Twin Weber 40 IDF's / Balance Pipe / Servo questions......

[Gütterßnipe]

Twin Weber 40 IDF's / Balance Pipe / Servo questions......

When fitting these to a 1776 would I need to fit a balance pipe?

If so, are there points on each Carb already in place so it would
Be a case of just attaching a pipe??

As my bus is fitted with a servo would I tap just one or both manifolds
For a the servo pipe or could this be incorporated into the balance pipe?


Cheers

Spence

 

[Alex VW Heritage]

never seen a balance pipe on a set of them,

Not sure about the servo i would think just one manifold would be fine, it's only to create the vacumn needed.

 

[Bay-low71]

It's on the manifold if it is present not the carb. If me I would drill and tap both manifolds but usually there is already a tapped hole to attach a fitting or a plug as required.

 

[Gütterßnipe]

never seen a balance pipe on a set of them,

Not sure about the servo i would think just one manifold would be fine, it's only to create the vacumn needed.

It's on the manifold if it is present not the carb. If me I would drill and tap both manifolds but usually there is already a tapped hole to attach a fitting or a plug as required.

Cheers for replies,

Bay-low71 - are you referring to the Servo pipe fitting?

Spence

 

[sparkywig]

No balance pipe required.

 

[Trikky2]

Tapping just one will be fine, you don't need more.

Balance pipe is not needed.

IDF and manifolds means you have an in dependant carb for each individual cylinder.

The manifolds are not siamesed.

 

[dustrat]

Sorry to disagree with coments about servo. If you tap into one manifold for vacuum you will creating a vacuum only on one revolution of engine rather than four as standard manifold does and getting a pulsateing effect. In reality with IDF's you have 4 seperate carbs. I dont run a Type 2 but a Ghia and had a simular problem when I changed from 009 dizzy to standard vacuum dizzy. I had to tap each intake of my IDF's and join into one to get constant vacuum.Although this was for dizzy same effect to get constant vacuum for servo. I know what I would do!! The servo was fitted to stop you and if it's not working properly when needed -----------!!
Robert
:!: :idea:

 

[Bay-low71]

never seen a balance pipe on a set of them,

Not sure about the servo i would think just one manifold would be fine, it's only to create the vacumn needed.

It's on the manifold if it is present not the carb. If me I would drill and tap both manifolds but usually there is already a tapped hole to attach a fitting or a plug as required.

Cheers for replies,

Bay-low71 - are you referring to the Servo pipe fitting?

Spence

Yeah sorry Spence the servo pipe!!! Ben

 

[Trikky2]

Sorry to disagree with coments about servo. If you tap into one manifold for vacuum you will creating a vacuum only on one revolution of engine rather than four as standard manifold does and getting a pulsateing effect. In reality with IDF's you have 4 seperate carbs. I dont run a Type 2 but a Ghia and had a simular problem when I changed from 009 dizzy to standard vacuum dizzy. I had to tap each intake of my IDF's and join into one to get constant vacuum.Although this was for dizzy same effect to get constant vacuum for servo. I know what I would do!! The servo was fitted to stop you and if it's not working properly when needed -----------!!
Robert
:!: :idea:

The vacuum is stored in the servo and its a sizeable reservoire, that's why it still works several applications after the engine has stopped running. There is no vac pulsing problem with running off one cylinder. Sorry but you are wrong.

For example, at 1500 rpm there is a pulse from one cylinder every other revolution. Hence (1500 / 2 ) / 60 which equates to 12.5 pulses per second. This on a reservoire with a supply pipe. There is no issue.

 

[Bay-low71]

I'm not sure what is being debated now??
2 things are definite to Assist your braking your servo needs a vacuum. If it doesn't have vacuum you can still brake but will need to push harder.

So does it effect the vacuum balancing of the carbs if just connected to one manifold??
I think it would, so I connected to both manifolds to my servo.

Twin carbs need to be checked for vacuum balance don't they!?

Vacuum is stored by means of a NRV isn't it as well as the servo design!!

 

[Trikky2]

I'm not sure what is being debated now??
2 things are definite to Assist your braking your servo needs a vacuum. If it doesn't have vacuum you can still brake but will need to push harder.

So does it effect the vacuum balancing of the carbs if just connected to one manifold??
I think it would, so I connected to both manifolds to my servo.

Twin carbs need to be checked for vacuum balance don't they!?

Vacuum is stored by means of a NRV isn't it as well as the servo design!!

You don't need a balance pipe for twin carbs but it does make them easier to tune since the balance pipe makes them less fussy. It also means it not so noticeable when they are a tad out of tune.

As I posted up there^^ the manifolds for IDF carbs are not siamesed. This means each cylinder is separate. If you wanted to put a balance pipe system in you would have to tap and connect all four. Doing just two would mean you have two cylinders with a balance pipe and two without.

If your carbs are solex or ict with siamesed inlet manifolds then you balance pipe idea is fine. If your running webers on non siamesed manifolds you have connected two of your four cylinders together.

The vacuum for the servo is built up when the throttle is closed and hence the tiny amount of air being sucked in compared to the total amount going through the engine is not sufficiently significant to affect the engine.

In theory what you say is correct but you would need to have laboratory conditions to be able to measure any difference. In addition the mixture strength on overrun is irrelevant, as proven by most electronic fuel injection systems on current cars which cut the fuel supply entirely on overrun to boost fuel economy and reduce emissions.

Sorry if my previous post was not clear enough. I hope I have explained it better this time.

It's fortunate I didn't go into the education profession, I think I would have made a terrible teacher.

 

[Bay-low71]

Ha ha!! Yes sir!! Now it's clear..!!

 

[Bay-low71]

I'll be in the corner with my hat on [SMILING FACE WITH OPEN MOUTH AND SMILING EYES]

 

[Gütterßnipe]

Thanks for the great discussion guys.

So no Balance Pipe and Servo attached to one manifold - sounds good to me

Would I be starting off another debate if I asked if the Servo went to LH or RH manifold :lol:

Spence

 

[Stevec]

Well I tried both when I installed my twin 34 webers! I ran a pipe first to only one manifold and the braking was really hard, once I did install a balance pipe it was back to how it was with a single carb

 

[neilswheels]

Well I tried both when I installed my twin 34 webers! I ran a pipe first to only one manifold and the braking was really hard, once I did install a balance pipe it was back to how it was with a single carb

Hi Steve, just to add to this, I'm gonna be running 34's, and have been pondering this. Did you run a servo pickup to the manifold, and a separate balance pipe, or did you T into the balance pipe for the servo?

 

[Stevec]

I put a T joint in the middle of the balance pipe.