Eliminating hose from valve cover to intake

[Dannyboy puckett]

So I seen this post where this guy eliminated his hose from valve cover to intake.people said don't cap valve cover side,instead use a inline filter(I believe is what they meant). Is this correct?to use an online filter from valve cover side and vent to Atmosphere. I think that's what they meant.can someone please help me understand? They said it lessens oil and carbon buildup in engine/intake.id love to do this if it's true. Thank you guys.

 

[Irish Pride]

You can cap the port on the intake but do not cap the port on the valve cover. The port on the valve cover is for positive air flow in the engine in conjunction with the line coming out of the crankcase valley and going to the underside of the throttle body. If you cap the port on the valve cover you will start to blow out seals and dumping oil. In my opinion, doing this is pointless if you still have the crankcase hose still routed to the throttle body. I suggest installing a catch can or just venting both to atmosphere. In this pic i have a filter on the valve cover and the crankcase hose running to a catch can. On my current moonlight 95 I have the crankcase hose running down under the car open venting.

-Chad

 

[Evan Silletto]

You can cap the port on the intake but do not cap the port on the valve cover. The port on the valve cover is for positive air flow in the engine in conjunction with the line coming out of the crankcase valley and going to the underside of the throttle body. If you cap the port on the valve cover you will start to blow out seals and dumping oil. In my opinion, doing this is pointless if you still have the crankcase hose still routed to the throttle body. I suggest installing a catch can or just venting both to atmosphere. In this pic i have a filter on the valve cover and the crankcase hose running to a catch can. On my current moonlight 95 I have the crankcase hose running down under the car open venting.

-Chad

View attachment 84110

What’s going on with the Maf/coil wiring in this pic? Just curious, wondering if that is the 80mm or something

 

[Irish Pride]

What’s going on with the Maf/coil wiring in this pic? Just curious, wondering if that is the 80mm or something

It is in fact an 80mm MAF but that isn't whats going on with the pigtail. If I remember correctly, the original pigtail had broken both of the retaining tabs and it would no longer stay in place. Instead of repinning it with another connector I went with a brand new one.

-Chad

 

[Dannyboy puckett]

You can cap the port on the intake but do not cap the port on the valve cover. The port on the valve cover is for positive air flow in the engine in conjunction with the line coming out of the crankcase valley and going to the underside of the throttle body. If you cap the port on the valve cover you will start to blow out seals and dumping oil. In my opinion, doing this is pointless if you still have the crankcase hose still routed to the throttle body. I suggest installing a catch can or just venting both to atmosphere. In this pic i have a filter on the valve cover and the crankcase hose running to a catch can. On my current moonlight 95 I have the crankcase hose running down under the car open venting.

-Chad

View attachment 84110

Ok.thank you.

 

[SHOZ123]

Well let me say this about that......

You will not be 'blowing out" oil seals doing this unless you have so much blowby it will pressurize the crankcase at low vacuum or you have a turbo/SC.

I ran my gen 3 like this for years. And with a sealed catch can so in the crankcase when the intake was in vacuum would have about 3-4"Hg of vacuum. This is regulated by the PCV valve.

This should give you better oil and control and compression.

 

[KlondikeKat]

You can cap the port on the intake but do not cap the port on the valve cover. The port on the valve cover is for positive air flow in the engine in conjunction with the line coming out of the crankcase valley and going to the underside of the throttle body. If you cap the port on the valve cover you will start to blow out seals and dumping oil. In my opinion, doing this is pointless if you still have the crankcase hose still routed to the throttle body. I suggest installing a catch can or just venting both to atmosphere. In this pic i have a filter on the valve cover and the crankcase hose running to a catch can. On my current moonlight 95 I have the crankcase hose running down under the car open venting.

-Chad

View attachment 84110

Won’t this allow unmetered air in where you have the filter on the valve cover? I agree that I’d prefer to not connect it back to the throttle bottle as at WOT it could allow dirty vapor back in but I also don’t think you want an open port (even with a filter) past the MAF. Then again the valve cover port is “above the valves” so I’m not sure how much it matters.

I actually have mine setup like yours (valley port is run to catch can and then back to port under throttle body; small valve cover port is connected to a filter) but run a little lean at idle and thought this might be contributing to it. It’s run just fine and riches up under load but I’m wondering is this allows unmetered air and potentially contributes to my lean at idle problem.

 

[SHOZ123]

Won’t this allow unmetered air in where you have the filter on the valve cover? I agree that I’d prefer to not connect it back to the throttle bottle as at WOT it could allow dirty vapor back in but I also don’t think you want an open port (even with a filter) past the MAF. Then again the valve cover port is “above the valves” so I’m not sure how much it matters.

I actually have mine setup like yours (valley port is run to catch can and then back to port under throttle body; small valve cover port is connected to a filter) but run a little lean at idle and thought this might be contributing to it. It’s run just fine and riches up under load but I’m wondering is this allows unmetered air and potentially contributes to my lean at idle problem.

The reason the hose is connected to the pre TB intake track is so it is going though the MAF and being metered.

The only advantage to putting an air filter on the valve cover hose and running things otherwise normal, would be if your engine was so wore out it has a blowby problem and is pushing oil into the throttle body.

 

[Irish Pride]

Well let me say this about that......

You will not be 'blowing out" oil seals doing this unless you have so much blowby it will pressurize the crankcase at low vacuum or you have a turbo/SC.

I ran my gen 3 like this for years. And with a sealed catch can so in the crankcase when the intake was in vacuum would have about 3-4"Hg of vacuum. This is regulated by the PCV valve.

This should give you better oil and control and compression.

Very healthy engine with recent upper and lower 60Ks started dumping oil out the front main, cams seals, and front valve cover right after I capped off the port on the front valve cover. Replaced all the seals and added the filter to the VC and engine stayed bone dry. 35k miles later this engine is still running strong.

-Chad

 

[Irish Pride]

Won’t this allow unmetered air in where you have the filter on the valve cover? I agree that I’d prefer to not connect it back to the throttle bottle as at WOT it could allow dirty vapor back in but I also don’t think you want an open port (even with a filter) past the MAF. Then again the valve cover port is “above the valves” so I’m not sure how much it matters.

I actually have mine setup like yours (valley port is run to catch can and then back to port under throttle body; small valve cover port is connected to a filter) but run a little lean at idle and thought this might be contributing to it. It’s run just fine and riches up under load but I’m wondering is this allows unmetered air and potentially contributes to my lean at idle problem.

It is a very common mod for modern performance cars to eliminate the breather lines and add filters. I have no regrets with my setup and I currently have the highest NA torque Gen1/2 and will have the highest NA HP car with a few tweaks.

-Chad

 

[SHOZ123]

Blowby is a terrible thing. if you got a turbo or S/C you got excuses..

 

[Irish Pride]

No blowby. Very healthy engine. First hand knowledge that plugging the VC port will cause problems on a healthy NA SHO V6.

-Chad

 

[Kebabaluba]

If you are worried about carbon in the intake you might get better results by removing or plugging EGR valve.