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Old 07-26-2005, 05:59 AM   #1
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Default A Little help here please

Ok just got a NTC3 of ebay...first nitro car owned... started fine the first time... took awhile to get it running the second time... the big thing is that after I was done it seemed there was gas/oil something all over the back of the car body... wiped clean with a rag... is this unburned gas??? whats the fix...??? car seems to build up speed as I throttle it... has some exhaust out the side...from about half power up to top speed... any ideas anyone??? thanks...

TJ
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Old 07-26-2005, 07:32 AM   #2
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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

CVEC Racing

Controlled Velocity Engineering Company, LLC
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Old 07-26-2005, 08:58 AM   #3
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Hi Joe,

Very useful information. I got some problems with the engine on idle, I will follow your instructions. Hope they help. My situation is following: Car is running great w/o any problems. When I come to the pits to get fuel, after the tank is full and I want to hit the gas, the engine makes a kind of bogging sound, stalls for 1 maybe 2 seconds and then fires right away. From what I understand, it is too rich on the low speed needle. Am I right?

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Old 07-26-2005, 09:09 AM   #4
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Could be rich on the low end. Try the step where you get it warmed up, and pinch the fuel line 1 or 2 inches from the inlet. See how long it takes to make the engine rev up?
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Old 07-26-2005, 09:25 AM   #5
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Thanks for the info... will have to get a temp gauge!!!
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Old 07-27-2005, 06:22 AM   #6
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might b to rich try leanin it out just a lil bit
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Old 07-27-2005, 10:45 AM   #7
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Thanks Mike!!!

TJ
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Old 07-27-2005, 08:34 PM   #8
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If theres gas/oil on the body of the car its running too rich.
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Old 07-28-2005, 07:19 AM   #9
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ok, so I leaned the top end and 1/4 turn... the car started and wanted to surge while sitting... which it didnt do before... turned it back 1/8 and it ran ok... pinched the line about 1 1/2 inch from carb... car rev'ed up and ingauged the clutch and spun the wheels... turned the low end 1/16 or so in to lean it alittle car died... wouldnt re start... set it to bdc and put in after run oil since I thought I would either pull arm off or break pull start trying to start the blip thing!!! not sure what the heck to do now... calling LHS in alittle while hope they can help...anybody in the Sunbury PA area that likes to tune a car and show the new guy the ropes would be helpful...

Thanks to all that have answered so far... and Thanks in advance to all that will answer now...hopefully...

TJ
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Old 07-28-2005, 09:19 AM   #10
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The higher RPM's is okay, just turn down the idle on the idle screw. When you pinched the line, how long did it take for the car to stall?
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Old 07-28-2005, 10:04 AM   #11
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It didnt stall just rev'ed up high, didnt want to run it at what seemed full throttle...I mean it ran for at least 30 seconds and then I let go...

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Old 07-28-2005, 07:26 PM   #12
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Got the car running again tonight, idles just fine but fuel still comes out the exhaust... and when I rev it it gets worse... so Im thinking its rich all around??? top and bottom... with the fuel line pinched it runs for about 4-5 seconds then dies...any ideas??? Thanks

TJ
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Old 07-28-2005, 11:28 PM   #13
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There`s some good engine tuning info on Josh Cyrul`s website, this should help you out-
www.cefx.net
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