RE: Scratch Built Ignition???
The CH Ignition only has the automatic advance you speak of if you buy it for extra. The small weekwhacker conversions they sell don't have automatic advance as it is not needed. These engines are small and low compression and by setting them at a full advance of about 28 degrees they still start without kickback and idle slowly enough. The automatic advance is recommended for larger and/or higher compression engines.
Take care,
AV8TOR