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

Hi Evil 340
My car does a similar thing , it was worse with my Holleys , one a 500 2bbl I converted to Blowthrough and my C and S 650 , and to a lesser extent my Thermoquad , however it did not suffer as bad when I use avgas , we have garbage fuel in Australia now , 91/98 and it has 5-10% ethanol which has a low boiling point , and after hot shut downs floods the crap out of the engine very bad with the metal carbs , if i remove the carb bonnet it is not an issue , I ended up putting insulating spacers under the carb instead of a aluminum ones this helps too . Good luck :)