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Edlebrock Valve Cover Breathers???

21K views 54 replies 13 participants last post by  Sweet-34 
#1 ·
I have a set of old school Edlebrock Valve Covers with Breathers on my 327 c.i. Chevrolet. The intake manifold has the oil fill tube and breather on the front.

Is it necessary to have the valve covers with the breathers on this engine seeing that it already has a breather on the intake manifold?

Can I just remove the plastic filters which are totally disintegrated and put an old sock in them and plug up the filter?

The engine has a slight amount of blowby and it comes out the breather on the passenger side. I want to plug it up but keep the breather look.....Is it OK to plug up these breathers so they are not functional on this old 327 c.i.?

I know I can tear it down and rebuild it to eliminate the small blowby smoke.......but I don't want to at this time.

All suggestions and input greatly appreciated.

Thank you~~~~~~~~~~:
confused:
 
#3 ·
Yes they come apart. I took out the old foam mesh filters that were deteoriating. Is it necessary to have either one functional when I have the original intake with the Oil Fill Tube and Breather cap on the tube?

This is a 1967....327 c.u.i. with no PCV as this old engine did not come with a PCV Valve.

Thanks~~~~~~~~Ron
:confused:
 
#5 ·
If the engine is old its nice to have as much breathing as possible
I agree. The oil coming out of the breather is evidence you are getting blow by because of the wear on your rings/cylinders. If you block it off, you might cause gaskets to leak. :sweat:

I would look for something to replace the mesh filter. A replacement breather (or filter element) might slow down the amount of oil out of the breather.
 
#9 ·
I had the same set-up you are describing on my Model A when I first built it. 1972 era 355 sbc (no road draft tube), intake mounted oil filler with breather, no breathers in the valve covers (corvette aluminum finned covers). I ended up using a cotton filter on the breather due to blow by, to keep oil drops from splattering on the body.

Worked great until after about 300 miles, the first time I ran the rpm's up to about 6,000. It blew the seals out of the fuel pump and puked oil all over the header. I thought for sure I blew up the engine, based on all the smoke I saw in the rear view mirror.

I rebuilt the fuel pump (Holley) and then installed a moon breather in the driver's side valve cover. I then installed a '67 Corvette oil filler tube (with a pvc valve port) in the manifold, installed a pcv valve, and used a cap instead of a breather on the filler tube.

I haven't had any issues since, no more drippy oil blow by issues, no more blown fuel pump gaskets.... it's been troubble free for the last 9 years.

Hope my experience is helpfull to ya!

 
#12 ·
My '56 Chevrolet had Corvette valve covers and a aftermarket breather arrangement as shown in the photo. The aftermarket breathers were mounted in the sides of the valve covers so the rocker arms would not flood the breathers with oil. I had a 1965 Chevrolet FI 30-30 solid lifter camshaft and the lifters would shoot oil over the fenders when I was adjusting the valves. I finally stopped the excessive rocker arm oiling by using 1965 Chevrolet edge-orifice solid lifters that restricted oil flow to the rocker arms. The GM edge-orifice lifters also saved my rod bearings!

The 1962-1866 Pontiac engines had problems with oil blowing out the valve cover breathers. The Pontiac 421 HO and SD engines had baffled valve cover stacks in each valve cover that were about 4" high. That was a fruitless attempt to prevent oil from blowing out the breathers at high RPM. The passenger side breather stack was in the middle of the valve cover, between the rocker arms and it did not throw oil. The other breather was in the front of the driver's side valve cover, directly above a rocker arm. That was the breather that blew oil all over the firewall. I reduced oil blowing out of that breather stack by pushing a piece of foam rubber down the stack and eliminated oil blowing by pushing a piece of rag down the breather stack. . I have even seen Pontiac owners at the drag strip wrap their breather stacks with a rag to prevent oil blowing. .

Conclusion:
Where you put those valve cover breathers makes a difference. Do not put them over a rocker arm. The oil blowing problem was finally solved when GM went to the closed PCV system in 1968.
 
#10 ·
I'm not getting any oil blowby....just fumes (light smoke). The engine stays clean. Just want to get rid of the fumes. I'm going to plug up the valve cover breathers and just use the factory breather on the oil fill tube at the front of the manifold and see how it works out for me.

Thanks for all your suggestions.
:thumbup:
 
#13 ·
I've never had the valve covers off this engine. Apparently there are no baffles under the breathers because oil puddles at the base of the breather.

I just want to get rid of the fumes. I know a PCV Valve would solve the problem of fumes.....but I don't want to drill a hole in the top of these old nostalgia valve covers and fit a PCV Valve setup.


As stated earlier...I'm going to plug off the valve cover breathers and use the factory fill and breather and see if it helps.

Thanks for all your interest.
:cool:
 

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#14 ·
Location, location, location.....If those breathers had been installed on the opposite side of the valve covers, no oil would escape. See the previous photo of the Corvette valve covers. The side mounted oil breathers should always be installed on the intake manifold side (high side) of the valve covers.

When the engine is running, oil is tossed off the rocker arm and onto the exhaust side of the valve covers and then it puddles in the breathers. If you remove the breathers and cover the breather hole in the valve covers with a plate, the fumes and oil will not have any path to escape. Problem solved.
 
#16 ·
From the OP

"The engine has a slight amount of blowby and it comes out the breather on the passenger side. I want to plug it up but keep the breather look"

Not to pick nits, but....

The PCV is the best answer, only if you are trying to maintain the period look with the valve covers and breathers would I consider omiting the PCV. But you still need to vent the gases. Only way you are going to stop the fumes is with a PCV.

Maybe fit a PCV valve into the breather then add a hose to vent gases to the intake.
 
#17 ·
I'm confused? Why not just install the 67 vette filler tube as I stated earlier, that has the pcv installed in it. You can leave the breathers as they are. Then the engine will pull fresh air into the breathers and suck that air along with any oil fumes through the pcv valve.
 
#19 ·
I found Corvette Central sells reproduction Oil Fill Tube, Cap and Threaded PCV Valves for '66-67 Corvette. Should be able to do the whole changeover for less than $100.00.

How do you get the old oil tube out after many years of being in the manifold?

Do you put some type of sealer on the new tube and just tap it in with a block of wood and hammer?

Where does the hose go?

Never done it before so I have a lot of questions before attempting. Thanks in advance~~~Ron
:thumbup:
 
#20 ·
If you have a Holley carb it has a dedicated PCV Port, as shown here:


To remove the old filler tube I used a slip joint wrench with a piece of inner tube rubber wrapped around the filler neck. Get the wrench as close to the manifold as possible.

Or you could use a strap wrench if you own one, I don't.

I put some Red RTV on the new filler neck before I tapped it into place. The new neck can be installed by placing a scrap piece of wood across the top of the neck and tapping it into place with a ball peen hammer. Just be sure to orient the PCV valve in the right direction before installing the tube.

:thumbup:
 

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#24 ·
I found a couple of pictures of the Quadrajet I put on my 327. Can a Quad man tell me where the PCV hose plugs in or not.

Thanks
Just found this oil filler cap with PCV hose hookup on eBay. This ought to work with my old filler tube, couple pieces of PCV Hose and a PCV for a 327 Chev. I could do the whole thing for about $20.00.

Please look at my earlier post with the pictures of my Quadrajet Carb and tell me if there is a place to plug in the PCV Hose.

I think it will work......Any comments or suggestions?
 

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#30 · (Edited)
The easiest solution is to connect the pcv to the rear of the block where the road draft tube is located, behind the distributor, I have done this a dozen times. You leave the stock open breather alone in the filler tube, and run a hose type pcv to the rear of the carb, or screw in type- screwed into the vacuum port in the rear base of the quadrajet! The v112 valve is made to run from the road draft breather tube to the pcv port in the carb on a 327 Chevy!
 
#32 ·
The hole on the back where the original factory setup has been plugged. It looks like it might have a rubber plug with a bolt in the center.

If I take that out what do I use to install in the hole to attach a pcv valve to the baseplate of the Quad? Are you saying that the V112 is the one to use? It has a 1/2" barb with the flow going to the 3/8" barb.

Whatever goes in that hole must have a way to attach a 1/2" hose to the V112 PCV Valve.

Thanks for your response.
 
#31 ·
Is PCV Valve really necessary?

I had an earlier thread on Edelbrock Valve Cover Breathers. I decided to post a new thread as many that responded to the Edlebrock thread probably wouldn't read that thread again because they already read it and posted.

I have a 327 V-8 with Edelbrock Valve Covers with breathers in each cover. I have a push on cap on the oil fill tube that allows air. I'm getting a small amount of fumes in the passenger compartment.

Would it work if I purchased a Mr Gasket push on breather with a pcv valve barb and run the pcv valve hose to the base plate of my quadrajet carb which has the barb for a 3/8" pvc hose?

The sealed oil breather cap with the barb/hose to carb and the breathers on each valve cover would provide the circulation to eliminate the fumes. I have no oil blowby...just fumes.

This car is a cruiser...local shows and cruise-ins. Never driven over 60 mph. Thanks for any and all input.
 

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#39 ·
Is a PCv valve really necessary?

I had an earlier thread on Edelbrock Valve Cover Breathers. I decided to post a new thread as many that responded to the Edlebrock thread probably wouldn't read that thread again because they already read it and posted.

I have a 327 V-8 with Edelbrock Valve Covers with breathers in each cover. I have a push on cap on the oil fill tube that allows air. I'm getting a small amount of fumes in the passenger compartment.

Would it work if I purchased a Mr Gasket push on breather with a pcv valve barb and run the pcv valve hose to the base plate of my quadrajet carb which has the barb for a 3/8" pvc hose?

The sealed oil breather cap with the barb/hose to carb and the breathers on each valve cover would provide the circulation to eliminate the fumes. I have no oil blowby...just fumes.

This car is a cruiser...local shows and cruise-ins. Never driven over 60 mph. Thanks for any and all input.
Why not get the new tube with the barb and try it. If you find you need a PCV valve at idle get an inline PCV valve for an early model chevy with a 327 engine. I looked my 67 Camaro up on Advance Auto Parts website with a 327 engine. It listed an inline PCV valve by Fram FV112.
 
#34 ·
It's only necessary if you don't want the fumes.
Isn't the job of the PCV Valve to regulate the amount of suction from the intake? Very little suction at idle and almost none at full throttle.

I really don't know....just a thought. I seen a setup like I suggested on a 327 V-8 Corvette with Tri-Power and he claims it works perfectly. Hooked up directly with no PCV.

Would there be a problem at idle if it was drawing full suction?

As I stated earlier....I really don't know and am just throwing out the topic for discussion.
:confused:

See attached picture.
 

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#35 ·
..... it was discovered in 1958 that the road draft tube was a major source, about half, of the hydrocarbons coming from the automobile. GM's Cadillac Division, which had built many tanks during WWII, recognized that installation of PCV on vehicles could bring the first major reduction in automotive hydrocarbon emissions.

Happy Reading... :welcome:

Crankcase ventilation system - Wikipedia, the free encyclopedia
 
#36 ·
Is PCV Valve really necessary?

I have read your other post. I really don't think you were understanding some of the threads that were posted. As you say you have fumes in the engine compartment. The purpose of the PCV valve is to pull the gases from the crankcase and pull them into the intake manifold to reburn in the engine again instead of to the atmosphere. The PCV valve regulates the vacuum pulled thru the PCV system. That is why your idea will not work. Here is an article on crankcase ventilation to give you a better understanding than I can explain. Crankcase ventilation system - Wikipedia, the free encyclopedia
 
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