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Adjusting idle mixture before first flight

Draker

Well Known Member
The one last thing blocking my (IO-360-M1B) first flight test is an incorrectly set idle mixture. I'm still seeing no RPM rise when pulling out the mixture, which indicates an overly lean idle mixture. Tried rotating the idle mixture adjustment wheel on the servo in the "enrich" direction. The only effect it had was to reduce my idle RPM to the point where it wouldn't even idle--obviously there is interplay between idle speed and idle mixture so you need to get them both right. I don't have a good intuitive feel for how much I need to rotate the wheel. 1/4 turn to enrich it properly? 1/2 turn? 3 turns? 10 turns? Who knows? I'm kind of fumbling around in the dark. Then, once I get it right, my idle speed will be off, so I'll need to re-adjust the screw again, which will throw off the idle mixture maybe? Good grief!

I fear that doing this by trial and error is going to cause me to start and stop the engine 100 times before first flight. That doesn't sound nice for a brand new build. Should I be worried about limiting the number of start cycles before I get off the ground?

Also, yes, I know you can do adjustments on a running engine, and no, I won't be doing that.
 
Had the same concern when I got my new IO360 Mattituck motor so I called them up. The engine had been run in a test cell already and the fuel servo was already calibrated for idle cut off and full rich mixture. All I had to do was to make sure the mixture control cable provided full throw to each stop. That took several iterations of turning the threaded cable adapter a half turn at a time and also adjusting the cable stay location to obtain full throw. If you're not seeing an RPM rise as you lean, then I would say your mixture is set too rich.
 

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My IO-360M1B from Lycoming had 2 hrs. run in at the factory and ran great right out of the box. I get little to no rpm rise on shutdown. Other than tweaking the idle rpm (Avstar) I have not touched it in 500 hours.
 
The one last thing blocking my (IO-360-M1B) first flight test is an incorrectly set idle mixture. I'm still seeing no RPM rise when pulling out the mixture, which indicates an overly lean idle mixture. Tried rotating the idle mixture adjustment wheel on the servo in the "enrich" direction. The only effect it had was to reduce my idle RPM to the point where it wouldn't even idle--obviously there is interplay between idle speed and idle mixture so you need to get them both right. I don't have a good intuitive feel for how much I need to rotate the wheel. 1/4 turn to enrich it properly? 1/2 turn? 3 turns? 10 turns? Who knows? I'm kind of fumbling around in the dark. Then, once I get it right, my idle speed will be off, so I'll need to re-adjust the screw again, which will throw off the idle mixture maybe? Good grief!

I fear that doing this by trial and error is going to cause me to start and stop the engine 100 times before first flight. That doesn't sound nice for a brand new build. Should I be worried about limiting the number of start cycles before I get off the ground?

Also, yes, I know you can do adjustments on a running engine, and no, I won't be doing that.

The RPM rise method is hard because it requires very small increments of knob spinning to see it after a whole lot of knob spinning just to get into the neighborhood. Very easy to blow right past the rise. If you are adjusting richer and RPM keeps dropping, you were already too rich to begin with and just making it richer and that is expected as most shops set it rich for the test stand run. FIrst engine run is recommended with a rich mixture

Suggest you try the lowest MAP method of setting idle mixture. Search under my name, you will find my posts with the procedure. It is much easier to dial it in that way, excluding the thrill of kneeling near the spinning prop of course. You can do it without the engine running but will take LOTS of starts and stops. Just dialing in the idle RPM will take forever if your not willing to go in there with the engine running, let alone the mixture. Every change on the mixture will make a change in the RPM also. Right now you are likely WAY off the mark (went way to rich if it started stumbling) and it isn't going to be easy doing it without the engine running.

Larry
 
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On the last engine I got from Thunderbolt, the idle mixuture was set way rich - as the engine sounded like a poorly tuned Harley at idle. It took a lot of adjustment to get it in the ball park. Final postion shown in this photo.
62996909-9-BEF-4-DDB-A2-A4-E659-B5546-D0-C.jpg


To the OP, you might be still on the rich side of the mixuture adjustment, not the lean side. I would not be too concerned with the number of starts you need to do to get this right, but minimize the time running at idle as best you can. It only takes a few seconds to figure out if your last mixture adjustment is going the right way or not.

One question - did you either install the Sniffle Valve or put a threaded plug in the Sniffle Valve hole?

Note - the stock AVSTAR fuel manager was recently replaced with the very nice AirFlow Performance FM-150C. This new version from AFP is designed for the Lycoming forward facing sump. The install kit from AFP is bolt on, no changes to throttle or mixture cable brackets and no change to the snorkel. I suggest those still waiting on their IO-360-M1B ask for the AFP system.

Carl
 
If you're not seeing an RPM rise as you lean, then I would say your mixture is set too rich.

Lean mixtures (leaner than Peak, stochiometric or ~15:1 AFR) show no rise, just a drop as you lean. The richer the mixture from peak/stochiometric, the greater the EGT rise as you lean up to that point and then will drop. Idle mixtures should be richer than peak/stochiometric. Best MAP sets for optimum AFR vs a target EGT rise that apporximates optimum AFR.
 
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On the last engine I got from Thunderbolt, the idle mixuture was set way rich - as the engine sounded like a poorly tuned Harley at idle. It took a lot of adjustment to get it in the ball park. Final postion shown in this photo.
62996909-9-BEF-4-DDB-A2-A4-E659-B5546-D0-C.jpg


To the OP, you might be still on the rich side of the mixuture adjustment, not the lean side. I would not be too concerned with the number of starts you need to do to get this right, but minimize the time running at idle as best you can. It only takes a few seconds to figure out if your last mixture adjustment is going the right way or not.

One question - did you either install the Sniffle Valve or put a threaded plug in the Sniffle Valve hole?

Note - the stock AVSTAR fuel manager was recently replaced with the very nice AirFlow Performance FM-150C. This new version from AFP is designed for the Lycoming forward facing sump. The install kit from AFP is bolt on, no changes to throttle or mixture cable brackets and no change to the snorkel. I suggest those still waiting on their IO-360-M1B ask for the AFP system.

Carl

Note that the upper lever is not indexed to the shaft. That means that most of the units will have a slightly different spacing on the turnbuckle. So the OP cant realistically set it based upon your picture.
 
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Lean mixtures (leaner than Peak, stochiometric or ~15:1 AFR) show no rise, just a drop as you lean. The richer the mixture from peak/stochiometric, the greater the EGT rise as you lean up to that point and then will drop. Idle mixtures should be richer than peak/stochiometric. Best MAP sets for optimum AFR vs a target EGT rise that apporximates optimum AFR.

Interesting. Thanks for the technical explanation of what I see when leaning for that extra long OSH taxi time ;)
 
Had the same concern when I got my new IO360 Mattituck motor so I called them up. The engine had been run in a test cell already and the fuel servo was already calibrated for idle cut off and full rich mixture. All I had to do was to make sure the mixture control cable provided full throw to each stop. That took several iterations of turning the threaded cable adapter a half turn at a time and also adjusting the cable stay location to obtain full throw. If you're not seeing an RPM rise as you lean, then I would say your mixture is set too rich.

I think you got it wrong.. if the mixture was too rich now, then leaning will sweep it through the ideal range, indicating a rise as it does so. I wouldn’t be too concerned with getting it right for the first flight, you want to minimize ground runs until break in. At your next shutdown, move the mixture from full rich to ICO in one brisk motion and listen and watch for a slight rise. If it’s not there, then I would make a half turn richer, readjust the idle speed and try again. But I would be more concerned with a proper break in first.
 
I think you got it wrong.. if the mixture was too rich now, then leaning will sweep it through the ideal range, indicating a rise as it does so. I wouldn’t be too concerned with getting it right for the first flight, you want to minimize ground runs until break in. At your next shutdown, move the mixture from full rich to ICO in one brisk motion and listen and watch for a slight rise. If it’s not there, then I would make a half turn richer, readjust the idle speed and try again. But I would be more concerned with a proper break in first.

What you described is exactly what I get. Pretty sure you meant to respond to Ryan's issue. Still think his is too rich.
 
Thanks everyone for your advice so far!

If you are adjusting richer and RPM keeps dropping, you were already too rich to begin with and just making it richer and that is expected as most shops set it rich for the test stand run.

Interesting--but if I'm already too rich, why don't I see an RPM drop as I lean-out to ICO?

Suggest you try the lowest MAP method of setting idle mixture. Search under my name, you will find my posts with the procedure. It is much easier to dial it in that way, excluding the thrill of kneeling near the spinning prop of course.

I think I found the post but am a little confused. I'll send a PM!

To the OP, you might be still on the rich side of the mixuture adjustment, not the lean side.

Same q as above, how would I explain the lack of RPM drop if I'm still on the rich side?

I would not be too concerned with the number of starts you need to do to get this right, but minimize the time running at idle as best you can. It only takes a few seconds to figure out if your last mixture adjustment is going the right way or not.

Is it really OK to start the engine, observe idle for a few seconds, then stop it, and repeat a few minute later, over and over?

One question - did you either install the Sniffle Valve or put a threaded plug in the Sniffle Valve hole?

I have a sniffle valve.
 
SNIP

Same q as above, how would I explain the lack of RPM drop if I'm still on the rich side?

Perhaps you are so rich that the way you are leaning does not allow adequate time for the excess fuel to go away.

I recommend you do this at the same RPM - perhaps 800 or so. If the engine is so rough you cannot run it at 800 RPM that would be another indication of too rich.

If you are too lean, do a couple of turns in the rich direction and try again.

If you run out of adjustment you need to reclock the mixure arm - but I suggest a call to whomever you got the engine for advice before doing this.

Carl
 
I think you got it wrong.. if the mixture was too rich now, then leaning will sweep it through the ideal range, indicating a rise as it does so. I wouldn’t be too concerned with getting it right for the first flight, you want to minimize ground runs until break in.

Yes, this is the root of my concern about doing dozens of start/stops before first flight. However, others have told me idle mixture is something that must be right during early testing because you don't want to be on final in your initial test flight and have the engine quit when you go to idle because the mixture is incorrect. In fact, one of the requirements for the FAA's "additional pilot program" is correct idle mixture setting, so clearly the FAA feels it's important.

At your next shutdown, move the mixture from full rich to ICO in one brisk motion and listen and watch for a slight rise.

This is also a question I had: What is "one brisk motion"? I have a digital (Garmin) RPM display, so the readout isn't instant. I think Garmin updates 2-3 times a second max. If I pull the knob too briskly, I'll never notice a slight increase on the screen. I also don't think my hearing is that attuned that I can notice a 1/4 second 50RPM rise. If I pull it out too slowly, I don't know--that's just not how the test is supposed to be done? Might be worth getting someone local in the cabin with me to show me how it's done :)
 
Hi power

Have you completed any high power runs and checked static RPMs at full power?

To the brain trust what is the risk of first flight with too rich of mixture, engine quits on final, not low enough RPM and force to land long?

Will the engine not being broke in contribute to this signature?
 
Same q as above, how would I explain the lack of RPM drop if I'm still on the rich side?

.

Because you went past it while twisting the red knob. It is easy to do, as it is a very fine resolution, which is why I recommend a different method. If you kept richening it to the point that it ran really rough it seems pretty un-imaginable that you are too lean. You can go a long way on the rich side before it runs really rough. Can't do that on the lean side; A few small adjustments and it just dies.

Larry
 
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However, others have told me idle mixture is something that must be right during early testing because you don't want to be on final in your initial test flight and have the engine quit when you go to idle because the mixture is incorrect. In fact, one of the requirements for the FAA's "additional pilot program" is correct idle mixture setting, so clearly the FAA feels it's important.
)

That is good advice and you are wise to think this way. Remember, the hotter the engine and the ambient air gets, the leaner you need to be. So if you set the mixture heavily on the rich side without the engine being fully hot, it may stall once it get to full temp and you pull the power back. It doesn't need to be perfect, but it should be in the general range for flight testing. YOu don't want the engine coughing and pucking while you execute your first landing in the aircraft. That's a lot of stress. Given that you have richened ti up so much, I feel you are obligated to get it back into range before flying.

Larry
 
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This'll work, but you're almost out of threads on the upper end. If'n it were me, I'd remove the linkage, measure, and then adjust the knob to re-center it in the gap and keep the same dimension.

As it is, it violates my sense of symmetry and order in the universe :).
 
Is it really OK to start the engine, observe idle for a few seconds, then stop it, and repeat a few minute later, over and over?

It is not torture on the engine but not recommended and I avoid it. Look at the hybrid cars, they are constantly starting and stopping without issue. Then again they are not 50's era ditch pump engines like our Lyc's.
 
Have you completed any high power runs and checked static RPMs at full power?

I briefly brought the engine up to no greater than 1800 RPM, but have limited my ground ops to low-ish RPM and about 5000 feet of taxiing. I recall from the docs Lycoming shipped, that they did do a little high power running at the factory, but I don't have it in front of me right now.
 
What you described is exactly what I get. Pretty sure you meant to respond to Ryan's issue. Still think his is too rich.

No I meant that for you.. you said that if he isn’t getting an RPM rise when leaning, then he’s too rich… that doesn’t make sense. If he’s too rich, then he WOULD get a rise in RPM as the mixture sweeps through the ideal setting on its way to becoming too lean.
 
Yes, this is the root of my concern about doing dozens of start/stops before first flight. However, others have told me idle mixture is something that must be right during early testing because you don't want to be on final in your initial test flight and have the engine quit when you go to idle because the mixture is incorrect. In fact, one of the requirements for the FAA's "additional pilot program" is correct idle mixture setting, so clearly the FAA feels it's important.



This is also a question I had: What is "one brisk motion"? I have a digital (Garmin) RPM display, so the readout isn't instant. I think Garmin updates 2-3 times a second max. If I pull the knob too briskly, I'll never notice a slight increase on the screen. I also don't think my hearing is that attuned that I can notice a 1/4 second 50RPM rise. If I pull it out too slowly, I don't know--that's just not how the test is supposed to be done? Might be worth getting someone local in the cabin with me to show me how it's done :)

With another person, you can get the mixture set in just a few minutes without multiple shutdowns.. Jesse’ here’s what I do, takes someone comfortable with working on a running engine.. Chock the aircraft, run the engine about 1200 rpm then close the throttle to idle. Have someone set the idle where you want it. 650 or so. Then pull the mixture to ICO. Just before the engine quits, you can put it back to rich and catch it from dying. If you didn’t HEAR a rise, then the helper can enrichen the mixture and reset the idle speed. Bring the rpm to 1200 for a few minutes to “clear it” then back to idle. Keep repeating until you can HEAR a definite rise in rpm when you cut the mixture. Since the engine isn’t really up to operating temp, things will change as it warms up, but this will get you in the ballpark very quickly without multiple starts and stops. When the engine gets warm, the idle should increase and the rpm “rise” May be more pronounced, so perhaps you can anticipate this by only setting a small rise, and a lower than ideal idle. After first flight while the engine is warm, you can double check things.

As for how fast I move the mixture from rich to ico, I’m not trying to start a chainsaw with it, but perhaps a half second pull. I’ve also done the really slow pull, but it’s trickier to notice the rise. Since your display has some lag, You can hear it just as well.
 
No I meant that for you.. you said that if he isn’t getting an RPM rise when leaning, then he’s too rich… that doesn’t make sense. If he’s too rich, then he WOULD get a rise in RPM as the mixture sweeps through the ideal setting on its way to becoming too lean.

Tom, I think we're saying the same thing. Like Larry explained, you get the rise as you sweep through the ideal setting. I see it on my engine so that's what I was trying to convey to the OP. Obviously Larry is much more eloquent about describing the whole process. IMHO his mixture is too rich.
 
Tom, I think we're saying the same thing. Like Larry explained, you get the rise as you sweep through the ideal setting. I see it on my engine so that's what I was trying to convey to the OP. Obviously Larry is much more eloquent about describing the whole process. IMHO his mixture is too rich.

I read that the OP IS NOT getting an rpm rise when he pulls the mixture. That typically means he’s not rich enough, because the engine just drops off without going through “just right”. You reiterated that you feel he’s too rich, which wouldn’t make sense. Imagine if he was so rich that the engine was idling low.. bogged down and sounding like a Harley. When he goes to ICO, the mixture becomes leaner and leaner, and the idle gets clean, raises, then cuts out. That’s the rise. I didn’t know if you mistyped when you wrote “ If you're not seeing an RPM rise as you lean, then I would say your mixture is set too rich.”. Your statement would be true if you replaced the words “too rich” with “too lean”. Because if he were too rich, there would be a rise GREATER than the 50 RPM recommended.
 
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I read that the OP isn’t getting an rpm rise when he pulls the mixture. That typically means he’s not rich enough, because the engine just drops off without going through “just right”. You reiterated that you feel he’s too rich, which wouldn’t make sense. Imagine if he was so rich that the engine was idling low.. bogged down and sounding like a Harley. When he goes to ICO, the mixture becomes leaner and leaner, and the idle gets clean, raises, then cuts out. That’s the rise. I didn’t know if you mistyped

Right now you are likely WAY off the mark (went way to rich if it started stumbling) and it isn't going to be easy doing it without the engine running.

Larry

On the last engine I got from Thunderbolt, the idle mixuture was set way rich - as the engine sounded like a poorly tuned Harley at idle. It took a lot of adjustment to get it in the ball park. Final postion shown in this photo.
62996909-9-BEF-4-DDB-A2-A4-E659-B5546-D0-C.jpg


To the OP, you might be still on the rich side of the mixuture adjustment, not the lean side. I would not be too concerned with the number of starts you need to do to get this right, but minimize the time running at idle as best you can. It only takes a few seconds to figure out if your last mixture adjustment is going the right way or not.


Carl

Nope didn't mistype. Apparently I'm not the only one who thinks his mixture is too rich.
 
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To the OP, you might be still on the rich side of the mixuture adjustment, not the lean side. I would not be too concerned with the number of starts you need to do to get this right, but minimize the time running at idle as best you can. It only takes a few seconds to figure out if your last mixture adjustment is going the right way or not.
/QUOTE]

Nope didn't mistype. Apparently I'm not the only one who thinks his mixture is too rich.

I see that, but it doesn’t make any sense. If he’s too rich, then there will be a rise when he leans to ICO as the mixture sweeps through the ideal setting.
 
READ THE BOOK!!

I think you got it wrong.. if the mixture was too rich now, then leaning will sweep it through the ideal range, indicating a rise as it does so. I wouldn’t be too concerned with getting it right for the first flight, you want to minimize ground runs until break in. At your next shutdown, move the mixture from full rich to ICO in one brisk motion and listen and watch for a slight rise. If it’s not there, then I would make a half turn richer, readjust the idle speed and try again. But I would be more concerned with a proper break in first.

I just had this situation. It is likely too rich - NOOO THAT IS CRAZY, RIGHT!!

No - here is what happens - if it is waaay too rich, then pulling back (mix) can reach cutoff before it leans enough to rise. I just had this happen, so I kept leaning the wheel, 3 clicks, 5 clicks, 5 more. Finally reached stoic. The book says 10-30 rise, then with seasonal changes allow it to be zero or as high as 50-75.
 
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Many thanks for this discussion--it's been very informative so far. Strange how difficult it is to know something as basic as whether I'm too rich or too lean. More experimentation is clearly called for. In the automotive world, I'd have a wideband o2 sensor and AFR monitor in the cockpit, and this wouldn't even be a question. I guess we don't do that in aviation because 100LL fouls the sensor(?)
 
One thing that complicates the matter is no where does any literature say how fast to pull the mixture and in my experience this can make a HUGE difference, especially if you are well rich.

Also, many mentioned this is important for first flight because the engine can quite when pulling power. You should be prepared for it. I flew a rather high steep approach on my first flight just in case. That being said, I had 7000' of runway to work with. Most will also do a lower power approach of stall speed at altitude real quick to verify airspeed working properly (let that be a time to test that your idle set-point isn't wildly off). Moral of the story, I personally felt I should always be able to glide to the runway on first flight (except right after takeoff). If a guy isn't comfortable with flying a slightly steeper approach than usual are you really ready for doing the test flight ones self? Not saying don't get the mixture close, just saying be ready if it's not.
 
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One thing that complicates the matter is no where does any literature say how fast to pull the mixture and in my experience this can make a HUGE difference, especially if you are well rich.

It’s been my experience that you pull the mixture quickly, like less than half a second from full rich to ICO. After the fuel turns off, the mixture goes from too rich, slight rise, then too lean to support combustion, and dies. The whole thing happens AFTER the lever is at ICO. I just don’t see how an engine that is too rich can go to “OFF” without the air/fuel ratio sweeping though stochiometric on its way to “OFF”.
 
If it’s not there, then I would make a half turn richer, readjust the idle speed and try again. But I would be more concerned with a proper break in first.

He is already richened it so much that the engine died. Why are you telling him to go even richer. You guys keep getting hung up on this EGT rise and we have already posted several rational reasons why he might not be seeing it.

Larry
 
Because

It’s been my experience that you pull the mixture quickly, like less than half a second from full rich to ICO. After the fuel turns off, the mixture goes from too rich, slight rise, then too lean to support combustion, and dies. The whole thing happens AFTER the lever is at ICO. I just don’t see how an engine that is too rich can go to “OFF” without the air/fuel ratio sweeping though stochiometric on its way to “OFF”.

Because the engine is not a continuous burning thing. It is firing only once every half a second or so. So one cylinder going thru stoic will not produce a noticeable rise. Especially with fuel injection and uneven idle.

I would pull a plug.
 
He is already richened it so much that the engine died. Why are you telling him to go even richer. You guys keep getting hung up on this EGT rise and we have already posted several rational reasons why he might not be seeing it.

Larry

First off all, I’m referencing a RPM rise at ICO, not an EGT rise. Second of all, his engine didn’t “die”, he said his idle rpm went down when he enriched his idle mixture screw. That’s normal. When you make a change to the idle mixture, you have to readjust the idle speed. Since he said when he moves his mixture control to ICO and gets no rise in RPM, that typically means he’s probably at stochiometric or lean of it at idle. He’s either too lean and not getting the rise, or he’s not detecting it with his ears. Perhaps Don at Airflow performance shed some light on this..
 
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I think if you pull a plug now, you might see if the previous running was too rich or lean. JMHO

So just the standard white = lean, black = rich? I've only run the engine for about 1 cumulative hour since new, not sure if that's even enough time to have a visible effect on the plugs.
 
First off all, I’m referencing a RPM rise at ICO, not an EGT rise. Second of all, his engine didn’t “die”, he said his idle rpm went down when he enriched his idle mixture screw. That’s normal. When you make a change to the idle mixture, you have to readjust the idle speed. Since he said when he moves his mixture control to ICO and gets no rise in RPM, that typically means he’s probably at stochiometric or lean of it at idle. He’s either too lean and not getting the rise, or he’s not detecting it with his ears. Perhaps Don at Airflow performance shed some light on this..

the following assumes no change to idle speed - Idle RPM will be highest and the MAP the lowest at the optimal mixture, which is about 13.5:1 for this type of engine. If he was already richer than this, further richening will drop RPM. If he was lean of 13.5, then yes he would have seen a rise. This implies that he was doing it while the engine was running and he stated that he didn't do that. If he shuts off, adjusts then restarts, none of this applies.

As mentioned two days ago, it is best to just get in there with the engine running and shoot for lowest MAP. That will be definitive.
 
It is firing only once every half a second or so.

I would pull a plug.

At an idle of 800 RPM, a cylinder is firing 26 times per second. Or stated differently, a cyl is firing every 38 milliseconds or .038 seconds. 800 RPM is also ~13 RPS and two cylinders fire on every revolution of a 4 cyl engine.

Larry
 
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So just the standard white = lean, black = rich? I've only run the engine for about 1 cumulative hour since new, not sure if that's even enough time to have a visible effect on the plugs.

I don't think a plug will get real black after only a minute or two of run time. This assumes that the bulk of that 1 hour was before you started richening the mixture from the factory setting.
 
Draker, I found this manual online..on Step 5, they have you move your mixture control really slow to note the RPM rise, then before the engine quits, you can go back to rich and keep it running. I know you don’t seem excited about making changes to a running engine, (and I don’t blame you!) but there are mechanics that do this every day and perhaps one of them can help you get it set very quickly.

https://precisionairmotive.com/wp-content/uploads/2019/06/SIL-RS-67.pdf
 
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Success

Had a day to tinker some more and met with success! Before I reveal the verdict, I want to give a big thank-you to everyone who chimed in to help. This has been a really informative thread and I feel I learned a lot here.

Verdict: So, even after my earlier attempts to enrich the mixture, the mixture was still too lean. When I initially adjusted it, I was afraid I was enriching it too much without results so I stopped and posted to VAF. But it turns out I should have just continued because I only needed about 1/8 of a turn more to get it right. As for why the engine had trouble after enriching last time, that remains a mystery—it was fine the whole time today.

As for detecting the RPM rise, what ended up working for me was very slowly reducing the mixture (twisting the vernier knob in the lean direction until I could see the rise on the glass display). Doing it this way it was very clear and easy to measure the RPM rise.

Started at zero RPM rise, gave it 1/8 of a turn and observed about 50-60 RPM rise on lean-out. Gave it another 1/8 of a turn and observed 100 RPM rise (too rich). So backed off 1/8 a turn, saw 50 RPM rise, and I think I'm done. After all this I had to re-set the idle speed. I could get it to idle smoothly at 700 RPM, pretty rough at 650 RPM, and 600 RPM was so rough it stumbled and would quit. So I'm going to keep it at 700 RPM at least for Phase 1.

Big thanks again, everyone. This is truly the plane that VAF built!
 
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