Guys,
Wow- I think I'm having a brain meltdown. Doesn't a closed flapper force the hot exhaust up to warm the carb and intake manifold (by not allowing it to go through the exhaust pipe) whereas an open (or missing) flapper would allow the exhaust to escape through the exhaust pipe normally and therefore not heat up the intake manifold and carb? Sorry if I'm just being numb!
Steve
