69 Deville Vacuum Diagram/Help

[MH69Coupe]

Hi Folks, I am a new member. I own a 69 Coupe Deville.

We had to remove the head to remove a broken exhaust manifold bolt!!! Now that is done but the Vacuum lines are I believe not 100% correct.
My current config is in blue diagram.

I also downloaded the correct diagram in blk/white from the web. My first question is there are TWO vac lines coming from the firewall Blk/White and Blk/Green ... where do these connect?

The Blk/White line seems to be connected to Carb idle vac advance port - dont I have to connect the Thermal Switch FI (fast idle) port to the carb idle vac port?

Not sure where to start but need help ...

[chrisntam]

I have a '70, maybe they are similar?

[MH69Coupe]

Thanks let me see it is a bit different i think ...

In your car do you have two Vac lines coming from the firewall all the way to the front near the distributor? one is BLK/White and the other Blk/Green.

I am trying to find the purpose of those.

Right now as  you can see in my diagram one is hooked to C and other directly to Carb idle valve (the thermal switch FI port should connect here or supposed too).

[69Deville]

Here is how mine was setup and it works as designed.

First, the second photo of the diagram you uploaded is correct. It is not showing the air pump though. Connect a line from the air pump to the diverted line shown next to the vacuum break.

The black/white line from the firewall runs directly to the idle speed up device located behind the vacuum break.

The black/green line from the firewall goes to a fourth valve on the thermal vacuum switch as mine has four outlets. The diagram is only showing three.

Smaller vacuum line on the rear of the carb goes to the vacuum unit on the transmission. Larger rear vacuum line to the brake booster.

I replaced all my lines and routed them like this. I did have a vacuum leak at the air pump. I made a new gasket and it made a huge difference.

Hope this helps.
Dave

[chrisntam]

I can't help other than providing the diagram, I removed my TVS and changed up a bunch of stuff......

Sounds like Mirrione3 has you headed in the right direction though.

chris.

[MH69Coupe]

Thanks Chrisntam ...

Mirrione3 ... thanks for the details ... see the cut out from the Shop Manual.

The FI (Fast Idle) port uses Manifold Vacuum and connects to the idle speed-up device at rear of the Carb (this is where your/mine current firewall hose is connected). Is my understanding correct that when the DIST switches from C to MT at high temp this FI port also gets manifold vac to speed up idle etc. seems like?

Should we connect the FI and Firewall black hose via T to the Carb idle?

Which bring to the Q where the Blk/Green line connects then?

[69Deville]

Green line goes from the neutral safety switch through the firewall to the vacuum switch. The white line goes from the neutral safety switch to the idle speed up.

What happens is that when the engine gets to 220 (I believe) the vacuum switch opens and sends vacuum from the green line to the neutral safety switch. When you shift into park or neutral with the AC on, the vacuum in the neutral switch is connected from the green to the white and that sends vacuum via the white line to the idle speed up.

[MH69Coupe]

Thanks Mirrione3 ... This definitely clears up everything. I will try to find the neutral switch reference in the shop manual as well.

Now going back to my very first diagram (blue boxes...) few questions:

1. Distributor is connected directly to the full Manifold vac --- Now I have read on few places that in order to be safe in terms of overheating heating etc. it is rather a safe practice to connect this way and take the OLD WAX switch out of the equation??? Thoughts???

2. Lets say if the thermal switch is faulty etc...should I connect the the BLK/GREEN line to the Carb Manifold Vac via T? along with Distributor and another one going to the air pump AIR valve etc. Any issues with that?

3. Does your thermal switch on the 69 works as designed? is it the original part car came with? just trying to understand the longevity of this part ...

[69Deville]

Let's start with question 3. Mine worked but one of the nipples broke when replacing the vacuum lines so I am not using it. I'll be replacing it as I like my car to be setup like the day it rolled off the line.

Question 1. I've had it both ways. I ended up leaving it on ported vacuum as it ran just as good. Plus my car guru advised me against it as it puts long term stress on the transmission. I'm sure others will disagree.

Question 2. That is how I am setup and it works. Because my thermal switch isn't functional, I had to disconnect the idle speed up.

Be sure to replace all your vacuum lines. I did and the difference was amazing. I still had a bit of a stumble and discovered that the gasket on the air pump was gone. I made a new one and that was it. It now runs like a champ. Be sure to use a vacuum gauge too.