The engine needs to have a lot of air flowing through the crankcase not just
November 22 2010, 7:52 PM
the gasses that result from blowby. When the crankcase can not expell the humid vapors the oil holds water ,,,,,water in oil makes SLUDGE.
Hence the PCV system it sucks fresh air in through the breather, churns it in the crankcase and pulls it out past the PCV valve and on into the intake to be burned. This is actually one method of how dehydration of industrial oil is done.
Another thing the stink of fumes out of a crankcase are gawd awful if they get down the front cowl vent or into windows. You have full race car no PCV is fine your changing oil frequently. But if your just hoping the water/condensation will get out of a crankcase by a breather tube in a street car your risking a mess...
early model FE's did not have breathers in the valve covers.
November 22 2010, 11:26 PM
... hence the name "baldies" given to 58 - 64(?) valve covers. The breather was in the intake manifold (it also was used as the oil filler), many racers would drill and install breathers in the valve covers. I think companies like Hilborn may still make them - usually out of aluminum.
Older engines like the Y-block, MEL also did not have breathers in the valve covers.
Not to forget, that huge chunk of metal whirling around in the the crank case.
November 22 2010, 11:35 PM
...Windage trays have a use too. The motion of the crank assembly creates a lot of pressure in the engine, it needs an exit. I would not recommend starting up an engine without any breathers, draft tube or intake filler. That was a common mistake made when Ford made the change in 65 + engines. A guy might not notice that his older FE didn't have breathers in the VC when he installed the new whiz-bang late model FE intake - where do you put the oil in? Where does the pressure go?
Could that lead to severe engine damage? Inquiring minds want to know....
For a racer, the rear intake breather should be fine.
However, if it's going to be a regularly driven street ride with lots of miles then rigging up a PCV valve (or the collector extractors) would be wise to prevent the oily mist that will accumulate under the hood and get pretty much everything messy over time.
How the hell does: "motion of the crank assembly creates a lot of pressure in the engine",
November 23 2010, 4:38 PM
That is bazarr lets follow the logic - you rev the reciprocating mass up and it blows massive amounts of gasses out and then I presume if you turn it off there's an enormous sucking sound as the gasses rush back into the motors crankcase...
Nobody mentioned it but PCV Systems use a breather which allows
November 23 2010, 8:06 PM
fresh air to be pulled through the motors guts by letting air in one valve cover and pulling the resulting gas mixture from the other valve cover . They do not simply pull a vacuum on the crankcase to pull the nasty gases out..