American Standard Hamilton 1-piece Flush Valve

[Gundraw]

Have a 1 piece American Standard toilet that had a constant trickle into the bowl. I see 1999 stamped in the tank and am assuming this is the DOM.

Fix 1: Pulling the top I noticed the old ball-float valve was letting the water get up to the overflow. I had a spare Flushmaster valve laying around, so I put it in... the water level is right, but I got the same trickle (wth?)

Then I noticed that the flapper had some kind of "adapter" between it and the flush valve. I pulled on it, and sure enough, it was one of these (and the putty seal underneath in bad shape) :

So I removed it, and saw this flush valve with "Hunter" embossed in the plastic.

https://www.guillens.com/AmerStd/2092.017 _.htm

Question 1: This adapter seems wrong in a couple ways. First, it makes the flush volume decrease due to the now higher flapper seat level. Second, the new flapper seat has a smaller diameter than the original, I am under the impression that this size will dictate how fast and effectively the toilet will flush. Am I on track here?

I've never had a one piece toilet before. Is there a way of fixing this RIGHT? Are these flush valves proprietary to A/S? I saw somewhere where there was a 4 digit code on the toilet bowl that identifies the correct flush valve (I do see a 2092 stamped in the tank)?

I noticed this video on YouTube that looked about right:

For all I know, the flapper was the only thing wrong. Are those available somewhere? (A Flushmaster adjust-a-flush flapper did not seal properly).

I realize this is a shotgun blast of questions. I am asking as there are three of these toilets in the house (I assume all put in at the same time) and all of them have these flapper adapters and ball-float valves. I'd like to be prepared to fix them all.

 

[Gundraw]

Update:

First, this site was very helpful in figuring out what toilet I even had: https://www.plumbingsupply.com/american-standard-toilets.html

Second, I believe the "2092" stamped in the tank is the code for the toilet model. 2092 is a "Hamilton" if you look at the link I posted above.

Finally, using that same site, they give a great breakdown of what parts fit, what parts are obsolete, and what replacement parts are available (https://www.plumbingsupply.com/americanstandardtoiletparts-hamilton.html). I used the Korky 100BP flapper from Lowes (after peeling all the sealant from the flapper adapter ) and so far it works great.

American Standard Hamilton, 150 grams

 

[Sponsor]

 

[Terry]

Oh yes, the Hamilton...............
Here is one I pulled out.

 

[Gundraw]

Oh yes, the Hamilton...............
Here is one I pulled out.

Terry, have you found these to particularly problematic? These are toilets that came with our current home. I have been less than impressed with the flush quality as well as the inclination to clog. I am hoping getting the flush valve back to factory will help.

On a side note: I've been a lurker on this site for years and found it indispensable on a number of home projects. Thanks!

 

[Terry]

I think I pulled three of those out of the home, all fairly new. We replaced them with the TOTO Ultramax.
The newer stuff from A/S is better than those vintage Hamilton's.