Vixen Weber 40 servo take off help...

[anonymous-user]

Does anyone know the servo vacuum pipe arrangement to the Weber inlet manifold? Having taken the giant leap of changing to twin 40's I find the inlet manifold has no apparent take off for the servo pipe. Common sense would say this should be on the top to prevent fuel draining into the servo, and that only one inlet is involved although is the suction enough or should it be two inlets with a T piece?
Photos would be very helpful!

[sonnylad]

I would just add that i recently had to do this and on the recomendation of a few people went for a single take off, now wishing i had done two as servo one way valve is constantly pulsing due to time delay getting back to that single cylinder to refresh the suction.

[Moto]

Does this help.



Moto

[Andrew Gray]

Cant say having a single take off makes any difference

A

[anonymous-user]

^ Thanks to you both - so you reckon one take off is OK so I'll drill and tap and give it a go, and treat any pulsing later with a second or leave it as TVR 1970 ABS !

[Grantura MKI]

Depending on what manifold you have, it is best to have a balance tube between the two manifold....if there isn't already?
If you do have a branch between the two, then a single port will do.
Best,
D.

[ephemera]

And if you really only want to use one take off, and want some quick experiment, people have used small fuel filters as a rudimentary damper, or a weber jet as a restrictor pushed in the vacuum hose, to smooth the pulsations. E.g. for ignition advance where the pulse is playing havoc. For a brake servo, you could even use a small vacuum reservoir with a one way valve somewhere in the circuit.

[anonymous-user]

Grantura MKI said:

Depending on what manifold you have, it is best to have a balance tube between the two manifold....if there isn't already?
If you do have a branch between the two, then a single port will do.
Best,
D.

No balance tube as there's no take off at the moment so I'll tap an outlet, get it blasted and get it rigged up. ^Good idea about the valve too.

[Grantura MKI]

You hold already have anti backfire valve fitted in the vacuum hose? While you are at it, check to see if the correct type of hose is fitted as well.
Best,
D.

[timelord]

Not had any problems with a single vac take off on my 1600M, vacuum advance distributor was binned when fitting the 40 side draughts replaced with a Lucas type distributor with side entry cap for clearance. Geoff

[anonymous-user]

Yep I'm sorted for that, got an Aldon unit ready and waiting