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Layout of Modified PCV system for LS with Holley valve covers
I am putting this thread here to show how to run a modified PCV system on a LS engine with Holley LS valve covers. It's pretty simple I just couldn't find a good thread to lay it out in the beginning
Step 1: Mount your catch can wherever you would like too, I mounted mine on the passenger side head.
Step 2: Run some 3/8's hose from the rear driver side valve cover nipple behind the intake cut it and then hose clamp the PCV valve in there. NOTE THE PCV VALVE HAS A ARROW STAMPED INTO THAT SAYS TO MANIFOLD, MAKE SURE YOU PUT THIS IN CORRECT.
Step 3: Run some 3/8's hose from the PCV Valve to the top of the Catch can.
Step 4: Fun some 3/8's hose from the side of the catch can to the nipple on the intake behind the throttle body. Note: the intake depicted in this write up is a LS6.
Step 5: This has Been drawn up in paint because I still have to Add a fresh air nipple on my throttle body. So basically all you have to do is run some 3/8's hose from the fresh air supply on the throttle body to the nipple on the front of the passenger side valve cover and then you are done.
Nice write-up.
FYI, you can also the fresh air line to any point before the TB and after the MAFs (if your running one), this way you don't need to modify/drill you TB if it has no fresh air port. Also if you want to maintain a cleaner look and/or maximize your CC's oil trapping efficiency mount it off the engine to the left or right of the radiator.
Nice write-up.
FYI, you can also the fresh air line to any point before the TB and after the MAFs (if your running one), this way you don't need to modify/drill you TB if it has no fresh air port. Also if you want to maintain a cleaner look and/or maximize your CC's oil trapping efficiency mount it off the engine to the left or right of the radiator.
Cool I will def have to look into that drilling and tapping the TB would suck some.
What did you do with the hose coming off the passenger side valve cover on the rear of it? did u cap it off or put a breather
I have Holley valve covers, they only have a nipple on the front of the passenger side valve cover and a nipple on the back of the driver side valve cover.
So how much oil (if any) is it pulling out of the rear barb? Could you measure the amount of oil you're pulling out and how long? The problem with Holley covers is that with a supercharger they will fill the catch can up very quickly using the rear barb.
So how much oil (if any) is it pulling out of the rear barb? Could you measure the amount of oil you're pulling out and how long? The problem with Holley covers is that with a supercharger they will fill the catch can up very quickly using the rear barb.
There's a easy fix, if that's the case. Just use the driver side rear port as the fresh air inlet and the passenger side front port as the dirty air outlet.
There's a easy fix, if that's the case. Just use the driver side rear port as the fresh air inlet and the passenger side front port as the dirty air outlet.
That will not do anything... It will just pull the same amount of oil from that barb.
Do you have a big cam and will that PCV valve work with less vacuum?
My setup is a 2004 5.3 with a 224/224 114 lsa TSP cam. As far as the PCV working I'm not sure yet, this PCV valve is the one that Holley recommends with these valve covers.
That will not do anything... It will just pull the same amount of oil from that barb.
IMO, as far as it pulling the same amount of oil I think you're wrong since the front of the engine is normally slightly higher and while under acceleration or WOT any oil up in the top of the heads will want to move to the rear, not front. I'm not saying it will make will always make a big difference but it normally will make some difference. Furthermore if you engine has too much blow-by that's filling up your CC quickly (even with forced induction) the valve covers are not the problem the piston ring/s or land/s most likely are.
Last edited by 99Bluz28; Jan 21, 2015 at 03:33 PM.
IMO, as far as it pulling the same amount of oil I think you're wrong since the front of the engine is normally slightly higher and while under acceleration or WOT any oil up in the top of the heads will want to move to the rear, not front. I'm not saying it will make will always make a big difference but it normally will make some difference. Furthermore if you engine has too much blow-by that's filling up your CC quickly (even with forced induction) the valve covers are not the problem the piston ring/s or land/s most likely are.
It's only with Holley covers. The OE GM covers work perfectly and the catch can catches next to nothing. I'm not the only one either... Many people running superchargers and Holley covers have the same problem.
Jontall,
This would be more of a issue with forced induction than a NA engine, but a orifice type restrictor in place of a normal PCV valve, like listed in that thread is a good option as long as you blow-by is down within exceptable limits. If a restrictor is used you really need to experiment to make sure it's not too restrictive causing issues with seals and gaskets. I'd starting with at least a 1/10" or 2.5mm ID bore hole on the restrictor and check for signs oil leaks and oil (or increase of oil) getting pushed up through the fresh air tube, and carefully monitor the amount of oil caught in the CC.. I'd gradually increase the hole size until you clearly see the amount of oil caught in the CC go up a very noticeable amount, then with a new restrictor make the hole 1 size smaller. A very easy way to make a restrictor if using 3/8" ID hose is to use a short piece(about 1/2" or longer) of 3/8" OD hose with a 1/8"(or smaller) ID hole right before the CC inlet (for easy access), or preferably aluminum or high temperature plastic with about the same dimensions.
Last edited by 99Bluz28; Jan 22, 2015 at 04:02 PM.
Jontall,
This would be more of a issue with forced induction than a NA engine, but a orifice type restrictor in place of a normal PCV valve, like listed in that thread is a good option as long as you blow-by is down within exceptable limits. If a restrictor is used you really need to experiment to make sure it's not too restrictive causing issues with seals and gaskets. I'd starting with at least a 1/10" or 2.5mm ID bore hole on the restrictor and check for signs oil leaks and oil getting pushed up through the fresh air tube, and carefully monitor the amount of oil caught in the CC.. I'd gradually increase the hole size until you clearly see the amount of oil caught in the CC go up a very noticeable amount, then with a new restrictor make the hole 1 size smaller. A very easy way to make a restrictor if using 3/8" ID hose is to use a short piece(about 1/2" or longer) of 3/8" OD hose with a 1/8" ID hole right before the CC inlet (for easy access), or preferably aluminum or high temperature plastic with about the same dimensions.
I just removed them and put the OE covers back on. The problem is gone now, but that's good information. I'll never use the Holley covers again.
I just removed them and put the OE covers back on. The problem is gone now, but that's good information. I'll never use the Holley covers again.
Hmm I am curious now I guess I will have to watch this when I start driving my truck. I am running that beck arnley PCV and my catch can has a built in filter in the top barb and very little area to pull air out of the side barb so i will see how this works I guess. Jontall thanks for bringing this to my attention I will keep you guys posted and let you know how it goes.
What difference in routing would I do on a 2002 WS6 with a Mighty Mouse Catch Can? I will be installing these covers with the catch can on my car which is equipped with the LS6 intake.
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Layout of Modified PCV system for LS with Holley valve covers 
