Don't know if the title makes sense or not, but here is my question.

I have a '78 F100 Custom with a 351W (I installed) and C6 transmission, 2WD, SWB. I just put a New Intake (Edelbrock 2181) and will be putting a New Carburetor on it in two weeks. Currently it has a Holley 4bbl Square Bore carb, the breather is a 9" . My question is this...The valve covers are new as well, and I took pretty much all of the EGR valves off the Intake upon removal...where do I hook up the breather line that runs from the Valve cover, to....(used to go into the breather)...now where do I run it? I made the mistake of just plugging it, and lets just say I have plenty of compression in the block...it blew the oil fill plug completely out...the only areas I have to hook it into are vacuum ports either on the adapter or the Holley Carb...is that where I would hook it into, a vacuum port? Help is appreciated...

 

Get a vented cap and pitch it.

 

Do I need one on both covers or just one, and plug the other

 

I have a vented cap on both.

 

Cool, I will go pick one up tomorrow...

 

what do you mean by a vented cap? i have a feeling ill have the same problem when i do my valve covers

 

What are these "vented caps"

 

Vented cap on each valve cover won't do.

The PCV valve sits in one valve cover, sourced by manifold vacuum. The breather filter needs to go on the other valve cover. The factory breather setup was housed in the air cleaner, with a hose running from the valve cover up to the breather. Aftermarket setups use a vented oil filler cap with a built-in breather.

PCV is a circular system - you need to be able to cycle fumes through. One side needs to pull, the other side needs to let fresh air in. If you just let both valve covers breathe, it will kill your motor oil and eventually the engine.

 

Hi fmc400, can you explain how it'll kill the oil then motor with both sides vented? Thanks.

 

Even with healthy piston rings, some of the engine's combustion mix will escape past the rings. This is called blow-by. As blow-by accumulates in the crankcase, it mixes with the motor oil to form sludge. This degrades the performance of the oil, which eventually takes its toll on the engine itself.

The only way to get blow-by out of the engine is by moving it through - hence the need for positive crankcase ventilation (PCV). Just venting the motor on both valve covers won't move the blow-by through. The effects of running a motor without a PCV system can be seen when tearing down a motor that was built before PCV valves were installed in the late 60's, and all that was there was a "road draft" tube (road draft tubes, in turn, where responsible for the light oil slick in the middle of the roads way back when).

 

Ok, so for my understanding...would the following set up work?

This installed on one of the Valve Covers...

Where would I run the hose? What does it hook into? I have a Vacuum port on the intake, or I have one on the adapter under the carb, or does it need to plug into the carb itself?

Then some type of set up like this on the other cover...


I just want it to run correctly...
Currently I have a PCV valve installed in the passenger side cover, but have it blocked off, just need to know where it needs to run into...

 

I have a 94 Bronco with a 351w, the PCV valve is on the passenger side and connects to the intake manifold. If you have a carb run this line to it. The breather comes off the oil filler cap and runs to the air filter. I also have 78 F150 with a 351m, the PCV valve is on the drivers side, oil filler, and runs to the carb. The breather on the passenger side runs to the air cleaner.

The Edlebrock cap in your photo does not have a PCV valve. You would need to add one. The other is a filtered cap and probably would work for the breather side.

I hope this helps.

Mark

 

CalebJns, what you have shown is not a full, functioning PCV system. All three of the pictures you have are for the breather side of the PCV system. Like FMC400 said, you need a vented breather cap one valve cover, and a PVC valve on the other. None of your pictures shows a PCV valve. The PCV valve simply fits inside the other valve cover and will have a smaller nipple to attach a hose to the carburetor spacer. This portion of the PCV system is what pulls the air through the engine.

Fram FV198 - Fram PCV Valves - Overview - SummitRacing.com

Are you using your original air cleaner, or an aftermarket air cleaner? That will tell you which one of the following breather caps will be the easiest for you to use:

You can use the Edelbrock breather oil cap you have shown, provided you still have the original air cleaner. The nipple on the end of that cap is for a hose to attach to, and from there the hose attaches to the factory air cleaner. The factory air cleaner has a hole cut out of one side of the casing that should have a small air filter attached inside that sticks through the casing. The hose on the nipple of the Edelbrock cap attaches here. In this way, the air that goes into your engine for that portion of the PCV system is filtered.

The second picture looks like a factory oil cap with a replaceable aftermarket air filter pushed in. If you use this, you do not use the Edlebrock cap or run a hose to the air cleaner, as the air filter is mounted on the cap itself. This is also used for aftermarket air cleaners that do not utilize an air filter inside the air cleaner for the PCV system.

The last picture you have is of a factory style stem that sticks into the factory valve cover oil breather cap. This bottom of the stem should fit inside the top of the factory oil cap (the one shown with the aftermarket air filter pushed in). The other longer end will have a hose attached, which goes to the little air filter attached inside the factory air cleaner casing. The Edlebrock cap you have shown takes the place of this nipple that goes into your factory oil cap.

No matter which "breather" cap you use, you absolutely must have a PCV valve on the other end!

 

Sorry for being retarded, and not catching on, busy getting ready for a mission trip to Ecuador tomorrow...the link you sent me, I have one from the old Engine I pulled out of the truck...again sorry for not grasping this quickly...but from their, I run the lower hose to________? and the upper hose to ________? or does it need to be blocked off? That is on the passenger cover, so what would be needed on the driver side? Also I have a 9" breather on top of the Carb, not the Factory breather...I have Edelbrock 4160's as Valve Covers, and an Edelbrock 1406 Carb...Again sorry for not grasping this so quickly...but thanks for the help and information...

 

Since you are running an Edelbrock carburetor, the larger, bottom port of the PCV valve connects to the large middle port in front of the carburetor itself. The smaller top port of the PCV valve could either be plugged or it goes to the canister purge solenoid, depending on what emissions your truck has. Go ahead and plug the top port until you find out; the top port is only for emissions.

The other side is where the breather cap (explained in my last post) attaches to. Since you are running an aftermarket air cleaner, the only breather cap you have shown that might work is the one that has the cap in your hand. If that cap doesn't fit tightly into your aftermarket valve cover, you will need to get a different style push-in oil breather cap with the air filter already built in:

Edelbrock 4403 - Edelbrock Signature Series Valve Cover Breathers - Overview - SummitRacing.com

That should be all you need to have a properly functioning PCV system!