Anybody have some tips on taping the valve cover to use large diameter breathers. The factory breather tube/hole is high on the valve cover, so you can't just enlarge it you have to drill a new hole which is offset lower. Then hope the old hole doesn't suck your drill bit in. Any tips there?

Also it seems that the walls pretty thin on the valve cover....

I'm looking to do something like this...

 

I don't know if the valve cover on the later Evo's is different to mine, but one thing I noticed was there is some very serious baffling going on underneath the cover. It made me wonder if enlarging the hole would make any difference considering it was so tightly baffled.

 

There's tons of baffling, but the cross-sectional area of the baffling channels is much larger than the pencil sized breather. It can support 1/2" hose no problem flow-wise.

 

Anyone have input?

 

I drilled out/tapped mine about 2 months ago and only really had to worry about one thing. Once you drill/ and tap you create alot of shavings and with the baffle's in there just gotta make sure you are very extensive with the cleaning out. It's not that easy because the baffle's pretty much create pockets you cant really get into, but I just used my parts washer which has a small end on the hose to put it right inside and washed out for about 20 min until I didnt see any other shavings comming out. I only drill/tapped for 7/16" and there wasnt much room for error as it was close to the corner/edge but everything worked perfectly and have had zero problems in the 600 miles I've driven so far. Don't know if this helps at all..

 

here is what I did, there is ALOT of space above the baffle, enough to run a 1/2" NPT fitting into

here are some pics of mine
the process,

for the breather hole that is already there, basically trace the size of the hole, around the original hole. You will notice, that the original hole will be offset to the one that you just traced.

simple strike with casing, so that your drill bit does not walk and start stepping drilling it.

the intake cam side is easy to do because you do not have to center anything. Just ensure that you are above the baffle datum line.


in the picture above you will see how thick the VC really is.

now to blow all off those shavings that are inside of your valve cover, basically hook up an air chuck and look at the drain holes, inside the valve cover, this is where you will insert your nozzle to blow all the shavings out.

I personally ran a whole bunch of alcohol through the vc, as well as air, as well as flushing with water,..... You want to ensure that you get everything out of there

here is my finished product




any questions feel free to ask

 

^^^ Awesome.

I'm working on it right now

 

Got it.

Drilling massive holes for 1/2 NPT fittings



Working around the hole where the stock fitting was. You have to start a new hole below it and then work up. This is after a 1/2 drill, next is the final 23/32 drill.



Tapping.



Voila

 

Would it be easier to grind down the factory port on exhaust side of valve cover flush or flat. Punch out the remaining piece, use the correct drill size and then tap it? vs cutting around it and making an oblong hole, and then tapping it? Just an idea. Thoughts?

 

Why would you that when you can just pull it out with pliers?

And drilling doesn't make the hole oblong. The bigger hole just consumes the smaller one.

 

I don't believe you take advantage of the factory baffling when you drill both ends like that. I just put -10 inserts in the factory locations. I also drilled out the factory baffles to make sure I got all the shavings and such out. I was in the process of powder coating the valve cover anyway so I had to remove the baffles.

 

I hope all you guys that drilled the holes and "blew" out the showings. Drilled out the baffles and properly cleaned it. When I drilled mine out for 12an lines. I cleaned the living **** out of it. Then got paranoid. Drilled baffles out and found a lot more shavings. Proper way is to drill out the baffles and then drill and tap for little bolts.

 

I'm interested in knowing if the side port you added on the intake cam side is baffled well enough to forgo a catch can like you can with the exhaust cam port.