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Discussion Starter · #1 ·
I've seen many photos, identifications, & modifications for the UIM throttle body coolant & EGR ports, but what is the port that the arrow is pointing to in this photo?
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That's the PCV port from the rear head. It goes through the throttle body on Series 2 engines, and to the external tube that leads in front of the throttle body on Series 3 engines (both access pre-throttle blade air after the MAF).
 

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Here's an old GM description of the PCV path on both versions:

(note, it shows that port going to front head, but I just confirmed with 2 sitting in my garage that it goes to the rear one... doesn't matter, general flow pattern operates the same: positive crankcase pressure is drawn past PCV valve to intake manifold/supercharger to be burned off, and back-filling that air is metered by the MAF just ahead of the throttle blade)

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Discussion Starter · #4 ·
Here's an old GM description of the PCV path on both versions:

(note, it shows that port going to front head, but I just confirmed with 2 sitting in my garage that it goes to the rear one... doesn't matter, general flow pattern operates the same: positive crankcase pressure is drawn past PCV valve to intake manifold/supercharger to be burned off, and back-filling that air is metered by the MAF just ahead of the throttle blade)

View attachment 11087
Thank you for the diagram & explanation. I've been trying to figure it out for quite some time. I found a couple of photo's that also help to make sense of it. I see a port on the front right side of the plenum where the throttle body attaches that I think is the one you're referring to. I also found a photo showing the crankcase ventilation channel for the PCV on the LIM surface of the head. It all makes sense now, so I definitely appreciate your help.
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