Vacuum hose confirmation

[Blagave]

Hello...I could use some help locating the correct connection of a vacuum hose on a 1980 911sc 3.0. When dismantling the engine, I labeled everything and after ordering some replacement lines, there seems to be a discrepancy of the connection of said line. The parts diagram on Pelican, shows the line going from the upper diaphragm to the throttle bottle my #8 label and the pictures I am supplying are as I removed, connected to the lower unit. I would appreciate it if someone could tell me the correct location and what the line does. Also, there was only one of the diaphragms connected, so where would the second line go?

Thanks

[Flat6pac]

With 2 identical diaphragms, you have the wrong part in place because the other pod doesn't have a vacuum connection.
I'll get a picture shortly as I have an 80 on the table complete.
Bruce

[DSPTurtle]

Just snapped this on the stand for the 3.0 almost ready to go home… hopefully it saves Bruce a few steps and clicks to confirm his point.

[Flat6pac]

and all looking good, I have a spare available
Bruce

[DSPTurtle]

Hey Bruce, you wouldn't happen to have a quick reference for the points to pick up on the two pot dizzy would you? Hunting down the service manual is always an exercise in frustration

[Blagave]

Thank you so much for the information and pictures.
Flat6pac, can I just plug off the other diaphragm? If not, I would be interested in your spare.

Thanks to both DSPTurtle and Flate6pac

[Flat6pac]

DPS, pictures for you
The vacuum idle retard is located below the butterfly so at idle there is vacuum and attaches to the pod front for retard.
The high speed vacuum is advance and located above the butterfly and doesnt vacuum until pulling in lots of air. Connects to the connection you see when looking at the pod.
Bruce

[Flat6pac]

On the vacuum pods, you have 2 "vacuum limiters"
You need "additional air valve" No. 911.110.273.01 which I have.
Bruce

[Blagave]

Originally Posted by Flat6pac

and all looking good, I have a spare available
Bruce

Bruce in the bottom picture does the red line from the throttle body go to the distributor pod?
In another picture you show a red line to backside of throttle body. My port has a cap on it. Where would the other end of the red line connect?

[DSPTurtle]

The top port on the dizzy pot goes to the connection on the throttle body above the throttle plate. The bottom port on the dizzy pot goes to the port on the throttle body below the throttle plate. Both of those ports are smaller that the decel valve port or the vent for the WUR. You can figure out above and below the throttle plate by blowing carb cleaner into the ports and seeing where it comes out.

[Flat6pac]

The holes are opened to inside the throttle.
Bruce

[DSPTurtle]

Just realized you had posted some answers above Bruce. Sorry to rehash it. Just went through the exercise yesterday so I figured I'd write it down so I could search on it in the future. Lol.

['78 SC]

This is a great thread. It identifies the throttle body connections much better than the standard vacuum hose diagrams. Thanks Bruce and DSPTurtle. Do I have this right?

Rear, upper throttle body connects to WUR vent (has no vacuum when throttle closed or open)
Rear, lower throttle body connects to Distributor retard (has vacuum at idle, none when throttle opened)
Front, upper throttle body connects Distributor advance (has no vacuum at idle, increasing vacuum with RPM)
Front, lower throttle body connects to Deceleration valve (has vacuum at idle, increasing vacuum with RPM)

BTW, it didn't dawn on me until reading this thread (cue sunrise over the swamp) that the front ports on the throttle body behave differently than the rear when opening the throttle. Since opening the throttle rotates the throttle plate down in the back, both rear ports end up above the edge of the throttle and see essentially no vacuum. Conversely, the front edge moves upward and both front ports end up below the edge of the plate and will have significant vacuum, depending on RPM and throttle position.

Here's the distributor on my '82. Which is the vacuum retard connection and which is the vacuum advance?



Thanks again guys for your contributions.

[Flat6pac]

The advance vacuum is the picture hose to the left.
The one to the right at idle should have vacuum if it's hooked to throttle body correctly.
At idle I would put my tongue on the hose to feel the vacuum.
Bruce

['78 SC]

So, the red hose shown in your photo connects the upper port on the front of the throttle body to the leftmost distributor connection shown in my photo. Looks like whoever last installed the hoses is 0 for 4.

I'm using a vacuum gauge rather than licking those nasty hoses.

Thanks, Bruce.

['78 SC]

Which throttle body port should the deceleration valve connect to? I thought it would need a vacuum signal with the throttle closed so I connected it to the front lower port on the throttle body. But when I tested it (at idle) by blipping the throttle, the engine would hang at about 2000 RPM instead of returning to idle . Connecting the decel valve to the front upper TB port results in lots of popping when closing the throttle at speed. Admittedly, I like the ruckus on overrun , but what is the right hookup?