Mailing List flyrotary@lancaironline.net Message #27437
From: Al Gietzen <ALVentures@cox.net>
Subject: Timing
Date: Thu, 3 Nov 2005 23:26:46 -0800
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

 

 

But I’m in a bit of a quandary.  I set TDC on the flywheel as Lynn described and it looked so perfect. But the timing light is showing it firing at 40+Deg. ATDC and when I turn the Crank Angle sensor as far as it will go trying to advance it I can only get up to about 20Deg ATDC. The engine, however, sounds MUCH, MUCH better as I advance the timing – although that may also be because I pickup about 100RPM when I do that. 

Oh, and the little red and yellow dots on the main pulley seem to be correlating with the flywheel marks at this point.

 

I guess I’ll have to see if I can re-position my Crank Angle sensor this weekend and see what happens when I can advance it further.

 

If you’re confident that the TDC mark is correct; then, yeah; 40 ATDC is “WAY” retarded.  I don’t recall how many cogs are on the CAS drive, but it seems you will have advance it just a bit more than 1/16th of a turn.  That’s at least one, and maybe to cogs.

 

It’s amazing how far the timing can be off on these engines and still have them run.  At first I thought my engine was running quite well.  Then I ran first on leading ignition only, then on trailing.  It was about the same either way; whereas it should run quite noticeably better on leading only.  Giant clue that the timing was very late.  Do you have any way to switch off leading and trailing ignition?

 

Al

 

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