Is this my deceleration valve?
 

If not what is it and should a vacuum line be plugged into it?? 1983 911sc 3.0 non-turbo...

Thanks in advance!
Don

http://forums.pelicanparts.com/uploa...1094495731.jpg

http://forums.pelicanparts.com/uploa...1094495751.jpg

Don, yep- thats it.

there is a small vacuum line that connects to that nipple. Looks like it comes from the WUR:
http://www.pelicanparts.com/911/911_Parts/1978-83/1-7-3.JPG

Nope, that is NOT your decel valve.

The decel valve is on the top of the engine, drivers side.

Not on an '80-83 its not.

Part #15 on the diagram linked above. looks very similar to the AAV, except for the nipple for the small vacuum line.

Didn't see the year!

It does look very similar to the AAV that is on the earlier SCs.

For 80-83 the configuration of the decelleration valve changed from the 78-79.

So yes that is what it is. The AAV is hidden behind the fuel distributor and the AAR is visible just below.

http://members.rennlist.com/jimwms/CIS/vaclines_80.gif


The vacuum nipple connection goes to the throttle body vacuum source.

edit: it is #13 in the schematic

'81 Euro 3.0 here and that valve isn't visible in that location.

I don't think he said his car was Euro????

Okay,

I looked around some more and stuffed under the AAV below was a vacuum line w/ a screw in it.

So the next question is, why would anyone want to bypass the deceleration valve? BTW, the car runs great.

I tried to hook it up but the rubber vacuum line is too brittle. It won't go over the lip anymore w/o falling apart.

Don

A lot of people unhook and plug that vacuum line connection because they don't like how the deceleration valve drops the idle slow on shift. They want it to drop faster.
That's if it was working correctly at all.
Unhooked is OK as long as the connection at the other end was plugged. That's what the screw was/is doing.
If the line is brittle and cracks behind the screw plug you will get an air leak that you do not want.

edit: the effect is at high RPM shifts that the RPM falls too slow for some people so they disconnect the line and plug it.

My decel valve is also disconnected. Both ends of the hose are plugged but where does the other (oppisite the decel valve) end of the hose connect to? I don't have any drivability problems, just curious. Anyone.....
Thanks

Okay, I can't spell oppisite.

KNS,

If yours looks like mine. Then it will go to a vacuum "T" connector that connects to the throttle housing. Look at Tsuter's picture. Decel valve is #13.

Don

Dillinger,
Thanks, I'll have a look.

Anyone know what the nipple/connection shown in the photos on the right side of the airbox is supposed to be connected to? My '80 SC doesn't have anything tubed to it either. Rob

RR,

That is supposed to be connected to the upper port on the side of the oil tank filler neck.

On an '83, the small vacuum line connects on one end to the decel valve(as pictured correct for '83) then passes behind intake housing and connects to a "T" fitting. The stubby end of the "T" goes to a nipple on the throttle body backside (below throttle plate) it is designed to send high vacuum signal when throttle is closed suddenly. This open the decel valve allowing additional air to the intake to prevent overly rich condition on throttle lift. And the opposite end of the "T" goes to the small nipple on cruise control unit on the drivers side. (if so equipped)