That car had a problem. It was going to catch on fire weather that vent was plugged or open. If the carb is going to overflow fuel it will come out onto the external parts of the carb and Intake manifold,

How do you know if it had either vent style or no vent at all? What was the cause of the fire?

Now these carbs are like Pinto gas tanks? They going to ignite, and soon. OOGA BOOGA!!