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1978 Trans Am - 400 - TH350 - 3.23 - Y82 - WS6
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Discussion Starter · #6 ·

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Ramblin' Wreck
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I added a link to the factory manual section above.
 
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Ramblin' Wreck
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Thanks!
Where about might I find this if a new one was installed and previous owner threw this in back? and... $200?!?!? Ass-uming this part is not necessary and just a bells 'n whistles cruise control feature?
Not necessary and probably not even wanted.
 
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1977 Trans Am W72 400/4speed (swapped)
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Geeze, they’ve gone up in price recently. They can go bad but there’s also not a lot to them. I wouldn’t trash it even if you don’t want factory cruise again. I added it back to my car though and it works great
 

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1978 Trans Am - 400 - TH350 - 3.23 - Y82 - WS6
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Discussion Starter · #12 · (Edited)
I'm back looking for more info! Thanks to the internet an the Haynes manual (no service manual yet) I have (what I think narrowed some down, but looking to pick y'alls brains as well. The following pictures are things I just don't know what they either go to or what they do.

First 2 pics, Fast idle solenoid for the aircon. It activates when the AC clutch is activated, and pushes the throttle linkage slightly to take up any rpm loss when the extra load kicks in. The appears chopped up or at least rejoined in a few places, perhaps the AC is not even intact.


3rd pic is the hot air connection for the choke, the tubes that are missing thread on and the other end runs into the exhaust crossover in the intake manifold. So at present, you have no choke as incomplete and not hooked up. You could correct this by adding an electric choke in place of current coil cover.


4th pic is the AC harness plug that goes to the compressor clutch next to it.


5th pic, one of several vacuum lines off the carb that often go to a TVS switch or fitting in front of intake, or similar depending on engine and emissions requirements.


6th pic, similar. They've removed or tried to bypass a few vacuum switches for different setups and eventually to distributor for vacuum advance. You'll have to see exactly what remains, what is needed and how to bypass correctly, what can be plugged or not.


7th pic, parts of your now incomplete cruise control your found in the back seat previously. Various power and vacuum controls and the speedo cable with stem poking out of the threaded cap.


8th and 9th pics, more disconnected vacuum sensors, temp sensors and switches related to previous missing vacuum lines. missing switches and looped hoses. Grab a copy of the correct year/engine/version of your emissions and vacuum diagram to see what's what. One old copy is often the sticker on the radiator support, if it remains.


8th and 9th pics, more disconnected vacuum sensors, temp sensors and switches related to previous missing vacuum lines. missing switches and looped hoses. Grab a copy of the correct year/engine/version of your emissions and vacuum diagram to see what's what. One old copy is often the sticker on the radiator support, if it remains.
 

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First 2 pics, Fast idle solenoid for the aircon. It activates when the AC clutch is activated, and pushes the throttle linkage slightly to take up any rpm loss when the extra load kicks in. The appears chopped up or at least rejoined in a few places, perhaps the AC is not even intact.

3rd pic is the hot air connection for the choke, the tubes that are missing thread on and the other end runs into the exhaust crossover in the intake manifold. So at present, you have no choke as incomplete and not hooked up. You could correct this by adding an electric choke in place of current coil cover.

4th pic is the AC harness plug that goes to the compressor clutch next to it.

5th pic, one of several vacuum lines off the carb that often go to a TVS switch or fitting in front of intake, or similar depending on engine and emissions requirements.

6th pic, similar. They've removed or tried to bypass a few vacuum switches for different setups and eventually to distributor for vacuum advance. You'll have to see exactly what remains, what is needed and how to bypass correctly, what can be plugged or not.

7th pic, parts of your now incomplete cruise control your found in the back seat previously. Various power and vacuum controls and the speedo cable with stem poking out of the threaded cap.

8th and 9th pics, more disconnected vacuum sensors, temp sensors and switches related to previous missing vacuum lines. missing switches and looped hoses. Grab a copy of the correct year/engine/version of your emissions and vacuum diagram to see what's what. One old copy is often the sticker on the radiator support, if it remains.
 

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Is your engine a Code Z? I found this old thread if it is:

 

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1978 Trans Am - 400 - TH350 - 3.23 - Y82 - WS6
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47 Posts
Discussion Starter · #16 ·
Is your engine a Code Z? I found this old thread if it is:


It is, thanks!

However going through that thread reading and comparing pictures, it does appear I am missing quit a bit of rubber and parts. Is replacement of all these lines necessary? The car did run and drive when first bought, hell, we even drove to the store. (It was a pain getting to stay idle, which I'm assuming is from the inop. choke) I do dislike the look of the charcoal canister and all the hoses everywhere. What is the bare minimum amount of vacuum to have this be a good "weekend" car?
 

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1977 Trans Am W72 400/4speed (swapped)
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To kind of answer your “bare minimum” vacuum line question, my 77 only has PCV valve, distributor advance, HVAC line (to actuate the blend doors inside) and the cruise control line. An automatic car would also have a vacuum modulator line to the transmission. Everything else was deleted (mostly before I got the car).
 
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