Valve cover breather and pcv needed?

[jcb9089]

Question on engine function. 302 carbed, no emissions.

Is it best to run a PCV Valve on one side and a breather on the other valve cover.

Or...Do I need the breather at all? Can I just put a screw in type oil cap instead of having a breather on one side?

Would like to cap off one side and run the pcv valve on the other but will this affect the engine at all?

 

[Steve83]

A working PCV system only helps the engine last longer, and it reduces oil leaks. Click this & read the caption:

 

[Broncobowsher]

You need the PCV to suck the air out
You need a source for fresh air to enter (as well as a secondary escape for crankcase pressure when under load the there is no vacuum for the PCV to pull)

The details are not a relevant as the function.

 

[chuzie]

A working PCV system only helps the engine last longer, and it reduces oil leaks. Click this & read the caption:

Cool diagram steve. So 3 connections (EFI) are valve cover 1 to upper intake, valve cover 2 to air box, and pcv to upper intake.

I only have one valve cover connected. The other is capped. I assume that is bad?

 

[Ourobos]

^ For speed density.. Sure..

For MAF, that would be introducing unmetered air via the airbox to valve cover.. Eliminate that one.

 

[BigBlueBronco71]

PCV valve on one side hooked to carb or carb base and breather on other side hooked to the air cleaner, needs a full circle

 

[chuzie]

^ For speed density.. Sure..

For MAF, that would be introducing unmetered air via the airbox to valve cover.. Eliminate that one.

i am maf but actually have the valve cover hooked up at the TB instead of air box so it should be accounted for.

 

[Ourobos]

Yours is right then Chuzie.. The PCV pulls crankcase air into the manifold, and the tube from the throttle body to valve cover is already meter air that travels back into the engine via that route..

 

[chuzie]

So no issue leaving the opposing cover out of the loop?

 

[Ourobos]

I suppose where it would be 'nice' to get more fresh air in from both sides of the engine, Ford designed it with just one side, as I don't know of a simple way to get meter air in from the other side myself. The way you have it is the way every 1989-1993 Mustang has it.

 

[jckkys]

jcb9089 asked about a carbureted engine. In that context, the best PCV arrangement introduces "air" from the crank case evenly split into the intake flow below the primary throttle plates where it blends with a mixture of fuel and clean air as a contaminant that needs to distributed as evenly as possible to the cylinders. More "air" is removed then blow by and water vapor can replace in a low mileage engine. The breather introduces clean filtered air to give the PCV a constant flow that won't change the idle mixture. The best and easiest source of clean air is the air cleaner down stream from the filter element. A flow through system with clean air entering one valve cover and pulled from the other valve cover keeps the crank case cleaner.

 

[Steve83]

So 3 connections (EFI) are valve cover 1 to upper intake, valve cover 2 to air box, and pcv to upper intake.

No, and it doesn't matter if it's carb or EFI; SD or MAF. Clean air (from the atmospheric side of the throttle plate) needs to go IN to the crankcase; vapors need to come OUT (and go to the manifold vacuum side of the throttle) - that's 2 hoses.

The only distinction for MAF is that the clean air needs to come from between the MAF & the TB so it has been measured.

 

[Ourobos]

I agree.. But the above diagram shows three, I think that is what Chuzie was questioning..

 

[TDubya]

I agree.. But the above diagram shows three, I think that is what Chuzie was questioning..

I only see two in the diagram, PVC on passenger side valve cover to upper intake and driver side valve cover to air cleaner intake. Just like my carbed setup.

 

[chuzie]

So i assume the vacuum from the pcv is greater than in the air intake tube. Throttle dependent obviously.

 

[Ourobos]

I only see two in the diagram, PVC on passenger side valve cover to upper intake and driver side valve cover to air cleaner intake.

Cool diagram steve. So 3 connections (EFI) are valve cover 1 to upper intake, valve cover 2 to air box, and pcv to upper intake.

I only have one valve cover connected. The other is capped. I assume that is bad?

I see these three also

 

[Steve83]

But the above diagram shows three, I think that is what Chuzie was questioning..

I see 4. %) 2 in the main (top) view for the 5.0L V8; 1 for the I6 engine in the lower L; and a close-up in the lower R detailing the minor difference for 5.8L V8s. All 3 engines have essentially the same tube from the air filter to the valve cover. So for each engine, there are only 2 tubes shown. If you can't see the details, click the pic again in the new tab/window to supersize it.

So i assume the vacuum from the pcv is greater than in the air intake tube.

The vacuum only exists in the intake (between the throttle & the valves); everywhere else is at or very near atmospheric pressure.