Starting a Quarter Midget
Back to Matt's Racing PageRacing a quarter midget requires starting a quarter midget. Starting can end with your driver confidently motoring away or with the handler hanging off the roll cage exhausted and out of breath with the car stopped in the middle of the track. With the proper technique and teamwork between you and your driver you can reliably start your car.
Quarter midgets are direct drive and have no clutch so they must be push started on the track. However, starting the car is a little more complicated than pushing it until it goes. There are three engine types used in quarter midget racing; Honda, Deco and Briggs. The basic starting routine with all engines is to turn on the gas, push the car with the throttle closed, hit the switch and slowly throttle up once the engine fires. However each type of engine has a slight difference in the starting ritual. Here are a few engine specific tips to help get things going.
Honda GX120 and GX160:
These are stock industrial engines that have been repurposed for racing. They are by far and away the easiest to start. They have an automatic compression release, a heavy flywheel, modest ignition and cam timing and a, float carburetor with a tiny venturi which all help to make starting easier.
With the ignition off and the throttle closed just push the car up to a fast walk and have the driver hit the switch. The car should start running and happily motor off. Sometimes a Honda will require a longer push if the driver has their foot on the gas. This prevents the carburetor from pulling fuel into the engine.
Briggs: Animal and World Formula:
These are factory built race motors designed for closed course racing. They are bigger than the Hondas, have higher compression, a light-ish flywheel, a race-oriented camshaft, advanced timing and a large venturi float carburetor. The two biggest issues are how hard these cars are to push and their tendency to kick back. They can be tricky to start if the driver and handler don't coordinate their efforts.
Before heading to the staging area, it is a good idea to start the car on the cart. A slightly warm engine will be much easier to start on the track. At the very least, it is a good idea to prime it by either turning the engine over with a hand covering the carb or by rocking the car back past the intake stroke to draw fuel into the intake. The car will start easier if the carb is wet with gas.
With the ignition off and the throttle closed, lean into the car until it goes over the first compression stroke. Once the engine is past the compression, push harder to keep the engine going and accelerate the car 2-3 car lengths and have the driver hit the switch. When the engine fires, the driver should slowly add throttle to drive away. If the engine does not fire turn the switch off and continue pushing another 2-3 car lengths with the throttle completely closed and try again.
What could go wrong?
The biggest mistake most drivers make is to not keep the throttle completely closed while pushing. This allows more air into the engine which makes it harder to push slowing it down and sapping the handler's energy. If the throttle is open when the switch is turned on the engine may kick back. This will sap your drive and may break the engine gear key. Hitting the switch before the car is moving fast enough can also cause a kick back. Make sure the driver waits for your command to start!
Deco: Stock, Mod, B-mod and AA-Mod
These are custom built race motors designed to optimize performance within the QMA rule structure. They displace 120 to 140cc, have a very light flywheel, battery ignition, low-ish compression, no compression release, really advanced timing and a pumper type carburetor. The carb can range from modest for the stock to super sized for the B and AA modified classes.
It is good practice to train your driver to turn off the switch whenever the car stops. It is safer and in the case of a Deco, it will save your battery. It is also a good idea to disconnect the battery after you cross the scales and the driver gets out. This prevents a battery drain if the switch gets bumped.
The pumper carburetor is a different beast than the typical float unit as it will not deliver fuel without a vacuum to “pump” the fuel. You can push a Deco around the track 100 times and there will be no fuel if the driver holds the throttle open. The pumper carbs are racing only items and have no idle circuit or idle stop. This makes throttle control very important to have a successful start.
As with the Briggs, the Deco likes to have a brief run on the cart before staging. A warm engine will be much easier to start on the track. They also like a primed intake. Rock the engine back and forth with your hand over the intake until it is wet with gas. On some B and AA-mods the frame prevents easy access to the intake. Engine makers offer a little paddle that can slip between the frame and the carb to cover the intake. However, in most cases your hand will work fine.
Pushing the Deco is different. The tiny flywheel and short gearing make it difficult to get the engine spinning. It is helpful to use the car's momentum to turn the engine over. Here is the routine:
- As with the other classes, switch off and throttle completely closed.
- Pull the car back a few inches until you feel compression.
- With your left hand on the roll cage and your right hand on the bumper lift the rear tires off the ground.
- Start running with the tires off the ground.
- Drop the car after about a car length and the engine should start turning.
- Push the car faster. (speed is your friend)
- After 2-4 car lengths tell your driver to hit the switch.
- The driver must crack the throttle and wait for the engine to catch then add throttle to accelerate.
- Keep pushing until the car pulls away.
The last step is important as the Decos will often stumble a bit when first started and can stall out. Following through with a good push while the engine clears its throat can keep you from starting the pushing process from scratch.
What can go wrong?
The engine may not fire due to lack of fuel. The engine will get ZERO fuel if the driver has his foot on the gas while you are pushing. Even with the proper driver technique you may have to choke the engine while pushing. With the engine turning over, reach down and cover the carb with your hand to choke it. You need to get a good seal to be effective. Hold your hand over the carb for 1-2 car lengths or until you feel it get wet. Take your hand off and tell the driver to hit the switch.
Figure 1, Choking a Quarter Midget While Pushing
The engine may not turn over when the car is dropped. Sometimes a stubborn car can be coaxed to turn over by kicking the top of the right rear while it is sliding on the track. The driver must have his foot off the gas to allow the engine to spin once it starts to turn.
The carb on the Deco is usually connected to the block with a solid aluminum intake manifold. This can heat the carb to the point of vapor lock if the car sits for more than a minute or two after a run on the track. This often happens after a pit stop during practice or if there is a red flag on the track. The vapor lock can be cleared with a healthy dose of choke while pushing.
Sometimes the driver can apply full throttle right after the engine starts, preventing the carb from getting a proper vacuum signal from the engine. In this case the engine runs, but runs poorly. The driver can clear this situation by closing the throttle and applying the gas slowly. The car should accelerate normally.
Other important tips:
- Have an exit strategy. Once the car starts, don't stop and admire your work! The competition is right behind you starting their cars. You never want to be in front of a 5 year old with a running race car. Always keep running and move to the side.
- Ask for help. Many feet make light work. Sometimes just having more weight pushing and coax the stubborn car to life. Remember to stay together after the car starts to give the other drivers fewer targets to avoid on the track.
- A handy tip for turning a car with a locked axle around on the track is to lift the front bumper up to waist high and pivot on the rear bumper. This is much easier than picking up the heavier rear of the car or trying to rotate the locked tires on the track.
- Communicate with the driver. When corner working you will be starting off cars that are not your own. Don't be afraid to tell the driver to turn the switch off before pushing. The other driver may be accustomed to a different signal to hit the switch. If saying “go” or “hit-it” does not work try a tap on the helmet to give the driver the signal to start.
- If a car goes backwards on the track (like from a spin) the air filter may be full of fuel. A wet air filter may catch on fire whent he engine first tries to start. You can reduce the change for fire by pushing the car for a short distance with the switch off which draws the extra fuel into the engine before you tell the driver to start.
- If you get an intake fire while pushing, don't panic, keep pushing and try to start the car. If the car starts the fire will be sucked into the engine where it belongs. This strategy only works for intake fires.
- Be careful! If a 5 year old hits a 45 year old it is not the 5 year olds fault.
©Joe Dille 2012