One of the more aggravating things you run into are missing vent tubes on 2100 and 4100 carburetors.
Here's a sketch I made from a notation in my 66 Mustang (and others) Shop Manual. The picture of the carburetor with the missing tubes were cropped (stolen) from one posted by Jeff.
In the tube sketch, the slot was cut to facilitate tube installation into the tube hole in the carburetor. The 0.375 MAX dimension mean exactly that. Brass tubes can be obtained from hobby stores, brick or online. The 0.219 inch diameter (7/32) is critical. A Dremel cutting disc was used to make the slot. That's the width of the slot, one disc. Use a 0.189 in dia drill bit (no 12) to clean up the insides of the tube. To install, squeeze the slotted end a bit and slip it in the tube hole. Tap the end gently with the handle end of a screwdriver until there is about an inch of tube sticking out, measured 0.985 to 1.015 inch.
Jim
