Dan,
Welcome!
To advance the timing, the top of the pump has to be rotated towards the valve covers. Another way to put it is that if you're standing in front of the truck looking at the engine, the pump gets turned counter-clockwise. Where did you take the measurement from when you turned the pump? There are 2 index marks that are used to mark the position of the pump when the timing was set at the factory. (assuming you have the original pump) One mark is stamped in the mounting flange of the pump that faces the battery and the other one is stamped into the timing cover. When the pump is set at factory timing the marks should line up. What many of us have done (myself included) to advance the timing is to rotate the pump so the index marks are separated by 1/8". This should give you plenty of advance (15. 5deg, approx). This will lower EGT 50-100 deg and boost by about 2 psi. If you have managed to turn the pump 1/2" relative to the index marks, then you have probably gone too far. As you advance the timing further and further, boost and EGT will drop and noise will increase. Power will also increase to a point then it will begin to drop if you advance too far. There isn't much room to turn the pump anyway because the AFC housing is going to hit the intake manifold, so this should save the engine from possible damage.
The reason you see reduced boost and EGT when you advance the timing is due to the fuel being injected sooner. This begins the combustion process sooner, such that it also finishes sooner. The effect being that more heat and work is put into driving the piston and less is allowed to be purged out when the exhaust valve opens. Since you have less heat and less expansion of the exhaust when it reaches the turbo, you get lower boost and lower EGT. The downside is that the elevated cylinder pressures also create increased emmision of NOx, (oxides of nitrogen), a greenhouse gas.
The easiest way to reach the bottom bolt of the injector pump is with a wrench that is specifficaly designed for that purpose. They are bent into a C-shape and allow you to reach under the pump. You can get a good deal on one of those wrenches at
PDR . Or, if you feel creative, you can take a blowtorch and bend one up yourself (I made my own timing wrenches this way
) If you want pictures of the timing wrenches and good info on the timing adjustment check this thread:
https://www.turbodieselregister.com/forums/showthread.php?threadid=60101&highlight=timing
For pictures of the pump and reference marks, look at BushWakr's gallery in the readers' rigs:
https://www.turbodieselregister.com/user_gallery/displaygallery.php?userid=5168
Hope this helps. Please reply with any questions you may have.
Cheers,
Sean
Attention: TDR Forum Junkies 
(This is the second time isn't it?) You guys are just too fast for me. 
Looks like I missed the mark. . Sorry Dan. . 
