and I did, the answer is they varied depending upon the use.  Joe did say pick a matched set and go with them.

You might try www.joecurto.com 718-762-7878

Jim my post on the Classic Mini asking about twin SU HS2 carburetors and a specific part in that carburetor ( AUC1432 ) has nothing to do with the new MINI engine, nor the competency of a mechanic.  A competent machinist could easily remove 0.100" from the top.  What I was asking was what is the length of the part from new.  Checking around a dozen of  these parts I find different measurements so I may already have a modified set,

Why couldn't a competent mechanic do the job? Is the new mini engine that complex? 

Ian, I can't say that he does but other sources say words to the effect of " lift the piston as far as you can from the bridge with a finger as far as it will go you will find it still projects partially into the choke tube because the piston is too long and fouls against the screwed damper cap.  The solution is brutal but simple - saw or grind an appropriate amount off the top."
What I am trying to find out is what is the starting point of a new AUC1432 - how long is an unmodified piston?

The piston protrudes into the throttle opening, so maybe to get it out of the way to improve air flow. Another less radical way is the chamfer the leading edge to reduce turbulence.

Does he explain what impact this might have?

Cheers, Ian

on the HS2's what is the length of the piston assembly as measured from the bottom (Where the needle is attached) to the top (where you top up with oil)?  Just trying to find the height of an unmodified AUC1432.  The SU Carburettor High-Performance Manual by Des Hammill shows removing a minimum of 0.060" to a maximum of 0.100" from the top of the piston.