Studor valve woes?

[Doug]

I installed a mechanical valve (Mini-Studor Valve) and one problem stopped but still have another. The sinks used to gurgle and drain slowly and with this installation, that stopped, but now, the basin on the right in the picture when both basins are full, will back fill until the left one is empty, then it will drain properly then. So did I install the valve in the wrong place then or what? It has me purplexed. I was under the understanding that the actual valve needed to be just above the basin, is this correct?

Anyway, any suggestions or comments welcome. What's wrong with this picture?

TIA,

Doug

[Speedy Jim]

Good pic. That's correct the way you have it.

Are you saying that water from the left bowl backs up into the right bowl? If so, then it suggests that the drain is partially clogged and not allowing full flow thru it.

Jim