roller rocker valve clearance

Help Again, please.

I recently installed a set of roller rockers in my 1275.
Factory manual calls for 12 thou clearance, but the
roller rocker info says to use a couple thou more. I
did that, but the valve clatter seemed a tad loud. I
have set them back to the standard 12 thou and
they are much quieter -- less embarassing if
ya ken wot I mean.

Performance seems better than ever, subjectively speaking.
Is this going to do any lasting harm?

Fergie