engine smoke>

[Jeff65]

Originally posted by mustangman65_79
Hey, tell me more about this please. I've never seen one before.

The tube is about 3/4" in diameter and runs from the right rear valve cover, over the right side of the engine and ends down near the bottom of the starter. It is a simple tube with no restrictors, valves or anything else.

Crankcases always need ventilation because some gases always escape by the rings. In the olden days engines simply had air inlet vent on the left front valve cover (it was part of the oil filler cap). Air circulated into the engine from crankshaft rotation then out the tube on the right rear valve cover and to the atmosphere.

Positive Crankcase Ventilation eliminated dumping the gases directly under the car and to the atmosphere. The PCV valve replaces the tube and the output of the PCV valve is fed to the base of the carburetor. Gases are inserted into the engine and are burned along with the fuel during combustion. In this way, crankcase gases are converted to hydrocarbons more environmentally friendly. In the beginning the input breather cap was open. This system is called an "open" pcv system. It is possible for gases to escape the crankcase through an open breather to the atmosphere so later breathers have a nipple with tube and the tube goes over to the air cleaner or carburetor. This is called a "closed" pcv system. It insures all crankcase gases are burned in the engine.