Jeff,

 

To maintain the original timing above 1200 RPM after setting mode 8 to 10 degrees retarded, one would set the mechanical setting to 45 deg BTDC as you stated.

The image on the website report for 5200 RPM shows the timing as 25 deg BTDC calculated based on a mechanical setting of 35 deg BTDC when the mode 8 setting is 10 deg retarded.  I need to add those conditions to the description of that image.

You are correct that setting the mode 8 timing affects the entire range. 

Tracy would be the one to definitively comment on this, but my measurements seem to indicate that the ignition timing calculated and applied by the EC2 is continuously based on both RPM and MAP.  This should be much better than just 2 ranges.  I’m sure that Tracy has spent a lot of time and effort on this.  There is just something strange going on at low RPM and when he finds out what it is,  the low RPM range anomaly will be corrected.  I consider the 10 deg retarded mode 8 setting a work-around until that occurs.  For many, the work-around doesn’t even appear necessary.

 

Steve Boese

 

 

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Jeff Whaley
Sent: Thursday, December 10, 2009 8:14 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: EC2 signals

 

Steve:

Yes, excellent work and report.

I understand the part about random EC2 dwell times during starting causing the weak or non-existent spark but I’m not 100% clear on the relationship to Mode 8 timing retard and the overall ignition timing result at cruise or WOT settings. Your conclusion states: “ A mode 8 setting of 10 degrees retarded is used for starting. Desired ignition timing is achieved by setting the CAS physical position in the engine block to compensate for this.”

Does this mean that the standard mechanical setting of 35 BTDC should be changed to 45 BTDC to compensate for the Mode 8, 10 degree retard?

What was the net ignition timing at high rpm result from this experiment?

 

If I understand the EC2 timing correctly, once you set it to +/- zero it affects the entire operating range.  A retarded timing would definitely improve starting and low idle but you have now also limited the maximum advance at cruise or WOT.  It would be great if the EC2 could have 2 timing settings based on rpm, similar to the 2 MAP ranges of below and above staging.

Jeff