valve cover breather

[m.lion]

Is there supposed to be a direction for better venting on a 604?

[brad hibbard]

Absolutely

this is a very common mistake----GM installs them on a new engine with the shield toward the header----I think their reason is so that the bow-tie logo looks correct but it is incorrect for proper crank case evacuation.

the shield should be towards the fan --blocking the fan air

any other position and the fan will force dirt into the breather and into the engine----it also forces air into the crankcase which hinders the ring seal and cuts HP.

Great question

Brad

https://www.race-1.com

[brad hibbard]

So all of us with unshrouded breathers have dirt blown into our motors?

I just zip tie a piece of cloth over my breathers?

If you are running a fan then yes you are forcing dirt and air into your breather

the breather sytem used on a GM circle track crate engine has to release pressure from the crank case to operate properly----when you force air into it you are defeating its function.

in my opinion the shields are a must and need to be properly located

an additional cloth over top of a non shielded breather is nothing more than an additional filter and actually hinders the evacuation even more.

Brad

[Matt49]

Brad,
What about just and Outerwear on the breathers along with the shrouds facing forward?
PRO - less dirt in
CON - less pressure out
Which one wins?

[Egoracing]

For anyone that is just putting a rag over the tubes like others have posted, you car limiting your engines ability to vent from the start and oil vapor hitting the rag will start pluging the air flow instantly.

[brad hibbard]

Brad,
What about just and Outerwear on the breathers along with the shrouds facing forward?
PRO - less dirt in
CON - less pressure out
Which one wins?

Matt,
The outerwear relly doesn't hinder air flow even if it does become somewhat oily or dirt covered it still usually has enough air gap at the top or bottom to breathe-----I have seen socks over top of breathers and rags wrapped around several times ----those guys might as well plug them off.

i will dig out some real world #'s about blow by and breathers as we have tested this extensively, and post them for you to see---------------
actually when R2C came out with a valve cover breather it did not have a shield-------we contacted Ed and relayed our tests about shields and now they offer a shielded breather

Granted it is not a huge gain but we spend endless hours on fuel curve and header design to find a horse or 2 ---

Brad

[joedoozer]

I run the shielded type with the shield facing the fan. I have to clean them weekly there is so much dirt on the backside of the breather. Most of the big money motors here run the breather right into the header.