Coffee Appreciation

I think there's also an adjustment you can make to regulate how much water you get per shot. Someone posted something like that around here somewhere a while back. May or may not have been a Classic though. Memory is too fuzzy to be useful I'm afraid.

Adjusting the boiler pressure would change the shot volume.

http://coffeesnobs.com.au/YaBB.pl?num=1175171794

http://coffeesnobs.com.au/YaBB.pl?num=1143118905/0

*Yep I can help with this one. The adjustment is hidden inside the OPV. You first have to identify the OPV which is attached to the inlet of the boiler. The pump feeds directly into it. There is a pipe that comes off the top and feeds back into the reservoir. That return pipe (silicone rubber) is attached to a hexagonal nut that you must remove to reveal the OPV adjustment. Then you'll need an allen key (either 3 or 4 mm) to adjust the OPV setting. I used a 270 degree turn anti-clockwise. That lessens the spring tension. I didn't have a pressure gauge at the time, so I used a blind filter basket and calibrated the OPV setting using the return flow rate when the pump is on. It should be about 100 ml in 30 sec. You can check the ULKA site for their pump specs, the flow rate vs pressure curves are there. After you get it about right, you can tweak it until you get what you want.

The result of my modification was amasingly thick crema, coming out like treacle, sometimes in globs. I know from my Faema Family, that this pressure corresponds to about 8.5-9 bar. This was the biggest difference in the Classic vs Silvia shootout I found. The Silvia's higher brew pressure made thinner crema for ristretto pours (30 ml in 30 sec from a double basket).*