triple carbs and brake issues due to lack of vaccuum

[crowe]

Hi all,

 

I am having some problems with (what i think is) not enough vaccuum for the master cyclinder brake booster running triples. When the brakes are applied first time I get alot of pedal travel and then on second stab I go through the windscreen. 

 

I have been told that when running triples you will have issues with the brakes due to the lack of vaccuum for the brake booster. At the moment the vaccum line is only connected to one throat on the manifold, it is also interesting to note that this sparkplug is always leaner than all the others. This would be due to the brake booster connected to this cyclinder??

 

Anyone with triples enlighten me on the fix, best way to manage this?

 

Thanks, Callum

[260Coupe]

Callum...........you are spot on I had the same issue until I swapped out the manifold for one with a balance pipe between all intakes

 

Is your booster still a standard 240/260Z ?

I would suggest you either find a manifold that has a balance pipe between all intake manifolds or you can tap of each intake manifold using T pieces .

 

See pic of "Cannon" manifold with balance pipe

 

Alan

 

[Glen]

I never had any issues using the redline manifold, they dont have a balance pipe. I know two other people using redlines that dont have issues either. Just a heads up for those looking at buying manifolds in the future and not having to worry about brake issues like above.

[Zedman240®]

Callum, what intake manifold are you using? I used a Redline manifold and they have the last two throats joined by a small drilled chamber. Like Glen, I never had any issues. Have you checked your one way valve thats in the vacuum line? take it out and test it by blowing through then try to breathe back through it. And did it just start to happen or has it always been like this?

[crowe]

Hi Guys,

 

Callum, what intake manifold are you using? I used a Redline manifold and they have the last two throats joined by a small drilled chamber. Like Glen, I never had any issues. Have you checked your one way valve thats in the vacuum line? take it out and test it by blowing through then try to breathe back through it. And did it just start to happen or has it always been like this?

I am using a Nissan Works Manifold ( it is quite old from back in the rally days i think), the car is a resto so brand new or recond everything brake and engine related, the one way valve is brand new and functions fine, I am not sure if any of my chambers are linked but i suspect not. Do all redline manifolds have this link between 2 throats. This link is to help get vacuum for the booster off two throats rather than the one?

 

Callum...........you are spot on I had the same issue until I swapped out the manifold for one with a balance pipe between all intakes

 

Is your booster still a standard 240/260Z ?

I would suggest you either find a manifold that has a balance pipe between all intake manifolds or you can tap of each intake manifold using T pieces .

 

See pic of "Cannon" manifold with balance pipe

 

Alan

 

 

Thanks Alan, do you remember what type of manifold you were using when you had the same problem? I can link 4 throats quite easily to increase vaccuum which might be a good starting point. The booster is standard 260Z reco.

 

Cheers, Callum

[260Coupe]

Callum

 

I had the same problem with a Nissan works manifold from memory # 6 intake had a vacuum fitting and # 2 had the flat spot cast on to allow for another fitting o be drilled and tapped.........the current manifold is a Cannon .

I found multiple hard stops would deplete the vacuum chamber and the pedal would drop 2" in height.........so I went to a manifold with a ballance tube linking all cylinders.

You could try a Redline manifold as they have four flat spots for tapping vacuum off from which spreads the vacuum load

 

Alan

[Scoota G]

This is my attempt at making a balance tube on a Kameari manifold, it runs the PVC valve and the auto transmission modulator. My first attempt at making a balance tube looked like a giraffe raping a seal :S