Clean air Dirty Air
The front red cap is your nipple for stream venting of the coolant system. The rear, larger red cap is for brake booster vacuum. You should do some research on catch can routing to see how these engines vent. Lots of catch can discussions here on Tech to help you see exactly how these things vent.
TECH Fanatic
Joined: Sep 2008
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So here's what I've done on my LS3 swaps.
1. The nipple on the left valve cover stays capped.
2. On the left side of the manifold close to the throttle body is a nipple for a purge valve connection. I don't need this on my swaps so I cut off the nipple and drill and tap it to seal it forever. In lieu of that you can just cap it.
3. On the right side of the intake is a u-shaped tube that goes from the intake to the PVC valve that is under the valley cover.
4. On the right side of the valve cover is a tube. I plump that tube with rubber hose from that tube into the air intake tube after the mass air flow sensor. That is the fresh air source for the engine.
1. The nipple on the left valve cover stays capped.
2. On the left side of the manifold close to the throttle body is a nipple for a purge valve connection. I don't need this on my swaps so I cut off the nipple and drill and tap it to seal it forever. In lieu of that you can just cap it.
3. On the right side of the intake is a u-shaped tube that goes from the intake to the PVC valve that is under the valley cover.
4. On the right side of the valve cover is a tube. I plump that tube with rubber hose from that tube into the air intake tube after the mass air flow sensor. That is the fresh air source for the engine.
