Noise can come from areas you dont expect too....
But check yer chain inna few different places cuz the chainrings
arent on the axles perfectly. If you have about 1/4-1/2" slack
you should be good. Also.....the cog sort of grinds until it seats.
Could be a little while(??)
On my Mercier, I can only assume the BB was stripped when it was
installed or rumors of Merciers being built from KHS seconds are
true. It would not come off even using the most scary tool 'o death
on it. I just ended up pouring real heavy oil down the seat tube