V6 engines: what size of shim to use?

[Chisheng Huang <cph@domain.elided>]

The recommended range of intake valve clearances on a V6 engine is
0.475mm ~ 0.500mm.  While I was buying shims at AR Ricambi last
Saturday, I got the impression that several sizes of shims are
available to make valve clearances fall in the recommended range. 
What are the pros and cons to adjust valve clearances close to either
the lower or the upper bound?  Any general rules for picking a valve
clearance to shoot for?  My instinct is to go for shims that give
valve clearances close to the upper bound.  This way, it'll take more
time for a valve clearance to shrink to an unacceptable level.  But,
this is just my wishful guess.  Could somebody with more experience
and knowledge on Alfa engines shed some light on this topic?

Thanks.

Chisheng Huang
LA, CA, USA

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