Helping out ? Ed is the manufacturer of the syncro spark chip...the ignition on a DA, 3W, ZDZ, RCS, etc.. is NOT controlled by a syncro spark chip..The ONLY ignitions that use this chip are C&H, RC, and Silent spark....
The low speed needle setting will affect the timing..If it's too rich the timing, controlled by the crank rotation, will not advance as fast if the low needle is too rich....
The ONLY timing that is completely controlled by the throttle is a C&H or an RC or a Silent Spark with mechanical advance connected directly to the throttle......
If you have an engine with C&H and you think the timing is inconsistent you would have to run it with a timing light and a degree wheel...Have you done this ?? Where does the timing begin to advance ? How many degrees at what rpm ? Anything else is pure speculation....
Only ignition in recent memory that had a "step" in the advance curve was the early Reichmuth...It would change rpm somewhere in the 1500-2500 range, from a few degrees to the final setting, around 28 degrees...a small change of 5 or 6 degrees at 1200 rpm would be barely noticeable in the running of the engine, if at all....If you doubt this, get a mechanical advance engine and try different settings..I have been making my own ignitions and mechanical advance units for 16 years, maybe I don't know enough about it yet....