[hoserrb]

not specfically a Mustang question but i figure the ford guys here can get me in the right direction.
I have a Mustang mini stock with a 2.3. we can use motorcraft 2150 carburetors insted of the stock 5200. I picked one up the other day and it's a bit different than the others I've seen. It has a "valve-like" device on the back of the carb. It apears that it is connected to ports that enter the carb down by the throttle butterflies. there is a small square opening at the top behind the regular choke opening.
It has 360 jeep painted on it so i'm guessing that's where it came from but who knows for sure. It is a stamped 1.21 model so it is a higher flow 2150 and i'd like to use it but i really want to know what this extra piece is and if it has any value to me.
any ideas or perhaps a forum somewhere with old ford carb experts?
(i will try to post pics but not sure if they will work)

[5.0 in a 66]

Smog crap. I had a 2100 and a 2150 side by side and you wouldn't believe how much extraneous crap there is on the 2150.

[Mark 59101]

I beleive that is and altitude compensater, it is basically an etered air leak . They used thore carbs at high altitude, I saw alot of them when I lived in Denver.