5 steps to first-race success
Bess, Stephen
As the old saying goes, “To finish first, you must first finish!” That cliche couldn’t be more true for nitro racing; many otherwise fast cars lose precious laps when the driver must pit to restart the engine, or worse, the car gets parked mid-race with an engine failure and earns a DNF-“did not finish.” Although it’s Impossible to get rid of the chances of a DNF completely in any type of racing, it takes only a few simple steps to eliminate the most common causes of mid-race engine failure. Follow the five steps outlined here, and your engine will be ready to go the distance.
1: INSTALL A FRESH GLOW PLUG. Glow plugs take a beating, so it’s no big surprise that they will occasionally burn out at the most inopportune times. Given the nature of a glow plug’s job-to keep a metal coil burning brightly under ridiculously high combustion temperatures-it’s amazing that coils last as long as they do. To avoid suffering a mid-race glow-plug-related failure, it’s always wise to install a new glow plug before any “big” race. A fresh plug will endure the rigors of racing much better than a worn-out plug could.
A new glow plug is also cheap insurance against a race-ending flameout, and it will allow you to concentrate on the race rather than worry whether your plug will last. Before you take out the old plug, blast away any grime that has accumulated around the glow-plug hole with a generous shot of motor spray or compressed air. When the area is clean, replace the old plug with a new one that’s of exactly the same type. Using a different brand or style of glow plug-one perhaps rated with a different heat range-will throw off your engine’s tuning, so always carry at least one extra plug of the type that’s in your engine.
2: INSTALL A NEW AIR FILTER. just like our lungs, nitro engines work best when they breathe unobstructed, fresh, clean air. Your engine’s first line of defense against airborne contamination is its air filter; a dirty filter will suffocate your engine and increase the chances o dirt being drawn into it. Before you place your vehicle on the track for a race, replace the dirty filter element with a clean one.
Most brand-new filter elements must be saturated with filter oil before they’re installed. The best way to do that is to put the element in a plastic bag (or the bag it was originally packaged in) and pour air-filter oil into the bag. Work the oil into the filter element by squeezing and moving it inside the bag to distribute the filter oil evenly; the element will then be ready for you to install.
3: START THE ENGINE AND “CLEAR IT OUT.” If you compete at a
track that has computerized lap timing, the race director will probably allow a few minutes of warmup before every heat. Experienced nitro racers start their engines a few minutes before the warmup and then carry their vehicles to the track for the warm-up laps. The engines must be started with the radios turned off to avoid their interfering with the vehicles already on the track. Manually work the throttle by pulling on the throttle linkage. Just be sure to do so with a good grasp on the car, and make sure that loose clothing and body parts are clear of the spinning wheels. To keep the wheels off the ground, it’s usually best to leave the car on a starter box or prop it up on a piece of wood.
Avoid losing valuable warm-up time by starting and then revving your engine in short bursts to “clear out” any fuel buildup in the carburetor or combustion chamber. Cold engines will run rich until they’ve heated up, and it isn’t unusual for a racer to start an engine, allow it to idle for only a few seconds and then plop his vehicle on the track, only to have the engine die when he applies the throttle. When you start your engine, rev it up a few times to “clear it out,” and continue to blip the throttle until your vehicle is on the track. This method will allow you to warm the engine in the pits until you can drive it around the track to warm it completely.
4: TUNE YOUR ENGINE SO THAT IT WILL IDLE FOR AT LEAST 5 TO io SECONDS WITHOUT STALLING. Your engine should be able to idle for at least 5 seconds without stalling. Don’t attempt to tune a cold engine in the pits because its tuning requirements will change as the engine warms up. Wait until the engine is warm before you tune it. If your engine doesn’t idle for at least 5 seconds, it’s likely to flame out at the start or during the race. Adjust the low-speed needle and/or idle screw to ensure that this doesn’t happen.
To check your engine’s low-speed-needle setting, allow the engine to idle when it has warmed up. If it slowly loses rpm and quits, the low-speed needle is set too rich. To lean the air/fuel mixture, turn the low-speed needle 1/8 turn to the right (clockwise), and restart the engine. Continue to tune the engine in this way until it idles steadily for at least 5 to 10 seconds.
If you bring the car to a stop and the idle speed slowly increases until the engine cuts out, that’s a signal that the low-speed needle has been set too lean. Richen the low-speed needle 1/8 turn (counterclockwise), and restart the engine. Run your vehicle for a lap, and then bring it back in to recheck the idle. When the engine idles steadily, you’re ready to complete the warmup.
5: CHECK YOUR TUNING AND TEMPERATURES AFTER THE WARMUP. When the engine has warmed up, you should check its performance and temperature before the race. Assuming the engine had plenty of time to warm during your pre-race laps, check its performance. For long Mains, you will want to run with a fuel/air mixture that’s slightly rich because the engine will lean out over the course of the race.
You should check the engine’s temperature. If you have access to a temperature gun, make sure that the engine’s temperature is less than 250 degrees Fahrenheit. In general, anything above that will increase the risk of overheating and flaming out. Although you should never tune to a specific temperature range, as a beginner, you should monitor your engine’s temperature and tune it away from excessively hot running.
If you don’t have access to a temperature gun, you can gauge an engine’s temperature by putting a few drops of water on its cooling head. If the water sizzles for a few seconds before it evaporates, the engine’s temperature is in an acceptable range, and retuning isn’t necessary. If, however, the water dances on the cooling head and evaporates almost instantly, the engine has been tuned to run too lean and is overheating (probably hotter than 27o degrees Fahrenheit). In this case, richen the high-speed needle 1/4 of a turn (counterclockwise) and run a few more practice laps. Then bring the engine back in and check its temperatures once more. Repeat these steps until your engine runs consistently well at an acceptable temperature.
Copyright Air Age Publishing May 2003
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