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OK Mike, here's where I think we are..
First question is: Is your mixture monitor is working correctly.
Once you get Mode 3 roughly set at 22" MP, you should be able to run
the MI smoothly up and down with the mixture knob. If not, it's not
working well and that needs to be addressed before going on.
About the MI confusion:
I refer to each character of the two character MI as being composed of 7 or 8 (depending on display type) bars each for a total of 14 or 16 bars.. Hence the confusion. 8 bars is about mid scale or 1 full character position. When doing this initial tuning, you should target where ever the engine runs strongest. That could be anywhere from 8 to 14 bars but even this guideline is not etched in stone. There are just too many variables to nail it down to an absolute number of bars. So, the first question is, Where does your engine run strongest at 22" of MP? THIS is your target for initial tuning with mixture knob at 12:00. Forget about the 1/2 scale theoretical stoic. mixture jazz. Once you have a handle on things, you can calibrate the EM2 mix monitor reading to be at mid scale if desired.
As far as where to run the mixture in normal operation, your piston engine is going to be somewhat different than what I specify in the manual which was originally for rotary engines. Rotaries can run with mixture off the bottom of the MI but piston engines will either not run at all or burn valves and/or pistons there. You should be able to lean it down momentarily for testing purposes at mid power settings without damage though
Let me know where you are in relation to these two points and if it is making sense to you.
Tracy
On Mon, May 11, 2009 at 10:50 AM, Mike Fontenot <mikef@apexconsultingservices.com> wrote:
Tracy (and other),
First, continued thanks for the feedback. Like Jim said, "You are making progress". That is very true, I am so far ahead of where I was in August 2007, when trying to run this engine and the original combination of igniters/coils burned out at 3300 RPM. I have a much better electrical system (that I know the details of), control of all the critical circuits, and the engine RUNS! Good things will come.
Tracy, good advice to get on the same page with terminology. I will start with the MIXTURE INDICATOR, rather than a shotgun approach.
1. EM2 Mixture Indicator (MI) - lets sort this one out, I'll try to explain how I understand the MI, and hopefully we can come to a common ground. My notes on tuning keep coming back to the general goal of: "Mixture Knob at 1200 with Mixture Indicator reading 1 BAR for the engine throttle settings, except for Idle where you want 60% or 1+ bars".
My understanding is that the MI on the EM2 Standard Display Page 1 is:
A. MI is right above the voltage reading (Yes I have EGT connected, now I know what those other 4 bars are to the right).
B. MI is 2 BARS HIGH TOTAL. So when I say "50%" I mean "1 BAR". If you define the EM2 display as having 4 LINES, and count
from the top to bottom, Line 1, 2, 3, 4. The MI is at lines 2 and 3.
C. My understanding is that 'stoichoimetric' is at 1 BAR
D. My understanding is that if the MI is below 1 BAR then that indicates LEAN, and visa versa, above 1 BAR indicates RICH.
E. My understanding for tuning goals, is that when the MIXTURE KNOB is at 1200
1. Low MAP/RPM - my goal is to have the MI reading at 1+ BAR, or around 60% because a little RICH is better at LOW RPM.
2. Medium to high MAP/RPM - goal is to have the MI at 1 BAR (or 50%)
3. High MAP/RPM - goal is to have MI around 1 BAR (or 50%). I want to avoid running too lean (below 1 BAR / 50%) to
prevent burning vavles, etc.
F. My understanding is that using the EM2 Table View or Track View, the MI is at the far right and it is a total of 2 BARS
HIGH (again Lines 2 & 3). So the corresponding statements about 1 BAR/50% hold here as well.
Tracy you wrote: >>2 bars is less than 20% of full scale. How can it DROP to 30% from 2 bars? What is your definition of 2 bars? We have an obvious problem with terminology here.<<
This has me completely confused, obviously.
2. I will work on the electrical/alternator system as a priority. I
think I know where the problem is, should not be hard to fix (I hope).
3. Jim: You said I should be able to idle down to 850 RPM. At my lowest throttle setting, when I start the engine the lowest RPM I've ever seen on the EM2 is around 1500 RPM. I can't drop it any lower than that, the throttle level just does
not go any further down. And I am letting it warm up before starting the tuning. I gotta tell you it is a joy to just sit there and listen to it run smoothly.
I'll stop here. Thanks,
Mike
PS. is there a way to simply 'REPLY TO' a posting in the flyrotary list, from that listing page ( http://mail.lancaironline.net:81/lists/flyrotary/List.html )?
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Mike Fontenot
Apex Consulting & Services LLC
Lakewood, Colorado
303 / 731-6645
mikef AT apexconsultingservices DOT com
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