Reducing servo pipe to balance pipe tee

[RednWhite]

Hi,

I'm fitting a set of Kadrons which have a fuel line sized balance pipe between the two carbs. I want to fit a tee to that pipe so that I can connect the servo to it but I can't find a suitable reducer - I need something like 15mm to 6mm (roughly). Does anyone have any idea where I can get something that'll do the job?

 

[Trikky2]

Where does your balance hose connect to?

Normally a balance pipe connects to the manifolds, not the carbs.

A servo has to be fed from the manifold.

A fuel line sized pipe is not sufficient for a brake servo.

This is the brakes your working with - a little knowledge.... is not enough.

 

[Bay-low71]

I, like you had the same issue. I have twin ICT's and the balance pipe fittings in the manifold are only 1/4" BSP with 1/4" barbs for fuel line sized hose.
My solution was buying a 1/2" BSP T piece with female threads. Then threaded into this 2 off 1/2" BSP to 6mm hose fittings this joins the balance pipe. Then fitted a 1/2" BSP to 13mm hose fitting into the T piece, providing vacuum to the servo. It is a bit bulky but you never see it and in my opinion it's fit for purpose.
Not sure on its performance as haven't got the bus MOT'D yet if it causes an issue which is picked up by the brake test I will have to drill and tap the manifolds to fit a bigger balance pipe.
The vacuum that goes onto the servo simply assists you when you brake, the better the vacuum the more it assists you, no vacuum and no assist you braking system is simply a hydraulic system, the vacuum is system is separate. Hope this helps Ben


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[RednWhite]

@Trikky2 - apologies - my description was sloppy - there's a connection off each manifold and the 6mm fuel line runs between the two manifolds - I want to connect the servo pipe to this balance pipe. The servo hose is the correct size (approx 15mm internal diameter)

@Bay-low71 - thanks - that's exactly what I was looking for. It sounds like a good approach so I'll give it a go.

 

[Trikky2]

Ok I understand what you meant now.

You still must maintain the minimum reccommended internal diameter of the vac pipe right into the manifold itself though.

The reason is that, if you reduce it too much, the vac supply to the servo will not be replenished quickly enough. Hence, although the servo will operate normally on the first push of the pedal, if you rapidly re apply the brakes or pump them, the servo effect will reduce or even cease altogether.