[TROYBOYONE]

Does the front carb vacuum tube need to be blocked when progressive linkage has been installed? 1965 GTO

[Tom Vaught]

The Vacuum system on a Tri-power works like this.

Vacuum signal picked up from the front carb base and travels thru a check valve to a TEE.

One side of the TEE goes to vacuum line that connects to a vacuum reservoir "can".

The other side of the TEE goes to a Temperature Vacuum Switch and from that switch to a Mechanical Vacuum Switch mounted on the center carb.

When that Mechanical Vacuum Switch is activated by a carb lever it supplies vacuum to a Vacuum Diaphragm that opens the secondary carbs.

When the Mechanical Vacuum Switch reverts back to its original position a "vent line" on that switch bleeds signal to the front carb air horn nipple.

Are you asking about the front carb air horn nipple and whether it needs to be plugged?

Stock mechanical linkage carbs have that nipple plugged with a rubber cap.

Tom V.

[Zimtok]

I only know about the tripower with the progressive linkage:"
The only vacuum port on the 2GC Carburetor is the port in the throttle plate base.
The front carb will have this port blocked off if you have manual brakes. If you have power brakes This port is used to connect vacuum to the brake booster.

The only other vacuum port is a small tube at the top of the carb that is located on the side of the air horn. These are crimped closed or capped when used on the tripower setup.


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[TROYBOYONE]

Thanks for your answers. Yes, I was trying to talk about the air horn nipple on the front carb. I will cap it. Thanks

[Dick Boneske]

Here are a couple of pictures showing the rubber cap over the line on the front carb.

[TROYBOYONE]

Thanks for the photos Dick. You are the Ultimate !!

[Tom Vaught]

Yes, that is the vacuum bleed location for the vacuum system carbs

The carbs were drilled in that location so they could be used on either a mechanical linkage or a vacuum linkage set-up. The rubber plug kept unfiltered air from entering the carb.

Tom V.