A Call to LSE helped clear up some questions:

 

Q: Does the dual LSE system rely only on the primary sensor for timing so that both sides would be sync'ed?

A: No, each side uses its' related sensor for timing.  If a sensor fails, the dual system will use the information from the remaining operating sensor.  Each side communicates with the other and that is how a timing difference between the two can be displayed.

 

Q: I note that when I use the mag hole sensors, I have to correct the displayed timing if I have, as suggested, retarded the timing by setting the apparent TDC 5 degrees after the true TDC because of high compression.  Why not so with the crank sensor?

A: The Mag hole sensor is fixed at detecting 45 degrees before TDC and TDC.  Based on sensor position (and other factors), the BTDC timing is computed and initiated at the correct moment.  The system still thinks true TDC is TDC, thus the displayed valued must be mentally adjusted.  If the engine base timing is 25 BTDC, the crank sensor magnets are 45 degrees apart unless it is a high compression engine where the lead magnets would be placed at 40 BTDC.  In this case, the computed and displayed timing is the true timing.

 

Q: Why is the display RPM so different than that shown by my VM system and what should I do about it?

A: There seems to be an effect from the hookup to the digital VM RPM back into the LSE unit, causing the analog display to be at a discrepancy.  Note that .01 V is 100 RPM on the LSE display.  There is no effect on the RPM used by the LSE unit to compute the timing. In a dual setup, one could hook the VM to one unit and the LSE display to the other.  The VM RPM display should be accurate. (Note: at some future time, I will take the digital RPM output from each LSE unit and run it through a selector switch and then to the VM input.)

 

Q: Why was my initial timing display at 1000 RPM off by 1 degree between left and right and, in flight at 2500 RPM it was off by 2.5 degrees.

A: Gear lash at the sensor/mag drive gears.  Timing should be verified at above 1600 RPM to eliminate the gear lash for 4-cyl engines at low RPM.