I have a pair of early 40 DCOE carbs and I have noticed that at some point someone has cut the end of one of the throttle shafts so there is now no room for a nut on there. When fitted the car ran roughly , it barely idled and when revved up the revs dropped very slowly. I didn't take much notice at the time because I wasn't going top use the cars and removed them but now I want to use them. Will they be ok without the nut of were all the problems I had because of the missing nut causing an air leak?

Go to the weber shop and get a new one.

http://www.ebay.co.uk/sch/sis.html?_nkw=WEBER%20DCOE%2040%2045%20CARB%20THROTTLE%20SHAFT%20SPINDLE%20BEARINGS%20X%202&_itemId=151011562444

[Edited on 22/9/15 by benchmark51]

If you think there are air leaks a set of bearings and seals would be a good move too whilst you have them in bits.