Anyone know the purpose of port N, located on the back of the carb? It's currently plugged on mine, and I'm wondering what it might be for.

thanks

 

I don't know them by letter. Where is it located? On the base, leading away at a 45* angle from the brake booster? Or where?

 

It is centered on the back, near the top, and points directly toward the firewall.

thanks

 

That's not a vacuum port AFAIK. Pull the plug and put your finger on it with the motor running.

IIRC it's a filtered air source for the hot air choke on the manifold...

 

If it is is a computer controlled quadrajet I think it is for the map sensor.

Ben

 

Momar,

That's what the one on the base of the carb running away from the brake booster port at a 90* angle can be used for.

It sounds to me like this port is on the air horn in the back... in which case it is not a vacuum source at all.

 

Port N is the one that goes at an agle from the base from what I can see.

Ben

 

Either he doesn't know which port he's talking about, that port isn't labeled N, or the letters change depending on the carb.

 

Well, I have diagrams from 84 and 86 saved on my computer and went and looked at the one on the hood of the 85 and have the carb from the 85 right here and nowhere found evidence of this port he is referring to if it is not N which is angled and for the map sensor.

Ben

 

Oh, and here is a diagram of what mine is like currently. I cleaned it up a bit. Any suggestions on what I should do with the line from the fuel tank. Should I leave the valve on there or take it off so it can vent clamp it shut or what?

Ben

 

If you aren't using the purge system at all any more, remove everything else and plug the line. Then purchase a vented gas cap.

As far as the port he's talking about, it shouldn't exist on any factory 82-87 F-body carb--but he didn't say what carb or even what car he has. I have two non-computer carbs that DO have a port exactly where he describes it, and they are filtered air sources for the integral hot air choke setup.

 

I see. Where would I get a vented gas cap?

Ben

 

Any store should have one. Find one for an old Chevy that looks similar and it should fit.

 

Sounds good, thanks for the help.

Ben