"=A0Joe,<= /font>

T= here was a posting some time back explaining how to find TDC, but a search = of my archives didn't turn it up.=A0 I think it was Lynn Hanover who ex= plained how to do this, but I won't bet my life on that.=A0 This proces= s worked for me on my 20B.=A0 So, I'll try to explain it for you.=A0

= =A0

R= emove spark plugs for easy engine rotation.=A0 On #1 rotor (nearest front c= over) rotate the engine in the normal direction until you can see an apex s= eal in the exact center of the trailing spark plug hole.=A0 Mark a convenie= nt tooth on the flywheel.=A0 (Helps to make a pointer)=A0 Then rotate the e= ngine backwards until you can see an apex seal in the exact center of the l= eading plug hole.=A0 Make another mark on the flywheel using the same refer= ence point as before. =A0Now count the number of teeth between the two mark= s and place a mark on this tooth.=A0 Rotate the engine back again to align = this tooth with the pointer.=A0 This will be TDC.=A0 Now you can mark the c= rank pulley at the pointer on the front cover, or just use the this new mar= k on the flywheel instead.=A0

= =A0

M= ark S.

= Bill B

=A0

Make the pointer so= it can be replaced into the same place again and again, or make it part of= the engine.

= This will get you to TDC within a degree = or so. Once you have a TDC tooth on the flexplate marked,

= (Or valley between two teeth) count the t= eeth on the flexplate and divide into 360 to get the number of degrees per = tooth. Put the TDC tooth or valley under the pointer on the rear iron (the = one with the reduction unit) and turn the engine backwards the number of te= eth to get to whatever degree of advance you need to mark. I think Tracy ne= eds a mark at 35 degrees. Normally I run 25 to 27 degrees total at 4,000 RP= M.

= So mark the teeth with colored paint. Say= red for TDC. Yellow for your correct timing say 25 degrees, and green for = that set up number at 35 degrees. The 35 is for setting up the controller a= nd you can adjust it back to whatever you want.

= If the colors are difficult to see, add w= hite paint to each side of your collors.

= Anything between 20 degrees and 27 degree= s is fine. The rotors operate at 1/3 the speed of the crank so actual timin= g at the rotor is very modest, so 27 degrees is 9 at the rotor and so on. E= ven 20 degrees on low octane fuel is good up to 9,000 RPM.

= =A0

Lynn E. Hanover

Check u= nder the back seat.

= <snip>

On Thu, Sep 16= , 2010 at 5:16 PM, Charlie England <ceengland@bellsouth.net> wrote:

=A0Hmmm...

I've seen a variation on that technique for piston engines using a prob= e in the spark plug hole, but I'm having a hard time seeing how it woul= d work on a rotary. If you do it using just one plug hole, wouldn't tha= t put the center of the rotor face over that plug's hole? Or is that TD= C, 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, & approache= d 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? =A0I recall it being mentioned before that you can't = rely on the timing marks on the pulleys as sometimes pulleys get swapped fr= om one engine to another and may not match up correctly. =A0I feel it is wo= rth checking. =A0Lynn H. has described how to locate TDC (check archives). = =A0Basically, you remove the leading plug on #1 rotor, rotate crank until y= ou see an apex seal in the center of the hole, put a mark on the flywheel (= use a temporary pointer for a reference point). =A0Then reverse rotation un= til you see another apex seal in the center of the hole, put a 2nd mark on = the flywheel. =A0Now split the difference between the two marks and that sh= ould be TDC. =A0Check 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:

=A0 =A0I've got a 74 x88 catto. The Co was a result of the band clamp = not
=A0 =A0sealing completely, but I was going to change to 321 or Inconel
=A0 =A0any way, so I figured I'd do it now and be done with it. I want= ed
=A0 =A0to be absolutely sure my timing was correct before going any
=A0 =A0further down the tunig road. I checked the timing yesterday, and I<= br> =A0 =A0was getting the leading plug firing about 10 degrees in advance of<= br> =A0 =A0those two timing marks lining up at 1400 rpm. I adjusted it so
=A0 =A0that it is now dead on at 1400 rpm. I set it there as a reference,<= br> =A0 =A0it's easy to change in Mode 8. There's no reason to go any = further
=A0 =A0in the tuning department unless I can be assured that the timing =A0 =A0is correct. I've got a factory manual, but have not found any =A0 =A0reference to the timng marks or exactly what they signify.
=A0 =A0Brian Trubee

=A0 =A0-----Original Message-----
=A0 =A0From: Don Walker <drwalker@gbis.com <mailto:drwalker@gbis.com>>
=A0 =A0To: Rotary motors in aircraft <flyrotary@lancaironline.net
=A0 =A0<mailto:flyrotary@lancaironline.net>>
=A0 =A0Sent: Thu, Sep 16, 2010 11:14 am
=A0 =A0Subject: [FlyRotary] Timing

=A0 =A0Brian,
=A0 =A0 =A0Timing is one of the few things I didn't have to mess with.= Once
=A0 =A0all the other problems were taken care of and the CAS was spaced =A0 =A0correctly, the engine started and ran fine. What a day! I am using<= br> =A0 =A0the EC-2 default setting for the renesis as programed by Tracy and<= br> =A0 =A0have not even paid much attention to it or even checked it. Good =A0 =A0luck on your next flight. I assume you are using the EM-2 and
=A0 =A0EC-2. What prop are you using? You make a good point on checking =A0 =A0for CO. I just have one of those stick on cards and should borrow =A0 =A0a real meter as I am running SS flex tube also.
=A0 =A0Don
=A0 =A0RV-8 renesis 76/88 cato

=A0 =A0-- =A0 =A0 Homepage: http://www.flyrotary.com/
=A0 =A0Archive and UnSub:
=A0 =A0http://mail.lancaironline.net:81/lists/flyrotary/List= .html

--
Homepage: =A0http:/= /www.flyrotary.com/
Archive and UnSub: =A0 http://mail.lancaironline.net:81/lists= /flyrotary/List.html