Fill valve for 3.5 gallon toilet
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.