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1968 Cadillac DeVille - engine vacuum lines - 3 ported vacuum switch

Started by Lexman, August 02, 2021, 03:07:27 AM

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Lexman

Hello!

My 68´ DeVille distributor vacuum unit currently only runs on the carburetor vacuum and I want to put it back on the 3 ported vacuum switch. The connections of the 3 ported vacuum switch are "C" for carbureter, "D" for distributor and "MT" for manifold.

Now my questions: the manifold connection of the carburetor (front right, passenger side) is currently connected to choke vacuum and to diverter valve next to the air pump. Do I have to insert a T-piece for the line to the 3 ported switch? Or how do the connections have to be made?

Does another solenoid have to be installed between the carburetor and the 3 ported vacuum switch?

Unfortunately there is no engine vacuum diagram in the 68´shop manual.

Thank you very much!

Alex

hornetball


Lexman

I have a new switch.
There are no informations in the manual how the manifold vacuum is connected.
but I assume that the vaccum line from the diverter valve to the carbureter has to stay and is only branched off to the 3 ported vacuum switch.

TJ Hopland

Slightly later manuals had the vacuum diagram on the back of the fold out electrical diagram which often seemed to become detached from the rest of the book.  Hopefully someone can confirm that and has one.   It would be nice to know how they did it, sometimes tapping off things works and other times it could cause issues with how things respond.

Slightly later engines had a threaded in fitting on the #7 runner that was used for some things.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

chrisntam

1970 Deville Convertible 
Dallas, Texas

Lexman

Hi,

thank you for your help. The 68´ diagram is slightly different.

I think it needs to be connected like in this diagram.

Thanks again,
Alex




bctexas

I found two references in the '68 book that might help.  One is the diagram for the AIR system which shows the diverter valve tee'd into the vacuum line to the transmission.  The other shows the "distributor vacuum connection" and "manifold vacuum connection" on the carb.

HTH!
1965 CDV
1970 SDV

Lexman

Great thank you!

I think that should fit. 
Then I can take the manifold vacuum directly from the front of the carburetor and put a T-piece on the back for the line from the diverter valve to the carburetor

Many Thanks!
Alex