There are two adjustments, a coarse adjustment by loosening the clamp where the vacuum advance attaches to the distributor housing, and a small slot where the bracket attaches to the block. Center the slot, and use the clamp at the vacuum advance to set the timing. Small adjustments can be made as necessary with the slotted adjuster.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!