Mystery box in engine bay

I have been trying to figure out what the box is for.. it is clearly there for a vacuum operation of some sort, but mine is not hooked up to anything.. the vacuum line in the bootom side goes no where, and the hard hollow line on the top goes accross the top of the bay to the passenger side and then goes into the harness and is gone.... thing is driving me crazy. I do know only carb'ed engines have it (all three of my camaros have it (83 Berlinetta, 84 berlinetta w/digital dash, and an 84 z28 HO) I can see where the rubber vac line goes..sorta.. but the hard plastic line all goes into the harness and disappear. the only thing on the 83 is that it went into the harness.. which was butchered from the previous owner, and it looks like it was cut.... since it ends in a hollow tube going nowhere...

here is a link to a picture of it
http://memimage.cardomain.net/member_images/11/web/2051000-2051999/2051900_2_full.jpg

help in finding out what this is for and how to hook it up properly would be very helpful. At least to know what it is... hooking it up will be determined on what it is actually for.

thanx

its just a vaccum tank, i dont know the reall purpose, but i guess it just holds vaccum for the hvac controls or something. At least on my car it goes to the hvac check valve.

here's some pics from shoebox's site, they are 4th gen but probobly very similar.
http://shbox.com/1/vac_check_valve.jpg
http://shbox.com/1/vacuum_tank.jpg

I dunno - my '85 2.8 and my '87 LG4 didn't have that....

- Justin

do you live in canada, those cars have things done differently...

my carbed 87 iroc does not have one of those

It's a vacuum reserve canister, and it's primarily for HVAC operation. It stores engine vacuum in case of a low vacuum situation (constant high RPM operation) and ensures that the HVAC controls operate as intended, instead of defaulting to defrost.

My car, originally an LG4 (carbed 305) came with one. I have since removed it and have not noticed any ill effects. I have a much larger cam now, and have subjected the car to continual high RPM operation with no effect on HVAC operation. However, if GM went through the expense of deveoping, manufacturing, and installing these, they must have some purpose...

i agree. thanks for the info on that.. I suppose i should hook mine up since i may have a low vac on the engine due to not having it tuned (might be way after the engine swap the controls for the heater are on defrost.. or stuck sorta in between anyhow) that answered alot of questions Thanx:) :D