Carburetor lesson.

[Gateway]

Just courious, on CV carbs when you twist thethrottle the butterfly's open. What causes the slides to raise up? Ya, I know I should have know this, but I don't!!

[Steve]

Air rushing under the slides will have a slightly lower pressure as it passes through the venturi.

There is a hole on the bottom of the slide that lets that vacuum get through the slide and get above the diaphragm, where it will lift the slide.

It has nothing to do with the engine vacuum, which is what you will see between the butterflies and the intake valve, it is entirely dependent on the velocity of the air under the slide.

Because the slides only open in response to greater volumes of air, it is almost impossible to bog them down by suddenly whacking them open at low speed.

While this feature makes them very friendly for everyday street use, it makes these carbs rather undesirable for track use.

.

[Nessism]

Vacuum

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[Gateway]

Thank You! That's almost to simple! I am guessing if you had a leaking diapgram that would cause problems!! Well, mystery over. I thought there would be a more complicated way of making them open. What'ya know!!

[Mekanix]

In real time this happens

http://www.youtube.com/watch?v=DbzWS76bpfU