Among the million combinations of LS parts, I can't seem to find any examples of this online to tell me what others have done. I am using a truck valley cover (no pcv port), LS1 intake, and truck DBW throttle body (no vacuum port).

So what I am thinking is that I use the port directly behind the throttle body on the LS1 intake to pull vacuum, put a PCV valve in line with that hose and connect it to a valve cover. From the opposite valve cover I will run some sort of bung from the intake before the throttle body as a source of clean filtered air. Does this sound correct? I don't want to run a catch can because I feel like if the system works correctly I shouldn't need one.

I'd swap center valley plates for an LS6 with PCV in it. Catch cans are always worth it in my opinion. Although they are more important for direct injection motors, they have a lot of benefits for any LS/LT swap. They become even more important the more power you make.

Maybe if I ever decide to swap intakes I'll switch out the valley cover, but at this point I don't want to buy another part and i don't want to take it apart again. The plain cover may not be quite as nice, but does my routing make sense?

I guess I don't give catch cans enough credit for what they actually do. I'll consider it since I've put so much time into this engine, now it's another thing I need to try and find a place for! I guess my real concern is will I get enough vacuum from the port right behind the throttle body on the LS1 intake?

you'll want to pull vapors from one side of the motor to the other. The PCV valve can be run in the line coming off driver side valvecover. I can't remember exactly how I have mine run but take a peak at the diagrams on MightyMouse. You can build your own setup.

The Gen-III/ Gen-IV SBC Engines require more help with Crankcase Ventilation, than the Gen-I SBC Engines.

I like to have a LARGE Fresh-Air Breather for the Valley-Plate...
Then have a one or two PCV Valve System pull from the FRONT of both Valve-Covers...
Each Valve-Cover will also have a Large Oil-Return Line at the BACK of the Heads, down to the Oil-Pan.

Vortec, can you go into more detail on this? Is your setup for a regular MAF street car, or a race car with a MAP only tune?
Because having a big breather that is not connected to the intake after the MAF sounds like a great way to get a lot of codes/ driveability issues.

Also, do you have any pictures of the rear drain-back setup you are mentioning?

Last of all: for an engine so well designed, why does it have such terrible crankcase ventilation problems? GM had been working on this thing since the late '80s, so why didn't they address these problems? (Aside from being cheap)

This type of Configuration is ideally for a MAP (ONLY) Tune Car...
LOL, but you already knew that!


I have TONs of Images...
However, I am Rebuilding and Servicing all of my Servers; and do not have access to the Images right now.

Instead of an Open/ Fresh-Air Breather in the Valley Plate...
Start the Clean side at the Air-Induction Tubing (as normally done)...
Instead, use an enclosed Breather that has a 5/8" or 3/4" Hose fitting, in the Valley Plate...
And connect the Breather to the Air-Induction Tubing with the 5/8" or 3/4" Hose.

Connect the Front of Both Valve-Covers (Y-Fitting/ Hose Assembly) to your Oil-Separator/ Catch-Can, and then to your Intake Manifold Vacuum with a nice big healthy Hose.
Allow the Oil to collect towards the Rear of the Cylinder-Heads (Drag Racing will help this ) so that it will go down the external Hoses that connect to the Oil-Pan.
Crankcase pressure/ Fumes will be pulled from the Front of the Heads.

GM's main goal was to have a structurally-sound ALL ALUMINUM Engine that was very small externally.
They were absolutely HAPPY to sacrifice Volume in the Crankcase to have a small Aluminum Block that is as Strong as it is!