Classic/Antique Car Repair: 1956 mercury monterey, crankcase ventilation, fuel air mixture

Question
what is the pipe on the bottom of the engine pointing straight down , and its pinched closed, it's about 1 1/2 inches in diameter

Answer
That is the breather pipe.  Cars built before 1961 or so used this system to let the fumes out of the crankcase.  Starting in 1962, cars had to have a closed crankcase ventilation system, and cars built earlier were modified by closing off the breather pipe.  Also, a PCV (Positive Crankcase Vent) valve was added to the engine - usually into the valve cover, which in turn was connected by a hose to the intake manifold. The idea was to have the intake manifold vacuum suction out the fumes from the crankcase and burn them along with the fuel/air mixture.  This was done to reduce the amount of hydrocarbon emissions from the cars, and as an added benefit, it eliminated the foul smell older cars have from the engine fumes under the hood.  Your car was probably modified in the 1960s to comply with the new laws - this was mandatory in some states starting in 1962 in California, and became nationwide a few years later.

Dick