What's the best setup for crankcase ventilation? I know the stock setup uses the PCV valve, is it just on one side or both sides? I think both valve covers vent into the air cleaner?

I see some folks using the open vents that plug into the valve cover holes and just vent to the engine compartment...does this lead to oil misting and build up in the engine compartment?

I'm using a pair of GMPP tall cast aluminum valve covers on my 455. Edelbrock Performer intake, Quickfuel carb and around 10.1:1 compression (approx as engine isn't assembled yet). Street engine, won't be spinning to high RPM very often. My machine shop will be opening up a hole in each cover to facilitate venting and installing baffles inside the holes, but at this point I don't know what air cleaner I'll be using and how much room there will be for fittings going into it.

So basically I'm looking for suggestions on the best approach to ensuring adequate venting that isn't going to leave a mess.

 

I think you're right to be hesitant to vent underhood -- sounds very messy.

 

I agree, venting to the engine bay leads to exhaust gases getting into the passenger compartment. I did that once while troubleshooting issues and it was smelly.

The factory setup for most engines is a breather in one valve cover and a PCV valve in the other valve cover. This allows fresh air to be drawn in via the breather, move through the crankcase to the opposite valve cover, then be drawn into the intake along with all the blowby gases and be burned in the cylinders. The connection from the valve cover breather to the air cleaner is to provide filtered air into the system. The blowby gases do not enter the air cleaner, they go into the intake manifold.

You can also use a breather in each valve cover and a PCV valve tapped into the base of the intake manifold where it's open to the lifter valley. This method pulls fresh air into both valve covers, through the crankcase, then into the intake.

 

Seems to be relevant-

https://classicoldsmobile.com/forums...vacuum-163468/

….

 

I purchased one of these for a BBC project but haven't started the engine yet.
http://mewagner.com/?p=444

 

That looks interesting...but overkill maybe?

 

Good info in there. I think I'm stealing that breather idea!

 

So I think I'll put the PCV valve towards the back on the passenger side, and the carb has a 3/8" PCV valve vacuum port on the back. Then a breather (probably the same as Powerm01 used...just a black Summit breather with a SS2 center cap decal on it) towards the front on the driver side. Should be plenty, no need to overthink?

 

I ran across your post while researching the same exact issue. I bought an Edelbrock Elite side mounted breather for each valve cover, I plan on putting the PCV in the manifold to the valley. In your opinion, it it better to drill and tap to go with a screw in PCV that wouldn't have a baffle or regular push in PCV with a baffled grommet?

Not that it makes any difference, but I'm swapping my tired 350 to a 455 that's built up a little... Aluminum heads, hotter cam and such that I got from Olds Rocket parts.

 

Good question. Are there integrated options that don't involve installing a baffle to the valve cover?

I came across this setup in one of the facebook groups. Leaning towards this implementation now to avoid machining/cluttering the outboard face of the valve covers. Breather on the passenger side, PCV valve on the right.

 

I saw the same FB post. I asked the guy for details but he didn't know, as his mechanic came up with this... are both sides PCV or is one a mini breather, don't know. I'm leaning towards the outside mounted side breathers, they look cool and old school at the same time and I'd put the PCV in the manifold.

 

The passenger side is a breather on a 90 degree elbow. The driver side has a PCV valve.

The PCV valve looks something like this one: https://www.summitracing.com/parts/sum-440308-blk
And the breather filter: https://www.summitracing.com/parts/spe-3991

 

I see that now, the breather is on that elbow a bit hidden. I just went into the barn to check my manifold and it appears as though they've already prepped it for a PCV, there's predrilled holes with knockouts in front and in back. The engine in the photo sure looks clean with that setup, still undecided.

 

Where in the heck is the evaporator housing on that thing? The compressor looks like a modern Vintage Air unit but the firewall is flat on the passenger side. Am I missing something?

 

I think Vintage Air uses an under dash setup.

 

I ran across your comment doing a pcv search. I plan on doing exactly what you recommended, a breather on each valve cover (side mount to keep my M/T covers pretty) and the pcv in the manifold tray to the lifter valley. My question is that my pcv has a 3/4" base with a 1.22 inch grommet, the knockout in the manifold is 7/8ths, do I just grind the hole to fit the breather grommet or do I have any other options, also I have a baffled grommet... is that really needed or is the oil slopping around there not going to reach that high?

 

Baffled grommet? Where can they be found? Would this replace the need for some sort of fitted baffle in the valve covers?

 

Yup, kind of cool. I have Moroso but Mr. Gasket makes it too. I might be off base, but I assume wouldn't have to worry about regular baffles on valve covers.

https://www.summitracing.com/parts/m...CABEgIMO_D_BwE

 

Cool, thanks! These could really simplify my life.