Hey everyone, new member here and pretty new to the whole Chevy LS scene. So I have a 1971 c10 that I’m doing a LS swap on. The motor I’m using is a new GM crate LS364/450, so essentially a gen III LQ9 block with gen IV aluminum L92/LS3 heads. I’m using a ls3 oem Intake manifold.

im looking for help on figuring out this whole pcv and vacuum line thing, seems like my research on the internet yields me with more questions than answers so I’m hoping someone on here can help the new guy out! I have a vent on each valve cover and the ports on the intake so basically how do I go about hooking all these up lol.

Port on passenger side of throttle body

Valve cover ports

Port on driver side of throttle body

 

In the factory configuration, PCV valve hooks up between the port on the driver's side to the DS valve cover, in the direction that will allow the port on the intake to suck out of the valve cover. The port on the intake / TB should connect inside there to the intake plenum. That port draws nastyficated gases out of the crankcase to keep the oil clean; free of combustion products including water vapor.

The one on the pass side VC hooks up with just a piece of hose to the port on that side of the TB. That intake port should go to a passage that leads to the front of the TB, ahead of the blade. It provides "makeup" air into the crankcase, to replace what the PCV draws out.

Verify which port on the intake goes where by blowing through them or whatever, before finalizing your plumbing setup.

If this is going to use a MAF, then ALL air that comes into the intake, including via the PCV, MUST pass through the MAF FIRST. That's why the "makeup" air is supplied from the front of the TB: that point is ahead of the throttles themselves, and therefore is at atmospheric pressure, but it's behind the MAF, so the MAF will have metered it. Otherwise the ECM will be unaware that it's there, and won't know to add fuel for it, which leads to endless driveability and running problems at or near idle. If you're going to be running a S/D tune then it's not as critical to how the motor will run, since that type of tune just sort of "guesses" at how much air is entering the intake, and fuels accordingly; idle tuning consists largely of dialing in the "guess", which the ECM must estimate based on manifold vacuum (MAP output), to get it as close as possible to what's really happening.

 

The port on the driver's side of the intake is for the EVAP hookup, so you can probably cap that off. Originally, on my Firebird, the passenger side valve cover port went to the valley cover. I can't remember for sure, but I think I capped off the driver's side. On my Camaro, driver's side valve cover port is capped off, and the passenger side valve cover port runs to a fitting on my CAI just in front of my TB. My valley cover port goes to a fitting on the passenger side of the intake manifold, behind the throttle body. If you don't have a valley cover vent ( it doesn't appear that you do ), you can run a line from the passenger side cover to the passenger side port on your intake, and leave the other two on the driver's side capped, I believe. Someone else may chime in with a better solution.

 

Generically speaking, you want to pull air after the MAF (if you have one) but ahead of the throttle blade. Run that to a valve cover with unrestricted nipple or valley cover nipple.
From the other valve cover WITH small orifice or PCV valve go to the throttle body nipple that sees manifold vacuum.

 

Sweet thanks for the replies, that definitely helps. I was contemplating the idea of an oil catch can and found this diagram online, does this look like the right way to hook everything up?

 

You can trust Mighty Mouse for the right way to do PCV.