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Hi Guys.

As far as I can find, the EC2/3 A8 (Renesis) version of the manuals does not have the section - ’Setting Nominal Timing’ that are referred to in Mode #8 instructions.

What is said is:

You should not make any adjustments in mode 8 until you have timed the engine statically as described on page 4 in INITIAL TIMING ADJUSTMENT.

Can anyone provide the instructions for timing the engine statically.

I’d always thought that the Renesis came statically timed, as the CAS is fixed.

I have now just found after a good deal of searching in the archives some info about timing the engine, but there are still bits missing in my mind.

I found a comment from Tracy:

If the MP is above 24" Hg the nominal timing is 23-24 deg BTDC but typically the MP will be lower than that while in-flight. The EC2/3 increases the advance below 24". This improves fuel economy. The lower the MP, the more the 'vacuum advance' is. Be aware of this if you are trying to set timing with a timing light (not recommended).

Tracy

So - is setting timing with a timing light not recommended?

I also found some thought from Tracy about adjusting timing in flight:

1. Establish normal cruise and get the plane *perfectly* trimmed in zero turbulance air.

2. Lean engine for best economy. This is about 1525 - 1550 EGT on mine. This varies with altitude & powersetting.

3. Put EC2 in mode 8 and advance timing 1 step (1.875 degrees) and note change in rpm (a digital tach w/ <= 10 rpm resolution is a must).

4. If you got an increase at step 3, repeat until there is no increase in rpm.

5. Retard the timing 1 step.

So is anyone able to provide:

1. Details from another version of the manual that has the ‘Initial Timing Adjustment’ section and whether this is defunct for Renesis?

2. Otherwise any instructions on how to set the Nominal Timing amount and at what RPM. Is timing set at idle OR do you set it at an rpm above a point at which the EC2/3 advance algorithm has done its thing?

3. Should ultimately the timing be set in flight via a procedure such as what I found above.

I’m just not understanding why this seems so hard to find, or am I missing something that is obvious to everyone.

Thanks

Steve Izett

On 25 Feb 2022, at 4:12 pm, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:

Hi Guys.

Here is an update on what I discovered in relation to timing of the Renesis 4 port.

I discovered that the trigger wheel has a stamped arrow at the edge (See top of trigger wheel in photo) and this lines up with a reference point on the front case adjacent and above the e-shaft and trigger wheel.
I believe this mark in the trigger wheel is likely 5 degrees ATDC.
I used the technique of connecting a manometer like tube containing coloured fluid to one of the plug holes. When I rocked the prop back and forwards I could see a peak in the fluid in the tube very near where that arrow lines up with the reference point on the front cover. I could not read it more accurately than 5 degrees.

I then put a bit of paint in the arrow and used a timing light to record nominal timing of ~16deg in advance of the arrow, meaning 16+5 = 21 degrees BTDC of nominal timing.

I’m hoping someone might be able to affirm I’m on the right track here, or not.

I then adjusted the timing using Mode #8 advancing it 5 clicks (5 degrees) and this was evident in the running engine when rechecked with the timing light.

I called our local rotary engine specialist friend and he said that he sets up RX8 engines with Motec ignitions at a nominal 26 degrees BTDC and that the OEM computers have even more advance for reasons of emission reduction and that retarding OEM RX8’s yields performance improvements.

So I’m wondering what this means.

Can others offer any further feedback on nominal ignition timing of Renesis engines and particularly the 4 Port.

It crossed my mind that different coils might have slightly different trigger circuit delays, therefore changing the timing, but I think any difference in delays would likely be very small and not a significant factor to be considered. We are using LS2 Coils.

I’m a bit shy to simply add 5 degrees of Advance and make the nominal timing 26 degrees BTDC. I thought I might Advance it 3 degrees and test fly it.
Appreciate your thoughts here.

I’m wondering the what kind of change those 5 degrees of advance will bring to EGT’s, Engine Cooling and power.
Tracy, Lynn H, are you there?

I realise now I should have sorted this out ages ago!

Thanks everyone.

Steve Izett

<RX8 Trigger Wheel.jpeg>

On 25 Feb 2022, at 6:42 am, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:

Thanks guys.

Dave, did your measure the timing with a timing light and with the prop on?
Must have been pretty windy getting that data!

I’ll mark up the ring gear with a TDC mark this morning and measure the current EC2 base Mode timing

Which method do people prefer to get TDC? I think I have read about these 3 methods.
1. Rotor #1 equal Screwdriver depth to rotor face through both plug holes
2. Rotor #1 volume null using water in a tube - I think this might be from Lynn H
3. Rotor #2 bisecting Apex seal across T & L spark plug hole

Can anyone else tell us their nominal timing at idle. Ours is ~1800rpm.
And particularly anyone running a 4 port renesis like Tracy’s RV4.

Cheers

Steve

On 25 Feb 2022, at 6:07 am, Pam & Dave Williams padajute@idcnet.com <flyrotary@lancaironline.net> wrote:

Hello Steve,

My timing is locked in at 35 degrees before top dead center from idle to 6500 RPM. You are on the right track because retarded timing will raise exhaust temperature. I have a 13b with Tracy's EC2\EM2 and the RD-1AB redrive.

Thanks
Dave Williams

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Wednesday, February 23, 2022 6:45 PM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Timing

Hi friends

On my last flight I experienced high indicated EGT’s so as part of looking into this I would like to check my timing.

I have a Renesis engine and Tracy’s EC2.
In his A8 (Renesis) version of the handbook under Mode#8 Timing Adjustment it says to refer to ‘Initial Timing Adjustment’, however I can’t find any such instructions in this version, probably because it has a fixed position CAS.
Can anyone enlighten me on what the static timing should at a given idle rpm?

Much appreciated.

Steve Izett

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