I'll give some technical background Info during Explanation - but please keep in mind, that I'm a Car-Guy. I have sound Experience with Brass- and Early-Age Cars, but Aviation-Tech sure differs somewhat...
If you want to skip the Blahblah - just read the Bold lines

Test subject is an SE5a Viper.

First thing I noticed is that this Plane does not have adjustable Radiator-Shutters (no wonder - in the Workshop-Settings they are called "Albatros-Ratiator-Shutters" LOL)

2nd was the Construction of the "adjustable" Ignition System.
The SE5a seems to have 2 separated Magneto-Type Ignitions, and all one can „adjust“ is, if you want the Engine to run with #1, #2 or both Ignitions simultaneously. This is, what we call „Twin Spark“ nowadays and it was relatively common back then, although for different Reasons:
Today you want to achieve an evenly spreading Flame Front in the Combustion Chamber for improved Performance.
Back then you just wanted to double the Chance of igniting your Fuel/Air Mixture.
Most of the Machines I know had a Magneto-Type Ignition (wasn't very reliable on low rpm) and a „traditional“ Induction-Type Ignition (wasn't very reliable on high rpm)
I can't tell why they used 2 Magnetos here, but technical Solutions to a Problem are often dictated by Price – maybe, it was simply cheaper...
Luckily, these Aircraft-Engines already had some kind of Automatic Ignition Timing Advance (VERY rare on Cars, then) – so you don't have to constantly alter the Timing, depending on rpm and Load (climbing etc.)

The Difference in Performance between running on 1 or 2 Systems is well below 5%, if there is any.


The Mixture:

To understand, what we are adjusting, here, a short explanation:
Simply put, you just add Fuel to the Air, your Engine sucks in, anyway.
The „Stoichiometric Mix“ (hope, that's correct. It's written differently in German Lanuage – but it is equally impossible to pronounce LOL) is the ideal Air / Fuel Ratio under ideal conditions @ Sealevel, meaning all of your Fuel gets burned completely. It is around 14.7 Kilogramm Air for 1 Kilogramm Fuel (14.7:1)
The Problem: The Conditions in your Engine are all but ideal. When accelerating, the atomisation of your Fuel is very bad due to poor negative Pressure in your Manifold (the Thing, your Carburettor is mounted on). Techs call that MAP (Manifold Air Pressure). When it decreases (meaning less NEGATIVE Pressure), the little „Drops“ of Fuel get bigger and need additional Time to burn completely (Ignition setting to „more early“) and less Fuel is sucked in – that must be compensated.
Luckily, all that happens automatically, exept one thing, that you have to by hand:

Adjusting the Mix to the current Altitude.
You are not interested in the Air, all you want is the Oxygen in it. The higher you go, the less dense the Air is, which means less Oxygen-Atoms per Cubic_____ (fill in your Country'a favored unit)
If you'd climb to a certain Height and would leve the Mixture-Lever at its Postition, that would result in a „Rich“ Mixture (meaning too much Fuel), so you have to go „Lean“ to compensate.

Good settings for the SE5a Viper:
The Viper likes to run on the lean side.
Go from „Full Rich“ to „Lean“ until your Engine makes funny Noises, then go back some 10-20 Clicks

@ 0-1k ft.: The Range from „Full Rich“ to „Funny Noise Area“ is ca. 65 Clicks.
@ 9k ft.: 85 Clicks

You can gain or loose a little more than 5% of your Engines' Performance depending on Adjustment.
The Supression of Engine-Heat equals the simple Reduction of rpm by the Accelerator-Lever...

The last thing I found out is, that you cannot „melt“ the Engine. Regardless of what you do, it stays below 100°C


Hope, that wasn't too boring... hello? anyone still awake?


P.S.:
Alb-Shutters need a lot of Clicks from "Full Open" to "Fully Closed" also.
I guess, the Amount of Clicks should be drastically reduced...

I get 8 clicks in albatross radiator range. Ctrl E & Ctrl SHIFT E
Never noticed any effect on performance or engine by adjusting the engine.

I mapped the mixture to a lever, I go lean until bad results occur, then bump it a tad richer. I see a difference in the tach, lower, when running too rich.

I've tried to "cure" a random engine malfunction via different magneto settings with no success. I seldom monkey with the magneto anymore, unmapped it from my controllers.

You can also hold down the Alb shutter keys on the keyboard and it shuts/opens with one key press - as does mixture etc settings usually

Interesting.
Thank you for the investigation and time.

@ Mud: Good Idea! Sadly, my Stick has a lot of Buttons, but only one Lever...
@ Pol: Thanks for the handy hint :-)
@ Duke: No Problem. Writing took more time than flying LOL

My Saitek X52 has more buttons, sliders, etc than you could map to these machines. I have the mixture axis on a slider and I'll see how your instructions work out - I have fiddled with it some and received advice (thanks again, Pol). It's a great way to shut your engine down at the end of a mission. But I haven't seen much effect from minor tweaks in flight - probably because I haven't gotten to more than 7000 ft.

Thanks again for taking the time to write this up.

Thx for taking the time to write that, Nietzsche, and congrats on your English - it would have taken me weeks to write that in German, and you would have laughed your socks off when you read it!

Nice summary of how mixture works. It was one of the more difficult things for me to grasp on the PPL course (along with aerodynamics, navigation, aeronautical law, radio comms, etc., etc.).

I have the mixture on a slider on an X52, which in my opinion is the way to go. Anyhoo you can really see the difference while adjusting it in flight, it does make quite a difference at higher altitudes.

Beard

Well you didn't bore me, I love this kind of thing. I've spent some time working on small piston engined aircraft, and I'll tell you not a whole lot has changed in many of these areas. Most small piston aircraft still use two magnetos (two are used for more complete burning of the fuel/air charge in the cylinder and for redundancy in case one fails - it's a little less convenient to lose your ignition system at 5,000ft than it is when driving down the road). Running on two vs just one magneto is usually a difference of between 50-100 rpm. I'm not sure what kind of timing advance was present on these engines, they aren't used today except for impulse couplings and a couple other systems, all of which are used only to get the engine started. Only the newest types on the market have a FADEC system. In this case price isn't so much the issue as getting the authorities to approve a new system for use on aircraft. If your average car these days is a spaceship, your average small piston aircraft is a 1950s tractor.

Great explanation on the mixture. I hadn't heard about the relationship of MAP to the size of the fuel droplets. And if anyone is flying without leaning the mixture as you climb (and enrichening again it as you descend), start doing it! You will get much more out of your aircraft. I guarantee you the AI is doing it.

Thank you for your kind words :-)

@Gecko: With Automatic Timing Advance I'm just talking about these Spring-and-Counterweight-Systems and/or the Vacuum-Advance-Units (I guess, Vac-Advance is pretty rare in Planes, right?) inside of your Distributor.
From a today's Point of View, these Systems are considered old-fashioned (they were common (in Cars) roughly between 1940-2000), but in the Brass-Age that was Experimental Tech Voodoo - so I'm quite impressed about Planes of that Age already had such Systems...
In Cars those Days, you had a Lever somewhere in the Proximity of your Steering Wheel, with which you were able to rotate the whole Distributor "by Hand" - and therefore could alter the Timing of the Ignition. You permanently have to fumble with that Thing while driving around in order to keep the Engine running decently... anyhow, driving pre-WW1-Cars isn't that joyful like most people think it is. Fun starts in the Upper-Class of the late 20ies imho, with the Introduction of some Commodities like automated this and that... and a lot more Power

Fascinating! I believe there are a few planes with vacuum advance, but you're right, it isn't common. I think things are finally starting to change and we'll start seeing some more advanced engine control becoming more common. As a pilot I love the thought, as a mechanic, it sounds like some of it could be a real pain to deal with compared to what we have now. Interesting about these old systems (on cars and airplanes) I always like hearing about the unique (though sometimes awkward) solutions devised for the problems of the day. And some were so practical I wonder why they have fallen out of use.

Does the position of the Alb (or any, for that matter) radiator shutters affect the engine temp in WOFF? I thought I read somewhere that they were cosmetic only. A shame, if that's the case. In Richotfen's Skies You had to manage the raiators of all water-cooled aircraft or risk overheat and engine siezure.

I prefer a slider (thumbwheel, in my case) to incremental button clicks for mixture, too...now that I've got a rig that allows for it. But the incremental method works just as well. My father flew B-17's and B-24's in the Second World War and private aircraft after it. He told me that the common method was to lean the engine(s) until they start to sputter or cut out (depending on how fast you're changing the setting) and then increase until it sparks back up, as described earlier. That's more reliable than X% at this altitude and Y% at that because actual density depends on more than just your altitude.

Hmm...
The Shutters sure were a nice Feature - but were they really neccessary?
In my Experience, it is hard to actually harm your engine by "Overcooling", once, it has had the Opportunity to warm up beforehands (I'm only talking about Water-Cooled Engines...)
Overheat-Damage sure is an Issue on the other hand... Pistons "grow" too large and get stuck in the Cylinders (Metal expands under Heat - the Piston more than the Cylinder-Wall, because it is mostly made from Aluminum and is more directly exposed to Heat), Oil gets too hot and stops lubricating the Rotating Assembly and so on.
I'd guess, they were flying "Full Open" nearly every time...

With the relatively low power output of these engines I would wonder if you could overcool them, especially in a high speed dive and low power setting. I'm not sure what issues this would cause, but I do know P-38s operating over Europe in WWII did suffer issues due to overcooling. Though I don't recall what the actual problem was. The other thing they do is help control the rate of temperature change, which can be just as important as keeping temperatures out of the extremes.

Typically at cruise you lean using the exhaust gas temperature gauge. You lean slowly until the temperature peaks, then enrichen it 25-50 degrees, though when the gauge isn't working (cessna EGT gauges are fairly unreliable) you use the "lean till it splutters" method described above, which is often just as good and probably the preferred method for WWI pilots.

You're right! Avoiding quick Temperature-Changes is propably the main Reason for these Shutters (I haven't thought about that, before)
Cruising around @ low Speed, low Load and low Temperature isn't a Problem... as long as noone is attacking you. In this Cases, you have to change form Snooze-Mode to Super-Pursuit-Mode (KITT! I need you Buddy!) within some Seconds. There is no Time to gently raise the Temperature.
So, these Guys might have kept their Engines relatively warm all the Time by closing the Shutters in Cruise - and fully opening them when engaging.

Changes in altitude also come with significant changes in temperature. When I was skydiving in South Carolina even in the heat of a southern summer at 90+ degrees on the ground it could be in the 40's at 7500' (2000m). They likely would have had to close the shutters at altitude, particularly in the winter, or possibly risk freezing their coolant in the radiator while the engine's running. (Not sure, was anti-freeze common 100 years ago?)

Methanol (also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits) was probably available as an additive for engines of the time. I don't know if it was used though.

additional note:

Antifreeze was discovered and not invented by a French chemist by the name of, Charles Adolphe Wurtz, in the mid 1800's.

When he tells his friends, "I'll drop in to see you sometime" he means he'll actually drop in! (sorry, sir, I just couldn't resist - I'll be here all week...)

Sometimes don't you just wonder how they did it? You're fighting for your life and worried about mixture and engine temperatures, watching our for negative g's and your gravity-flow carbs, gyroscopic effects in turns for the rotaries... Sheesh! I've got nothing to add, but thanks to all for a very informative thread!

How they did it? Not very well, I guess. Most of the Pilots must have been hopelessly overcharged. We tend to share a View on this Era, that is a little bit "sentimental" - but we often forget, that there were ordinary, normal Guys sitting in those Cocpits. They've gotten some basic Training and were directly kicked to the Front after that. As always with everything, you have a very small Group of "natural Geeks", who are not good for anything except THAT... and the Rest is average at best...

Compared to today, or even a couple decades later, the systems work load was fairly light. The flight environment was not so complex either. The difference was that all of it was very unforgiving. Today airplanes are designed with the benefit of years of experience, then, they were on the sharp end of a brand new technology. Today if you mess up your enemy is a lawyer, then, it was another pilot wielding twin spandaus who got up extra early this morning just to kill you.

And while I'm sure they realized that wood-and-canvas weren't as strong as metal and had structural limitations, I'm equally sure they looked on each new (successful) design the way today's pilots do..."Let me in one of those!"