Engine Tuning Advice
 

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?

Also, car would run great on the bench and had a 3 second count if I pinched the fuel line close to the carb.

for me i wouldn't tune during happy hour the motor will always going to lean out what plug and percent of fuel you are running
but for picco engine .6 is where you want to be on the gap and if the engine if to responsive just richen the bottom like 3 hrs and what clutch spring are you using
O and also if the tires are small that will also lean out the engine and being over and under geared

Capricorn clutch, set as per Cap Video...with a .6 gap. This is not a clutch, tire or gearing issue. Plug is Nova medium and Sidewinder Race Blend 20%

for me personally i would only use picco reds or os plus for picco engines
i ask about clutch if the spring is to tight it will make the bottom flat i would hand tight the spring I'm guessing you using 417 m spring and go 3 hrs richer on the bottom and try the picco plug ., and if you pinch the fuel line for you need to do atleast a 6 count benouse the picco has more timing then the novas

Add 0.1mm head shim and retune the engine, make sure tune on operating temperature

Not only the tuning matter, but make sure the clutch is installed correctly.
Assume everything is right, warm up the engine and run on track to tune the HSN until good high end speed and barely smoke.
Drive hard and bring it back to listen the idle, of course assume the engine won't stall and idle not too high, lean the LSN until achieve a slow idle drop
to original idle.

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....

Never use Nova plugs on Picco, it distorts the shape of the taper on the combustion chamber and it causes it to leak. On Picco, Reds or OS plugs