It appears to be the idle air control. It uses vacuum to adjust the engine speed at idle, by opening or closing the throttle plate.

 

It works in adjusting your idle when the car is using the Air Conditioner and is under load.

It's a transmission downshift switch. It's called a Dash Pot. Part Number 1483692

Mine is actually missing so I am looking for one.

 

Dashpot, a throttle damper, keeps the throttle from suddenly returning to idle when you release the gas pedal to prevent stalling of the engine. So, you don't have to replace it if your car doesn't stall when suddenly releasing the throttle pedal, since it's broken, then just remove it. And it's not supposed to work as an idle stop, there is an idle speed screw for that. About hard starts, on carbureted engines it's recommended to depress the gas pedal slightly before starting.

 

The part´s name is Throttle Dash pot. When the engine is cold, it pushes the throttle adapter plate (connected to the accelerator lever) until warming up to increase engine speed and as manual says it prevents engine stalling in the way Fleetwood70 has told. Here you are the removal, installation and adjustment instructions from the 69 shop manual (69 and 68 carbs. are the same):


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It´s difficult finding a new throttle dash pot. Only found one at Caddy Daddy for a 64 (But I think it´s the same): http://www.caddydaddy.com/FUEL-amp-...Carburetor/Dashpot/-1964-Cadillac-Carburetor-Dash-Pot-Check-Assembly-p4783.html

Another option is asking a carb. shop if they could fix your broken part.

BTW, You can buy a 68 CD Shop manual very cheap. It will be much more useful than the Chilton. That book contains much more info about 80s cadillacs than 60s. I first bought the Chilton and then bought a 69 CD Shop manual. It helps you a lot about every detail of your caddy: http://cgi.ebay.com/ebaymotors/1968...tem20b8a80ac5QQitemZ140536974021QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

Thank you all for your assistance... I've been out of town so I apologize for the late response.

The '64 version is not the same as the threaded rod is much shorter.

The appropriate part # is 1483692 from GM.
Other equivalent after market part numbers are D5-112R and 40-431 (Hope that helps others looking).
I was able to find (rare find) one on ebay for $14.40 shipped.

The installation image will be very helpful. Again, Thank You all.

 

Yeah, that was the only one for sale! I´m glad you could find it finally and thanks for the info. You never know when you´ll need a new one :thumbsup:

 

I had a 70 Fleetwood and that dashpot never worked properly, wound up ditching it. The car never stalled.