Drilling and Tapping Inlet Manifolds

[TeamBrian]

Whereabouts do I drill and tap my CSP inlet manifolds for a vacuum supply for my distributor and brake servo. Do I take them off one manifold or one off each side. Thanks.

 

[jonboylaw]

What carbs and dizzy are you running?
If a VW vac advanced dizzy the you need a PORT vacuum take off signal the will come from the carb base plate next to the butterfly at closed position.
If an aftermarket or EFI system then read the recommendations of the manufacturer.


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[Supertramp]

For my 36 DRLA's I tapped the left manifold, somewhere in the middle, you can just make it out in this picture:

 

[TeamBrian]

Ah bloody hell, I've had a blonde moment...of course you take the vacuum from the carb! (I'm fitting a pair of Dellorto 36s). Cheers Supertramp, that's just what I'm looking for. John, do you frequent Volksfling?

 

[gvee]

Your distributer vacuum needs to come from the carb.

Your brake servo vacuum needs to come from the inlet manifold(s).

Where, depends on whether you are running a single or twin carbs.

If it is a single carb, you should tap in to the manifold just below the carb.
For twins: I believe (but don't know for certain) that it is better for the servo vacuum to come off both inlet manifolds to get a more even balancing between the carbs.

 

[Supertramp]

For twins: I believe (but don't know for certain) that it is better for the servo vacuum to come off both inlet manifolds to get a more even balancing between the carbs.

I have twins and and when doing my reading found that there is no need to tap more than one.

Just tap into #3 intake. As soon as the engine starts it draws a vacuum and the flow stops. When you hit the brakes a small amount of flow happens but soon stops. It won't affect the engine. No need to tap all four because it's not a constant drain of vacuum. Do it like this:

 

[gvee]

Really? :shock:
Mine came tapped on both sides, but I will gladly blank one of them off because it's a PITA! :mrgreen: Next time the engine is out, that's top of my hit list!

 

[jonboylaw]

Team brain, yes I do Volksfling, usually the early one.
I have twin dells but run a megajolt ignition so my vac takeoff is a bit different.

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[TeamBrian]

Very nice looking motor, John. If I can get this engine in we'll be there too as we're not too far away. Many thanks for all photos and comments Folks....will be getting the drill out at the weekend!

 

[jonboylaw]

Where abouts are you?
If close by then I'll give you a hand. I'm near Kirkcaldy.


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[TeamBrian]

Cheers Jon, but we're down in Annan, about 40mins away from Biggar. Very kind of you, though.