How to vent LS3?

My LS3 is starting to smoke a little bit at cold idle and recently fouled the spark plugs after a few hundred miles. Smoke is from both sides and all spark plugs were fouled evenly, so I don't think its valve seals. When I looked in the intake it had puddles of oil in it. I'm hoping that maybe it's as simple as the way I'm venting the car is drawing too much oil into the manifold and getting caked on the valves.

Right now I run the valley cover snout to the fitting on the intake manifold after the throttle body. I run the the passenger valve cover fitting to a fitting welding onto the intake tube after the MAF.

Instead should I run the passenger valve cover fitting to a catch can vented to atmosphere? Or will that introduce unmetered air and mess up my tune? Or should I run the passenger valve cover fitting to a sealed catch can and from there run to the fitting on the intake tube after the MAF? Or something else???
 
Alex, since it is very important how and where you mount the MAF in the intake duct, introducing more air, clean or “dirty” after the air mass has been metered will screw up your tune.
Oil puddles in the intake is a sign of either a worn out engine (valve seals together with large overlap cam) or a problem with the crank case evac system. An oil catch can would most likely solve it if it is the evac problem.

I’ve seen your kind of problem (crank case evac) on several threads on the LS1tech.com so searching that forum or ask your questions there might solve it. They are more specialized on the LS engine.
 
This is a common problem with LS engines. Absolutely run a catch can They do work. I use them. Do not try and use a cheap ebay one though. It has to be well designed to be effective.

Here is the one I use. https://www.briantooleyracing.com/elite-engineering-c6-ls3-corvette-catch-can.html

Here is the best on the market currently https://www.mightymousesolutions.com/gm-systems

The first place to install one is shown in the following picture. This is the most important place to install it. It's called the "dirty side". 90 to 95% of the oil found in the intake manifold comes from the "dirty side".

LS7 Wet Sump-SingleDirty_CC.jpg
 
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You can take it a step farther and also install one on the "clean side" as shown in the following picture. Most people that install one on the clean side report that not much oil is caught in the can. Only 5 to 10% of the oil found in the intake manifold comes from the "clean side". You can just buy two Elite Engineering cans or one like shown in this post that has dual cans on one bracket. (Ignore the LS1 valve covers with the second port hooked up to the other valve cover)

LS2 Dual_NA.jpg
 
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The Mighty Mouse system is currently the cream of the crop on Corvette Forum. If you want to save a couple of bucks, they come up used on Corvette Forum occasionally. I personally just recommend a Elite Engineering can on the dirty side as shown in the first diagram if you have a fairly mild engine. If yours is boosted or very high horsepower than the Mighty Mouse Solution might work better due to the higher blow by from the cylinders.
 
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Here is a new idea that is effective and simpler for the clean side. Instead of a catch can it uses a trap on the valve cover fill port. It mentions, like I state, that very little oil is ingested on the clean side unless you are doing lots of full throttle pulls. This would be great for road racing. Gm uses this on the Camaro 1LE track package. The GM version is just plastic. This is a simpler install then trying to add a second can.

https://www.briantooleyracing.com/elite-engineering-clean-side-separator-prem-gm-ls-v8-css1.html
 
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Here is a new idea that is effective and simpler for the clean side. Instead of a catch can it uses a trap on the valve cover fill port. It mentions, like I state, that very little oil is ingested on the clean side unless you are doing lots of full throttle pulls. This would be great for road racing. Gm uses this on the Camaro 1LE track package. The GM version is just plastic. This is a simpler install then trying to add a second can.

https://www.briantooleyracing.com/elite-engineering-clean-side-separator-prem-gm-ls-v8-css1.html
That looks interesting - so if I understand it right, I would screw this in place of the oil cap, run the hose to my intake tube with a fitting after the MAF and then cap the 2 ports on the valve covers?

Also, assuming one of my issues is that I've been sucking in a lot of oil and the valves are caked in it, is there anything simple I can do to clean them, or just run like that and let it burn off over time? I read a lot of negative things about products like seafoam.
 
I've used seafoam in the past. It does help. More so for carbon deposits though.

The Elite Engineering oil fill adapter would be considered step 2. I would first address the dirty side with a catch can. That is where 90% of the problem lies.
 
I am going to install a catch can on the dirty side; just wanted to make certian my undertsanding on the clean air side was correct (install that instead of oil filter cap, cap the 2 breathers on the valve covers, and then run a hose from that to my intake tube after the MAF but before throttle body)
 
I am going to install a catch can on the dirty side; just wanted to make certian my undertsanding on the clean air side was correct (install that instead of oil filter cap, cap the 2 breathers on the valve covers, and then run a hose from that to my intake tube after the MAF but before throttle body)
That is correct!
 
Fantastic; I've got fingers crossed it's just from drawing in all the oil. I find it hard to believe it would be a valve seal, or worse, issue because everything is happening on both banks (i.e., bit of smoke out of both sides and spark plugs were all evenly fouled)
 
Installed the Elite Engineering can - it's a nice piece, compact, easy to mount. Now I wait until next year to see if that was the issue or not.
 
No - somehow after 5 years of no problems my tune went "bad" and basically started pouring fuel at idle, which was then washing the cylinder walls and causing the smoke. How a tune works fine for 5yrs and then goes bad I dunno; if I hadn't seen it I wouldn't have believed it.

But the catch can itself wasn't a bad idea - when I change my oil I look in it and there's residue, so it definitely works.
 
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