Paxtoned 416 won t fire with lid on when engine is cool

Well it’s not an actual blow thru carb. Just a factory intake and carb. The norms box was set up just for the carb that’s on it so it would be kinda difficult to fit a different carb inside the box. The engine was run for a short while before the blower went on. The blower did make a minimal improvement but it’s more there for looks then anything.