[Gaz64]

Rick,

If you have any old school fuel hose between pump and carbs, the line could be disintegrating, so when you remove a hose and refit it, the "bits" end up in the carb inlet fittings.
Some carbs without filters allow the rubbish into the needle and seat with instant flooding as the result.

I drove a mates car home for him one night when I realised what was wrong with his Edelbrock 600, flooding on one bank, stripped the carb the next day to find fuel hose in the needle and seat.