Rochester 2GC question

I'm curious what these small ports are for in the base of these two barrel rochesters? They're above the throttle plates. Are they to lean out the mixture? Thanks , Bill

 

Forgot the pics.

 

I dont think those are factory. I have several dozen of those carbs and none of them have holes in that location. You guess is as good as any why they drilled them

 

I have five carbs, 1 2GC and 4 2GV's and they all have the same holes( puzzled ) Bill

 

68 Camaro has them. Unfiltered air drawn right in there.

 

A friend of mine has been collecting 2gc parts to put a set up together and one of the bases has those holes. Seems strange to me like he said unfiltered air.

 

Top Secret plot by GM to increase engine replacements?

 

when that ****erfly closes..is it below it or above it?..(the hole)

i have an idea

if used in a multiple carb set up..like tri-power..or 4x2 6x2 etc,..as a non primary carb.

the carb when at idle still ****s a little bit of fuel past the ****erfly..this helps add some air to the mix so it doesnt affect the idle mixture set on the carb used as the idle or primary carb..

just my feel for it..i could be wrong, and im sure someone will tell me if i am

 

When the ****erfly is closed, the hole is above them. bill

 

Those holes are to vent the fuel vapors in a "hot soak" condition. When you shut the car off hot sometimes the gas cooks in the carb from the heat and the vapors go down the throat flooding the engine. They are supposed to let the fumes out to stink up your garage.

 

Merf, That sounds reasonable. Bill

 

Here's a link that explains it. merf was right.
http://www.oldcarmanualproject.com/...Manual/pages/64Rochester2Gmanual_0005_jpg.htm