Paul
I was thinking about how to lower the effective idle speed.
I wondered if we couldn't make a second set of injectors
that would be for idle and the primary set would be for running.
A relay could switch between the two. Just a thought.
Peter

Why would you want a lower idle speed?
with a 2.85:1 gar box the prop is only turning
at 632 RPM when the engine is turning 1800.

If you are flying a sea plane perhaps you could use
a lower prop RPM. In that case use a 3.17:1 ratio
and a lot larger prop for getting on the step.
The idle speed would then be 567 RPM.


BTW I discovered something about Tracy's  gear box chatter.
Dave Leonard was making a steep approach to SZP and he let
the engine RPM get down to 1500 with a 2.17:1 box. I did not
detect any gear box chatter. Apparently the reverse load
on the prop kills the chatter. Lycoming made
the same discovery on their geared engines.

That is not to say I would do that all the time.
Dave has had a lot of trouble with his flex plate
and sun gear to input shaft connection.

We will see after Dave gets another 600 hours
on the new flywheel and sun gear connection. :)

Paul Lamar