Vave cover/engine venting opinions wanted

[Fordman]

So I'm putting a competition style cast aluminum set of valve covers on my engine. These have 2 threaded openings in them. My thought was to create vacuum to the top end and increase ring seal do I install Plugged caps at the front holes and a PCV style fitting to the rear with pan-vac plumbing to go to the header collectors. I was thinking of a Filtered fitting in the front and the pan-vac plumbing to the rear breather holes but my brain says this would defeat the Vacuum created with the front holes being vented. Looking for opinions. Thanks....John

[wowens]

You can not create a vacuum with vented valve covers. Vented covers and a header Evac system will get you to, or close to, a neutral pressure inside the block and keep fresh air circulated through it. Probably will not help oil aeration

[Fordman]

Thanks for the reply. Again....Common sense wins the day.

[Falcon67]

Echo - header evac requires sealed covers or at least the caps with the hose connections need a good tight fit if using rubber bushings.  Threaded is even better.  Same with a vacuum pump, except you need even tighter sealing.

[Fordman]

Will blocking the front valve cover holes and fitting the rear with AN fitting and braided line to a header/evac system suck oil from the engine and deposit oil to the track?. I remember Tom.P  telling me a story of a time he hooked up a similar system to the rear breather hole in the intake manifold and had that happen. he said track officials were less than impressed. If so, any ideas to prevent that?. Thanks...John

[wowens]

From  your description I am assuming you have Blue Thunder covers, unbaffled.
You will need 1/2 or 3/4" line to header and a good air/oil separator/accumulator on each side.
Header Evac systems don't work well with mufflers or low rpm use.

[KMcCullah]

Will blocking the front valve cover holes and fitting the rear with AN fitting and braided line to a header/evac system suck oil from the engine and deposit oil to the track?. I remember Tom.P  telling me a story of a time he hooked up a similar system to the rear breather hole in the intake manifold and had that happen. he said track officials were less than impressed. If so, any ideas to prevent that?. Thanks...John

I think the easiest way to ensure your pan evac system doesn't suck oil is to plumb them to the front of the valve covers. I don't have a way to prove it but I bet under hard acceleration, a lot of oil accumulates at the rear of the covers.

Jay has a slick little plate baffle that bolts to the roof of his valve covers. Maybe they would work for you if you need baffles?

[TomP]

I had valve covers with no openings so I used a tall standpipe off the rear manifold breather and tee'd two heater hoses off that. It suck two or three quarts of oil in a nice mist all down the track.
 The manifold opening was baffled at the bottom with the mesh basket but apparently that won't work in a hard launching car. I then changed it to the hoses coming off the front filler tube and that worked.

[1967 XR7 GT]

TomP, question.

Were you running a lifter valley splash shield ?

I had valve covers with no openings so I used a tall standpipe off the rear manifold breather and tee'd two heater hoses off that. It suck two or three quarts of oil in a nice mist all down the track.
 The manifold opening was baffled at the bottom with the mesh basket but apparently that won't work in a hard launching car. I then changed it to the hoses coming off the front filler tube and that worked.

[Falcon67]

Will blocking the front valve cover holes and fitting the rear with AN fitting and braided line to a header/evac system suck oil from the engine and deposit oil to the track?. I remember Tom.P  telling me a story of a time he hooked up a similar system to the rear breather hole in the intake manifold and had that happen. he said track officials were less than impressed. If so, any ideas to prevent that?. Thanks...John

I take my evac from the top of the valve covers - front on one side, rear on the other.  Vacuum pumps typically take from an -AN fitting on the front of one cover.  I would not do the rear down low.  Any oil is likely to find your tires first, so keep that in mind.  Top front with baffles is the best location.

[TomP]

TomP, question.

Were you running a lifter valley splash shield ?

Yes, even will roller lifters, they fit when turned backwards, link bars towards the walls.