Rick is right it would advance the timing on a manual pump but the td27i has an electronic pump so the timing is done electronically anyway, If you look at it this way the pump will wear over the years so what is happening at the front is not necessarily happening at the rear, so by advancing the pump slightly we remove the wear. There is a section in the manual that shows how to do it properly with a dial gauge in the rear of the pump. But I trust someone who's been setting up diesel's for 30 years to do it for me
. Its not a nice job to do as Rick said its slacken the fuel pipes and remove the vac pump to get at the bolts.