What is this
 

I've got an 80 with a 305 and I noticed this. What is it?
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Re: What is this
 

Vacuum actuator for the heat riser valve located between manifold and exhaust pipe.

Re: What is this
 

It looks like it's all one assembly that has 4 plus on it. Does anyone have a part number or know what the part is called?
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Re: What is this
 

This is what the other end looks like.
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Re: What is this
 

Looks like smog crap

Re: What is this
 

As noted above, it is the vacuum actuator for the heat riser. When the engine is cold, it uses exhaust heat to help the engine warm quicker, improving cold driveability and yes, reducing cold emissions. The tubing is part of the vacuum control system that goes to a Thermal Vacuum Switch (TVS) that looks at the engine temp to turn the actuator on or off. One line vacuum to the switch, the others are to devices to be turned on or off.
If you do remove the actuator make sure to wire the valve in the open position.

Re: What is this
 

Ok. We're getting closer. Is it possible to replace the tubing or do I need to replace the entire plug. Is there a name or part number for the thermal vacuum
Switch plug.
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Re: What is this
 

Vacuum tubing should be available over the counter at any auto parts store, just need to size it correctly. Vacuum tubing can be sized in increments of 32nds of an inch, I'd just make sure it fit snug and didn't leak. I've always maintained this portion of my '83 and I find that it runs well and performs well from cold-hot.

I'd be surprised if there was an original/NOS one of those vacuum tubing harnesses laying on a shelf somewhere, but I suppose it is possible. If you want to find on I would suggest, looking for a user on here named "Hatzie" he's got a link in his signature to many .PDFs including the original parts catalogs. You can use them to find the part number and then go hunting.