[DriftR]

From a previous post it seems that most people running MIGHTY MOUSE catch cans for 6th gens (recommended for direct injection) despite debates, are not "hollowing" out the stock pcv valve as directed in their installation guide. The easiest way to remove the plunger and spring is to just sand the large end down to the threads and it will fall right out (the plunger is metal). BTW, I used a deep 15/16 socket to remove it from the car and a GM replacement pcv part # is 12691880 for a 24 Camaro... would think it's the same for most years.

[bishopts]

Wouldn't it run like shit since it's now a huge vacuum leak?

[DriftR]

Nope, just lets excess oil get to the catch can easier.

[bishopts]

You mean it created a less restrictive path with way more vacuum so that it will pull more oil than it ever did in the first place?

[SS_Don]

I never read anywhere that the PCV valve needs to be hollowed out. Please reference your source.

[DriftR]

Originally Posted by bishopts

You mean it created a less restrictive path with way more vacuum so that it will pull more oil than it ever did in the first place?

Exactly.

and here is the documentation that comes with the mighty mouse mild.

[bishopts]

Ok I'm going to break this down for you.

You can't hollow out a pcv valve and not have a massive intake leak. You will lose idle control and end up with a code related to engine rpm higher than commanded limits.

Mighty mouse sends a dummy pcv valve for the valve cover because it relocated a pcv valve into the catch can itself. Which would not cause idle surging and check engine light.

The point of a catch can is to catch possible liquid oil that MAY make it's way up the pcv system. Not to create a bigger flow path with more vacuum to try and see how much of your oil you can suck out of the engine.

A stock pcv valve creates a vacuum leak into the crankcase that the pcm understands will be there and can account for.

[Spaceme1117]

Originally Posted by bishopts

Ok I'm going to break this down for you.

You can't hollow out a pcv valve and not have a massive intake leak. You will lose idle control and end up with a code related to engine rpm higher than commanded limits.

Mighty mouse sends a dummy pcv valve for the valve cover because it relocated a pcv valve into the catch can itself. Which would not cause idle surging and check engine light.

The point of a catch can is to catch possible liquid oil that MAY make it's way up the pcv system. Not to create a bigger flow path with more vacuum to try and see how much of your oil you can suck out of the engine.

A stock pcv valve creates a vacuum leak into the crankcase that the pcm understands will be there and can account for.

100% correct. They system needs to have a PCV valve in it.

Some Mighty Mouse catch cans have an integrated PCV valve. If that is what you are running, you can ditch the factory PCV valve.

For example on my C6 Corvette, I am running a Mighty Mouse catch can that does have a PCV valve integrated into the can. So I was able to remove the PCV valves that I had on each of the valve covers.

But if you are running a catch can that does not have an integrated PCV valve, you need to leave the OEM PCV valve alone. Otherwise, you will have a massive vacuum leak which will cause all kinds of problems.

[DriftR]

I edited my post so people understand this is for the Mighty Mouse catch can that I installed... thanks for the clarification.

[DeuceCam]

I'm no expert in LT1 crank case ventilation. However, in theory, one could remove the pcv valve and vent the crankcase to the atmosphere (disclaimer: this is not legal and I don't condone doing this); to do this one would need to:

1. Gut the PCV valve, or remove it and find a barbed fitting to go in its place.
2. Run a line from the old pcv valve location to a catch can with a breather port.
3. Plug the open pcv inlet port on the manifold.
4. Remove the clean side tank and plug the port where the drain line terminates at the engine, or cap all the ports at the top of the tank.
5. Plug the open port on the intake tube.
6. Run each valve cover breather to a catch can with a breather port.

[bishopts]

Originally Posted by DeuceCam

I'm no expert in LT1 crank case ventilation. However, in theory, one could remove the pcv valve and vent the crankcase to the atmosphere (disclaimer: this is not legal and I don't condone doing this); to do this one would need to:

1. Gut the PCV valve, or remove it and find a barbed fitting to go in its place.
2. Run a line from the old pcv valve location to a catch can with a breather port.
3. Plug the open pcv inlet port on the manifold.
4. Remove the clean side tank and plug the port where the drain line terminates at the engine, or cap all the ports at the top of the tank.
5. Plug the open port on the intake tube.
6. Run each valve cover breather to a catch can with a breather port.

You would be removing pcv and double down on ccv. It would work but it would be less effective at idle and low throttle cruise. And with nothing more than blowby gases as a pusher, it would be more likely to end up slowly running more rich through your oil change cycle with unburnt fuel vapor settling in your oil.
So yes you're theoretical build the engine would still run. But it wouldn't be better than if you just left it alone.
Pcv doesn't really have many negatives other than it has the potential to pull oil particles. The standard catch can will dramatically reduce that.

[DeuceCam]

The engine oil does need to be changed more often with vta.

I agree that pcv is better. What I described is an old school race car approach to ccv. It's not something that she be considered for a car used on the street.

[GreyGhost702]

When it comes to PCV and Catch Can systems the objective is to remove positive crank case pressure at all times as well as extracting, what I prefer to call, the waste fumes as well. With the exception of some setups in the 1000+ bhp realm, I'm not a fan of the VTA setups. If plumbed properly and line sized properly, you should be be able to completely contain your PCV/CC system. Some big power setups truly need a breather, depending on how they are set up (displacement, ring gap, power adder). The more akin they are to OE specs/tolerances, one should not need to vent.

As far as the check valve built into the catch can, it's primarily there for FI, so that under positive pressure that line closes as to not pressurize the can or the rest of the PCV system when under Boost conditions. Yet another reason for FI cars to especially avoid VTA cans, and have proper line routing and sizing so a vacuum can be maintained in the crank case. Please, don't operate under the assumption that the PCV valve is being gutted because the can now operates like the PCV valve. It does not.

For NA cars, I agree the PCV should be neutralized, and in the case of the mild setup it looks like MM wants you to gut the PCV valve, which is fine. If you were running FI, you'd want the MM Wild setup by default. The wild setup is going to replace the PCV with an open AN fitting anyway. The goal for NA is the same as FI, create a constant vacuum on the crank case and remove the fumes that would otherwise be causing wear and/or unsafe conditions. Keep in mind, catching oil is the byproduct of the PCV process. Hence, the catch can. To condense any vapor from the air/gasses, and capture as much of it as possible, allowing the least saturated air back into the intake system to be recycled.

Now if we want to get down to the nitty gritty, if we really wanted to keep the engine as clean as possible, instead of routing back to the intake, all lines would feed to a vacuum pump and scrubber before being pumped to atmosphere. Because honestly, none of the shit that is going back into the intake is good for the engine or combustion process. Even the unburned fuel vapor is contaminated or not up to par for another round of burning, and if anything leads to a lower quality burn. But you're talking nitty gritty, like I said. The vented cans do not avoid this, either. The only thing a vented can is good for is sudden PCV surge, and I still think if the lines are properly sized this type of surge can be voided.