PCV help needed on ls swap
Thread Starter
Teching In
Joined: Feb 2012
Posts: 13
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PCV help needed on ls swap I put a 5.3 from 2004 trailblazer in 1963 corvette. I used a ls1 intake manifold on the 5.3 with the trailblazer throttle body. I have read every post I could find on pvc routing, none are exactly like mine; so here i am. Most post talk about using port on throttle body, I dont have one.
The ports I have are:
pass side on intake behind throttle body
front passenger side valve cover
rear driver side valve cover
driver side on intake behind throttle body
my thinking is:
rear driver side valve cover to -pvc valve- to port on intake pass side
front passenger side valve cover to (install barbed fitting on cold air intake tube)
plug driver side port on intake.
Does this sound OK? Thanks Tom
The ports I have are:
pass side on intake behind throttle body
front passenger side valve cover
rear driver side valve cover
driver side on intake behind throttle body
my thinking is:
rear driver side valve cover to -pvc valve- to port on intake pass side
front passenger side valve cover to (install barbed fitting on cold air intake tube)
plug driver side port on intake.
Does this sound OK? Thanks Tom
Joined: Aug 2007
Posts: 2,458
Likes: 129
From: Where the Navy tells me to go
Sounds to me like that would work.
If there are ports available on both sides of the intake, why go from the driver side valve cover over to the passenger side port on the intake? Why not just go to the driver side port? I'm assuming both ports are connected to the intake plenum, so they should work the same.
If there are ports available on both sides of the intake, why go from the driver side valve cover over to the passenger side port on the intake? Why not just go to the driver side port? I'm assuming both ports are connected to the intake plenum, so they should work the same.
I put a 5.3 from 2004 trailblazer in 1963 corvette. I used a ls1 intake manifold on the 5.3 with the trailblazer throttle body. I have read every post I could find on pvc routing, none are exactly like mine; so here i am. Most post talk about using port on throttle body, I dont have one.
The ports I have are:
pass side on intake behind throttle body
front passenger side valve cover
rear driver side valve cover
driver side on intake behind throttle body
my thinking is:
rear driver side valve cover to -pvc valve- to port on intake pass side
front passenger side valve cover to (install barbed fitting on cold air intake tube)
plug driver side port on intake.
Does this sound OK? Thanks Tom
The ports I have are:
pass side on intake behind throttle body
front passenger side valve cover
rear driver side valve cover
driver side on intake behind throttle body
my thinking is:
rear driver side valve cover to -pvc valve- to port on intake pass side
front passenger side valve cover to (install barbed fitting on cold air intake tube)
plug driver side port on intake.
Does this sound OK? Thanks Tom
1.) Cap off the driver side behind the throttle.
2.) Connect a hose from the rear port on the driver side valve cover to the rear passenger side valve cover and then to an inline pcv valve and finally to the port on the passenger side of the intake behind the throttle body.
3.) Cap off the front port on the passenger side valve cover.
If you do not want to introduce the oil and water vapors into your intake manifold and into your combustion chambers then.
1.) Cap off both ports on the intake manifold.
2.) Connect both valve covers to a good breather can or install a breather on the passenger valve cover and then another breather on the oil fill cap and cap off the passenger side ports.
I ended up welding a 10AN bungs to each of my valve covers and ran a Morose breather can. I'm a MAF tuned vehicle and I have had no issues with capping everything off and running each valve covers to a breather can.
Hope this helps!
TECH Senior Member
Joined: Jun 2016
Posts: 22,306
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From: Central Cal.
Only issue with the last scenario is there is no way for air to circulate thru the crankcase. All you're doing is relieving crankcase pressure. Ideally there should be a way to get rid of crankcase vapors.
With the engine running the moisture and oil vapors can be seen coming from the breather can. Are you saying no fresh air is making its way into the crankcase?
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PCV - POSITIVE crankcase ventilation. The P refers to using manifold vacuum to pull fresh air through the crankcase. Absent that you have a ventilated crankcase much like the old draft tubes on cars from the 50’s. When pressure inside exceeds atmospheric pressure it comes out and into the catch can where any liquids can (hopefully) be condensed/scrubbed/drop out. Nothing wrong with that approach - although any robust emissions inspection is usually a fail.
OP - if any of those openings have an orifice in them (both my LS3 valve covers had orifices) you don’t need a PCV valve.
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Verdad Gallardo PCV - POSITIVE crankcase ventilation. The P refers to using manifold vacuum to pull fresh air through the crankcase. Absent that you have a ventilated crankcase much like the old draft tubes on cars from the 50’s. When pressure inside exceeds atmospheric pressure it comes out and into the catch can where any liquids can (hopefully) be condensed/scrubbed/drop out. Nothing wrong with that approach - although any robust emissions inspection is usually a fail.
OP - if any of those openings have an orifice in them (both my LS3 valve covers had orifices) you don’t need a PCV valve.
TECH Senior Member
Joined: Jun 2016
Posts: 22,306
Likes: 3,621
From: Central Cal.
Yes. What you see coming out of the can is coming out under combustion-induced pressure. Though introduced to reduce emissions, it was found that there are other benefits to positively ventilating the crankcase.
I do have an extra set of LS7 valve covers along with a sealed catch can. I'm running an LS2 valley cover and one of these days I will install the sealed can and connect the valve covers and throttle body the way it was originally designed and see if my oil life actually improves. My conventional oil with added zinc still shows clarity after 3,000 miles running the breather can. I've changed the oil twice now and have yet to see any oil dripping out of my breather can when I opened the valve and for me that's a good thing.
I change my oil more frequently than I did with the stock engine but that's because I want too keep my engine running with fresh oil. Again I'm not a DD car that has to meet emissions but if I chose to be a DD car The sealed catch can and throttle body would be hooked up correctly knowing that oil vapors will be introduced into to the intake fuel charge and eventually gumming up my expensive parts...
I change my oil more frequently than I did with the stock engine but that's because I want too keep my engine running with fresh oil. Again I'm not a DD car that has to meet emissions but if I chose to be a DD car The sealed catch can and throttle body would be hooked up correctly knowing that oil vapors will be introduced into to the intake fuel charge and eventually gumming up my expensive parts...
Your right! It's my engine, it took me a long long time to purchase the parts build it and put it into my car. If your right then I guess I'll be pulling sooner than later and building it again.
TECH Senior Member
Joined: Jun 2016
Posts: 22,306
Likes: 3,621
From: Central Cal.
A GOOD PCV system has never been shown to be detrimental to any engine. The ONLY reason to hook it up as yours is, is because it is easier that way. All the snot is caught in a bucket instead of being harmlessly burned in the engine
LOL - all that was said was that the oil would stay cleaner with PCV. With a modern efi motor and 3-5k mile change intervals ( many of us even less than that on our party cars) and most of us with synth oil — with or without probably won’t make a big difference.
And yes - PCV was one of the first emission control devices. But crankcase vapors don’t dirty up anyone’s fuel charge. They mingle with the air charge. 😉
And yes - PCV was one of the first emission control devices. But crankcase vapors don’t dirty up anyone’s fuel charge. They mingle with the air charge. 😉