My ECU is at fault. I was lucky enough to have a lend of a 164 Q Manual ECU which ran the car straight away however given the slightly different map on the 164 chip, the car ran rich and rough.
The 164's use slightly smaller injectors than the 75 Potenziata's do. 189cc/min vs 200cc/min or about 5% different. The 164 injector open times should be slightly longer because of that and so the Potenziata engine would run a bit rich when run by a 164 computer. This shouldn't make a huge difference to the running of the engine. NO
, the thing won't make more power because it has slightly bigger injectors and longer injector open times.
There is a bigger potential difference, though.
The 164 engine may locate the CAS in a different spot than the Potenziata's engine.
For some absurd Bosch/Alfa Romeo reason, there are 2 sets of CAS mounting bosses on the front plate of the engine, maybe the 164 engines used the more retarded/lower (retarded by at least 20 degrees) set of mounting points.
Double checking where the 164 Q located its CAS would be a very good start.
If you plan to keep the engine near enough to standard, just keep the factory set up and have a 164 computer retuned (a bigger air flow meter would be a benefit, too).
Get in contact with Festy on the AlfaBB, he's a fellow Aussie who is trudging his way though the factory Motronic system and might be able to help you out with the converting the original Potenziata's maps into the 164 computer.
Double check those CAS mounting points are the same between the Potenziata and the 164Q first.