I’m sure we can all agree that setting your engines mixture correctly is very important for a number of reasons. Maximum power, best fuel economy and highest reliability. So first let’s assume you have no directions and you have never set a model engine’s fuel mixture before. For best results a tachometer should be used.
1: Install a length of fuel line to the carburetor.
Open the throttle to between 1/8th and 1/4th open and close the needle making sure not to force it closed once it stops. Next open the main needle valve one turn and blow through the line, keep blowing while opening until you hear a clear flow of air (hiss) then stop. It is always better to start from a point of too open than too closed remembering that too open is too rich and too closed is too lean, a bad place to be. Reattach fuel line to fuel tank.
2: Turn the engine over while turning the compression out so as to reduce it.
3: Attach electric starter for a few seconds then turn in compression a 1/8 of a turn at a time until engine starts.
4: Allow the engine at least a full minute to warm up before making any further adjustments.
5: Slowly turn in the needle valve allowing the engine to speed up. If you go in too far the engine will do one of two things, slow down or miss. If it slows down then back out the compression slightly and repeat until you reach a point that when you turn the needle in too far the engine misses at which point you back out the needle until the miss goes away. This is called a safety miss. Next, open the throttle for more power. If power drops off while doing so, back out compression and open the needle. Full power will be achieved at between 60% and 90% open rather than 100% open throttle. The reason for this is that the maximum opening was designed for higher speed and greater fuel flow than required for diesel operation. Since you are using a much larger propeller you will be producing greater thrust at a lower RPM.
6: This procedure is valid for all R/C diesel engines.
The optimum setting for power is a balance between the compression and the mixture settings.
Example: An OS .46 LA running on glow will turn an APC 10X6 at 11,000 RPM and produce .575 HP. It will achieve a thrust level of 3.43 Lbs.
The same engine on diesel will turn a 12X6 at 9,500 RPM and produce .768 HP. It will achieve a thrust level of 5.36 Lbs. You can see the diesel produces 34% more power with a thrust increase of over 50%.
In addition, there is a 25% reduction in RPM leading to a significant reduction in engine wear. All this does not even consider the lubricity of glow fuel a solvent (alcohol) based fuel versus diesel and oil based (kerosene) fuel, which equates to longer engine life for the diesel.
If you ever have any questions, I'm always at the other end of a phone.