Adjusting the A/C Compressor

In an effort to figure out why I have almost no clearance between the A/C Compressor pulley belt and the coolant filler neck, I decided to remove the compressor and investigate.

I soon realised that Jaguar used spacers under the rear compressor mounting bracket to lift the compressor slightly. I fit the spacers and remounted the compressor but I don't think I gained anything. Perhaps I should add my own washers to the spacers to increase the height even further.