If they've got flow with a velocity, with a venturi tap (the extractor) installed, it will draw a vacuum. These were OEM on 80's GM's Grumpy Jenkins pioneered them in racing. GM liked it so much, the adopted it until the EPA wanted all crankcase emissions to pass through the combustion chamber before hitting the catalyst.
Most autos with mufflers according to some people on Honda-Tech have reported positive or almost no negative pressure on the slash cut.
Oh, really? I guess when I merely installed the hose to the extractor on the normal fresh air connection on the valve cover since my PCV was one of those dinky poppet deals tapped to one intake runner on my Mitsubishi 3.0 ...the seal just coincidentally let go a short time later. My crank pulley doesn't believe you. This is not something I've pulled out of my behind
Most engine have leaky seals, thus no matter what you read on the web, you will never achieve negative vacuum in the crankcase,
While not something I'd normally do, which one(s) are you talking about? The anti-back fire valves? They're check valves. Are you sure you had them forward biased in the suction test??
have you tried sucking on those valves?
Here you lost me. You stated that your catch can caused too much restriction. I merely offered an alternative to the catch can in the form of MUCH BIGGER hoses. You have NO VELOCITY ..hence anything that's heavy will drop out. The lighter vapor will not be inhibited. Naturally you would want it laid out in a manner where it would drain back after the severe event.
plus when the opposing side of the PCV system is a 5/8ths tube with no restriction.