Fill valve for 3.5 gallon toilet

[Chuck711]

I live in an older home and one of our toilets needs a new fill valve. It has a 3.5 gallon tank. I tried installing a fill valve for smaller toilets, but now I have very weak flushing power. I have searched the internet high and low for a fill valve that will actually fill my tank, but haven't had any luck. My understanding is that while the new code requires the installation of more water-efficient toilets in new homes, my toilet should be grandfathered. But good luck finding parts for it! I would rather not replace the toilet, because some genius installed carpet in the bathroom and around the toilet. A new toilet probably wouldn't fit the installed carpet properly. And I'm not ready to rip the carpet up just yet (though that's coming).

Anyway, that's the long-winded way of asking...Where can I buy a fill valve for my 3.5 gallon tank? And please, no generic answers like, "Check your local plumbing supply." If you can, please provide a specific dealer or website.

Thanks.

[jadnashua]

Nearly all replacement fill valves are adjustable in height, either of the tower or the float to accommodate tanks of different height to get the water depth right. Depending on the model of fill valve you have, you may need to twist it (like a screw), or give it a slight turn to unlock it so it can be adjusted in height. If you have the instructions and didn't throw them out, it should describe how to do it, or if you can indicate what model valve you have, someone here may be able to tell you. The only ones that typically are not adjustable are some proprietary ones made for a specific toilet, and even many of those can be adjusted as well.

[Chuck711]

Yes I've tried adjusting it, but even at its max adjustment, it doesn't fill the tank to its proper fill line. It's a Fluidmaster 400 model.

[Terry]

The 400A Fluidmaster has two adjustments.
The first one to make is at the lower end. Since your's is installed already, turn off the water, reach down and pull up the sliding collar at the bottom. This allows you to lift the fill valve higher. I normally have the top of the cap a little higher then the tank edge. Then push the sliding collar back down to secure it.
The final adjustment, or the "fine tune", is the "screw and thread" from the top.

[Chuck711]

Thanks, Terry! I'll try it.

[Chuck711]

That worked! Learn something new everyday. Thanks!

[hj]

quote; reach down and pull up the sliding collar at the bottom

I just twist the top of the 400A to adjust its height.