From: Larry Klein
Date: Sun, 17 Jun 2001
Subject: Re: webber plumbing questions


Your dad may have everything done, but everything is not done RIGHT.

> #1)  This is a hose which comes off the motor from below the manifold on the
> rear carb.  On the Zenith it connected to the choke housing.  What does it
> do and where should it go on the new setup?  One guess we had was for there
> be a way to tell when to turn the choke on or off based on temprature.
> unless it's a vacuum line.

This is where the water line that runs serially through the choke covers
on the carbs ends up.  It's not vacuum!  (you'd find this out if you
filled the cooling system without plugging the hose)
The water line comes out the aft side of the front manifold, goes up to
a nipple on the choke cover of the fwd. carb.  Then, from the other
nipple on that fwd choke cover, goes another line to the rear choke
cover, then from the other nipple on the rear choke cover back to the
block under the aft manifold.  The plumbing is the same for the Zeniths.

> #2)  This hose comes off the rear carb and I'm not sure where it's supposed
> to go.  I am looking at the diagrams of this area in the manual but they
> show no such hose connection on the carb.  I don't know if this is something
> obvious, but I should have taken a picture at a better angle.

There is a vacuum connection on each carb at this point.  This draws
vacuum from the venturi area of the carb, giving you high vacuum at open
throttle (as opposed to manifold vacuum, high at closed throttle - that
blue line in the "choke hose" picture - which should go to the
distributor RETARD, and NOT TO THE FWD CARB as it does).  What I did was
connect this hose to the same hose from the front carb (where you have
the blue hose connected now) into a tee, and run a line from there to
the distributor ADVANCE.

The distributor retard connection is on the FLAT side of the vacuum
diaphragm, the advance is on the CONE side of it.  Long story (already
told) short: run the blue line from the manifold where it is to the
connection on the engine side of the distributor and tee the two lines
from the pass. side of the carbs together and connect to the outside of
the distributor.

> #3)  This is the T-connection for the air cleaner... he wants to know where
> these two ends go.  I'm not sure what he's doing with it, but maybe there's
> something useful in the photo.

The connections to the air cleaner are as follows:  one from the
charcoal canister (under the battery), which tees into the oil breather
pipe underneath, the oil breather connection which is about 1/2" in
diameter and comes out through a fitting above the fwd carb, and another
that connects under the air cleaner inside the rear element area - this
one goes to the emissions system somewhere and had been ripped out of my
car before I got it.  What does the other end of this hose go to on your

It took awhile for me to get all this stuff straightened out - but it
was the difference between a car that ran like hell and a car that runs
nice and smooth.  Use new hose wherever possible - I skimped when I
first put my Webers on and lost one hose after another - and BOY are
some of them (like that water line under the rear manifold) a bitch to
replace once everything is buttoned up.  After replacing the head (when
ALL this stuff was disconnected) I lost the water line between the
chokes on the carbs, then the water line mentioned above, then a heater
hose (you NEVER wanna replace one of those!) and had the vacuum lines
all kludged up until a BMW mechanic in Signal Hill fixed me up...

Now all is great.  Hope it goes great for you too.