Proper PCV arrangment for a 2L, A little help please Options

[North Coast Jim]

Have a newly rebuilt 2L in the car with 40 IDF Weber carbs which is running fine except for a RMS dripping oil. We believe we installed it correctly and took careful steps assembling the rest of the engine/flywheel/clutch/transmission. We believe that the crankcase vent system is not working properly which is pressurizing the crankcase as RPM builds, thereby pushing oil out the RMS.

My oil fill assy has a 022115542 PCV assy in it and a solid oil fill cap. I took the valve out to see if it was working. When I blow into the bottom it is initially open. Increased pressure it closes the valve. Seems backward to me. My oil fill tower has no vent in it.

I do know that when I got this motor, 6 years ago, the PCV assy was in pieces all captured in the oil fill assy. I took it out and reassembled it thinking it was correct. Maybe not ??

I have Len Hoffman heads when he sold them direct and the vents are capped shut per his instructions.

Any help is appreciated.

[914werke]

Lens suggestion (from that article) is in addition to capping the head vent lines also change the oil fill tower to the late version w/o the PVC & run a larger catch /vent line to a can

[North Coast Jim]

Lens suggestion (from that article) is in addition to capping the head vent lines also change the oil fill tower to the late version w/o the PVC & run a larger catch /vent line to a can

The direction I'm heading. Thanks

[JamesM]

We believe that the crankcase vent system is not working properly which is pressurizing the crankcase as RPM builds, thereby pushing oil out the RMS.

I suspect you are correct in that it is not working properly. This is something I have seen a lot, along with many many different ways of venting completely incorrectly.

the 72-74 motors especially with the head vents and oil tower valve can cause various issues when ran on anything other than the stock FI setup. The 022115542 valve is not a standard PCV valve and requires manifold vacuum to operate as intended (which even when operating as intended is not great) When that valve is used without manifold vacuum and with vents on the heads you will blow liquid oil out the head vent lines to the extent that you can eventually cause oil starvation and loose oil pressure. Removing that valve and running an open vent from the oil tower is a start. Doing that while capping the head vents is even better. Enlarging the vent at the oil tower (like they did on the 75 2.0s) is even better than that. Best of all I have found is then adding an actual PCV on to that enlarged vent.


So my preferred setup:
Plugged head vents
Modify oil tower for 19mm (3/4") open port
Add modern 19mm inline PCV (there is a cheap Awdi/VW part for this)
vent PCV to air filter

An additional special note, on the oil towers that originally came with 022115542 there is a hole cut that allows the installation of the valve. During engine operation THIS HOLE SHOULD NOT EXIST. The factory installed a plastic plug in this hole that at this point is missing on pretty much every car. On old more original cars you can sometimes find this plug sitting in the galley under the oil tower. It was installed for a reason. The oil tower itself acts as a baffle/separator that drops oil out of the airflow before it gets sucked into your intake. Where there is an open hole in the bottom of the oil tower directly under the vent line you loose this oil separation feature. Making matters worse is the distributor drive/cam gear flings liquid oil directly where this hole exists. End result, if this hole is not sealed is that at higher RPMs you are shooting liquid oil droplets directly into your crankcase vent airstream. This is where a lot of oil consumption issues come from. Modified tower or stock, seal this hole!

[emerygt350]

Interesting. I did not know this. Is that plug sold by anyone? Does it have a name?