Small stacks on Webers

Hi all,
Please forgive what might be a stupid question, but I am not very familiar with Weber carburetors. All of my cars to this point have had SUs. I was wondering what the small velocity stacks above the main larger ones were for on a triple Weber set-up. My Webers have these small intakes in a slightly different position, but no stacks in the holes. Are these needed and if so are they available?

I have never seen such: is that tiny velocity stack just hooked into the bowl vent?

If so, I seriously doubt the velocity stack has any other purpose except it looks cool.

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The photo with the stacks is from the Jaguar Continuation C, the other is my car. Here are some other photos from XKC052:

Ok, so after a little more research on other sites, I believe you are correct. These probably go into the bowl vent. Apparently, you should have your bowl vents piped into the incoming filtered air of the intake. I’m guessing this helps the venting process because of the vacuum created by the air going past them in the cold air box. I’m also guessing the purpose of these little stacks is to get the vents further into the box and closer to the air rushing into the intake stacks (better vacuum?)

Wouldn’t this be like the economizer devices that decrease float level using vacuum?

Hi David,
Short answer, I don’t know. That’s exactly why I was posting. I know they were used on the '53 Le Mans cars, but really don’t know what exactly they do. My above comments are pure speculation.

I have no idea how that would work: there’s a float that works a valve, once the level is up to the point where the valve shuts off flow, vacuum is probably not going to help that much, if at all.

On float control carburetors, I certainly have never heard of such a device.

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Here, paul. It’s very complicated and iirc it allows the carbs to be tuned rich after the choke is off and before fully warmed up. Don’t know how Webers work.

Interesting article, but I don’t think it applies to the Webers.