Does anyone know what goes in this spot on the firewall?

[j_anderson]

I'm putting my Dart back together. Its a 1972 Dart Swinger with 318 & auto trans.

My dad and I do not know what goes in this spot. I've searched google for reference photos but most darts I'm seeing dont have this hole. Some seem to have a relay or something bolted in that spot but I cant tell of there is a hole behind them


Here is mine. Circled in red is the spot I'm talking about. There is a hole and 2 dimples to the right:

Like most I've seen in google images.... Just 3 dimples there but no hole.

this one has the the same hole with 2 dimples but it appears the dimples had screws in them at one time:

This one has some kind of relay bolted there:

Any help is appreciated. Thanks in advance!

 

[townsend]

72 Swinger - Some wiring questions.

I'm currently cleaning up all my wiring and connections, fixing things that need fixing along the way. The FSM (for a 72 Valiant) wiring diagram has been extremely helpful, though it's still a tough slog. Someone did a crappy black spray bomb in the engine bay a long time ago, covering the true...

www.forabodiesonly.com

Scroll to beginning of post.

 

[1WildRT]

Osac Valve... Emissions crap...

 

[George Jets]

Osac Valve... Emissions crap...

Vacuum valve of some sorts for emissions.

Other cars have nothing there.

 

[MoparMike1974]

osac valve started in 73 and the hole was not round.

 

[70dart340]

That's where you run your BIG wire to your aftermarket amp.

 

[j_anderson]

Thanks all!

 

[Dartswinger70]

That's the mounting spot for the go faster switch. LOL you just switch it on to go faster.

Sometimes I just crack myself up.

Some feller in high school had a toggle switch on the dash of his 71 Chevelle with a 307. He'd get the girls in the car and say it was "the nitrous button" LOL

 

[vames]

It’s part of the NOX system. I believe it was a 1972 California only setup. Wires go to a sensor in the middle of the speedo cable (right below the master cylinder), the ballast resistor, and to the OSAC valve between the carb and vacuum advance. It measures ambient temp and takes info about your speed to determine whether or not to block your vacuum advance. Mine had long been out of commission so I removed it and put a 1” round rubber seal which fit the hole perfectly. It’s also straightforward to remove the wiring sub-harness for it. You can also change to a one-piece speedo cable once it’s gone.

 

[j_anderson]

It’s part of the NOX system. I believe it was a 1972 California only setup. Wires go to a sensor in the middle of the speedo cable (right below the master cylinder), the ballast resistor, and to the OSAC valve between the carb and vacuum advance. It measures ambient temp and takes info about your speed to determine whether or not to block your vacuum advance. Mine had long been out of commission so I removed it and put a 1” round rubber seal which fit the hole perfectly. It’s also straightforward to remove the wiring sub-harness for it. You can also change to a one-piece speedo cable once it’s gone.

View attachment 1716045194

Someone above linked me to your thread when you were going through this. I found it helpful. My car was a California emissions car but I don’t ever remember having anything in that spot and no extra harness to make it work. One of the PO’s must’ve removed it. Good to know I can just plug it and move on!

 

[MoparMike1974]

They were playing around with the emission systems these years. I think 73 was the only year they installed the osac valve in that location and later moved it to the air cleaner.
Here is a pic of a 73 Swinger with the holes and a 74 without the holes.

 

[1WildRT]

They were playing around with the emission systems these years. I think 73 was the only year they installed the osac valve in that location and later moved it to the air cleaner.
Here is a pic of a 73 Swinger with the holes and a 74 without the holes.

View attachment 1716045325

View attachment 1716045326

Being from Maryland you probably aren't aware California cars of the early 70's have lots of crap 49 state cars don't.... 72 got an Osac valve that was slightly different from a 73 Osac valve...

We got unique fuel filler necks that took special gas caps... We got EGR valves before anyone else.. We got cars that couldn't have exhaust tips when 49 state cars had them... California has had mental giants in positions of authority for waaaaay to long

 

[MoparMike1974]

Im aware, just not knowledgeable on the details. What impact could exhaust tips have on emissions?

 

[67Dart273]

OP do you not have a factory service manual? FACTORY, not Haynes or Clymers. Run over to MyMopar.com and download one, free. SOME OF THOSE GOT THERE because of the guys right here, and the 72 manuals is one of those. If you are thinking of going with the later disk brakes/ big bolt pattern, download the 73 manual as well. Sometimes you have to do quite some reading. There's a fuel chapter(s) and emissions way back in the back.

These also outline the incredibly important 1/4" vent line for the fuel tank. Which originally is the EVAP/ carbon canister system.

 

[vames]

OP do you not have a factory service manual? FACTORY, not Haynes or Clymers. Run over to MyMopar.com and download one, free. SOME OF THOSE GOT THERE because of the guys right here, and the 72 manuals is one of those.

Yes to this. The site has a 1972 Chrysler factory manual - virtually all of the Valiant info is relevant for Darts.

 

[1WildRT]

Im aware, just not knowledgeable on the details. What impact could exhaust tips have on emissions?

Apparently they decided to impose restrictions on noise emissions as well as exhaust & evaporative emissions..

The no tips rule only applied to 426 Hemi & 440-6 cars and even with them there were some cars that snuck through with tips...

 

[pt70]

Decades ago someone from CT restored an AAR Cuda. He bought the complete original factory exhaust system from the dealership. [$$$$$]. Went down to motor vehicle department and got rejected because the exhaust exited in front of the rear tire. Talk about a bad day!