I'm confused... Why did you need to shim? It's a screw to preload the pressure relief spring... Or is this some other valve body design?

Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.