Can't advance timing?

Why?
Because if you had any understanding of the internal combustion engine, you'd already know...
90 degrees?
Okay...
The spark has to be ignited at a precise point in the compression stroke to light the fuel/air mixture at the right time. Too early and the piston wants to reverse direction/kick back. Too late and the engine is lazy and inefficient.
The reason for it to occur 7-10 degrees BEFORE TDC in a relatively stock engine is because it takes a brief time for the ignited flame to spread. Again, if it lights too early because of too much advance, the mixture tries to burn before the piston is close enough to TDC. This will result in detonation, maybe bent rods, broken piston ring lands, etc.