Re: Carb Q's

[Dan Bubb <jdbubb@ix.netcom.com>]

Actually, what opens the secondary is the "unterdruckdose" or vacuum
diaphragm. At low throttle openings the plate (cam) that bears against
the "rolle" or roller keeps the secondary plate from opening. At higher
throttle openings the plate/cam moves out of the way of the roller. This
allows the secondary to open. If there is enough vacuum drop across the
primary barrel the vacuum diaphragm will contract and open the
secondary. If the throttle is closed the plate will contact the roller
and force the secondary closed no matter what the vacuum diaphragm is
trying to do.
The primary linkage has no direct connection to open the secondary. It
simply gets out of the way at high throttle openings to allow the vacuum
diaphragm to open the secondary. What you refer to as the pin that
misses the roller by .1" , I believe, is only there for the throttle
stop screw to bear against.
In summary, it sounds like there is nothing wrong with your carb. You
will never see the secondary plate open by blipping the throttle or
revving the engine because it won't generate enough load to contract the
vacuum diaphragm.
A way to test this is pull the vacuum hose off the unterdruckdose and
plug it. This will disable the secondary. Then drive the car. It should
be really gutless compared to normal if the secondary is operating
correctly when the vacuum hose is connected.
Dan
PS. Thanks for reminding me of my 76 and how much I disliked this carb.

Morten T Nielsen wrote:
> 
> Hi
> 
> Anybody here know anything about the Zenith/Solex 2B2 carb that VW used?
> The second stage throttle plate doesn't engage on my carb. From what I can see in the Haynes, the throttle linkage is supposed to push the little wheel attached to a vacuum box which then controls the opening of the 2. stage. But on my linkage, the pin on the linkage passes right by the little wheel (on the carb side) and therefore doesn't push the throttle plate open... But (And this confuses me!) the plate which holds the wheel in place, when the throttle is only lightly depressed fits right on the little wheel. So...it's like the pin for the 2. stage is unaligned or something - but that cant be, since the whole assembly (linkage) is one whole unit that turns with the throttle...what is wrong!?!?!
> 
> If you don't get it, look: http://www.ismi.net/riecherttuning/german/bilder/verg_zenith-fallstrom.jpg
> In the bottom right is a word "rolle"...this points to the little wheel i'm talking about. Now...you see the plate which already touches it? When the throttle is middle pressed, the wheel will slip off the plate (the plate is rounded) and then the pin above the plate (on the drawing it is just left of the item which the word "pumpenstange" points at) should push the "roller" down in order to push the stick on the vacuum (unterdruckdose) box up inside the box...
> Well as said...the pin just passes the wheel 1/100 of an inch left of it...but the rounded plate is perfectly aligned...HELP!
> 
> Thanks!
> 
> Morten T Nielsen
> 
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