[Rick Parker]

I think what you will find is that the TP (Which in a perfect world should be sealed to the underside of the hood) prevents radiated heat from being absorbed by the carburetor BUT forces ALL the Intake air to be pulled through the hood scoop. Now you say that your scoop isn't sealed to the TP, then you are pulling all the HEATED air from the top of the engine compartment into the carb. You spend thousands for the trickest heads, had them ported (more$$$), spent $800 for the latest and greatest Holley and then choke it down by forcing it to swallow nothing but hot air via a very poor path. The air/fuel ratio becomes out of wack (hot air) at a give throttle position. This is why it happens when you close the hood. Same thing happens with Webers, you're pulling the air of of the upper heated layer within the engine compartment.