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As I’m slowly sorting through my recently acquired 84 C4 I noticed a port on the front of the intake that has been blocked off with a plug. I see on other unmolested engines there is a vacuum line that comes off of this port. Could someone tell me what this should go to and provide a photo of what should be there including hose size/dimensions?
Thanks Tom
If that's the one I think it is that's actually the way it's supposed to be. People that have rerouted and Bubba'd their vac lines will use that to the PCV sometimes. The PCV valve is actually connected by the large rear port on top of the manifold by a hard rubber tube running parallel with the valve cover
It might be used for the plumbing route on the 305³" Camaro and Firebirds that used the same intake
If it helps any here is a photo I grabbed off the net showing the intake with a hose attached for better clarification. I suppose one could use it for PVC however, my PVC comes off the valve cover and follow a line down the left side of the engine towards the firewall and goes into a fitting on the intake back there. The red sealant just doesn’t look factory to me. Looks more “bubba”.
Tom
^^^^^^
That is either Bubba or maybe a Camaro/Firebird routing, that would be headed past our smog pump and darn near to our AC compressor, not sure what it is for. Our PCV is the opposite direction, at the beginning of your yellow arrow, so it wasn't intended for it....
Our PCV connects back where the marker says 1984
@Tom400CFI had the Firebird CFI, he might know if that's the routing used on it
Thanks, yes mine connects at the back where the 84 is written but someone along the way replaced the hard line with rubber. If anyone has a photo of their correct engine routing it would be greatly appreciated.
Thanks Tom.
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by '78CorvetteS.A.
That is 100%, without a doubt, the FACTORY port for the PCV!!! Buccaneer is right!!!👍 If Bubba did this, he worked on the assembly line for GM!
Good picture.
Just a short FYI for '78-'84 owners. Keep an eye on the power brake booster filter shown in the lower right of the picture. I experienced near total brake loss at a track day this spring due to the filter degrading/disintegrating, and plugging the vacuum line at the booster. I had always assumed that the filter was a simple screen type, but it has a carbon construction (similar to the fuel tank carbon canister) to absorb fuel fumes to reportedly protect the booster diaphragm. I'm told Chevrolet recommended regular replacement of this filter, but it seems to have been a well kept secret.
84 Crossfire Intake Port
