I am having difficulty getting my compressor tight enough. The bolt is in the right hole in the lower front bracket (455 should be in the middle). The compressor needs to twist UP, and that is the difficulty. When I use a crowbar, it pushes the compressor to the left, but it also needs to rotate UP.

I see no procedure in either the Service Manual or the Assembly Manual. Any ideas? Pontiacs I have have a square hole in the bracket and the drive or extension of a wrachet or breaker bar can be inserted and it rotates.

 

Have you loosened the bolts so that the compressor can move easily?
There are three:
one on the 'slider" bracket under the compressor
one on the front top bracket
a nut & bolt at the rear of the compressor

Once those three are loose, the compressor should pivot by prying as you described.

Are you certain you have the correct length belt?

 

The compressor moves freely. I will double check the belt length. Do you put the bat at the top, between the compressor and bracket? It rotates but then stops, and to rotate it more, the compressor would have to lift up. The lower boltis about in the center of the slot.

 

This is the best shot I could find of the AC compressor on my car. The belt is tightened and it looks as if the compressor is slightly below level, with some more adjustment room before it would need to start moving upwards as you said.