Valve cover breathers

[fact5racer]

I see that on my new Holley valve covers on my LS2 that the breather tubes on the top come capped off. Are they supposed to be hooked up to something? I see in the "after" pics that they are still plugged.

[LCD Gauges]

Should both be part of PCV system to remove gasses from the crankcase.

[crash]

It really all depends upon what the engine is built for and how it is meant to vent. If you leave it generally "stock" then those vents should go to either a breather tank, or back into the intake manifold. Just dumping it into the intake, however, without using some sort of control valve, could cause some problems. On the FFR MENDEOLA BAJA DESIGNS PDG GTM(notice how the sponsor list is getting longer :) ) we just vent them to the braether box for the oil system.

[RF RIDER]

1092510926
I've been unable to work on my car for a bit and noticed this thread and thought I would ask.
I have 3 vents that I need to take care off. Two located on the valve covers and 3rd on intake area. Can I run all 3 to a breather tank or?? Do I need to add a control valve to any of the lines?
On the second picture I have already capped the vacuum ports, just not shown in this pic.
this is one of the last pumbing parts of my engine and would love to complete this. thanks for your time.

[LCD Gauges]

The intake port is where you want the others to terminate at some point. The tube extending from the manifold provides the low pressure (vacuum) required to vent the crankcase.

The port on the throttle body is where the clean air enters. This is happening after the MAF (filtered, and metered), and before the throttle blade.

I would definitely recommend using a catch-can, or some sort of trap as opposed to connecting directly to the intake. You don't want oil feeding back into the manifold at any cost.

There are several options depending on how emission friendly you want to build.


Crash: To clarify, are you excluding the port on the manifold when you mention the breather tank, or is the "breather tank" a
closed circuit system that doesn't not allow outside air to enter the engine unmetered?

[crash]

The "new" setup is Top Secret, but the current one, the valve covers just go into a catch can that drains back into the dry sump tank. The tank is then vented to atmosphere via another catch tank arrangement. This allows the valve train to be vented to atmosphere, but not lose any oil as it will fall back into the dry sump tank.

Putting ANY potential open path for air to enter the engine AFTER the throttle plate that does not have a control valve, is asking for having idle issues. The stock vette system has a valve to control PCV issues. I believe it is computer controlled.

[LCD Gauges]

Right on, the racecar system sounds pretty high tech. The drag racers sometimes connect the valve cover vents to the headers to draw out the gasses, but that's not ideal
for street cars that don't change the oil every race :p

PS: I should clarify my previous post (which is now edited). The termination point is the manifold port for the tubes (engine vacuum). The tube coming directly off the throttle
body is allowing fresh, metered air to enter.

[LCD Gauges]

Found a pic to help out.

Factory setup shown below. Keeping this setup allows oil deposits to enter the manifold port, as well as the throttle body port
10929

Installing catch cans on each tube prevents the oil from getting back into the intake manifold, or pushed back to the throttle body port.
You need to ensure these lines remain independent of each other (IE: don't use a single catch can for the manifold line, and the throttle body port).

10928
Many people (including myself) have had oil pushed into the throttle body port during extended open throttle blasts down the drag strip.

Using two separate cans will let the oil drip down into a catch system (by gravity), and allow fresh air to circulate in, and blow-by gasses to
get pushed out of the crankcase.