Originally Posted by
dyoungre
Is there any way for you to reduce your heat load? Do you have a stainless header? If so, I found that a fiberglass wrap named "Inferno" survives, and the header survives as well (Even running a race on secondary ignition only!)
If it only occurs at the end of the run, you are probably on track. It couldn't hurt to check your float level, though. I can't believe how insanely sensitive these carbs are to float level !!!
Reducing the underhood temp is key; I was on the dyno yesterday, and found that carb was getting too hot to touch. No matter how cool the fuel is, we were getting breakup at high RPM when the carburetor was too hot.
For the curious, it was an electric dyno, saw 121 HP at 7600 - 8000 RPM at the wheels, had one run that hit 125 HP at the wheels at about 8400 RPM, but what Dick said occurred, for the most part; above 8000 RPM, indicated AFR went lean and power dropped off. HOWEVER, observers heard ignition break up, so I'm not sure root cause is fuel. The lean indication could be due to misfire, due to insufficient spark at high RPM. Coil? Who knows, I couldn't afford to keep diagnosing ...