[92GTA]

My Butler 461ci has always had a bit of blow-by when driving aggressively on the street and at the local road course. I had been running a Holley 4150 carb with a stock PCV valve and hose going to the back of it. My passenger side valve cover has the air tube that dumps into the Ram Air pan, and my driver's valve cover has an oil cap that is a breather. I get oil mist out of that breather onto my valve cover and that tube to the air cleaner gets that white slide-in air filter dirty looking in no time flat.

I'm installing a Holley Terminator Stealth (you know, the Holley 4150 look-a-like) and I'd like to take this opportunity to run a catch can. It's not a ventilated open-air catch can, it's an in/out type air/oil separator.

What is the best way to do this? Should I still keep my PCV hooked straight to the rear of the TB? Should I install the catch can inline between the PCV and the TB? Do I keep the breather on the driver's side valve cover?

I've read that the PCV only flows like a max of 4 cfm which I don't think will be enough for the catch can, but I might be wrong. I really have no clue on this aspect of engines so I've come here for help.

Thoughts/suggestions? Thanks!

[Scott65]

If it's a separator, run it between the pcv and the vacuum connection, leave the breather. Likely what you actually need, from your description, is a good, well baffled catch can. This would be plumbed directly off of each valve cover, with no vacuum connection. I ran a separator for awhile and it worked well in normal driving conditions. But at low vacuum/wot, you're basically only getting the breather action as vacuum is low/non existent.

[92GTA]

That's what I'm sorta struggling with in my mind is yeah; the air/oil separator in line with the PCV is good for street driving, but for performance driving, it sounds like a vented catch can off the valve covers is the way to go.

It seems like an over-complication to run both and it makes more sense to just relegate this car to zero-track use and keep spirited driving to a minimum - which sucks lol. I guess that is the downside of a performance engine in a street car.

[Scott65]

I wouldn't sacrifice the fun factor... I went back to valve cover breathers with hoses ran down the fenderwells til I can decide on a catch can, which is what I will do eventually. I have seen examples where people have fabricated their own and used a line from each valve cover to a catch can with a pcv plumbed in the top to allow vacuum to help during cruise.

[Scott65]

Here's one example, with a vacuum pump added in for good measure.
https://grannys.tripod.com/evac.html

[65madgoat]

Check out these guys to get squared away with what is best:

https://www.mightymousesolutions.com/catch-cans

I run a Super Duty style pcv (in the OEM valve cover) oil cap set up from this guy so you would put the catch can in this line to the efi. Then other side valve cover has a breather to air cleaner.

http://www.tachrev.com/SDOilCap.htm

And I use this M/E Wagner PCV set at a higher fixed flow so like a constant vacuum leak in a way:

https://mewagner.com/?p=444

[jamaca85]

i run the two breathers and a catch can off the pcv. no pcv valve just a fitting in the whole and mounted the can on the firewall. No issues with this for years

[ta man]

Solve the issue to keep having fun, nothing more satisfying then pushing your car to the limits and opening the hood after and it is leak free. I had a previous engine with a bit of blowby and fought leaks, misting etc..once I went to a vacuum pump and a catch can end of issues. If I would have called it quits back then and said no more track time. I would have missed many good times at the track with friends and family as well as the constant tuning to whittle the et down from a mid 11 to a mid 10.

[Formulajones]

Those simple style oil separator cans were basically designed to run between the PCV and engine to catch the oil vapor before it reentered the engine. The goal was to keep the intake charge cleaner.

We used them all the time on LS engines back in the late 90's and early 2000's because the PCV design on those were horrible for sucking oil from the crankcase and would cake the intakes with oil sludge over time.

Honestly I haven't found a need for them on a hotrodded classic car engine as the PCV tracks stay relatively dry and clean with no visual seepage as you would expect as long as the engine itself is healthy internally.

Installing a separator between the PCV and vacuum source won't fix your oil blow by you're seeing at your breather that runs up to the air cleaner, as Scott described. The separator just keeps the intake charge clean and really doesn't work under WOT conditions anyway.

You'll have to reconfigure the entire engine PCV/breather system for something that is effective under WOT to get that blowby under control. Most will tell you to go to a vacuum pump system, or something that draws a vacuum under all engine conditions.

[Scarebird]

I ran this, kinda small but seems to work fine:

https://forums.maxperformanceinc.com...8&postcount=97

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[92GTA]

Originally Posted by Scarebird

I ran this, kinda small but seems to work fine:

https://forums.maxperformanceinc.com...8&postcount=97

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

How do you have that plumbed?

This is what I have, very similar:
https://www.summitracing.com/parts/mio-mmbcc-uni-bk

[92GTA]

Originally Posted by Formulajones

You'll have to reconfigure the entire engine PCV/breather system for something that is effective under WOT to get that blowby under control.

Exactly what I'm here to figure out.

A vacuum pump is not an option, this car is driven way too much given the service intervals I've seen on these. The price is a barrier right now. Plus my serpentine belt setup won't allow for it and there is no way I'm going to dick with that after what it took to install and dial in lol.

[92GTA]

Originally Posted by jamaca85

i run the two breathers and a catch can off the pcv. no pcv valve just a fitting in the whole and mounted the can on the firewall. No issues with this for years

Interesting. So a catch can that's vented on top with a filter I presume, and you run all 3 into that with no PCV valve? What did you use as the fitting out of the valley pan grommet?

[Scarebird]

Originally Posted by 92GTA

How do you have that plumbed?

The engine is a L84 (2020 5.3). I simply have a line from each valve cover leading to a tee, then into the catch can. Another line exits the can into the filter box downstream of the filter but upstream of the MAF - engine runs, you get light vacuum.

[92GTA]

Originally Posted by Scarebird

The engine is a L84 (2020 5.3). I simply have a line from each valve cover leading to a tee, then into the catch can. Another line exits the can into the filter box downstream of the filter but upstream of the MAF - engine runs, you get light vacuum.

Ok, now I see how you are exhausting the pressure. Thanks.

[Formulajones]

Originally Posted by 92GTA

Exactly what I'm here to figure out.

A vacuum pump is not an option, this car is driven way too much given the service intervals I've seen on these. The price is a barrier right now. Plus my serpentine belt setup won't allow for it and there is no way I'm going to dick with that after what it took to install and dial in lol.

We have a street driven car here with a vacuum pump. Not sure where you heard bad things about service intervals but there isn't any when setup properly.
Dad drives his several thousand miles a year on the street with a vacuum pump and haven't touched it.

If you can't run a belt driven then you might have to think about an electric, but the issue with those is they generally don't pull enough at higher rpm to be effective.

Or do it the old school way and run hoses down to the collectors.

[jamaca85]

Originally Posted by 92GTA

Interesting. So a catch can that's vented on top with a filter I presume, and you run all 3 into that with no PCV valve? What did you use as the fitting out of the valley pan grommet?

i got a fitting that matched the pcv valve size like this but mine is plastic it has to match the two sizes on the pvc valve i think there 1/2 to 3/8

[mklinger]

Have a look at this thread and the route I went.

https://forums.maxperformanceinc.com...d.php?t=864137