Technical GM Soup Can Oil Baffle/Separator? Revised, PCV Baffle in Intake Manifold

I'm wondering if anyone has cut a Chevy road draft/early pcv soup can oil baffle/separator apart to see what's inside and how it works?

I've drilled my intake near the distributor for a pcv install without drilling the Corvette valve covers. The baffle I made is obviously not up to the task as the new engine is passing a lot of smoke and the pcv is wet/oily. So, the intake needs to come off again, and I need a "do-over" on the baffle. Yes, I've read close to all 7 page results when I did a HAMB search for "intake pvc baffle"...and have seen and noted how many of you have made your baffles. Just curious as to what and how the GM engineers addressed the problem. Thanks in advance.

I'll include a photo of the first attempt finished install...just cause it's the HAMB...and well pictures count. I like the nearly invisible aspect on the install.

 

Bttt

 

Scroll thru the images. https://www.ebay.com/itm/3259303417...MIpMOYj66xhQMVeHJ_AB02yAWvEAQYAyABEgLSE_D_BwE

 

It would have been easier to put the pcv in place of the road draft tube like Chevy did for a few years. Putting the pcv in the intake without any kind of baffles ends up with your problem.

 

Thanks. I need to study these photos to understand how it works.

 

The outer canister slopes to the front and has a drain for the liquid oil that collects there. The inner tube slopes the other way and has a hidden drain there, too.
I wouldn't use that Ebay one that has been sandblasted in any engine. There's no way they could get all the sand out of it.

Gary

 

I don’t know if this would fit in your application, but I’ve had some success with these grommets/baffles. At least in a Yblock ford, it’s the oil spraying off the distributor gear that gets sucked into the PCV at the back of the valley

https://www.amazon.com/Moroso-68776...53ztVcJ6afHHIbXR8Mk4-fWzN59rkMP4aArzHEALw_wcB

 

It's probably a tight fit with that firewall but the adapter that goes in in place of the road draft tube and uses the stock early baffle workes pretty good. It uses the pcv valve that screws into the base of the carb in the orignal design.

 

I would show you my solution but I still haven't put enough miles on the car to know if it works well. I'm just curious about where your air cleaner came from. It looks great.

 

^^^^^ My 327 uses this nipple with an in-line PCV valve behind the distributer.

Gary

 

Yes, the road draft hole is a solution provided the engine in question is pre ‘68. It sounds like the OP has a later block hence the reason his PCV was put on the intake.

 

I think it's just a slight baffle (or a few small baffles) to let the oil drop out of the mist and just vapor through. I believe it might also help that it has a longer run through the baffle, into the block, up and into the 90 deg fitting, through the hose and pcv. I welded a nipple on the back of my intake (close to a rib on the underside), welded a baffle piece to cover the nipple (which I should have made it closer to the nipple bottom) and have a hose to a pcv......it leaks a little but no oil consumption or smoke.

 

Ford used this filter for the pcv system, it went in the rear of the intake.
There was a bracket on the bottom side of the manifold that held the filter , which was held in by a grommet and then the pcv valve plugged in the grommet. It was used in the 90's or so. https://foxbodyproject.wordpress.com/2016/11/28/foxbody-pcv-valve-replacement/

 

Thanks @goldmountain, I hammer formed the base out of 18 gauge mild steel and then sprayed it with silver/aluminum paint. For the top, I spent some time making small aluminum chips on the milling machine and then polished it with the buffing wheel.

BTW, thanks guys for all the feedback, I'll post some pictures of my first attempt at the baffle I made once I get the intake off later today...and will document my attempt at the "do-over".

 

^^^^^ I wish I could show the set up I did for myself on a 70’ 350. But I’d have to pull the intake off. Looking forward to seeing your set up.

 

So, back story...I built a fresh 350 engine that during the first 50 miles used over a quart of oil. It smoked like a wood fired barbecue. I was convinced it was not a problem with the rings or valve guides sealing so I investigated. I found the PCV that I had drilled into the back of the intake manifold was drawing oil in spite of the baffle that I had made to prevent it. So, the intake manifold had to come off again. I thought I would show the my first (failed) attempt at the baffle.


Here's a sketch trying to show and explain how I was thinking this should work.



I think there were a few problems with my plan/design...first, I didn't weld the upper plate in at enough of an opposite angle to the bottom plate (I under estimated the angle the baffle would sit under the intake) so it didn't let the captured oil drain quickly enough, 2nd the distance between the upper plate and the PCV valve was too close which allowed any oil that was on the plate to be sucked up the PCV and third, there is a slight gap between the bottom of the intake and the top of the baffle which also allowed air/oil mist to be drawn directly into the PCV valve.

I'm going to make this a couple posts...because I have lots of photos.

 

Thanks to @Johnny Gee for posting the ebay listing for the GM soup can. I then was able to lay my hands on one to more fully investigate and understand the way they work.

After studying the assembly carefully, below is my sketch with my explanation of the way it works.

 

^^^^^ see the gap at the end of the small tube to the back wall of larger tube? Your set up is tight to the intake and possibly the grommet. I would say you’re sucking oil from your drain.

 

So armed with this example and new found understanding, I decided if it worked for the GM engineers, it should work for my project (although admittedly, it seems like a bit of overkill compared to some of the simpler solutions that I've seen out there). That said, I have no interest in removing the intake manifold again.

So, first to address the seal between the baffle and the intake, I decided the simplest solution was to use the baffled grommet that was referred to above by @miker98038 (and others on various PCV baffle related threads). I had already purchased one of these but felt it wasn't going to do a thorough job of the task on it's own. It looked like it was better suited for a valve cover type install. I then began duplicating all the components necessary to make a GM "soup can" like assembly.

And began assembling...

I duplicated the oil drain "louver"...

And added the baffle for the louver drain...
I then added the baffle plate to the drain and then the center ring.

Followed by the outer can. I drilled holes around it in the area of the center ring so I could spot weld it from the outside.
The inside tube is spaced back from the outside plate on the outer "soup can".
And then the outside cap was added...

And the assembly was then welded to the upper tube so it can be mounted to the intake.

I plan to epoxy a small brace to the bottom of the intake and up to the bottom of the "soup can" to eliminate any vibration. And, I will use the baffled grommet to prevent any oil that makes it's way in between the intake and the top of the baffle tube from being sucked directly up the PCV.

So, yeah...probably overkill, but I'll post the results once it's all back together again.

 

Does it sit down with out touching any thing within the valley?

 

Just enough room...but that is a good point. Thinking about it further, I may cut and section 1/2" out of the vertical section of the tube to provide additional clearance.

 

You did a nice job making your own baffle.I used the original one and put in a round pcv grommet from Rockauto where the road draft tube would go. The valve is sitting in there nice and tight.

 

I'm happy to report that I've reassembled the intake/engine and the oil consumption issue has been resolved!

Edit...or so I thought, see below for the result of the first drive at highway speeds...spoiler alert...it still used a lot of oil!!

 

I was also going to suggest using some stainless steel screen inside to act as a coalescing filter.

 

I could still do that if necessary. I could remove the baffled gromet and stuff some stainless steel scouring pad/wool under the grommet/above the 90 degree elbow and then reinstall the baffled grommet. I'll monitor the oil consumption as it is now before deciding.

 

Lots of thought and fab work, nice solution.
I wonder though if this could be a situation where modern stuff could be used.
Catch cans are common on late model high performance builds. Yes, it's another external, visible component with hoses and you need to drain it on a regular basis. Perhaps disguise it as a vintage part.
https://www.roadandtrack.com/car-culture/buying-maintenance/a27182434/how-oil-catch-can-works/
The video in there talks about it in depth.
Again, I dig your efforts and hidden approach, but this may be an alternative.

 

Most rocker shafts engines put a small amount of oil to the top compared to a SBC. so less oil in the valley

 

So your point is ?

 

So, I just wanted to provide a further update to this thread because I think we need to show both our successes and our flops. I just came back from my first 150 highway road trip since the pcv was installed in the fresh engine...by the 100 mile mark, I noticed the oil pressure was trending downward. At 120 miles, I stopped at a shop that would have oil. Checked the dipstick, and sure enough it was low (not showing anything on the dipstick). Added 2 1/2 quarts to bring it back up to level and carried on home. Investigating the issue once back in the shop revealed 8 oil fowled plugs and removing the pcv line at the carb showed it was still drawing oil. I removed the pcv from the back of the manifold and stuck my fingers into the baffled grommet and they came out wet.
I'm trying to have the car ready for a 2500 mile road trip with some of my buds in less than a couple weeks...I think rather than pulling the intake again (and trying to figure out a solution that works...I'm currently wondering if the retro-fit roller lifters might result in more oil mist in the intake valley than flat tappets???), I'm going back to my previous drilled valve covers and will turn some plugs on the lathe to fill the holes in the intake as the short term solution while I ponder the issue further. All this because I wanted to run a non-drilled set of early Corvette valve covers.

 

Thanks for the update. I am currently having the same issue with my Ford FE engine.