LT1-LT4 Modifications 1993-97 Gen II Small Block V8

PCV Question

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Old 08-31-2016 | 01:51 PM
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The motor I bought doesn't have the little pipe that runs from the PCV to the hole under the throttle body, it is plugged.The throttle body is also capped where the hose from the valve cover goes to, and has a airfilter oil cap. My question is should I leave it the way it is and put a breather on the valve cover and what do I put on the actual PCV that is on the intake, just leave it open? The guy I bought from was running boost, I won't be for sometime.
Old 08-31-2016 | 02:01 PM
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From: Jackstandican
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If you use a breather chances are it will require more frequent cleaning of the engine bay or you may end up with oily film all over the place. There is no benefit to running a breather over a breather tube.
Old 08-31-2016 | 02:03 PM
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Originally Posted by SS RRR
If you use a breather chances are it will require more frequent cleaning of the engine bay or you may end up with oily film all over the place. There is no benefit to running a breather over a breather tube.
So it sounds like I should uncap the throttle body and just hook the tube back up? What about the actual PCV? There is no pipe there right now since the hole under the throttle body is plugged.
Old 08-31-2016 | 02:10 PM
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The PCV system sucks crap out of the oil (which is why you want the oil near the boiling point of water) and helps reduce crankcase pressures (which also reduces the boiling point of water). If no boost, you really want to have it. Even with boost you want it, but it needs to be set up a little differently.

Replace the PCV valve and run the hose from the valve to the vacuum port under the TB. Then run the CCV (Crank Case Ventilation) hose from the Passenger Valve Cover to the port on the side of the TB.

Your oil should last longer with a properly working PCV system installed.
Old 08-31-2016 | 02:21 PM
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Originally Posted by hrcslam
The PCV system sucks crap out of the oil (which is why you want the oil near the boiling point of water) and helps reduce crankcase pressures (which also reduces the boiling point of water). If no boost, you really want to have it. Even with boost you want it, but it needs to be set up a little differently.

Replace the PCV valve and run the hose from the valve to the vacuum port under the TB. Then run the CCV (Crank Case Ventilation) hose from the Passenger Valve Cover to the port on the side of the TB.

Your oil should last longer with a properly working PCV system installed.
Okay cool thanks for the input guys I appreciate it!
Old 08-31-2016 | 04:14 PM
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Originally Posted by hrcslam
The PCV system sucks crap out of the oil (which is why you want the oil near the boiling point of water) and helps reduce crankcase pressures (which also reduces the boiling point of water). If no boost, you really want to have it. Even with boost you want it, but it needs to be set up a little differently.

Replace the PCV valve and run the hose from the valve to the vacuum port under the TB. Then run the CCV (Crank Case Ventilation) hose from the Passenger Valve Cover to the port on the side of the TB.

Your oil should last longer with a properly working PCV system installed.
Just curious what is the proper way it should be setup when running boost?
Old 08-31-2016 | 04:30 PM
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Originally Posted by z28jimmy
So it sounds like I should uncap the throttle body and just hook the tube back up? What about the actual PCV? There is no pipe there right now since the hole under the throttle body is plugged.
What year is your car? Non-vented opti cars had a PCV valve with a hose off of it that went 180* right back into another port in the manifold next to the valve. That port is used for the opti on vented cars so they then used the port under the TB for the PCV valve.
Old 08-31-2016 | 04:44 PM
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Originally Posted by SS RRR
What year is your car? Non-vented opti cars had a PCV valve with a hose off of it that went 180* right back into another port in the manifold next to the valve. That port is used for the opti on vented cars so they then used the port under the TB for the PCV valve.
I have a 97 but I believe the motor is from a 96.
Old 08-31-2016 | 08:57 PM
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From: Jackstandican
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Vented opti so vacuum source will be from under the TB.
Old 08-31-2016 | 09:35 PM
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You can apply small pressure(1-2psi max) to the crank case through any hole (i.e. breather tube or oil fill hole etc) And when this pressure is inside the crankcase, it will try to find a way out, showing you all the holes and leaks.

Once you found ALL the holes and leaks (you dont necessarily need to do a pressure test for that; its just so you can imagine the crankcase as a sealed unit with a couple holes in it)

You have to run one of the holes to the intake filter tube, and another one of those holes to the intake manifold. The intake manifold side gets the PCV valve (check valve). The other side does NOT need a check valve (air filter tube side). Both of these "holes" need to be well baffled i.e. not leak any oil while driving (check periodically for oil in both of these lines, keep it out of the engine).
Old 09-07-2016 | 06:34 AM
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Put the CCV back to stock, I had a breather and it allows unmetered air into the intake and ***** up everything. Your PCV draws air normally through the CCV tube AFTER the MAF then it goes into the intake through the PCV, with a breather it takes unmetered air and your PCM can't account for it. I fought low rpm issues for a long time and then got a new CCV tube on eBay for $20 and it's all better.
Old 09-07-2016 | 08:19 AM
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Originally Posted by z28jimmy
Just curious what is the proper way it should be setup when running boost?
Breather on one valve cover, and suck from the other. Use a good can, and get vacuum prior to turbo/SC. Under engine vac it pulls fumes from crankcase, under boost it allows fumes/pressure to leave motor.



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