79- 2nd vacuum line on distributor

[Rupesy]

I'm pulling stuff off since it will be snowing next day or two. Amazing what you find out! The vacuum line coming off the top of the distributor is connected to the back side of the throttle housing. I didn't know there was a second vacuum line. It is disconnected and I don't know where it should be connected. It doesn't appear that it has been connected for a long time. Where should it plug in? You can see the end in the middle of the second picture.

[Danglerb]

I haven't looked on the bottom of the thingie before, hope I don't have one thats disconnected.

Wild guess is that it goes to one of the throttle ports maybe on the front, maybe just try both and see how it runs? Check the timing etc.

[rhjames]

a shot in the dark--

the disconnected vacuum hose is on the back side of the diaphragm, so my guess would be that it retards ignition advance for emissions requirements.

sorry I don't have an emissions manual to verify.....


--Russ

[Danglerb]

All of the emissions stuff is a little retarded, so that sounds right, maybe an anti nox feature?

Or maybe retarded during starting or idle?

[DPW928]

It is the retard for the ignition. IIRC it plugs into the second port from the right on the front of the throttlebody. It may T off the line to the decel valve. The WSM has two diagrams, one with no retard and one with. I would check it out to make sure.

[Rupesy]

Could this be part of the problem with an idle that cycles up and down? I guess I will look for th place to hook it up and try both ways. When you say front of the throttle body, are you considering the front looking at it from the front of the car or from the drivers seat?

Sorry, what is IIRC and WSM??

Thanks

[DPW928]

It could be a cause of the hunting idle if it doesn't hold a vacuum. By front I mean front of the car. IIRC means If I Remember Correctly (I was at work and didn't have a copy of the diagram) and WSM is an acronym for the 9 volume work shop manual.

[Rupesy]

OK, pulled more stuff off and found the break. You can see the end just to the right of the center of the picture under the connector. From the looks of the ends, this hasn't been connected for a while. It does connect on the front of the throttle body about midway like you said. Starting to get a little excited.



Thanks for the help so far.

[DPW928]

WYAIT (while you are in there) I would pull the air filter housing and check/replace the vacuum lines that attach to the back of the throttlebody.