I am going to be running evac system to my headers from valve covers.
I have seen guys do this .. and it pulls nothing but smoke.
However some guys have welded a small metal baffle/shield on the underside of the valve cover where the breather goes.
* I think I even saw these shield for sale from one of the aftermarket vendors.
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Anyone have any experience with this?
Anyone seen the baffles?
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Thanks,
B

You should have open headers with an e-vac to work

I agree with the open headers.
I am running a 4" exhaust thru big Lemon headers.. so it surely will breath.

I had baffles welded to my cover....I also believe that the evac system does not work with mufflers and needs open headers for best results....

I am also thinking about doing something different....right now I have 1 filter on each of the valve covers....for street, is it better to go to a pcv on the one of the covers?

Yanniz,

In all our race engines we use an e-vac system, they work good but we have a race engine on the street in our personal car and we are trying to find a better system than just breathers.

The problem with exhaust on an e-vac is when it builds up back pressure it has no where to go and depending on which e-vac, they have a check valve, the back pressure can be forced back by the check valve and into the engine

And on my engine a baffle is almost out of the question. My valve springs are installed @ 1.950" plus we run a locator which is .055" thick. We also run stud girdles,we only have around 1/2" clearance and we use a thick valve cover gasket with our dart valve covers. This is why i think we are gonna switch to a jesel or crane shaft mount rocker system.

Pan evac wont work with an exhaust system, gotta have baffles in the valve covers too. The valve going into the header needs to be at the right angle too. A buddy of mine welded a bung on his collector, then put a 90* elbow on it, not enough suction, it works better with the breather caps connected to puke tanks hanging on the core support.

thanks for the input.
Yes my bungs on the collectors are at the correct angles.
Moroso sells part # 68790 (or you could make it...) for under the valve cover.
*Designed to mount under the breather hole. Keep oil from getting up into the breathers and or sucked straight out.
* I do know a guy who welded a similar set up under the beather hole and ran the evac system on the street with out a smoke cloud like he was headed back to the bat cave.
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Pretty sure breathers had check valves in them too.

Picture of exhaust...

No proof but from what i have been told the closer the muffler is the more back pressure? I dont know if iys true or not but does make sense as the exhaust gasses hit backpressure sooner

I know a guy with a BB pontiac that tried to put his pan evac in the turn down of his dumps and it didnt work either, not enough flow to create a vacuum back there.

And on my engine a baffle is almost out of the question. My valve springs are installed @ 1.950" plus we run a locator which is .055" thick. We also run stud girdles,we only have around 1/2" clearance and we use a thick valve cover gasket with our dart valve covers. This is why i think we are gonna switch to a jesel or crane shaft mount rocker system.

I can take a pic of my cover and send it your way.....I used to have a vacuum pump, and I am using that front hole on the pass. side now for the breather/filter....it has a baffle welded underneath.....

I am using similar set up as you (thick gaskets, et cetera) but I do have the T&D shaft rockers and have no clearance issues at all....

again, if you are runnign full exhaust evac is waste of money....best would be vacuum pump if you have the room in the bay...

happy new year....

Picture of exhaust...

ain't going to work...

Running an 8:71... so will have plenty of pressure....?

ain't going to work...

Why not? I've run mine that way for 4 years. The oil level has never dropped, nor has it smoked any. I have 3.50" pipes, Dr. gas X pipe, and Dynomax round welded race mufflers turned down in front of the axle.

Evidently you dont have much crankcase pressure. Even a free flowing exhaust system has back pressure, and a pan evac wont work with back pressure, the exhaust velocity creates a vacuum that evacuates crankcase pressure. Would you care to post pics of your motor?

Yes Please post some pix.