1. Late timing will build heat much faster.
2. If your vacuum increases then your combustion is more efficient.
3. Late timing sends unburnt fuel out of the tailpipe.
All HAIL to the one who got it right, ESPECIALLY with number THREE!
That ONE reason alone right there could be called the only reason the factories specced timing so low. Because it DOES send unburned fuel through the exhaust to run retarded timing. GUESS WHAT? Even to this very day, vehicle inspections STILL don't test the correct way to measure an engine's true efficiency. They measure for hydrocarbons. Hydrocarbons are only emitted when fuel burns. The more hydrocarbons, the more fuel has been burned, so an engine that emits a lot of hydrocarbons is putting more fuel to USE!
This is why backin off the timing will cheat your way out of that test, because it tests the WRONG way. Sure, pollutants aren't good, but what about RAW FUEL coming out of the tailpipe. That's both BAD and a WASTE of energy. Pulling the timing up makes more use of available fuel while making more power. There is no down side.
