Adjusting Timing

[Harris Goldstein <hgoldstein@ibm.net>]

I'm having difficulty in setting the timing on my '74B.  I loosen the
nut on the collar (the bolt that sits along-side the block and runs
perpendicular to the shaft), but I can't turn the distributer - at least
with moderate pressure.  Don't know how long its been since the last
time it was adjusted (I've had the car since last summer).

Am I loosening the correct 'thing'?  Is there something I'm missing?
Thanks in advance.