Unknown vacuum line

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Calipag

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We are just about to put our 318 into out 1970 Dart. It is a California car non A/C car, original slant six. Looking at the passenger side firewall to the left of the heater blower motor I have a vacuum line that has been cut/broke off before we bought the car that goes to a hard line and goes into the firewall. I have a assembly manual and looked in the heating and A/C area and can't find anything about what that may be.

Any help identifying this would be great.

Thank you!
 
If the metal lines runs down and alongside the fuel line under the car and towards the gas tank, it is the vent line or the return line.
 
I just stripped my CA emmisions 1970 Dart GT of it's lines in prep for restoration and that hideously long return line sure doesn't go through the firewall as described by the OP - again, photos would get you a correct answer in no time, I think!
 
Sounds like the main vacuum line for the HVAC.
 
If the car has N95 & you are talking about the metal tube that runs down the firewall it connects to one of the small nipples on your three nipple valve cover breather with a rubber hose.
 
I was thinking it went to the HVAC. I know it is not the fuel return line. I'll get back int he garage tonight and take a pic. @Alaskan_TA what is N95? The engine going in to this car has aftermarket valve cover and intake. Where would that vacuum line go in that case.

Thank you all for the help
 
Are you saying it goes on into the passenger compartment? If so, there is nothing else inside the passenger compartment besides heater/ AC that is vacuum. Cars (Ralley dash or console) that had an opitonal vacuum gauge was routed through over by the bulkhead connector somewhere
 
I don't recall HVAC vacuum supply attached to a hard line at firewall. Its a rubber hose through a firewall grommet.
 
As noted, A/C cars only had vacuum for HVAC control, heaters only used twin cable mechanism. On 1970 California emissions followed by 1971 federal emissions there is a capped end vapor separator tube in the trunk ahead of the fuel fill pipe that is 5/16 hard line back to the three port right side valve cover breather. It connects to one of the ports, another port goes to air filter housing through 5/8 hose, and the other port goes to carburetor bowl vent. PCV is on left valve cover. To my knowledge, the vapor lines where always routed outside the car. I have seen otherwise, I just can't remember exactly on what, although I am wanting to say on a '71 charger I parted out. HVAC vacuum line source seems like it was 3/16 on the A/C \6 '71 Duster I had, and rubber line went through from manifold vacuum on left side and the hose ran through a grommet on firewall to the spherical reserve canister on top of heater box. Dart design is "different enough" from duster design, though. Just a wild guess, what size is the line that goes to firewall and does it enter and maybe exit back out somewhere behind the right rocker panel under the car on its way back to fuel tank?
 
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N95 Is California Emissions.

I saw you mention 318 but I missed the OE /6, so in that case it would have had a 2-nipple breather.
 
Correct, no float bowl vent on that year of the \6... this may help, as this is an \6 with A/C in 70 swinger, you can see the manifold to heater control vacuum line... you can also see where that one breather line routes near fuel pump to connect to vapor vent line.
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Going by memory, looks a whole lot like what was under hood in my first ‘71 Duster.
 
Here is what I have. I was not hooked up when we purchase the car. I replaced the heater core and didn't see a place where that would go.

IMG_5264.jpg


IMG_5265.jpg
 
At first I though of maybe a vent/drain from something and then I had flashback to some hack moments I've had in the past... Is there actually a nipple under that or has someone lost a nut off a heater box stud and twisted a tight piece piece of vacuum hose down in it's place?
 
Well, that is similar to '71 Duster, here is a pic of what that piece of tubing is over, I don't think you'll have to worry about hooking that one up to anything...
 
Once I can get my steam powered hardware to respond, it is a picture of a plastic pull through stud that helps secure the heater box in...
 
A simple reminder of how much fun it can be when you start one of these projects, Daing, I need to detail under hood again, getting grimy again! Honestly though, my beater truck I had years back had this option (as well as many other much worse non-factory options) on every stud that stuck through the firewall... Rubber, Rust, and profanity is the only thing that held it together!
 
@Garrett Ellison WINNER WINNER!!!!!!

I can't believe I didn't investigate that a little more. I spent more time in the manual looking for that and I could have yanked it off and been done!

Sorry and thank you!

Nipple.jpg
 
No apologies required, glad to help! I am waiting for a break in the weather (fingers crossed for tomorrow!) so I can pull car out and do some more work before spring gets back here...
 
No apologies required, glad to help! I am waiting for a break in the weather (fingers crossed for tomorrow!) so I can pull car out and do some more work before spring gets back here...

We are waiting for a break in the weather also here in CA; lots of rain for us. We should be picking up our motor Friday and installing it this weekend!
 
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