anyone know what this part is called?

[johnnymoon]

anyone know what this part is called and where I could get a new one? Its from a 68 Deville

Thanks!

[Jon S]

It's a ported vacuum delay valve - used for emissions. 

[35-709]

Depending on who is describing it, it may be called a Thermal Vacuum Switch (GM's description in the '73 shop manual), or a Ported Vacuum Switch (Rock Auto's terminology).  Should be able to get one at NAPA, Carquest, maybe even Advance Auto Parts, or any good independent auto supply store.  Rock Auto lists them for about $41.00 but the one they picture has 4 ports whereas yours has 3, but that may just be a generic picture.  I have removed them on both of my 472s and plugged the hole with a brass plug.

Sounds like you could use a '68 Cadillac shop manual for your car.  Readily available on eBay and an absolute must-have in my opinion.  Here is one I would jump on if I had a '68 Cadillac ---
http://www.ebay.com/itm/1968-Cadillac-Shop-Manual-Fleetwood-Calais-De-Ville-Eldorado-Original-/261884464538?hash=item3cf987cd9a&vxp=mtr

[DeVille68]

Since this photo is taken near the ignition system I suppose it is the thermo vacuum switch.
There should be a threaded hole behind the distributor on the engine block where the switch is screwed in. It switches the vacuum used for advancing the timing from carburetor vacuum to manifold vacuum if the engine temperature is above 230° Fahrenheit.

USA Parts supply sells the correct switch with three connections.

I just bought one a week ago and also tested it. Switches ports right at 230°.
I added a picture showing its location on the engine. And added a page from the manual describing the functionality.

According to the parts catalog a vacuum hose of size 6/32 should fit right. (probably also 5/32)

Hope this helps
Best regards,
Nicolas

[Glen]

Johnny, the one you have is broken, the rest of it is probably still in the front of the head. 

[Jeff Rosansky CLC #28373]

I believe the technical term in Ex-pen-sive.

[johnnymoon]

Thanks to everyone for the advice!!! This is a huge help!

["Cadillac Kid" Greg Surfas 15364]

Johnny,
I found the one that came off my 72 Eldo. If you are interested in an excellent used one pm me.
Greg Surfas

["Cadillac Kid" Greg Surfas 15364]

here is the switch.
Greg Surfas

[johnnymoon]

It's a ported vacuum delay valve - used for emissions. 

Depending on who is describing it, it may be called a Thermal Vacuum Switch (GM's description in the '73 shop manual), or a Ported Vacuum Switch (Rock Auto's terminology).  Should be able to get one at NAPA, Carquest, maybe even Advance Auto Parts, or any good independent auto supply store.  Rock Auto lists them for about $41.00 but the one they picture has 4 ports whereas yours has 3, but that may just be a generic picture.  I have removed them on both of my 472s and plugged the hole with a brass plug.
Sounds like you could use a '68 Cadillac shop manual for your car.  Readily available on eBay and an absolute must-have in my opinion.  Here is one I would jump on if I had a '68 Cadillac ---
http://www.ebay.com/itm/1968-Cadillac-Shop-Manual-Fleetwood-Calais-De-Ville-Eldorado-Original-/261884464538?hash=item3cf987cd9a&vxp=mtr

What's the advantage to removing the switch?? I might just do that, it would be cheaper... any advice on removing the switch and plugging? Thanks!

[35-709]

Sorry I brought that up. 
I would suggest you keep the system stock, as the factory designed it.   

[DeVille68]

What's the advantage to removing the switch?? I might just do that, it would be cheaper... any advice on removing the switch and plugging? Thanks!

The previous owner of my car "removed" the switch. Cars runs perfect. You can just run the vacuum hose from the carburator vacuum port directly to the distributor vacuum diaphragm.

You could read about how the switch functions in the pdf page I attached to my posting above. In short: you can disable the switch if you never experienced high heat or high engine temperature where more spark advance would be welcome to help cool the engine.

I would keep the system original though. It's about 50 dollars and you have an original system.
It is only original once! 

Best regards,
Nicolas