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Date: Thu, 16 Sep 2010 17:16:01 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Timing
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  Hmmm...

I've seen a variation on that technique for piston engines using a probe 
in the spark plug hole, but I'm having a hard time seeing how it would 
work on a rotary. If you do it using just one plug hole, wouldn't that 
put the center of the rotor face over that plug's hole? Or is that TDC, 
or is there some geometric characteristic of the rotary gear train that 
moves the TDC point?

Would the technique work if you used *both* plug locations, & approached 
one in the forward direction & the other in reverse rotation?

Charlie


On 9/16/2010 1:46 PM, Mark Steitle wrote:
> Brian,
>
> I was curious, have you verified that the timing mark you believe to 
> be TDC is actually TDC?  I recall it being mentioned before that you 
> can't rely on the timing marks on the pulleys as sometimes pulleys get 
> swapped from one engine to another and may not match up correctly.  I 
> feel it is worth checking.  Lynn H. has described how to locate TDC 
> (check archives).  Basically, you remove the leading plug on #1 rotor, 
> rotate crank until you see an apex seal in the center of the hole, put 
> a mark on the flywheel (use a temporary pointer for a reference 
> point).  Then reverse rotation until you see another apex seal in the 
> center of the hole, put a 2nd mark on the flywheel.  Now split the 
> difference between the two marks and that should be TDC.  Check that 
> it matches the mark on your pulley.
>
> Mark S.
>
> On Thu, Sep 16, 2010 at 1:33 PM, <bktrub@aol.com 
> <mailto:bktrub@aol.com>> wrote:
>
>     I've got a 74 x88 catto. The Co was a result of the band clamp not
>     sealing completely, but I was going to change to 321 or Inconel
>     any way, so I figured I'd do it now and be done with it. I wanted
>     to be absolutely sure my timing was correct before going any
>     further down the tunig road. I checked the timing yesterday, and I
>     was getting the leading plug firing about 10 degrees in advance of
>     those two timing marks lining up at 1400 rpm. I adjusted it so
>     that it is now dead on at 1400 rpm. I set it there as a reference,
>     it's easy to change in Mode 8. There's no reason to go any further
>     in the tuning department unless I can be assured that the timing
>     is correct. I've got a factory manual, but have not found any
>     reference to the timng marks or exactly what they signify.
>     Brian Trubee
>
>
>
>     -----Original Message-----
>     From: Don Walker <drwalker@gbis.com <mailto:drwalker@gbis.com>>
>     To: Rotary motors in aircraft <flyrotary@lancaironline.net
>     <mailto:flyrotary@lancaironline.net>>
>     Sent: Thu, Sep 16, 2010 11:14 am
>     Subject: [FlyRotary] Timing
>
>     Brian,
>       Timing is one of the few things I didn't have to mess with. Once
>     all the other problems were taken care of and the CAS was spaced
>     correctly, the engine started and ran fine. What a day! I am using
>     the EC-2 default setting for the renesis as programed by Tracy and
>     have not even paid much attention to it or even checked it. Good
>     luck on your next flight. I assume you are using the EM-2 and
>     EC-2. What prop are you using? You make a good point on checking
>     for CO. I just have one of those stick on cards and should borrow
>     a real meter as I am running SS flex tube also.
>     Don
>     RV-8 renesis 76/88 cato
>
>     -- 
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