My buddy has just aquired this and there is a black plastic cylinder thingy above the master cylinder on the firewall.
What is it ?
It appears to have a vacuum line and a cable coming out of it.
Cable looks to go into the cab.
Any ideas ?
TIA

 

got a picture?

 

Had one but couldn't get the scanner to work.
Its in all of the haynes and chiltons but doesn't say what it is.
I might have to go over there and take a closer look.
Its right out in the open on the pic.
Sits horizontal just above the brake booster. He told me it had a vacuum connection on one end and a cable coming out the other side.
I'm wondering if it might be an early EFE actuator or something.

 

cruise control part maybe?

 

Shaped like a little plastic mail box? That's your HVAC vacuum reservoir for the early model 3rd gens. One rubber vacuum line in from the intake manifold, one small plastic vacuum hardline out to the HVAC controls under the dash.

They sometimes crack and become a massive vacuum leak, causing rough running for the engine. Ask me how I know.

 

I think you are right on that. I suspected some kind of heater control but neversaw anything resembling that before.
He's got a real rough idle that won't calm down.
I'll probably take a look at it tomorrow.
Thanks,
Jp

 

We thought it was the vacuum canister like Damon said but then he found the "orb of power" behind the headlight.
I haven't been over there but here is the picture of it.
What could this thing be?

 

that right there is for your HVAC system.. the large hose goes to a vacuum source, the small plastic hardline (what you think is a cable, but is really a hard plastic vac line) goes to the hvac controls in your dash like stated above.. I know this for fact, since all three of my camaros have the same exact thing, and i just got done replacing that hardline vac to the controls on my '83.

 

If you have cruise control that's why you also have an "orb of power." Trust me, the "mailbox" is for your HVAC controls.

 

Thanks again for re-confirming that.
John