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Re: [T3] 72 square, rough idle, #1 missing?

On 7 Mar 2002, at 9:30, Drake . wrote:

> Well it sounds like I have some sort of cobbled together thing then, or 
> something inbetween years perhaps? (and possibly unique to california)

My 72 was a CA version, too, so I am familiar with those. Yours has just 
been changed for some reason. The most likely reason is that the proper 72 
dual vac advance ( #883) is very expensive compared to the earlier ( #265) 
and later (#505) single vac advance units. (This is the number stamped on 
the vacuum can arm; it's the last 3 digits of the Bosch part #.)

> >There should be NO Tee. I strongly recommend that you
> >just connect this vacuum line straight from the dist to the intake air
> >distributor...<cut>
> That I can do, this will elimiate the small line that goes to the 
> deceleration valve though. I have been thinking about the function of this 
> device, which unfortunately isnt described in detail in the manual. The 
> decel valve would supply air into the air distribution manifold, either 
> under vacuum or without. The large ports on this valve connect from the air 
> cleaner through the valve then to the air disribution manifold, AFTER the 
> butterfly (if I remember correctly) Since this was only installed on 
> california models, (extra pollution controls) I will surmise that this thing 
> is there to lean out the mixture even more while decelerating only. But 
> since the vacuum source is connected to the small port just in front of the 
> butterfly, then it would only see a vacuum when the butterfly is open. So 
> that would mean that with no vacuum on this deceleration valve (and hence no 
> vacuum on the vac adv the way its currently connected) you get a lean, 
> unadvanced mixture when the butterfly is closed? So only while pulling a 
> vacuum on this port, you get some vac adv and a tiny bit richer mixture (by 
> virtue of a little less air being drawn into the air box). Does that sound 
> plausible?

Okay, I skipped over this earlier. The big hoses on the decel valve sound like 
they are connected right, but the small hose, the one that controls it, is not 
in the right place. The small hose is supposed to connect to a small nipple 
that connects directly to the interior of the intake air distributor. The vac adv 
and retard ports connect to special drillings that go into particular places 
near the throttle valve so that they will give the correct vac signals to the vac 
advance and retard.

Frankly, I don't think your decel valve is doing anything and you would be 
better off just disconnecting it. To do this you would just need to cap off the 
special Y where it enters the intake air and the hole in the air cleaner where 
it's air came from. 

You should also cap off the 2 small ports on the side of the intake air dist 
that you aren't using.

> > >I am glad you mentioned this....the bently manual states .024 as >does a 
> >haynes manual. The owners manual states .028 why the
> > >difference?
> Well I did take a look at the spark through a plug with it set to .024 and 
> it was a nice blue spark. Perhaps I misread something in the bently manual 
> and .024 was for a different year? At any rate I will likely re-gap them to 
> .028 just to see if there is any appreciable difference.

I just set mine to .027 because that's a setting that my gapping tool has.

> >Note my comment in another message about the loose injector wires. This is 
> >a common problem because it appears that Bosch changed the
> >thickness of..<cut>
> Yes I did read that article, and already have checked that issue. I have 
> tightened them up some, but they are still too loose for my satisfaction. 
> What I need to do is really ensure that the male ends on the injectors are 
> clean, and take the female pins out of the connectors to clean/crimp them as 
> well.

Yes, the only way to tell how tight they are, or to tighten them, is to get 
them out of the connector bodies. How clean they are really isn't all that 
important. If the connections are tight, they will make a good connection and 
a little oil around there just helps keep things from oxydizing.

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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