Following the advice of some forum members, rather upgrading I added the Coffee Sensor flow control kit to my Zaffiro to occupy myself. I also have the quick mill pulsor en route to help quiet things down.



Installation was easy, but my old mushroom valve had some pretty nasty scale inside. Trying not to think about what my boiler must look like. I did not replace the stock spring-- I don't really see the point if your machine isn't plumbed.

I haven't had much time to experiment pulling shots but I did take some water debit measurements. I need to take more measurements at each position, but here's a rough curve. It appears there are diminishing returns after a full turn, so I assume I'm getting close to the maximum flow for my machine.

0.25 turn: 1.6 g/s
0.50 turn: 3.88 g/s
0.75 turn: 5.5 g/s
1.00 turn: 7.2 g/s
1.25 turn: 7.27 g/s
1.50 turn: 7.68 g/s
2.00 turn: needed a bigger cup!

I've read that Decent says 3 g/s is ideal for preinfusion, and that the stock water debit on most E61 machines is 7-9 g/s. I decided a good place to start profiling was a few seconds at 1/2 turn (~3.88 g/s) for preinfusion, followed by full turn (~7.2 g/s), and then returning to 1/2 turn to finish the shot. I initially installed the flow control lever to be fully closed at 9 o'clock, but I reversed it so that the lever can rest at one full turn (~7.2 g/s) positioned at 3 o'clock for when I don't have time to fiddle with FC or someone else is using the machine. My theory is that from a resting position of 1 full turn at 3 o'clock, I can easily sweep back and forth 180 degrees to 1/2 turn at 9 o'clock. This should also allow me to sufficiently increase or decrease flow beyond these points without needing to turn the lever against the machine, which just barely squeaks by the hot water switch.

I do the same thing based on Decent readings. I go just passed half a turn and hold it there to start the shot. When the pressure goes up to 3 bars I hold it at 3 bars until I see drips in the cup then go to 6 bars until the end of the shot.

Started shot at 1/2 turn this morning and it ramped right up to 8bar. Tried another at 1/4 turn and that seemed to work better. Will probably reposition handle to prioritize 1/4 - 1/2 turn positions.

I just bought an Isomac Tea 2 with electronic control and thinking if I can add a Flow Control Valve.
I have a Bezzera Única with FC and love it. What valve did you install? Let me know how it works for you
In my Bezzera, I hold 1/8 of a turn and let pressure build up to 9Bar then ramp down to zero at yield point. I feel like it mimics a lever machine.