This is the statement from Tower Hobbies DLE 30 manual which is a disgrace to the intelligence of anyone who has every worked on small ignition engines. It destroys the validity of the whole manual. And they copied this into the other DLE manuals also.
I must make note here that Tower does not send you this manual when you buy an engine from them.
AFAIK it is only as a PDF file on the tower site adjacent to the engines.
Original: Tower Hobbies
Ignition Timing Adjustment
For most applications mount the sensor with the mounting screws
centered in the slot. The ignition timing is preset on the DLE-30 at 46°
before Top Dead Center (TDC). The ignition timing can be advanced
or retarded slightly by loosening the (2) ignition sensor phillips
head screws and sliding the sensor to the full extent clockwise
(47° advancing the ignition) or counter clockwise (45° retarding
the ignition). Be sure to retighten the phillips head screws after
adjusting the ignition timing.