Stupid question: Can someone go into depth on this 'time by ear' business?

Thanks! :)

The gear that drives the pump has marks on it; the gear that drives that gear has marks on it. Line up the marks and the pump gear is timed.

Put the pump into the pump gear and the timing should be close enough to run.

Retarding the pump at that point will cause real crappy performance, advancing it will give better performance and efficiency in almost all cases. In reality, most applications will gain better performance and efficiency with the injection pump gear jumped an entire tooth.

The only time advanced timing is a liability is if you're running drugs, under which case it makes headgaskets much more likely to blow, or if you're operating under a really heavy duty cycle, in which case the advanced timing has a noticeable affect on engine coolant temperatures.

People rail about EGR and catalytic converters castrating engines in order to reduce emissions... The stock timing position is just as neutering.

To "time by ear" you move the pump around until you find the spot where it runs the best.