283 PCV question

[Vance_cortino]

Howdy, all. Got some PCV questions for you.

Truck is a 67 C10 283 that was rebuilt by PO about 10 years ago. Truck has an Edelbrock Performer intake with an open style oil fill neck/breather tube, Holley Street Warrior, and the bolt down style PCV vent cap, not the road draft tube.

Currently, there is no line coming off of the vent cap next to the distributor. This appears to be adding to the oily mess that is my engine compartment.

I'd like to hook this system back up somewhat correctly, so this is what I was thinking. I have my power brake booster vacuum line running to the full manifold pressure port at the bottom of the Holley carb. The Performer also had a vacuum tree in a port between the carb and distro, which I capped off with a brass plug and moved the booster line to the Holley.

Would it make sense to run the PCV line from the vent cap at the back of the block to a brass tee fitting with an in-line PCV valve somewhere along the way, connect the brake booster to the other half of the tee, and connect both to the manifold port on the carb base?

Because of how close everything is in that area and how long the barb is on the carb port, I cannot make use of the port in the intake manifold.

Thoughts? I have included some pics as well. Thanks all for any insight.

[Steeveedee]

In general, there will be a port on the carburetor that is calibrated for the PCV flow, and the brake vacuum would come off the back of the manifold. But I'm a bit rusty on that smog control stuff. I think that the fitting on the back of the block should have a hose that goes to the bottom of the air cleaner, on the inside of the filter, and have a flame arrester screen. That fill tube would be sealed and there would be a PCV valve in it. Those pics are huge on my screen; maybe you could re-size them?

[CAMAROBOY68SS]

Most 67s didnt really have a PCV system. That was the last year of the draft tube. There should just be a rubber hose basically coming off that port on the block and running down. Under the intake manifold should be a oil separator canister that is supposed to keep the blow by down. That can could be full or missing if you have not pulled the intake on it.



If you want a PCV system, look at how the L79 (327ci/350hp) or the 67 Z/28 302s were ran. You need an Oil fill tube with the provision for the PCV valve, that is then routed into the carb base (on a factory L79 Holley its on the base on the passenger side at the rear. Then they had a special tube that fits into where that road draft tube is on your block and it routed it into the air cleaner base. They dont make the bent metal tube any more but you could route a rubber hose to the air cleaner base off that fitting in the block.

[67 twins]

Originally Posted by Steeveedee

In general, there will be a port on the carburetor that is calibrated for the PCV flow, and the brake vacuum would come off the back of the manifold. But I'm a bit rusty on that smog control stuff. I think that the fitting on the back of the block should have a hose that goes to the bottom of the air cleaner, on the inside of the filter, and have a flame arrester screen. That fill tube would be sealed and there would be a PCV valve in it. Those pics are huge on my screen; maybe you could re-size them?

No, that's not how it was from the factory. A hose went from the fitting at the back of the engine to a PCV valve that screws into the base of the carb. The oil tube supplies the fresh air. OP has the right idea

[cwcarpenter98]

The 283 that was in my 63 when I bought it came from a 65 Chevy car, I believe. It has the PCV system in question. Ran to a valve on the base of the 2 barrel carb. When I went to a 4 barrel, I continued to use the same setup. Seems to work as intended

[Accelo]

GM had a PVC system in 1963.
below is a picture of the set up.


The last year for the road draft tube was 1962. After that the 283's and 327's still had the tube hole in the back of the block up until '67.

[Vance_cortino]

Thanks for the info so far, everyone. I resized the images a bit to make them smaller but still be able to see detail.

Without pulling the intake off, I have no way of knowing if the oil baffle is still in there. I'm hoping that it is. I'd really rather not break this down in the middle of driving season while it's running so well.

Also, the front cap on the oil filler is the open, mesh style one. Not a closed system.

I'm sure eventually I could do like some others on here, and remove that rear vent and hammer in an 1-1/4" freeze plug, and change my valve covers to a later style with the valve and breather in them.

But for now, I'm gonna pop over to Napa today and see what kind of small in-line PCV valves they might have that I can incorporate.

[Bigdav160]

On my California '67 327, in the rear is the vent that's attached to the air cleaner base. The PVC is located in the oil fill tube.



What ever you do, do not just hook up a vacuum hose to the rear vent opening. That would be a giant vacuum leak that would suck oil out of the crankcase.

[67C10Step]

Originally Posted by 67 twins

No, that's not how it was from the factory. A hose went from the fitting at the back of the engine to a PCV valve that screws into the base of the carb. The oil tube supplies the fresh air. OP has the right idea

This is correct. My 67 283 is all stock and this is the setup. From that fitting on the block to the base of the carb. I can get a photo if needed.

[Vance_cortino]

Ok, so I have a few days off and some time to dig in more. I got out my original service manual, and I also have the original complete intake system. Pics to follow.






As far as I know, that is the actual, original system that came with the truck. Looking at the air cleaner housing, there are no ports for valves or flame arrestors.

Then, looking forward of the old 2bbl carb, you can see the open, vented style oil filler tube, and the original PCV valve at the back of the carb where that elbow is.

Further, looking at my manual, that picture shows the identical setup to mine.

So, I am unsure any other way I should be hooking this system back up, other than adding in an in-line PCV valve right before the hose connects to the large manifold vacuum port at the bottom back area of my Holley carb.

Am I missing something?

[67C10Step]

Vance,
That is exactly how mine is set up with the 2 barrel carb. Mine had an oil bath breather stock that I have converted to paper element.

[Vance_cortino]

Originally Posted by 67C10Step

Vance,
That is exactly how mine is set up with the 2 barrel carb. Mine had an oil bath breather stock that I have converted to paper element.

Interesting. I take it you mean the filler tube at the front of the manifold?

[geezer#99]

He means the actual air cleaner.
Maybe he’ll post a pic.

[RichardJ]

Remember that the valve flows air in one direction only. A PCV valve that threads into the oil fill tube, flows air directly opposite a valve that threads into the base of a carb.

The end of the valve that is connected to the vacuum source, will shut down tight if you blow into it from that end.

[NGN]

My 67 327,,,from the vent tube off the back of the block then folloow with an attached rubber hose that's then attached too the PVC, the PVC which is screw in the center back base of the carburetor. That's my set up. My brake booster and automatic transmission are off the top back manifold, if you have A/C it would also hook up there.
NGN
Nick

[67C10Step]

No connection to the oil filler tube or the air cleaner. Just as shown in your picture that says 283-327 typical, the connection on the rear of the block has a hose that goes to pcv screwed into base of carb.

[Vance_cortino]

Excellent, thanks, everyone. Hopefully should have an update here this weekend when I get it hooked back up.

[RichardJ]

>>the connection on the rear of the block has a hose that goes to PCV screwed into base of carb.<<

That part is good. Now you still need a provision for clean fresh air to enter the crankcase.

The drawing on post #10 shows a vented cap for air intake. That is period correct, but it is what they call an OPEN PCV System.
The single problem with that is that during WOT, when blow-by is at its maximum, vacuum is at its lowest and the PCV System can't pull much of the crankcase fumes into the intake manifold to be burned. The excess crankcase fumes spew out into your engine compartment from that vented cap.
It you use a closed vent cap with a side port and connect that to the air cleaner, it becomes a CLOSED PCV System and your engine should stay cleaner.

[Tomchev]

The 64 Chevell I had in the 60s had a pcv valve in the back of the carb on a 90 deg fitting with a rubber hose to back of motor