[T3] Dual Carb Shift Vacuum

Tony Rongey trongey at sbcglobal.net
Thu May 15 20:44:09 PDT 2014



Adam,
I might have missed this somewhere in the long thread, but does the car shift into reverse OK?
If not then most likely your direct/reverse clutch is shot since it does both 3rd and reverse.  I've been through 3 automatics that all had that same problem after they had set for 20 or 30 years.  The rubber seals in that clutch seem to be especially prone to drying out if the car sits for too long.


Tony
'70 Fastback AT/FI


________________________________
 From: Craigs List <craigslistcsprings at gmail.com>
To: type3 at vwtype3.org 
Sent: Wednesday, May 14, 2014 7:46 PM
Subject: Re: [T3] Dual Carb Shift Vacuum
 

Guys,

I have a little bit of an update. I decided to dive into drilling and
tapping all 4 manifold ports today. After work I got the passenger side
manifold drilled and tapped. I will finish the drivers' side manifold
sometime next week. I have few plans over the next few days that will keep
me from finishing.

I went on a test drive with just the one manifold ported with BOTH
cylinders tapped. You  can tell that it has helped quite a bit. With the
erratic vacuum signal that I was getting with only the one cylinder tapped,
it would downshift hard when you were coming to a stop. Just porting the
second cylinder on that side has taken that away. It rolls to a stop and
downshifts like it should. It is almost unnoticeable.

It sill does not want to shift into third, but it does shift a lot smother.
I can't wait to get the other side tapped and a balance tube ran. I am
happy with what it did so far. I will let the pictures do the talking.

In this first picture, you can get a feel for what I wanted to do. I could
not think of a way to get this to work,.

http://one4house.com/images/manifold6.jpg

Because of room constraints and such, I decided to go with the setup you
see below. It ended up working out great.

http://one4house.com/images/manifold1.jpg

http://one4house.com/images/manifold2.jpg

These last 3 pictures are the manifold bolted into place before I put the
carb back on.

http://one4house.com/images/manifold3.jpg

http://one4house.com/images/manifold4.jpg

http://one4house.com/images/manifold5.jpg

I will post some more pictures next week when I get the other side done.

Adam


On Wed, May 7, 2014 at 10:42 AM, Jim Adney <jadney at vwtype3.org> wrote:

> On 7 May 2014 at 8:37, Craigs List wrote:
>
> > The only thing that scares me about this is that I had a balance tube
> > between the two manifolds when I had the 34 ICT's. I had this same issue
> > with those carbs. and not wanting to shift.
>
> I have no idea if this will actually cure your  problem. Once you get
> off the beaten path, you're either on your own, or you're looking for
> someone who has already blazed this particular trail for you. What I
> can be sure of is that this should give you a better vacuum signal
> (more pulses per engine cycle and lower average vacuum.)
>
> > I am more than willing to put a vacuum port on all 4 barrels. I am just
> not
> > convinced that it will make that much of a difference. Here is a picture
> of
> > the setup I had before.
> >
> > http://images.thesamba.com/vw/gallery/pix/1127904.jpg
>
> Those hose sizes look fine. Note that the OE AT engine breastplate
> has a cutout at the bottom so that the VM hose can go straight down
> toward the VM. That shortens the hose, which should speed up the
> response time slightly.
>
> You also want the vacuum ports in the manifolds to be nearly as large
> as the hose ID. If they are small, that will slow down the response
> time.
>
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
> _______________________________________________
> VWType3.Org mailing list - type3 at vwtype3.org
> http://lists.vwtype3.org/listinfo.cgi/type3-vwtype3.org
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