'77 911S Fast Idle

[AndreasK]

Originally Posted by boyt911sc

The ‘76-‘77 CIS have a slightly different vacuum routing than the later SC’s except those with non-vacuum assisted WUR’s (engines with lambda).

Using the same diagram above and WUR-033 (‘76-‘77):
a). Connect the vacuum hose (BLUE) to the top port of WUR-033.
b). Connect the vent hose (YELLOW) to the side port of WUR-033.

In summary, BLUE hose goes to vacuum port and the YELLOW hose goes to vent port. You could use WUR-045/-069/-089 for your ‘76 & ‘77 CIS with -033 in case your -033 is having problem.

Tony

I altered the diagram, as explained. If anyone would find it usefull.

[boyt911sc]

Originally Posted by AndreasK

I altered the diagram, as explained. If anyone would find it usefull.

This will surely help a lot of CIS owners. And I will be using this diagram too. Thanks.

Tony

[93nav]

This is what I saved. Hope Tony does not mind, if so let me know.



I did save AndreasK's also.

[Ginger77]

Funny, I also made an edit of the diagram with the clues that were given in the text below.



However, something that confuses me is are these pages (source unknown) that were uploaded on this forum in a similar 77 CIS thread. They differ in the sense that there is no T in the vacuum from the top of the DV (8) to the throttle body. Instead the vacuum from the top of the WUR is routed via the TV (4) to the front of the throttle body (port 10) and the distributor is teed off of that vacuum line.




This was the factory routing of the vacuum lines and I have searched a lot of photos of stock 77 engines on google for reference. All of those show the distributor hose going into a tee. However, essentially ports 1 and 10 of the manual copy receives vacuum in the same position. Below the throttle plate in the throttle housing, correct?
Then both depictions are identical and correct save for the functioning of the ignition retard?

What to do with the distributor? I read that some people even capped the vacuum off?

[boyt911sc]

Ginger,

That is a good technical bulletin you posted. However, I found some contrary data for the thermo valve opening temperature. It says that opening temperature for the TV @ 20°C/68°F based from the chart in the technical bulletin. My investigation showed the thermo valves were still closed well above 90°F.



Tony

[Ginger77]

Hi Tony, I can't vouch for the data on the bulletin. But does that anomaly alter its place in the system? My point is that the '77 CIS is different from the depictions that are available online.
What is the correct routing of the vacuum lines for the 033 WUR on a 1977? And how does the distributor link into the system?

[boyt911sc]

Originally Posted by Ginger77

Hi Tony, I can't vouch for the data on the bulletin. But does that anomaly alter its place in the system? My point is that the '77 CIS is different from the depictions that are available online.
What is the correct routing of the vacuum lines for the 033 WUR on a 1977? And how does the distributor link into the system?

Ginger,

I am not contesting the content of the Technical Bulletin (thermo valve). I was just sharing my observation from my investigation. With respect to WUR-033, vacuum hose is connected to the top and vent hose to the side nipple. About 25 years ago, I used a -033 for my ‘78 SC while I rebuilt the -045. The vacuum hose connection was revised accordingly.

Tony

[AndreasK]

When the TV opens it supplies vacuum to the top of the -033 WUR. I get that much. But, does this vacuum cause the mixture to lean out or get richer? I have some cold running issues on my 77, and I think my TV is the next bit for me to investigate.

[Ginger77]

Good question. I was wondering if it's possible to accidentally reverse the hoses or even the electrical connector. Both can go on either way.