SU Needle difference

[Eriks Skinkis <eriks@netspace.net.au>]

I have two sets of 1.25" SU carb's. Looking at the needles one pair has
the later type spring loaded needles stamped "AAC" while the other pair
has the earlier type fixed needles stamped "M".

Is there much difference between the "AAC" and the "M" needles, would
one be better than the other?

Thanks,
Eriks.

Midget '70