Thanks, B85. Having these parts that have been sitting on the shelf 95% complete for a long time finally get installed is fun!
Figuring out the revised pcv system was a bit of a challenge, though: Where to route another layer of little hoses?
In a stock setup, the LS3 has a closed loop pcv system. Crankcase vapors are pulled from both the valley cover and the driver-side valve cover and fed into the intake manifold via a vacuum port located just behind the nearby throttle body. Both the valley cover and the valve cover vapor ports are restricted, flow constrained by an orifice of about 0.10” diameter in each. Both are baffled on the wet side to reduce the amount of oil carried by the vapors into the intake manifold. Metered and filtered “make up” air flows into the crankcase via a port on the passenger-side valve cover to keep the MAF sensor honest. No traditional pcv valve is used.
The goal was to replicate the function of the stock pcv system, add an oil catch can to clean up the crankcase vapors on their way to the intake manifold and keep the plumbing clean, simple and tucked under the nose cone. It took a whole bunch of head scratching and a pile of spare parts and scrap hose, but turned out reasonably well.
Several issues had to be overcome. The intake manifold in my setup is reversed, placing the throttle and its vacuum port over the bellhousing. My Holley valve covers have vapor ports that don’t include flow restrictors (but do have some baffling on the wet side.) The valley cover nipple was too long and protruded into the path of my steam lines so had been trimmed shorter.
On the plus side, the LS3 intake manifold has a brake booster vacuum port on what’s now the front-end of the intake manifold. That nipple just needed to be reduced from ½” to 3/8” hose to connect the pcv vacuum line. The stock vacuum port behind the throttle body gets capped. Metered/filtered air is now let into the crankcase via the driver-side valve cover port back near the firewall. A tee fitting is used to join the vapor lines from the passenger-side valve cover port and the valley cover port and then connect them to the catch can. A flow restrictor for the valve cover port was added by drilling a 0.10” hole through a 5/16” ss set screw and threading that into the tee fitting.
Attachment:
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A br@ck^t was made to mount the Mike Norris catchcan to a chassis tube. The outlet side of the catchcan was connected to the old “brake booster” vacuum port. Here’s what resulted:
Attachment:
IMG_2437-1.jpg
Attachment:
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Hopefully, the revised setup will function like the stock pcv system with the catchcan providing some oil separation to clean up the intake’s vacuum feed.
After all the pondering, the pcv plumbing actually turned out to be pretty simple. And most of the extraneous hoses hide under the nose cone.
Attachment:
IMG_2430-1.jpg
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