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Noting, my carb had same stuff, I don’t know if it was a casting for some future project or carb plan, or maybe it was done to add structural integrity to the back wall.

I also noticed that your base plate is not taped for power brake vacuum port. Most are taped 1/4” NPT.
 

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I think I once ran across a Quadrajet picture with something attached to that recess, but it’s blank on the two carbs I have. And both my carbs are tapped in the area below for the power brake booster connection.
 

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That recess in the casting is for a hot idle compensator. Some versions of the Qjet used one to admit a small amount of additional air at idle under hot conditions. The compensator has a bimetallic spring that causes the valve to open under hot conditions. All castings had the provision, but carbs that didn't use it don't have the passageway drilled. Yours doesn't use it. Don't lose any sleep over it. You aren't missing any parts.

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Discussion Starter · #6 ·
Noting, my carb had same stuff, I don’t know if it was a casting for some future project or carb plan, or maybe it was done to add structural integrity to the back wall.

I also noticed that your base plate is not taped for power brake vacuum port. Most are taped 1/4” NPT.
Noting, my carb had same stuff, I don’t know if it was a casting for some future project or carb plan, or maybe it was done to add structural integrity to the back wall.

I also noticed that your base plate is not taped for power brake vacuum port. Most are taped 1/4” NPT.
Thanx
 

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Discussion Starter · #7 ·
That recess in the casting is for a hot idle compensator. Some versions of the Qjet used one to admit a small amount of additional air at idle under hot conditions. The compensator has a bimetallic spring that causes the valve to open under hot conditions. All castings had the provision, but carbs that didn't use it don't have the passageway drilled. Yours doesn't use it. Don't lose any sleep over it. You aren't missing any parts.

View attachment 622840
Thanx
 
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