If the car has sat for a while, a likely cause is that the floats in carburetors are stuck in the down (open) position, allowing gas to flow in continuously. It the overflows the float bowls and runs down onto the exhaust manifold. Not a good situation.

The fix is relatively easy. There are three screws holding the top on each float bowl. Take the air filters off for better access, then take the top off the bowls (do them one at a time to avoid inadvertent swapping of parts) Carefully clean everything and put it back together. Hopefully the leak will be fixed.

Also a good idea to replace all the rubber hoses. Cheap insurance.