The Stovebolt Site Forums The Shop Area Engine Shop Valve cover mount for ??

Hi guys I’m trying to figure out what this mount is for and if it should be closed. Any ideas? Thanks

Year, model, engine size would help.

Opps sorry, 1952 gmc 228 engine.

My 49 gmc 228 does not have that. Is it possibly part of a pcv system installed by a previous owner? John

I’ve looked at a ton of pics of other trucks and never seen it, I’m assuming I can take that out and it shouldn’t effect how the truck runs. I just wanted to double check to see if anyone knew what it was.

PCV

Picture from Chevy 1955 1st. 261 engine. This would have been the version from the factory.
Also there was an AC retrofit kit (CV and KV) that can be added to meet California Emissions.
It would be nice if you could add pictures of your intake manifold and draft tube if this is what you have.
A PCV system is beneficial for the life of the engine.

If you choose to plug that vent, be sure there's another way for air to get into the engine like a vented oil filler cap, or slots in the valve cover, etc. It doesn't matter if there's a PCV valve or a road draft tube, there needs to be some way for fresh air to get into the engine.
Jerry

Well Bouymaker it’s my belief that this truck was in California it’s whole life until now. The oil bath air cleaner does not have a connection like the pics show so I’m wondering what I should tie into or not. If it’s a California add on for emissions shouldn’t be fine to just block it since it’s not a factory thing. Jerry, the valve cover has vents in it so I imagine that’s the air vents needed from the factory?

Well this is on eBay. So I guess I could put it back to “original”

Notice the difference in the air cleaner connector (attachment).
I believe this one is original GM with the clutch head screws.
Your valve cover and your picture of an air cleaner is most likely the retrofit AC kit.
Both versions are "period correct" I guess as far as originality.
To do your valve cover functionally correct, the vents need to be blocked because it defeats the purpose.
Do you have a PCV valve on the draft tube or intake manifold?
It's also possible your PCV is the "closed" type system (attachment).

An example of the AC "KV" kit 1003(Chevy V8) with various connector options.
I do not have a picture of the AC "CV" kit.
From the AC catalog page for GMC (attached), it looks like the KV1004 kit and CV hose is required in California (black triangle).
If you live in California you would need this before you could pass inspection today.

Wow bouymaker thank you for the info! So this being a California truck, that make total sense but if it’s a add on by California for emission control I should be able to remove the fitting from the valve cover and be back to normal? The main reason I’m addressing this is the opening in the valve cover is located directly below the cowl vent. Whatever comes out the cowl vent goes directly into the opening in the valve cover. So I either need to remove the opening or put a hose connecting it to where it should go. What your opinion?

Jim K, a couple questions:

• Do you have a road draft tube on the passenger side of the engine?
• Are the vents in the valve cover plugged?

Yes! Not the best design to have water draining out on top of the valve cover.
The 54 and maybe 55 1st Chevy 235 has vents or slits in the valve covers.
I borrowed a picture (attached) to show the drain hose moved over to one side.
The 216 engines have vents.

From what little I have read, the original Chevy/GMC PCV system option was for big trucks (typically working in dirty environments).
Attached is another "borrowed" picture of a 48 2 ton.
Most trucks didn't have them but the option could be purchased.

I would think you can remove the California Emissions parts if it was not required in your state.
BUT, a properly implemented PCV system can be beneficial for the health of your engine.
It can also reduce the the burning oil smell (the bouquet of AD truck lovers) or blow-by smell inside the cab.

There is tons of information available on adding your own PCV system.

Well upon further thought I’m going to buy the kit on eBay you ( Buoymaker) posted and complete the connection to the air cleaner. Thanks guys for all the info, I would have never figured that our on my own.

Would you please post the link to the kit listed on eBay?

The kit was made for a V8 Chevy but has the similar connectors that can be used on the I6.
(https://www.ebay.com/itm/AC-Delco-GM-NOS-KV-1003-6419926-Crankcase-Ventilation-Kit/382958873327).
I meant for this to be used as an example. You don't have to buy this kit. There are other elbows and straight fittings available.
You haven't posted pictures of your intake manifold and oil fill/draft tube so we can't assist you any further on making you system work.
I guess you have your mind made up so good luck to you.

There is more to the PCV system than just the connection from the valve cover to the air cleaner. There isn’t much your going to accomplish with just this addition, aside from plugging the hole and keeping the vent drain water out of your engine. You could accomplish the same with a plate and gasket.

To get a properly operating PCV, you will still need the connection to the crankcase. The idea is to pull vapors from the crankcase where the original road draft tube is attached and direct them to the intake manifold to be re burned with the gas. GM made special parts to accomplish this. The part you are trying to reconnect provides clean fresh air from the clean side of the air cleaner to the valve cover. This air finds its way to the crankcase thru oil drain holes open to the crankcase replacing the vapors. There are plenty of post on how to accomplish this, so if you want your engine to run and be cleaner as buoymaker has explained, than do a search on PVC.

If your happy with just plugging the hole, thats OK too. It won’t hurt anything.

Well I thought I was getting off easy but if I’m going to make that connection I guess I should see it though and do it correctly. I was a little confused in that the post with the California emissions requirement only showed the connection between the valve cover to air cleaner, I didn’t realize there’s more to it. Anyway let’s do this right. Here’s some pics of the engine any guidance on the whole system is appreciated.

What I would suggest is to use a plate and gasket to blank it off so you can use the truck while you do research on the proper parts to complete your system.

Unfortunately, I am not a GMC expert (I own a ‘52 3100 w/ ‘59 235) and GMC did their PCV systems different than Chevy, so I can’t help you with those details. I’m hoping that the GMC experts will weigh in on this subject.

I would also try Old GMC Trucks and maybe some military truck sites as they all came with PCV systems so they could ford a river.

I’ll keep an eye on this thread and offer advice when and if I can. Good Luck!

A note on the drain hose pictured above, while you often see them straight, correct placement according to the FAM is 45 deg +/- 10 as shown.
https://www.flickr.com/photos/advance-design_parts_co/50873980423/in/album-72157631872034068/
A rare factory shot of the above angle.
https://www.flickr.com/photos/advance-design_parts_co/44568231895/in/dateposted-public/

Thanks Brad! I’ve never seen one that wasn’t pointing straight down. Your library of GM literature, videos and photos are unrivaled and we “Bolters” are privileged to have you aboard! THANKS AGAIN!

Here is a breather on a 302, note the valve.

Ed

Thanks for the pictures Jim. Everything looks stock except for the connector on the valve cover.
Check that the vents on the valve cover are open. A small screwdriver or a piece of wire will do it.
Remove the oil fill cap on the road draft tube and check inside with a flashlight. Make sure it is not blocked somehow.
If these are not blocked, I would plug (rubber cap) the valve cover connector or remove it and block the hole.
I don't see a PCV valve so my guess is that you have the original ventilation with a connector that has no purpose.

That valve pictured above is the same set up used on 228 motors also. You would not have a down draft tube on your oil fill. Instead it is a small version of an oil filled air cleaner as that is where the air enters the crankcase. The valve connects to the intake at the base of the carb and draws air through. There was an excellent thread on oldgmctrucks.com that illustrates the complete set up.

Rich

The system that you are showing, (buoymaker) draws the vapors from valve cover and draws fresh air from a small air cleaner fitted to the oil fill tube. Exactly opposite to the way Chevy did it, but it accomplishes the same thing.

There is an example of one on ebay. [LINK] Really rough, but it will give you an idea of what to look for.

Guys thank you for all your input, the information was extremely helpful. Knowing this truck was from California I believe this was a attempt to be emission compliant as in the post by Buoymaker. Since there is only the one attachment still in play, removing it seems to be the best route, it also puts my truck closer to “original “ from the factory. One of my goals for this truck is have the driveline as original as possible. To me there’s no better feeling than cruising around in a machine older than me. Thanks for the help!

There are a couple of valve covers on eBay that have no extra holes for PCV that you may be interested in. Just search for “GMC 228 valve cover”.

Hi Jim K,

So, looking at your posts, it appears that your engine was modified at one time for California emissions compliance, and subsequently modified again at some other point in its life by removing/modifying the installation.

I would try to keep a PCV system on the engine if at all possible. While it may have been added as an emission control device, PCV does much, much more, by helping to mange blowby gasses that make it into the crankcase - resulting in a significant reduction in oil contamination. The U.S. Army realized this during WWII, which (in addition to fording capability) is one of the reasons they used PCV on so many of their vehicles.

As mentioned, you will need the valve and associated plumbing to the valve cover. If you don't want to use the modified one with the fitting on the side, examples are available on places like Ebay with the production fitting on the top.

You will also need to add a fresh air intake, with a filter to remove dirt from any air being pulled into the crankcase. Attached are images of a production PCV system installed on a 270.

Best Regards....

Ok so if I’m to keep the system I need to go from the valve cover to the air cleaner as California emissions dictates (this I have). Then I need to go from the manifold to the oil fill tube? Since I have a draft tube / oil fill do I need to change that to eliminate the draft tube? And what type and where will the filter go?

Also do need to block the vents in my valve cover?

Jim, we have overwhelmed you with too much information. Sorry about that.
To make it simple, I recommend you keep your engine stock.
Your original question was about the elbow connection on your valve cover.
The answer is that it has no purpose and is not needed.
Either plug the connector or remove it and install a cover plate.

Well, it was a very interesting conversation but I agree back to stock. Thanks!

Hi Jim K,

As Buoymaker suggests, the easiest road to take is to just keep the road draft tube, and run sans PCV.

BTW, when you plug that fitting on the valve cover, I would check to make sure that the vent slots on the valve cover are clear. I am actually surprised, BTW, that when installing the PCV kit ( which includes adding that fresh air inlet fitting ) the instructions do not include plugging those vents. At least I did not see that referenced in the instruction sheet posted by phak1.

It seems strange to me that they would have the installer go through the trouble of installing that fitting (which provides filtered air to the crankcase) and still leave the slots open - which would be a source of unfiltered air.

Perhaps if anyone has access to more detailed instructions, they could shed light on this.

In the event you ever move to California, or decide to run with PCV, I will try to clear up some of the confusion.

There are several air flow paths for various PCV systems:

In the one on my truck, shown in the pics, fresh air gets pulled into the crankcase through the small oil bath filter on the filler tube. It gets pulled out from the top of the valve cover, via the tube connected to the PCV valve, through the valve and into the intake manifold. In addition to a reduction in oil contamination due to improved management of blow by gasses, this system also ensures that only filtered air goes into the crankcase. Some may debate the effectiveness of that small oil bath filter, but it is better than just being open to atmosphere.

In the kit, the airflow appears to be in reverse. Air enters the valve cover from the add on fitting, as supplied by the tube connected to the carburetor air filter. Air is pulled out of the crankcase from the filler tube, through the PCV valve and sucked into the intake manifold.

To answer your question, in either with-PCV configuration, I would consider blocking those valve cover vent slits. Once again, it seems pointless to me to configure a filtered fresh air inlet, while still leaving an opening for unfiltered air to enter the crankcase.

Best Regards...

The instructions on the sheet I posted were from the Factory Assembly Manual. They were instructions for the truck assemblers to install the PCV system at the factory and not retrofit the engine for PCV. The valve cover would not have the vents or they were plugged at the factory.

Ahh.... OK. that makes sense.

Thanks for the clarification.