For your reading pleasure I found this post by Dr. Jim on an old thread:

"The Conti 'Prestina' is about as big a machine as I'd want in my kitchen, and the kindest thing you can say about its looks is "Well, it's not obviously ugly ... But boy, can it make coffee!" I believe that the Conti lever group may be the finest group design ever - certainly it wins the prize for sheer mechanical insanity- and it has proven itself to be a magnificent espresso machine.

I'm surprised that Moschetti still has their Conti - yes, the asking price is stiff, but you'd be getting a machine which should be good for 20 years of home use with no significant service required. "

Dr. Jim wrote:should be good for 20 years of home use with no significant service required. "

Gem of a quote.. perhaps it should be qualified by, "no significant service after you've taken 2 years to tear it down and rebuild from scratch like Dr. G"

Hey Jano:

But it's a simple machine, isn't it? Simple wiring, big spring lever, 1000W element. I'm just doing the 20 year service!

So others don't get scared off by my huge ristretto earlier, this morning I tried 18 gm of Hairbender in the double basket with a much tighter grind. Very slow flow. If I'd let it run itself this would have been a two minute pull. So I was glad to be able to assist the lever and had a very layered shot. Unlike my home levers I wasn't concerned the force I was using would harm anything.

Dialing in starts by choking the machine, so I'm there. Optimal grind seems to be about what I use for my e61 machine or thereabouts. That means the spring must exert about 9 bars of pressure, like my Isomac Amica's pump. Dr. Jim was right, of course, about needing more than a double basket for 18 gm as it was hard to lock in. I won't need to consume half decaf but can just use this as my daily wake-up. Very happy about that.

I have it hooked to an appliance timer and found it has to overcome a much larger air bubble than my home levers. I had to bleed the air out twice so it could properly come up to temperature. So the vacuum breaker I'm about to put in will be essential for running it on the timer.

Gary,

I am now in the process of fixing my Prestina. I'm not doing a full restoration yet as I need a functioning espresso machine too quickly for that. My question for you today is, does your Prestina have a swiveling steam wand on it? The one on mine did, but now that I need to replace the gasket/washer on it, others (Allan Brothers and Orphan Espresso) are telling me that they are not familiar with a swiveling steam wand. I know it had some sort of conical-shaped washer on it because 1) I saw it when I removed the wand, and 2) the end of the wand is rounded, to allow swiveling, and not flat like the end of the hot water wand. I can purchase a new, fixed steam wand, but would prefer to keep the swiveling one since that is what my machine came with. Have you heard a such a thing on a Prestina?

Thanks for your detailed restoration journal on this site. It's giving me more confidence to tear into mine.

Albert

P.S. If anyone else has some useful information on this, please chime in.

Alberto:

Can you post a photo? What you describe as a swiveling feature may be a compression fitting.

Yesterday I took some temperature readings using a thermocouple threaded into the filter basket and what I saw surprised me. Water can hit the coffee cake fairly hot and then it declines gradually and steeply during the pull. I was searching for whether a PSTAT with less temperature swings (smaller deadband) would be better than the stock one in place, which has 0.55 bar deadband. I answered that question but confirmed Allon's observation in a thread that's too old to allow comments now. Here's what he wrote.

"One thing that the lever group has over a pump machine in this regard is that it allows a hot preinfusion followed by a cooler extraction, because the water for the extraction is pulled from the boiler and cools during preinfusion. Trying to do a hot preinfusion with an unflushed pump HX machine would do a hot preinfusion followed by a hot extraction. The temperature of a lever group isn't constant, that is clear - it would be interesting to log the temperature during a shot as well, and graphing the changes during the whole process."

This is the originating thread, where I've added my observations:

The temperature profile of a commercial lever group

And here's what I found. I believe the initial hot water from the boiler followed by a steep temperature decline reveals more layers of flavor in the coffee while softening the intensity of the shot.



For more on my preliminary temperature readings see my restoration thread here.

Gary,

After reading your reply, I looked at the steam wand with a magnifying glass, and sure enough, it has a compression fitting! The photo should be attached. It is so worn out that it looks like a part of the tube itself. Now that that's established, what's the best way to restore it?

Albert

Here's a second attempt at a photo of the steam wand end of my Prestina:

That looks normal and not worn down. With my machine I sealed it against a Teflon washer that I created quite easily with a couple of punches. It gets held in place with the compression nut.

Notice how the end is flat like yours and where it fits inside the nut. The Teflon gasket goes into the hole in the valve.



Sorry for the fuzzy picture, but the Teflon gasket seals against that flat end and inside the port where it attaches. This way you're locking it down onto something that has some "give" to create a good seal.



I think from here more discussion of this issue should be on the restoration thread. This thread is about owner experience of using the machine. I think you'll really like it when you have it working.

Thanks Gary, very helpful. I'll give your suggestion a try.

I just now realized your Prestina was on two threads - restoration and use. I wondered what you were talking about! My apologies.

Albert