Valve cover breather technical question...

[Eternalfootman]

Okay, so I've been wondering, since I know very little when it comes to carb'd vehicles: What are the pros and cons of these two options? Are there any at all, or do they basically do the same thing?



1) A valve cover breather filter, with no connection to the air cleaner.

2) A hose that goes from the valve cover to the underside of the air cleaner.



I know why you need to vent the valves, but I was just wondering what the differences in ventilation might be. I also have a PCV on the other bank.

Oh, and just FYI, the engine is a 360 with Edelbrock intake, carb, MSD 5 ignition, on an '85 Ram.

Thanks everyone!

Dave

[BJSracing]

The hose just helps recirculate the blow by when the motor gets a little more on the tired side of life. It sends the blow by back into the motor and reburns to help eliminate polution and smoke.

[jelsr]

When new the PCV keeps a slight vacuum in the crankcase and the hose lets the engine draw air that has been filtered by the air cleaner element. The small filter on the cover does the same but not as well.

[Eternalfootman]

Originally Posted by BJSracing

The hose just helps recirculate the blow by when the motor gets a little more on the tired side of life. It sends the blow by back into the motor and reburns to help eliminate polution and smoke.

I understand all of the theories behind the PVC and breather stuff - it's not the PVC that I'm asking about. And I'm also not asking why a breather is needed on the other side of the engine.

What I'm really asking is which is better - a simple filter from Summit on the top of the valve cover, or a hose connecting the valve cover to the underside of the air cleaner. (This is not the PVC valve, mind you, which goes back to the intake.)

Here is a link to the breather that I have installed on the truck now:

http://store.summitracing.com/partde...5&autoview=sku

Then I purchsed a new air cleaner for the truck, but it has a hole on the bottom for a hose to go from the valve cover to the air cleaner. So I'm wondering if I should return the air cleaner and get one without a hole, or get rid of the little breather that is on the valve cover.

[BJSracing]

I typically won't run the hose. I just run the breather filter that you are talking about. Or I run the vent tubes down to the collector on the header like you see on most race cars.

[dodger1]

Depends what you like. Air filtered by the carb air cleaner MIGHT be a little cleaner. It'll also keep any residual hydrocarbon products (crankcase gases) relatively contained while the engine is shut down, to be re-burned at start-up. The valve-cover breather looks cooler, especially on an aluminum cover. Either way I don't think it would affect power unless you're making big numbers, in which case I guess the header-extractor or other forced-evacuation systems are the ticket.

[moparmussel]

vent the breather through a cheepo cap,cut a small piece of sock to put over the cap to keep oil residue off valve covers.

[Shaun]

They need to breathe,but I don't like putting a hose from the cover to the cleaner,because sometimes it'll let water(condensation) in. It is strange,but I have seen it time and time again,especially on rebuilt engines.
If you don't want to go to the collectors and get some extra HP,just go with the breathers.
BTW,a PCV only works at low rpm's,you are better off without it.

[Eternalfootman]

Okay, sounds like I'm gonna keep the breather and go with a different air cleaner (or just cap the one I have.)

Thanks!

Dave

[Tarrbabe]

[FONT="Arial Black"]Running the hose from the breather cap to the Air Filter creates a vacuum and helps remove moisture and other unwanted gasses from your motor. Would you rather have to clean your air filter or your engine?
Not to mention you’re helping the environment too.[/FONT

[Madman Stephan]

Originally Posted by BJSracing

I typically won't run the hose. I just run the breather filter that you are talking about. Or I run the vent tubes down to the collector on the header like you see on most race cars.

Tell me more about this. I don't know much about race engine set-up's. You would take a hose (1/2" braided?), connect it to the valve cover, then weld a barb fitting (is it perpendicular or at an angle?) to the header collector, and then the speed of the exhaust coming out will create a vacuum in the line and suck the gases out of the heads?

[winston]

Originally Posted by Tarrbabe

Running the hose from the breather cap to the Air Filter creates a vacuum and helps remove moisture and other unwanted gasses from your motor. Would you rather have to clean your air filter or your engine?
Not to mention you’re helping the environment too.

ETERNALFOOTMAN!

I would take "TARRBABES" advice. The condensation that shaun is talking about is true! Only because that individual is not running the engine long enough.
TO MANY short trips!

take it as it is then.
Winsto

[Shaun]

Too many short trips? Think about it a second. If you have a rainy day,you drive your vehicle 20 miles at operating temp and shut it off,it'll get a little warmer before it starts to cool right? Will the warm air be right at the air cleaner height? Yep. Right under the hood. So with your air cleaner being warm on a cold rainy night,what will happen as it cools? It will draw a little moisture in. Yep. It happens on every engine. But when you have a breather connected to the air cleaner,it gathers the moisture and then it drips down the tube. It's not necessary to have the breather hooked into the air cleaner. If you want to go that route,why not hook it up to full manifold vacuum,from the base of the carb? You will not have condensation this way.

[Shaun]

Originally Posted by Madman Stephan

Tell me more about this. I don't know much about race engine set-up's. You would take a hose (1/2" braided?), connect it to the valve cover, then weld a barb fitting (is it perpendicular or at an angle?) to the header collector, and then the speed of the exhaust coming out will create a vacuum in the line and suck the gases out of the heads?

You weld the barb fitting to the collector at an angle that would be closest to parallel with the flow of the exhaust. In other words,run your braided hose from the breather down to the collector and have the little tube welded in(air tight)at about a 35-40* angle,coming out of the collector facing towards the engine. So,the exhaust is running out the back,weld the fitting in facing towards the engine at a good angle. This angle is important to prevent it blowing air at low rpm's from back pressure.
Check out summit. They sell these weld in evac units.

[Madman Stephan]

Thanks for the info!

[Fig]

Originally Posted by Shaun

You weld the barb fitting to the collector .

For a street car you may want to consider putting the fitting past the mufflers due to back pressure.

[BJSracing]

Originally Posted by Fig

For a street car you may want to consider putting the fitting past the mufflers due to back pressure.

It would still pull enough vaccum if the bung was installed right to clear the crank case. You wouldn't need to go that far back. If you do you just run more of a chance of burning the hose and possibly starting a fire.

[go-fish]

Originally Posted by Madman Stephan

Tell me more about this. I don't know much about race engine set-up's. You would take a hose (1/2" braided?), connect it to the valve cover, then weld a barb fitting (is it perpendicular or at an angle?) to the header collector, and then the speed of the exhaust coming out will create a vacuum in the line and suck the gases out of the heads?

Also, Do you need to do both sides or just one? Does it have to be at the collecter or can it be on a tube? I have never seen this done either.