Originally Posted by
jjmudd
O.K. my nitro loving friends, not the best night of racing I've had. I stayed for a bit after racing tonight and tried to get a tune into the car. I am running a Picco EDO X .12. High end is easy and perfect, but I can not get a tune into the low end. When the car is just starting to warm up, it is super responsive off the line, but after 3 minutes of hard racing it seems to get incredibly lean on the bottom end. I pull the trigger and nothing happens for about .5 - 1 second and the idle is screaming. I am almost thinking there is an air leak somewhere. I am going to reseal the carb and front plate with high temp ATV and also check the lines and tank. Any other ideas?
sounds like normal engine behavior ..Basically your tune is too lean and the engine is misbehaving once it heat soaks .........these engines take several ( 5-10 ) minutes of continuous running for the tune to completely stabilize and until that point the tune will get continually leaner and leaner as you run it ...So when you first start the engine cold the tune should be stupidly rich but as you run the car the tune will naturally lean itself out as the engine heat saturates....A engine that is tuned cold will run properly for the first 3 minutes or so but as it it heat saturates the tune will quickly become too lean...resulting in a loss of power and a screaming high idle.....The tune on these engines is extremely reliant on temperature and you can see huge swings in the tune from cold to heat soaked.... composite or insulated carbs take longer to stabilize then aluminum as well preheating the engine helps but doesn't heat saturate the engine enough to stabilize the tune.... they still need several minutes of continuous usage to completely saturate and stabilize....