Here is a similar thread: Elektra Microcasa a Leva and Olympia Cremina groups interchangeable?

max wrote: So far I've had a bit of trouble with the coffee. I believe most of it is caused by too low group temperatures (pressurestat set to maybe 1.1 to 1.2 bar).

I suppose that with the heat from the water soaking into the heavy frame and body through the group, a suitable water temperature at the coffee is achieved at a higher pressure to the group, relative to a machine with a lesser heatsink.

I guess that this higher pressure would make for a tastier (what does this mean?) coffee. I suggest that a higher boiler pressure with a weaker spring is preferable to a lower boiler pressure with a stronger spring achieving the same pressure at the coffee.

With higher boiler pressure, pre-infusion pressure would be greater, allowing a shorter pre-infusion period. With less spring force achieving the same pressure at the coffee, the flowrate would be less. The same flowrate could be achieved with less backpressure at the coffee creating a different brewing dynamic.

There is also the factor of the difference in compressibility of the water vapour in a machine at different boiler pressures.

Will a Zacconi group mounted to a Sama Club make better coffee than the same group mounted to a Zacconi boiler?

I think there are probably a few points where the thermal efficiency curves of the pieces of a machine compliment each other and nice coffee is made. I'm sure that this rendement achieved with correctly matched components is more of a factor than the considerations of pressure and temperature above. A coffee machine can be perfectly balanced along a golden curve but likely at only one specific ambient atmospheric condition.

mrb wrote:I will try the Ponte Vecchio basket. I plan to swap in a Elektra Leva group at some point, partly because I already have some matching portafilters and baskets. With the group and boiler mated to opposite sides of the firewall and not to each other, I suppose one could mount group heads with different bolt patterns with relatively little modification.

Let me know how it goes. Since you have a higher boiler pressure, maybe that's all that's needed for mine to make good shots.



I don't know precisely how the other groups are constructed, but since I believe my machine is too cold, I worry that a larger group like the Elektra would be even colder. Therefore I'd be very happy to hear how the machine works out for you with a higher set pressurestat.

I have been out of the country for a while so I haven't had any time to make more attempts, but when I get back I'll try to measure the temperature more extensively. If it's not the temperature, I'm not sure what it could be.

There is another version of the machine with what could be precursor to the Elektra group: https://www.kaffee-netz.de/threads/was- ... rli.82163/
It is apparently also 45mm and looks shorter as well. I will contact him to ask about it.

I forgot to mention the patent as well. Here is the Decarli patent for a steam driven machine: http://www.google.com/patents/USD196629
My guess is that out machines came later (i.e., later than 1963)

max wrote:Let me know how it goes. Since you have a higher boiler pressure, maybe that's all that's needed for mine to make good shots.

I will. When pressure testing and flushing my machine I was impressed by the force of the water coming from the group and imagine this should make for a tasty cup.

https://www.kaffee-netz.de/threads/was- ... rli.82163/

Thanks for the link. I'm thinking you and I may have the same group and the Ponte Vecchio seals may fit.

The machine shown rebuilt here is a la Romana like mine and the group bell is the same shape and in similar proportion: http://www.orphanespresso.com/La-Romana ... 602-1.html

It is noted here that the same unit was compatible with a Pavoni Professional basket: https://www.coffeegeek.com/forums/espre ... ers/419603

This 51mm nominal basket and portafilter is too wide for my group at both the lip and ears. The Elektra leva portafilter doesn't fit either.

I forgot to mention the patent as well. Here is the Decarli patent for a steam driven machine: http://www.google.com/patents/USD196629

--from here: https://www.coffeegeek.com/forums/espre ... sso/643496

mrb wrote: The machine shown rebuilt here is a la Romana like mine and the group bell is the same shape and in similar proportion: http://www.orphanespresso.com/La-Romana ... 602-1.html

It is noted here that the same unit was compatible with a Pavoni Professional basket: https://www.coffeegeek.com/forums/espre ... ers/419603

This 51mm nominal basket and portafilter is too wide for my group at both the lip and ears. The Elektra leva portafilter doesn't fit either.

You are right; the OE group does look bigger than mine. I never noticed that before.

Popped of the shower screen to clean, which was sorely needed. The holes are uneven so maybe it should be replaced?
At least the shots are now better, but they still suffer from low temperatures.

To battle the temperature, I've tried both flushing a bit before the shot as well as reducing the preinfusion time so that less heat is lost to the group. I could probably flush more aggressively. Even after a second shot I have only reached 90°C on the outside. I would prefer a solution where I don't have to empty half the boiler for every pull.

I'm not sure the pressurestat will help too much. Went through the numbers, and raising the pressure to 1.5 bar would only give me roughly 2.5°C. Since the 125°C-130°C water currently entering the group seems to have too low volume heat sufficiently, I doubt that a few degrees extra would help.