake cleaner spray, you scrape the valve bore clean(make sure you don't nick it) and then wipe it clean with brake cleaner spray.

You then blow dry the F&A tube and inspect for any corrosion, blockage on the orifice on the other end of the F&A tube, and the upper air inlet part is not clogged with corrosion, etc.

Also remove/inspect/clean the inner F&A rod that came with the unit, making sure that no corrosion is present.

Install the shrader valve into the F&A tube with a proper tool (usually you can get a shrader valve removal tool for car tires from the same automotive
parts shop for a dollar or 2). Make sure that you insert the inner F&A rod + spring back where they belong.

(3) with the valve shaft turned to close/off position and the generator retaining nut removed, you carefully blow air into the generator mating outlet while you slowly thread the F&A tube portion in. With the shrader valve in your F&A tube in a closed position, you shall feel 100% resistance in letting the air through the valve (valve still in "off" position)until you get to the point where you begin to get some air through. Rotate the F&A tube back and forth (this is where most of the time spent on carefully finding this point)
until you locate the point where the shrader valve is barely touching the valve (valve still in "off" position) and it is still in the closed position.
From this point onwards, you rotate the F&A tube counter-clockwise for 1/4 to 3/8 of a turn (that is, with the F&A orifice facing towards you whereas the
generator mating outlet facing away from you). This is to give the shrader valve a bit more slack. Try blowing some air through from the generator side of the valve to ensure that you are not accidentally doing it the wrong way (meaning that you are not slightly opening the shrader valve when the valve is in "off" position).

With this step done, you then rotate the valve to "light" position and you may either suck air or blow while you listen to the valve. Air should be coming
out from the upper portion of the F&A tube (that oval opening close to the thread) and also when you flip valve upside down with the orifice facing you, you shall see that the inner F&A rod is perfectly flush with the orifice opening, thus closing the orifice nicely.

Last step to check is to turn the valve to "on" position and inspect the F&A orifice part to ensure that the F&A rod protrudes from the F&A orifice and
either a slot or a cut appears (to let liquid fuel to go in). Also, try blowing air through from the generator side and it should come out from the orifice
nicely.

That's it!

Lastly, it would be to my recommendation to put on some Permatex non hardening thread sealer before you screw the valve back into the fount to ensure proper sealing (that's Permatex #2).