Ok so I'm at a loss.
I figured the dark matter had to do with the efficiency so I upgraded to Enderium Casing, with Electrum combustion.
I have 3166 HU 3166 Max, 1372% efficiency. Still won't make dark matter.
I tried with the auto dropper from sky resources. stone blocks surrounding the chamber and iron blocks.
Not sure what to do here and the guide doesn't address this really.
EDIT: Tried again after making Signallum combustion heater, still does nothing =(