Lister D Amal carburettor fettling.

Evening all,
I am sorting a couple of Amal carburettors for my Lister D's. The float chambers are well plastered with a vaguely white coloured powdery residue that could be some form of oxide. Is there a tried and tested way to clean all this stuff off? I was thinking of soaking the whole lot in Coca Cola or vinegar and soda but am a bit concerned about the effect on the zinc alloy. The copper float in one carb is absolutely blathered in this stuff that looks like limescale so I am also wondering if anyone has had any success using something like Calgon? Any and all advice or comment will be very much appreciated.
Cheers
Bilmac

Evening all,
I managed to find some distilled white vinegar that I knew was lying around somewhere, there was about 3 litres left so I soaked the carburettor parts in it overnight. It appears to have worked a treat as all the calc has been removed from every nook and cranny. I popped the copper float in also and the has cleaned that off perfectly where it came into contact so I will turn it upside down and do the other end tonight. All the brass has also come clean. All the gunge and nasty stuff was left in the bottom of the vinegar so I filtered it back into the container through a funnel lined with kitchen roll so it is clean ready to use again.I should have done some before and after pics, next time I will engage brain and take some, if I remember.
Cheers
Bilmac