Bicycle Mechanics - mixing crown races

In short, I am putting a new fork on the bike. The old crown race is a 27mm and the fork requires a 26.4 mm. Instead of getting a whole new headset (threaded one inch), would a replacement 26.4 race work with a headset that came with a 27mm race.

What I think is odd, this is a 96 Bianchi Eros with a campy headset. I would have sworn it should be iso?

Any thoughts?

(Dang, I have not posted here is quite a while)

As long as the bearing cages and the other side of the race match so it runs solidy in the track no problem. I've done it a few times and the earth did not stop in its orbit. The key is to ensure that the coning angle is still decently close to the 40 to 45 degree angle you should have.

Thanks!

I did it with a tange race. Not pretty by any means, I heated the race and still had trouble getting in seated. I had to use the bearings that match the race (they were made better) but the rest was butter. I also gave my pinky a good whack and took off a chunk of skin, but it grafted back on pretty well. I can't really say I am happy with the way it turned out as it seems "rigged" despite who well if feels. If anyone searches this post just get a new headset to go with the modern fork.

What brand/model of headset? Some brands offer both sizes and offer just the race seperately. You may have to email them directly to find out.