Nitro RC car tuning basics

In this article, we are going to talk about RC Nitro engine tuning and about the most important factors that influence the performance of your RC car engine. Also, you will see what are the basic tools that you can use to get better performance of your RC car engine.

RC nitro engines are pretty easy to tune, but if you’ve never done this before, it might seem like a challenge. Keep in mind that, in order to run properly, nitro engines require a balance of air and fuel. Also, humidity and temperature may affect the performance of the engine. Your RC nitro car has to be broken in before tuning it.

First, gather the following tools: a 1/8-inch flat blade screwdriver, glow plugs, a temperature gauge, and a medicine dropper. And, of course, you’ll need some nitro fuel.

Adjusting the carburetor

Around the carburetor, you’ll find three tuning adjustments. The first one is the high-speed needle-valve, which adjusts the air to fuel mixture at the engine’s maximum RPM. The second one, the low-speed-needle-valve, makes the same adjustments during acceleration or when the engine is idle. The third one is the idle-speed screw. As its name suggests, this component adjusts the idle speed. In order to get better performance, it’s very important that these valves and screws are properly adjusted.

To tune the carburetor, grab a screwdriver and turn the needle-valve clockwise to lean out the air to fuel mixture and counter-clockwise to make it richer. As for the idle-speed screw, turning it clockwise raises the idle, while turning it the opposite direction lowers it. Make small adjustments and test the vehicle, to see if it’s improved until you get it right.

When tuning your RC nitro car, always start with the high-speed needle-valve. This is the first item that needs to be adjusted. After making the adjustments, let the engine warm-up and drive your RC car around for a while, to see how it works. Then take it outside and test it on the street. Keep leaning out the air to fuel mixture, until you notice a considerable improvement in your RC car’s speed and performance.

Now for the low-speed needle-valve: start the engine, apply the brakes and allow the vehicle to idle for about 30 seconds until the carburetor is full of fuel. You can tell that the needle-valve is adjusted to too rich if the engine stalls before the 30 seconds are up. If this doesn’t happen, you need to stab the throttle and watch how your RC car accelerates.

Set the valve properly and keep leaning it out until your vehicle accelerates without bogging down. If it looks like it doesn’t receive enough fuel, you’ve leaned it out too much.

Once you’ve adjusted these needle-valves, you’ll notice a gradual increase of the idle speed. You have to get to a point where the engine idles enough to keep it running, without the need to engage the clutch and force the car to move forward.

It’s recommended that you check the engine temperature regularly and buy a temperature gauge. An engine should run at 190-230 degrees F. High temperatures can cause damage to your motor. Another way to check the temperature of the engine is to apply a few drops of water on the cylinder head. If the water drops evaporate immediately, the motor is too hot. If it takes more than six seconds to evaporate, the engine is running cold. Ideally, the evaporation time has to be between three and five seconds.


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