I have a question, tried this in the external section with no results. I run a Metco breather on my 5.3 Silverado engine. I have Crane Cam, headers, intake, etc. I installed the breather on the valve cover and plugged off the fresh air tube going into the throttle body. This way the pvc is still functional and pulls air in through the breather and at WOT eliminates crankcase pressure. I did have to drill the TB to 3/16 to cure some stalling issues after the cam install. Truck runs excellent and is pretty damn fast for 5200 pounds but my question is this. Since I have bypassed the fresh air intake to the valvecover (by blocking it off) the maf does not read the air that the pvc is pulling into the intake at high vacuum levels such as idle. Should I reinstall the tube from the valve cover to the tb so the maf can read the extra air at idle and part throttle or leave it alone. Truck idles well (a bit lumpy due to the cam) and I do not have any surging issues. My idle IAC counts in gear are about 30 and I have excellent throttle response. This is a street driven truck. Thanks for any ideas you can provide. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> <img border="0" alt="[Truck]" title="" src="graemlins/gr_truck.gif" />

 

My first thought is that you would be running a little rich at hig Vac levels. But after thinking it through, I dont think you'll have a problem with this setup at all. The air pulled through the PCV system was going into the intake after being routed through the crankcase. At idle under high Vacuum levels, you may not be getting enough air, but thats why you drilled the TB larger. As long as your IAC is where it should be, then I think you are OK.

 

I think so too. Just wanted a second opinion. Thanks Tex. Got that new cam installed?