Hi folks,

I'd like to understand something I observe happening when pulling shots on my Gen 3 La Pavoni with different coffees dialed in to different grinds. When I lift the lever a single time to pre-infuse, then pull the shot after about 8 seconds, I find that the amount of liquid I get in the shot varies quite a bit from coffee to coffee.

For each shot, I grind 15g of beans. The results I get for different beans are as follows:

Sulawesi, roasted City+, pretty hard/dense bean, roasted a bit finer: 25-27g
Natural processed Guji Hambela roasted City+, more delicate/softer bean, roasted a little coarser: 17-20g.

These grinds are what I've dialed in for best flavor after experimentation. To satisfy my taste in espresso, I compensate with an appropriate amount of Fellini pumps to reach around 37-40g, and my result then is pretty enjoyable.

Mostly out of curiosity, I wanted to get some insight into what's causing the differing amounts of espresso output. Intuitively, I would've expected the coarser grind / softer bean to create more of a pressure disparity between the group / boiler and thus result more water flowing from the boiler. But that's clearly not what's really happening

Thanks, Eddy

Eddy, this may help.

Bleeding pressurestat lever machines. (Especially 2nd gen La Pavonis)