Internals of an E61 Brew Head [video] - Page 3

Need help with equipment usage or want to share your latest discovery?
User avatar
Paul_Pratt

#21: Post by Paul_Pratt »

Beenbag wrote:Again i suggest, if the designers had wanted this manual control of pre-infusion , they could have simply re arranged the timing of the pump switch cam to be in the "top" detent lever location. That would ensure the brew valve is fully open to the un pumped line pressure for a predictable flow.
I believe the original E61 group is designed to give the user the ability to PI at line pressure just by setting up the elaborate cam system as you prefer. I think this function has largely fallen by the wayside on modern replica groups since they use a simple microswitch.

On the original, pictured below, adjustment is really easy by adjusting the cams position on the metal bar.





With regards the middle position I am in the "no function at all" camp, that is all valves are closed so that you can remove the lever cam easily and that they are both closed. The original cams were made from bronze not brass.

It would be interesting to test a modern group if the middle valve does open correctly, you could do this by removing the lowest (drain) valve and playing with the pump pressure to see if it does still open at a lower pressure.

DaveC

#22: Post by DaveC »

Paul_Pratt wrote:It would be interesting to test a modern group if the middle valve does open correctly, you could do this by removing the lowest (drain) valve and playing with the pump pressure to see if it does still open at a lower pressure.
Or simply put a pressure measuring portafilter on the machine.