I don’t have your type of engine right now, but know it from the Alfa 75 no TS and it’s not normal with the noise you describe. How is your oil pressure? It should be about 3-4 kg idling (8-900 RPM) and 4,5+ kg at 4000 kg. presuming your gauge is right reading. If your reading is much below you might have worn crank bearings. If the reading is OK, it can be a number of things; you have to listen to the engine. Have a Dealer or an Alfa specialist listen they probably know right away what’s wrong.