# my gaggia classic is not pulling great shots



## Tshane (Aug 20, 2021)

hey guys

so I have been a barista for a few months now but have been into coffee for many years. I recently bought a used older Gaggia classic and a Baratza 30 grinder. I have been using the same technique, recipe and beans as we do at the coffee shop just while getting to know my new setup that I work at but have had very poor results. I have cleaned and backflushed the machine with Cafiza I have a VST basket, the flow seems really even, and I do temp surf. now I know that I am not going to get exactly the same results as the multi thousand dollar setup at the coffee shop but I know I should be getting better shots than I am so any suggestions would be great


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## Acorn (Jul 10, 2021)

Tshane said:


> hey guys
> 
> so I have been a barista for a few months now but have been into coffee for many years. I recently bought a used older Gaggia classic and a Baratza 30 grinder. I have been using the same technique, recipe and beans as we do at the coffee shop just while getting to know my new setup that I work at but have had very poor results. I have cleaned and backflushed the machine with Cafiza I have a VST basket, the flow seems really even, and I do temp surf. now I know that I am not going to get exactly the same results as the multi thousand dollar setup at the coffee shop but I know I should be getting better shots than I am so any suggestions would be great


 Hi @Tshane, you're right: it's never going to be the God shot, but Classics can produce very enjoyable coffee. If you're a barista then I won't try to tell you how to suck eggs, so to speak. So I'll assume you're weighing the dose, weighing and timing the shot and that all looks sane. Let's also assume that your grinder is working OK.

The most common adjustment needed on Classics is the Overpressure Valve (OPV). From factory it's set to something high like 12bar. This is so you can use it with store bought espresso in a pressurised basket. But you want it to be at 9bar (or lower, if you prefer). If you're not sure whether this adjustment has been made by the previous owner, the pressure is the first thing I would check.

Here's a great explanation on how to do this:

https://www.coffeeforums.co.uk/topic/3412-adjusting-the-opv-over-pressure-valve-gaggia-classic/?do=embed

You will need a pressure gauge for this. There used to be one on the forum on a "pay it forward" basis, meaning: you pay postage to whoever has it, then you send it on to the next person who wants to use it. I'm not sure it's still going, if not I have one that I'd be willing to send over for postage (assuming you're in the UK? Otherwise it may not make sense vs. the cost of the part, see below) on the same basis: when you're done, post on this forum in the Pay It Forward section of Classifieds and send it on to the next person. Alternatively, you can buy the gauge and fit it to your portafilter, the one I have is this: https://www.amazon.co.uk/Portafilter-Pressure-Espresso-Machines-ESPRESS/dp/B00ONTGKNA


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## Tshane (Aug 20, 2021)

yes I am weighing my in and out and timing my shots

okay I was already thinking about doing the opv adjustment so I guess this seals the deal. My only issue is that the machine did not come with the standard portafilter that has a removable spout, it just has two holes in the bottom, I also have a bottomless portafilter so I was thinking about drilling a hole in a backflush basket and then screwing in a pressure gauge, do you think this will give an accurate reading?


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## Rob1 (Apr 9, 2015)

You're using a different machine and grinder and won't get the same results. You could alter the recipe to get the best shot with the equipment you have at home rather than try to force that equipment to match what you have at the shop. Water might be different too but I'm guessing the grinder and recipe is where things are falling apart and the pressure won't be helping.


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## ratty (Sep 22, 2019)

Tshane said:


> yes I am weighing my in and out and timing my shots
> 
> okay I was already thinking about doing the opv adjustment so I guess this seals the deal. My only issue is that the machine did not come with the standard portafilter that has a removable spout, it just has two holes in the bottom, I also have a bottomless portafilter so I was thinking about drilling a hole in a backflush basket and then screwing in a pressure gauge, do you think this will give an accurate reading?


 You usually have to use PTFE tape when screwing in the pressure gauge in a threaded portafilter to stop leaking. I can't see a drilled blind basket sealing properly as it's relatively thin metal unless you use a longish threaded bar, O rings and nuts to secure the threaded bar tightly in position in the basket drilled hole. Then use PTFE tape on the bottom of the thread where the gauge screws on.

If you take the pipe and top bolt off the OPV then measure 11.5mm from the top lip of the OPV to the top of the adjustment screw you will usually be in the ballpark of 9 bar. Obviously not as accurate as a gauge but will get you nearer the 9 bar setting than the factory setting of 15 bar.

I use a vernier guage's depth gauge to measure the 11.5mm depth.

You can then look out for a used portafilter at a later date.

I use this pressure gauge that's lasted a few years costing £11.99 on the threaded portafilter's spout's thread (same thread) with PTFE tape applied round the portafilter thread.

https://www.ebay.co.uk/itm/161207194396?hash=item2588b2931c:g:N7EAAOSwAF5UZ2~1


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## El carajillo (Mar 16, 2013)

Tshane said:


> yes I am weighing my in and out and timing my shots
> 
> okay I was already thinking about doing the opv adjustment so I guess this seals the deal. My only issue is that the machine did not come with the standard portafilter that has a removable spout, it just has two holes in the bottom, I also have a bottomless portafilter so I was thinking about drilling a hole in a backflush basket and then screwing in a pressure gauge, do you think this will give an accurate reading?


 NO it will not work,

Correction!! should have read further and seen @Rattys text, it could work if the joint was secure.

I was thinking basket in threaded P/F does leak when checking OPV pressure


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## Evergreen88 (Jun 7, 2021)

What's the issue in the cup? Bitter, ashy, sour, lack of body?

What beans are you using?


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## Tshane (Aug 20, 2021)

Okay so I should have been more clear I am going to put a gasket and nut on the other side of the blind basket to secure the gauge

as far as the adjusting the recipe I have tried adjusting the in and the out and letting the shots take longer or shorter but still nothing tastes even close to what I know a good shot to be.

the taste ranges but most of the time it's far more bitter than it should be

I am using a fairly light roast by a local roster


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## El carajillo (Mar 16, 2013)

How long do you allow the machine to warm up for with PF in place ? What temperature does the machine at work use for this coffee ?

It is possible the brew thermostat on your machine is defective / inaccurate / running cool.


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## Tshane (Aug 20, 2021)

Okay guys so last night I adjusted the POV by just measuring the depth of the set screw and this morning I pulled the best shot I've had out of the machine! I am amazed at how much cleaner and brighter the shot tasted it can still use some improvement but I think the opv was my main issue thanks everyone for you input and help!

I will keep my eyes out for a used portafilter so I can dial that opv to exactly 9 bars especially since I now know how much of a difference it can make!


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## ratty (Sep 22, 2019)

I've used one of these Shockwaves shop's portafilter's before and they are good quality at a fair price.

The old used advertised as original Classic portafilters, seem to go for silly money. More to do with 'authenticity' than function I think.

https://www.ebay.co.uk/itm/162051584478?hash=item25bb06f1de:g:13QAAOSwiCRUgdUv


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## Tshane (Aug 20, 2021)

Wow that is pretty cheap I might just do that!

thanks for the link


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