Ok, so a couple of nights ago I swapped the flow rate restrictor (aka gicleur or jet) from the standard one ( 0.8mm ) to the one recommended ( 0.6mm ). No issues encountered with installing it.

How to install a new gicleur on a La Marzocco Linea Mini

I did a 30-second run tonight, no portafilter present and measured 325ml of water output. The expected output for 0.6mm jet is 250ml, and for 0.7mm jet is 350ml.

http://www.lamarzoccousa.com/wp-content ... Guide.docx

My pulls are a bit better, but not amazingly better. I get less pinholes and otherwise disturbed pucks, but they are still getting a water blast, just not as much.

Did a pressure check with a blind filter and I'm seeing 10 bar on the built-in gauge. I have not touched the settings on the pump. I see about 9 bar while brewing normally.

So what is reference for setting up the brew pressure? Blind disk and 9 bar?

For what it's worth, the manual states "The water pump pressure should be adjusted when the machine is operating and coffee is present in the portafilter." A technician at LM clarified that the water pump adjustment screw can be safely turned without the pump turned on. Making adjustments with a coffee-loaded portafilter in place and pump turned on allows you to see the brew boiler pressure changes in real time.

I don't know the standard method by which LM techs calibrate pump pressure before shipping. Probably does involve a blind disk or some kind of fixed resistance in the portafilter as you suggest.

Pressure against the blind filter will typically be about 1 bar higher than against the puck. Pressure for brewing is measured against the puck with a standard flow rate (this is why the Scace device has a valve to simulate flow through the puck).

So if you want 9 bar on the puck you would typically adjust to 10 bar against the blind filter, then pull a few shots to confirm and adjust if necessary.

BTW, you really should try a lower pressure with the smaller gicleur it will reduce your flow rate further.

What about just reducing your brew pressure, without the .6 modification?

I would try the 50l pump.! The .6 Gicleur/restrictor should be just right.
In Denmark They come with the bigger 150l pump
On my Machine the 50l is perfect.

/Uldall

thecatch83 wrote:What about just reducing your brew pressure, without the .6 modification?

Go for it. It's free, reversible if you want, and doesn't void the warranty. All you have to lose is time and a few shots to dial in.

Follow the specs I listed on other threads and you will be most of the way there.

The .6 will get you the thick body and mouthfeel that you lose from 9 bar and will will also give you more consistent and even and higher extractions.

I'm really not seeing much evidence of improved shot quality. I'm getting less channeling and pinholes with the 0.6mm jet, but not tremendously different.

I reduced the pressure on the pump to where I see 8 - 8.5 on the gauge during actual brewing. With this setting, I'm pumping about 280ml of water in 30s from the brewhead with no portafilter in place. I'll let this roll a few days and some more shots.

Your toes are wet but you've got to jump in to be able to swim!

Between Michael at his shop and myself at home we have pulled over 40,000 shots CAD (cntl alt delete) style. The work has been done for you. Just jump in and try the whole protocol. After 25 plus years of chasing espresso I promise You won't regret it.

Between Michael at his shop and myself at home we have pulled over 40,000 shots CAD (cntl alt delete) style.

Could you please explain what "CAD style" means? And is there a reference to these 40K shots somewhere?

Please read :

https://strivefortone.com/2016/05/18/th ... re-rehash/

It explains most all of it. Some other info is on the installing new gicleur on a La Marzocco Linea Mini thread.

Over the past 4 months Michael has pulled over 500 shots a day at his shop, while I've been pulling a relatively minuscule dozen or more shots everyday at home.