[jeff denton]

Hey, let's open this can of worms again! We were almost getting somewhere in a closely related thread recently but it died off.
With my top end oil control issues I am presently using a pcv valve to create a vacuum, and at idle (mine idles about 1200 rpm) it is pulling a good crankcase vacuum. Haven't measured it yet. I wonder what it's doing at 7000 rpm. Then there's Bob's input that this method causes lower fuel octane. And what about using the header collector to cause vacuum like in drag race cars? Any input out there from our resident geniuses? Thanks!

 

[jeff denton]

I guess the question would be, how much liquid can you remove from the crankcase vapor? It seems the way to find this out would be to take a tube about 2" in diameter, maybe about 18" long, loosely stuffed with a coarse steel wool. Then cap both ends. Each end needs a 3/8" barb fitting to hook a hose to. Mount the tube vertically in the engine compartment. Run a hose from the bottom of the tube to the valve cover vent, and a hose from the top of the tube to manifold vacuum. Then go enjoy your Opel for a while, stopping a couple times to check your oil level. If you have to add oil, the missing oil may be in the tube, gravity should make it be at the bottom. Pull the bottom hose off and see how much oil comes out.
If this seems to work, and isn't collecting so much oil that it fills up the tube and puts oil into the intake manifold, maybe a tiny drain could be put in the bottom of the tube so it drains back to the pan when the lack of vacuum allows it to.
Anybody wanna give this a try? Speedway GT is put away till spring, maybe we can do it then.
Offhand I can't think of any other way to do it. Anybody else got an idea?

 

[jeff denton]

Hey, another thing to consider here: just how does oil get into the air inside your engine in the first place? In all out high tech racing, part of the plan for oil control is to keep oil in the pan so it is available to be picked up by the pump. And you want it to be just oil, not a frothy oil/air comb. That's the reason they have dry sump systems, but let's not go there.
Anyway, the oil coming out of the main and rod bearings is being whipped around by the crank and rods. We've discussed the crank scraper, it strips a bunch of this "windage" off the crank and rod caps and drips the oil pack to the pan. So there went some of it. Next, in the case of the Opel idea of draining the head down the block and dumping it onto the crank, I don't like that one bit and you may recall how I changed that on mine. Then, upstairs, the timing chain must throw a bunch of oil up, especially as it goes around the corner (cam gear). So on my valve cover spacer, (which is really a baffle to keep some head oil from climbing the right side of the valve cover) I made it run real close to the timing chain to help strip some oil there. Better yet might be a little hood over the timing chain/cam gear to keep the oil from wanting to be pulled into the vent.
That's it. The valve cover is coming back off soon. We got work to do! Still got to perfect the valve timing anyway, I know it isn't quite right...