Join Date: May 2003
Location: Palm Bay
These cars are a two stroke engine, meaning that they have oil in the fuel. If you don't have blue smoke / oil coming out of the engine, your in trouble, so it is normal for you to have that.
I would check with your local hobby shop, to have them show you some basic steps in tuning the engine. As a beginner, you should get a temp gauge, and take temp readings every day you run the car. Every day is different in tuning the car. Humidity, air temp, all effect the engine, just like in any other form of motorized racing.
This is a modified tuning guide that I updated for CVEC:
Engine tuning: So many variables that you need to consider when tuning your nitro engine: Air temperature, atmosphere pressure, humidity, pipe selections, and even the differences in fuel. All of these things affect a nitro engine. Here is a basic guide line to consider.
To start your nitro engine, raise the idle by closing the idle needle, or turning it clockwise about ¼ - ½ turn from where the engine ran last. This will help keep the engine from flaming out when running it through the tune up routine. Next, start the engine. Make sure to “blip” or “stab” the throttle a few times to keep the engine from loading up. Get the engine up to a reasonable temperature (usually I will try to drive the car / truck around a bit to help get it to temp, around 200 degree’s). Open the top end needle a full turn, and slowly open up the carburetor to full throttle. Don’t run at full throttle more than a few seconds at a time (usually 2 – 4 seconds). Once at full throttle, continue to open the top end needle until it nearly flames out, or stalls out. If it does stall, or flame out, just close the top end needle about a ¼ turn, and restart the engine. From here, close the top end needle until the clutch starts to engage and the wheels start to spin, at full throttle. You’ll hear the difference in RPM’s while you start leaning out the top end. Remember; don’t run at full throttle more than a few seconds at a time. Keep in mind, that you are only adjusting top end at this point. You want to keep a constant smoke trail coming out. Once I find peak RPM’s, I’ll richen the top end 1/8 – ¼ of a turn, counter clockwise. I’ll fine tune on the track, for the conditions. If I’m just playing around with friends, I’ll let it stay a little on the rich side.
Setting the bottom end correctly can not only improve throttle response, and bottom end power, but it can also increase the consistency and reliability of your engine. To set the bottom end, you should listen to the idle speed of the engine. Pay attention if it speeds up or slows down over a 10 – 20 second time frame. I usually will make an adjustment and run the car up and down a small parking lot, or on the race track. If you stop the car, and the idle is racing and then idles down, then your low end needle is set too lean, and you need to open the bottom end needle, usually very small adjustments, 1/16th at a time. If you let the engine idle, and it flames out after 30 seconds or less, then the bottom end is too rich. You should be able to idle your car for 45 seconds, without it flaming or stalling out. A quick way to help you get the bottom end adjusted close, is after the engine is at operating temperature, pinch the fuel line 1 – 2 inches from the carburetor inlet. It should idle for 3 – 4 seconds before stalling. If it takes less than 3 seconds, you are too lean on the bottom end, open it 1/8 of a turn. If it idles with the fuel line pinched for more than 5 seconds, your too rich on the bottom end, need to lean it out a little bit, 1/16th of a turn. At this time, you can set the engine idle to the desired range.
Remember, it’s always better to be too rich vs. too lean!
This should get your engine ready for use, each day before you run. While you’re driving, remember to listen to the engine. Watching the smoke from the engine’s exhaust is okay, but a lot of times, it doesn’t always give you a consistent read of your engines tune. Different fuel mixtures (different brands will use different amounts of oil in the fuel) don’t always yield the same amount of smoke, so it’s important to have another gauge, such as a temperature gauge, sound, and throttle response.
Be patient, and have fun...
Joe Anderson III
Controlled Velocity Engineering Company, LLC
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