'78 carb unidentified vacuum (?) ports

[Freeborn]

First off, big thanks to anyone and everyone that's helping this guy through his first classic car encounter. Hopefully I can give back as much knowledge as I'm getting at some point in the near future. I certainly feel like I'm getting enough experience to become a contributor.

I'm trying to figure out where the circled ports on my stock carb are supposed to be routed. Is it possible that they have something to do with my engine not running 100% smooth? Both pics are looking in from the driver side. First shows 2 ports right at the base of the carb and are a part of the heat shield/insulator. Second is more obviously at the top of the carb.

 

[Solace in Solitude]

Re: “Is it possible that they have something to do with my engine not running 100% smooth?”

Absolutely.., both (unconnected/uncapped) are big vacuum leaks.

If you aren’t desmogged, you can see where they should go in this pic... of course, you need the evaporator system... the charcoal canister at a minimum... to connect this up...

If you’re desmogged, the routing may change somewhat

 

[Freeborn]

I get a little confused on smogged vs. de-smogged. I have a smog pump that is connected to stuff if that helps to identify my situation.

Thx for the diagram. That helps a lot with the top-most port.

 

[Solace in Solitude]

If you haven’t specifically desmogged it... it still has an air pump, air rail, etc., I’d consider it “smogged”... but, unless you’ve validated the emissions functionality, much of it may not work properly.

Your “bottom” port is also in the diagram... connected to the VSV.

 

[Freeborn]

If you haven’t specifically desmogged it... it still has an air pump, air rail, etc., I’d consider it “smogged”... but, unless you’ve validated the emissions functionality, much of it may not work properly.

Worked well enough to fool the state of CO.

Your “bottom” port is also in the diagram... connected to the VSV.

Bottom 2 ports?

 

[Solace in Solitude]

Worked well enough to fool the state of CO.



Bottom 2 ports?

Just cap the other one, otherwise huge vacuum leak