Q. How do you tune a nitro engine
A. This is a good starting point but always refer to the manufacturers instructions for defined settings
The Idle Screw I always start with the idle screw, I adjust it so that the car will idle high when I'm first dialling in the engine.
Once I get the engine up to temperature and with a tube that can keep it running without stalling I slowly adjust the idle down to the point where it's about to stall, then I turn it back about 1/4 to 1/2 turn depending on the temperature. If your car stalls often it can be worth while increasing the idle to prevent this, it's only a temporary fix while you sort out the other tuning issue, but it helps keep frustration levels down.
Low Speed Needle. One of the great debates is which needle to adjust first, if your carburettor only has one needle adjustment screw then it's not a problem, but if like most glow engines you have two you need to decide which to tune first. I always start with the low speed needle, this is because when you adjust the low speed needle you change the high speed needle. Once the low speed needle is dialled in you shouldn't have to adjust it again. Make sure you keep it slightly on the rich side, when you RC Car idles the combustion chamber should start to fill up with fuel, this helps keep it cool. After a while the engine will stall, by measuring this you can tell if it should be richer or leaner. A good time is about 30 - 60 seconds before it stalls. The RC Car should pull off quickly from a standing start and should not bog down or flame out when you apply full throttle.
High Speed Needle. Once you have your low speed adjustment needle dialled in it's time to start getting the power out of the RC engine. This is done with the high speed needle, which adjusts the air to fuel mixture of the engine while it as high RPM (about 40% and up). Keep an eye on the trail of smoke as this is your first clue about the tune. You want to have a lot of smoke coming out of the engine at all RPM, if at some point there is little or no smoke then you are running too lean.
Hints, Tips and Tricks
Turn the needle clockwise to lean out and counter-clockwise to richen the mixture.
A lot of smoke means you tune is rich.
The sound can tell you about your tune.
Reading your glow plug after a run will tell you a lot about your tune.
Make sure to run your engine on the rich side, this will extend it's life.
A lean engine will always put out more power, but it will shorten the life of your engine.
Temperature, air pressure and humidity play if big part in the tune, different days will need different settings.
Q. What do the different compunds of Foam Tyre mean for pan car 1/12th
A. Jaco have produced this definition for foam tyre compunds and has been widely adopted
1/12th Tire Guide This is a quick reference list for tire durometers and applications for any 1/12th car
Black - 40S: Special tire for insane traction carpet tracks. Does not get gummy like Purple. If you don't have insane traction you car will push with these.
Purple - 40S: Good for medium bite conditions in stock racing. This compound is getting popular again because of Jack the Gripper traction compound. With Jack Purples do not get too sticky.
Lilac - 37S: Great front tire for stock carpet or if dbl. pink is too much steering.
Double Pink - 35S: This is the standard front tire for carpet in all classes. Its is used front and rear for 10.5T, 13.5T and Mod carpet and front and rear in all classes on asphalt.
Grey - 35S: This is a low natural rubber compound. It is just as hard as dbl. pink but it had FAR LESS traction. It is used to free up the rear of stock powered carpet cars for more efficiency and corner speed. This is the old standard rear carpet tire, most stock carpet racers use the softer yellow compound now for more forward grip.
Magenta - 32S: Its softer than dbl pink so if you need more steering than dbl. pink use these up front. If you need more rear traction than dbl. pink use these in the rear.
Pink - 30S: This tire is used in mod 1/12th on carpet and asphalt if the traction is low. If the traction is high it will lock in the rear of the car and make it push.
Yellow - 30S: This is a low natural rubber compound. It is the standard rear tire for Stock racing. It is used to free up the rear of stock powered carpet cars for more efficiency and corner speed.
White - 25S: This is a low natural rubber compound. It was the standard rear tire for 1/10th on road carpet racing. Its a little softer than yellow.
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