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Old 03-23-2016, 06:56 PM   #1
Bruin_26
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Question about vacuum port

So I'm just trying to figure out where the vacuum port between the carb and distributor leads to in my '72 C20 with a 350.
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Old 03-23-2016, 07:27 PM   #2
cleszkie
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Re: Question about vacuum port

It leads to the vacuum modulator on the rear passenger side of your TH350 tranny case. The modulator controls the shifting of the tranny.
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Old 03-23-2016, 07:31 PM   #3
70STOVEBOLT
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Re: Question about vacuum port

What do you mean "leads to"? Do you mean whether it is a ported vacuum source or not? If it's above the throttle plates it is ported if it's below the throttle plates it is considered manifold vacuum.
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Old 03-23-2016, 07:38 PM   #4
FirstOwner69
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Re: Question about vacuum port

The one below? That's on my 69. Lines hooked to it are brakes, trans and A/C vacuum canister. Sometime after 1969 and before 1972 the brakes were hooked to the rear carb base if I recall correctly. It is a full engine vacuum port. Not sure what you mean by asking where it leads to.

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