| Author |
Message |
Paul Wilson
Samba Member
Joined: August 30, 2003
Posts: 608
|
 Posted: Sat Jul 09, 2011 5:21 pm Post subject: Weber ICT Balance tube |
 |
|
I am very aware that the dual single barrel carbs need a balance tube. My 66 Squareback has one and is is a single port engine. Do dual port engines need another balance tube ? Is there any advantage to using two balance tubes? Front tube for 1 & 3 cylinders and a tube in the rear for 2 & 4 cylinders? Has anyone tried this?
uglyoffroader |
|
| Back to top |
|
 |
Erik G
Samba Member
Joined: October 16, 2002
Posts: 13270
Location: Tejas!
|
|
| Back to top |
|
|
Paul Wilson
Samba Member
Joined: August 30, 2003
Posts: 608
|
| Posted: Sun Jul 10, 2011 7:29 am Post subject: |
|
|
| Erik G wrote: |
| yes it needs one. maybe even more so than a single port. Never tried running more than one |
Yes, I knew dualport engines need one, I just wanted to knoe if anyone had used two balance tubes.
uglyoffroader |
|
| Back to top |
|
|
mxracer
Samba Member
Joined: April 09, 2011
Posts: 568
Location: NC
|
| Posted: Sun Jul 10, 2011 7:45 am Post subject: |
|
|
| Don't know if they NEED dual balance tubes but I'm assuming it does help. The dual carb 71 models (I'm assuming European) had dual balance tubes from the factory according to the Henry Elfrink manual I have. I thought about doing it to mine as well. |
|
| Back to top |
|
|
Mike Fisher
Samba Member
Joined: January 30, 2006
Posts: 17970
Location: Eugene, OR
|
| Posted: Sun Jul 10, 2011 8:05 am Post subject: |
|
|
The single balance tube on dual port engines is hooked to the intake manifolds not the carburetors. Dual balance tubes sounds redundant/unnecessary.
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold
Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey |
|
| Back to top |
|
|
Paul Wilson
Samba Member
Joined: August 30, 2003
Posts: 608
|
| Posted: Sun Jul 10, 2011 8:09 am Post subject: |
|
|
| Mike Fisher wrote: |
| The single balance tube on dual port engines is hooked to the intake manifolds not the carburetors. Dual balance tubes sounds redundant/unnecessary. |
You are right, the tube does connect to the manifold. But on the dual port manifolds it would only balance the no. 1 and 3 cylinders and not the no. 2 and 4 cylinders? |
|
| Back to top |
|
|
Mike Fisher
Samba Member
Joined: January 30, 2006
Posts: 17970
Location: Eugene, OR
|
| Posted: Sun Jul 10, 2011 12:24 pm Post subject: |
|
|
I would think that the vacuum probably draws all the way into the sump and all 4 cylinders end up equal? 
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold
Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey |
|
| Back to top |
|
|
Bobnotch
Samba Member
Joined: July 06, 2003
Posts: 22410
Location: Kimball, Mi
|
| Posted: Sun Jul 10, 2011 1:44 pm Post subject: |
|
|
| Paul Wilson wrote: |
| Mike Fisher wrote: |
| The single balance tube on dual port engines is hooked to the intake manifolds not the carburetors. Dual balance tubes sounds redundant/unnecessary. |
You are right, the tube does connect to the manifold. But on the dual port manifolds it would only balance the no. 1 and 3 cylinders and not the no. 2 and 4 cylinders? |
If you look at the dual port manifold, you'll see that it's pretty open up near where the carb attaches. That's where it gets it's vacuum from the 2-4 side of the manifolds. Yes, the vac signature is probably stronger on the 1-3 side of the manifold, but it does balance out. On the OE VW manifolds, they pull vacuum from the center of the manifold, so it's more evenly spread out between the 2 cylinders on each side.
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
|
|
| Back to top |
|
|
Slow 1200
Samba Member
Joined: July 02, 2004
Posts: 2105
|
| Posted: Mon Jul 11, 2011 12:21 am Post subject: |
|
|
| mxracer wrote: |
| Don't know if they NEED dual balance tubes but I'm assuming it does help. The dual carb 71 models (I'm assuming European) had dual balance tubes from the factory according to the Henry Elfrink manual I have. I thought about doing it to mine as well. |
having an euro '71, I don't think the dual balance tube make a big difference (it surely does make vacuum leaks more likely!), actually they only used them for part of the year and then went back to a single balance tube (but still taking the vacuum from the 4 ports)
Now I don't remember if in my car vacuum to the modulator for the trans is taken from the 1-3 or the 2-4 tube, I'll check just out of curiosity |
|
| Back to top |
|
|
Root_Werks
Samba Member
Joined: December 31, 2007
Posts: 813
Location: San Juan Islands
|
| Posted: Mon Jul 11, 2011 7:50 am Post subject: |
|
|
If you have single/dual carbs, you want to run a balance tube. If you have dual/dual carbs, you don't.
Dual ICT's - The balance tube should be hooked to the threaded part on the manifold that grabs vacuum from both intake ports. It's just under the flange the carb bolts to. So no need to have multiple balance tubes.
_________________
When I set my timing, why do I flush, then take a pee? |
|
| Back to top |
|
|
Bobnotch
Samba Member
Joined: July 06, 2003
Posts: 22410
Location: Kimball, Mi
|
| Posted: Mon Jul 11, 2011 3:25 pm Post subject: |
|
|
| Slow 1200 wrote: |
| mxracer wrote: |
| Don't know if they NEED dual balance tubes but I'm assuming it does help. The dual carb 71 models (I'm assuming European) had dual balance tubes from the factory according to the Henry Elfrink manual I have. I thought about doing it to mine as well. |
having an euro '71, I don't think the dual balance tube make a big difference (it surely does make vacuum leaks more likely!), actually they only used them for part of the year and then went back to a single balance tube (but still taking the vacuum from the 4 ports)
Now I don't remember if in my car vacuum to the modulator for the trans is taken from the 1-3 or the 2-4 tube, I'll check just out of curiosity |
I had a set of VW manifolds here that had a plastic "F" connecting the 2 ports on each side with a single outlet. I suppose you could have used 2 hoses to tie both sides together (run 2 balance tubes) if you wanted. But my thought is that it would look more crowded with the extra hose in there.
On my wife's Fastback (back when it had carbs), the AT modulator was connected to the balance pipe that tied both sides together.
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
|
|
| Back to top |
|
|
|
