HB - Thanks for point that out. I stand corrected.
Though I still feel it shouldn't be necessary to remove it to find a fine enough grind to get a good shot on a Silvia.

erics wrote:Measure the flow in the return line using a pyrex cup while pumping with a blind filter. With a stop watch, time how long it takes to go from the 2 oz mark to the 6 oz mark or 4 oz to 8 oz etc, etc. You'll come up with 4 ounces in "X" seconds. "X" should be between 27 and 28 seconds. Adjust the OPV as necessary to get this time.

Hi, Does the above go for all models? My Silvia is from 12 06. I just tried this, and unfortunately i reached exactly 40 seconds...what way should I adjust...and how many rounds should i adjust?

Thank you!

Update: Now i turned it counterclockwise (loosened?) - 1½ turn - and now i reach the 4oz in 29 sec!

I have the new silvia mode. I've tested measuring OPV by the volume of water coming from the overflow tube with a blind filter. Then later I got a hold of real portafilter pressure gauge. All I can say is: Don't trust the overflow water volume measure method. Also when measuring with PF pressure gauge one should take it to account that when there is actual liquid flow trough the puck, the pump can produce less pressure.

I did my experiment by opening the pressure PF valve just enough to have flow that was approx 2 oz in 25 secs. (Aimed to 30-40gr of liquid). Looking at the needle and it looked to average at about 9 bars. The pressure without any flow was aprox 10-10.5 bars. According to overflow volume measuring method my OPV would have been set at about 7.5 bars. I ended up not adjusting.

The "overflow method" of determining Silvia's brew pressure is based on this pump capacity curve:

The solid "curve" represents a production average whereas the long dashes and short dashes represent highs and lows off the production line but still acceptable to be "sent out the door". Most of the pump manufacturers that have their products installed in machines discussed in this forum report performance in the same manner.

Adjusting an OPV such that you achieve 3.67 ounces in 25 seconds (4 ounces in 27-28 seconds) has its faults as the pressure at the pump can be anywhere from ~ 7.0 bar to ~10.5 bar. Measuring with a typical portafilter pressure gage also leaves room for improvement. Most portafilter pressure gages (the Scace II Thermofilter excepted) have NO PEDIGREE, i.e. the manufacturer of the gage didn't even want to put his name on it. The pressure pulsations are SOMEWHAT damped out by a small orifice screwed INTO the gage connection rather than supplying a reputable and traceable gage filled with glycerin for $ "X" additional.

I'd say that the best portafilter pressure gage is one you construct yourself (if possible) with an adjustable flow valve such that you can vary the flow to your liking and check/adjust the OPV similarly.

Damn guys...do you want a laugh ...on my behalf!?

It turns out i read on my "pyrex"/Bodum cup wrong. I read "flour oz" and not "US flour oz" which are about 1½ wrong ...i will correct this....and my 40 seconds might just turn out ok after all...

Update: Now i ended up tightening 1/4 round. I now hit 29 sec...

erics wrote:
Alternatively,

Measure the flow in the return line using a pyrex cup while pumping with a blind filter. With a stop watch, time how long it takes to go from the 2 oz mark to the 6 oz mark or 4 oz to 8 oz etc, etc. You'll come up with 4 ounces in "X" seconds. "X" should be between 27 and 28 seconds. Adjust the OPV as necessary to get this time.

This will give you very close to 9.0 bar blind filter pressure and about 8.5 bar with a normal double-shot flow.

I am bumping this rather then starting a new thread. I have a 2008 Silvia, about 3 weeks of use. I believe that my pressure is in the correct range (not getting overly bitter coffee etc) but thought I would double check. I have so far been unsuccessful in getting my spout off my PF to build a pressure gauge so I tried this test instead.

My question is, when do I start my timer, when I press the brew button or when water first starts flowing? With the timer starting when pushing the brew button I am getting 34 sec which would indicate pressure is too high (I think...?). With the timer starting the moment water hits the pyrex I am getting 28-29 sec which tells me I am good.

Thanks

thefly wrote:With the timer starting the moment water hits the pyrex I am getting 28-29 sec which tells me I am good.

Correct, you want to measure under full flow and not include ramp up time.

Perfect Dan, thanks. That made the most sense.

Hi Medic, I have had Silvia and a Lelit grinder since Jan 1, 2009. Here are some of things I have found helpful in getting consistently good shots. And yes I made numerous harsh shots that I didn't want to finish.

Pressure - I backed off about 1 full turn on the opv from the original factory setting.

Dispersion screen bolt - replaced it with a smaller screw (metric) I found at Ace hardware.

Tamper - until the bolt was replaced, I found the concave plastic Rancilio tamper useful as it allowed more
clearance around the bolt head, and bolstered the outer edge of the puck.

Dosing - a scale accurate to 1/10 gram is very useful for analysis, it helps consistency and eliminates this
variable. 3/10 gram can significantly alter your flow rate. Aim for a 14g double to start.

Temp surf - before you lock the portafilter, put a small container under the open grouphead and hit the brew
button.
-if water and steam come sputtering out, it's too hot. Run water until about 3-5 seconds
after the sputtering steam stops. Then lock, load, and brew.
-if no sputtering steam emits, and a gentle flow is observed, go for it. Lock, load, and brew.
I strongly believe that what is often described as harsh, sour, bitter, and undrinkable shots
(all together) are the result of too HIGH a brew temperature. For me, going to a lower temp
eliminated those awful drinks.

Tamping - I have found that attending to the outer edge of the puck has paid big dividends. I use the
stock Rancilio double basket and a reasonable tamping pressure, firm but not super hard. A gentle
'joystick' maneuver followed by a solid tamp, making certain the edges are well tamped has
given my best shots. Pour starts with dark slow drips, followed by a thin slow pour - dark caramel,
then finishes with a faster caramel pour. Approx 2 oz in 29 seconds. ( no more blonding!!! )
Shots are full bodied and full flavored.

From what I have read, I suspect the 'temp surf' and 'tamping' comments will help you the most.

Good luck and stay with it. I hope you and other newbies find these observations helpful.

HB wrote:Correct, you want to measure under full flow and not include ramp up time.

Dan, I have always thought one times from turning on the pump, though I have seen it written both ways. I guess again it is the results, not the method that really counts.