Bianchi Specialissima and Gran Sport headsets

(Scroll down for pictures)

The circa 62 Specialissima headset parts are on the left in each picture;
the parts on the right are from a circa 64 Gran Sport, a cheaper model.

Note the Specialissima headset has a cup-and-cone design and the Campagnolo C-in-a-diamond logo.
The Gran Sport headset has a V-groove design similar to some Stronglight headsets
and is more cheaply made - I doubt it was made by Campy.

Does anyone know which models these headsets might have appeared on?
I'm guessing the other early 60s top-end models like the Competizione & "Team Issue"
probably shared the Campy headset with the Specialissima.

Anyone know what the Folgore or other older Bianchi top-end bikes used?

Some observations:

Diameters are the same, so the Specialissima and Gran Sport parts will each press into the other's frame and fork.
The depth of the bore in the lower head lug is greater on the Specialissima; or, put another way, the thickness of the pressed-in race is thinner on the Gran Sport, with the effect that the Gran Sport race goes in too far into the Specialissima lug. When you assemble it, the crown race then hits on the frame lug before the bearings touch the races, making this a non-workable fit.
One could file, grind or machine the lip of the Specialissima's lower lug, until its bore was the right depth for the Gran Sport headset. Then it would work fine, except then you couldn't easily put a Specialissima (Campy) headset back in later. Taking the lip down to put the Gran Sport headset in the Specialissima would be easy enough and doesn't have to be done precisely, but to go the other way, deepening the bore would have to be done very precisely and would be an expensive job, for an expert machinist only.
The Specialissima (Campy) top screwed race has four holes for the adjusting spanner, where the Gran Sport has only two. If this is a consistent difference, this might be an easy way to tell which headset you have, without having to disassemble it.
Interestingly, the Specialissima (Campy) crown race is a cup, unlike most all other headset out there, whose crown races are usually cones. We often speak of the head tube pressed races as the "head cups", though only one is usually a cup (the lower) and the other one a cone (upper). But on this headset, both head tube pressed races are cones!

Click on the pictures below to see them larger-sized.

head_races_bottom.JPG

head_races_top.JPG

screwed_races_bottom.JPG

screwed_races_side.JPG

screwed_races_top.JPG

Specialissima_crown_race_bottom.JPG

Specialissima_crown_race_top.JPG

Strange Campy Headset part, from mid-late '60s
Click here for more info

Modified "Park" brand pin wrench for adjusting Bianchi-style headsets

I took a Park "SPA-3" (the one with the blue handle) and filed down the rectangular pins
until they were round, and just small enough to fit the holes in the headset.
I used a smallish (~6") 2nd-cut or smooth file, and took my time.

Didn't take long, and I've used it lots over the years, so I'd say it was worth it.

I think the SPA-3 model may not be made anymore; look for old-stock where you can find it.