White spot in ignition knowledge

[ebola]

Basic timing, vacuum/spring distributors I know well. But hall...What actualy do I change moving distributor cap clockwise and opposite? Its a static ignition(idle advance), isnt it? If so, ecu recognises somehow, that changes are made, or it just adds certain programmed advance to the static I do adjust with distributor cap? Im not sure if my question is clear, but what I actualy need is to retard ignition per all RPM by 2 degrees for nitrous shot on my 87 daytona. Can I do it WITHOUT reprogramming ecu?
Thanks
Andrius

[lametec]

Yeah, just turn the distributor to back off timing 2°.

The computer only advances or retards timing relative to your dist. timing. So lets say at some certain point it adds 20° advance timing. This, on top of 12° advance equals 32° total advance. Now, if you turn the dist to 10° advance, the same situation only has 30° total advance.

Note: Numbers used are just for clarity. Actual advance numbers change a lot depending on several factors.