Understanding The Basics Of A Nitro RC Car Glow Engine

The first and foremost consideration when attempting to tune your glow engine is understanding the basic parts and their functions. By understanding the fundamentals, you can better tune your engine for maximum performance while at the same time, expanding the life of your engine.

Carburetor

The carburetor is the mechanism that mixes fuel and air in very specific proportions and passes it on to the engine through the vacuum intake. The natural operation of the engines causes of flow of gases to pass through the engine (through the carburetor) and out the exhaust manifold and on to the pipe or muffler. The exact mechanism for this is unimportant for the scope of this tutorial, however it is important to realize that air and fuel pass into the engine by this vacuum method. Depending on how you adjust your carburetor, you can either adjust how much of this gas/air mixture reaches the engine and to what proportion of gas to air passes on to the engine. By reducing the amount of fuel per volume of air, you are making the mixture "lean" and by increasing the amount of fuel, you are making the mixture "rich".

Idle-Speed Adjustment

This is the most basic and easy to understand part of tuning your carburetor. This spring-tensioned screw limits the closure of the barrel aperture. Although this doesn't affect the mixture of the fuel it does affect the idle speed. The more closed the aperture is, the slower the idle, the larger the aperture, the faster. As you close this aperture up and the idle speed decreases, you will eventually (sooner than later) stall the engine out. In order for the engine to run, it must have enough inertial energy built up in the engine and flywheel to carry it through the entire ignition cycle. Generally speaking, you want to adjust this down to the slowest idle, just before it begins to stall.

Low-End Mixture Adjustment

Adjusts the fuel mixture at or near idle. Some engines lack this low-end mixture valve for reasons of simplicity, however this makes accurate tuning difficult.

For barrel carbs, this mixture valve is generally found where the throttle-arm pivots. Some are countersunk; others are clearly visible from the outside. On slide carbs, they are generally found on the opposite side of the carb from the throttle slide shaft (has an accordion billow type rubber boot over it) next to, but below the fuel-inlet and high-end mixture valve.

High-End Mixture Adjustment

Also known as the Main Needle adjustment, this is the primary fuel mixture adjustment. This is generally found on the top end of the engine, typically next to where the fuel line goes into the engine. Some are flat-head screws like the low-end mixture, others are hand adjustable valves.