It's not a particularly difficult conversion - especially if you're a rude
and crude hot-rodder like me....
I just followed the output line from the Ulka vibratory pump to where it
joined an obvious 'intake manifold' and patched the output of the Procon
pump (mine uses 3/8" standard fittings and 40" braided pressure hose) in
there using a 3/8" NPT Male (National Standard Thread) to 1/4" BSPP (British
Standard Parallel Pipe) female adapter. I went through a stupid search to
find these parts - but both Espresso Parts NW and Chris's Coffee are
supposed to stock them.
I then used the existing power wires to the Ulka pump to control a 20 amp
SSR (possibly overkill to use a solid state relay, but I had one handy) to
feed power to the Procon pump.
Note that the pump is controlled by two devices - a microswitch behind the
E61's lever (for pouring shots), and a lead from the machines's control box
(for auto-filling the boiler).
I just dropped the Procon's input hose into a 5 gallon Mineral water jug,
the pump appears quite happy drawing about a 30" head - but I did have to
prime it prior to final installation.
If your machine is a pour-over style, you may need to jumper the internal
tank's 'Out of water sensor' to ground. On my Isomac with a Giemme
controller it was easy to jump from pin 12 to pin 15 to ground this sensor.
Since this conversion is fairly simple, and easily reversible, it's worth
your while to try for yourself - my take is that the taste differences are
fairly subtle - your varietals will retain their unique characters, but that
there was more 'clarity,' more fullness, and more depth to the coffee. Plus,
now I get to play with pressure as well as temperature variables.
I've post a number of threads over at the Home-Barista Espresso machines
forums about this project - they might be useful too.