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I once had a circa-62 Specialissima and a ~64 Gran Sport apart at the same time, so I took pictures of the headsets, made a little webpage about them here. As you can see, the non-Campy Bianchi headset uses V-races, like the Stronglight Competition, rather than a cup-and-cone. Upper and lower races have the same Vee shape, and the balls touch at four places instead of the usual two places as with cup-and-cone.

As the pictures show, the Campy parts have the <C> stamping in them, but you have to remove the parts to see the stamp -- not visible from outside. The Campy top screwed race has four pin-holes for adjusting with a pin-spanner, versus only two holes in the Gran Sport, so this may be a way to tell if a headset is Campy. Can anyone confirm, did the non-Campy Bianchi headsets always have two holes for adjusting?

Interesting to me that on the early '60s Specialissima, both races pressed in the head tube are cones, compared to the more usual setup where the lower head race is a cup, with a cone on the crown. This headset has the cup fitted to the crown. Later Campy/Bianchi headsets reversed that -- the lower head race was a cup, using a cone on the crown. I think that later model was late '60s - early '70s. I made a little webpage about that later head cup here.

You can tell which one you have (newer or older style Campy) without disassembly, because with the earlier one, you see the crown race turning with the fork. On the newer one, that thing that looks kinda like a Bianchi crown race is actually pressed into the head tube and does not rotate with the fork. Either newer or older style can be installed on the same frame, so the later headset may be found on an older frame, say if the original headset wore out.

Note on knocking the head races out of the frame, if you need to do that: You need a fairly sharp-edged punch, because the ledge that you have available to hammer on is very thin. The cone inside diameter is only slightly smaller than the head tube ID. You can't use the Campy "rocketship" 4-pronged headset punch (or clones thereof) because the Bianchi head tube ID is quite a bit smaller than a standard head tube. So I used a drift punch, long enough to go through the head tube, but since it was an old punch with a rounded tip, I had to take it to the bench grinder and remove the rounded off tip, making it very sharp. Hit the cone on one side then the other, going back and forth as many times as it takes, quite a few hits required in my experience. The cone is very hard and the punch does no damage to it.

Mark B in Seattle