81SC CIS part identification

[Coastr]

Need confirmation on parts here.

The bottom valve is the deceleration valve, or the AAV? I'm trying to troubleshoot an intermittent high idle (2100rpm), I've read a few threads and was experimenting with pulling the vacuum line but couldn't work out if I had the right one.

[Flat6pac]

The lower pod has a vacuum connection on the outside. Many times I find the line disconnected and plugged.
Bruce

[Coastr]

Yes, it has a vacuum line. Is it the deceleration valve?

[gregoryp]

That is the auxiliary air valve. Check out this web site. Has a great description of everything. 911 CIS Primer - Index

[tirwin]

The one with the vacuum line is the decel valve.

[ossiblue]

Here is another view of an engine similar to yours



You can see the AAV and decel valves look nearly alike, but the decel valve has the vacuum port on the front. In your photo, you can see the port at the very right side of the valve, identifying it the decel valve. The two valves in the picture are in reverse location to yours--your upper valve is the AAV and the lower is the decel.

[Coastr]

Originally Posted by ossiblue

Here is another view of an engine similar to yours



You can see the AAV and decel valves look nearly alike, but the decel valve has the vacuum port on the front. In your photo, you can see the port at the very right side of the valve, identifying it the decel valve. The two valves in the picture are in reverse location to yours--your upper valve is the AAV and the lower is the decel.

Ah, thanks for this. The descriptions I have seen/read match your picture, with the decel valve on top, but mine has the decel valve on the bottom.

I wonder why mine would be around the wrong way then? I suppose someone might have a reassembled them incorrectly. If that is the case, then I wonder if that is causing an issue?

[ossiblue]

Here is a picture of a set up like yours, from a 1981 SC



and a picture of how the devices are connected



You'll notice both devices connect to the metal tubing, and both connect to a molded rubber fitting. In short, it wouldn't matter if the devices were switched as both are connected to the same vacuum system.

[Coastr]

Gotcha, thanks. I notice that last picture looks like it has had the 'crush' treatment for the decel valve.

Not sure if I am going to try plugging the vacuum or try the crush treatment.

[turbo nut]

Also check the that the advance is not sticking in the distributor.

[Coastr]

Originally Posted by turbo nut

Also check the that the advance is not sticking in the distributor.

Any advice on how to do that?

[Coastr]

Originally Posted by turbo nut

Also check the that the advance is not sticking in the distributor.

Bump in the off chance that someone can answer this Q

[Bob Kontak]

Originally Posted by Coastr

Ah, thanks for this. The descriptions I have seen/read match your picture, with the decel valve on top, but mine has the decel valve on the bottom.

Your's is not on the wrong way, The decel is on the bottom. Without a doubt. Word to Your Mother, as Vanilla Ice says.

Lemmie get a pic.

[Bob Kontak]

Originally Posted by turbo nut

Also check the that the advance is not sticking in the distributor.

Chill on this for now. You gots you some vacuum advance and mechanical advance. Both can be tested. You have a timing light?

[Coastr]

Originally Posted by Bob Kontak

Chill on this for now. You gots you some vacuum advance and mechanical advance. Both can be tested. You have a timing light?

Actually I don't think I do. I did have once, long ago when the earth was green and children respected their parents. This is the way to test, with a timing light? Maybe I can find one somewhere.

[Bob Kontak]

Ossiblue's second pic is correct.

[Coastr]

So I golf tee'd the vacuum line and the driveability of the car at low speed is transformed. It's like it had three flywheels in it before.