FYI...if you decide to calibrate the fuel level with clear site plugs, they only need to be finger tight as they use an O ring to seal, otherwise you may break off the outer bezel section, then it's a bear to try and remove the threaded portion without removing the fuel bowl as a last resort



I generally find that the sixpack performs better with the float level at the center of the site window/plug esp the 340 set up, I'd start with bringing up the end carbs first, then a GOOD roadtest, then try the center carb, see how it performs under various throttle conditions, hard braking, hard launches/cornering etc, etc.... if you do buy the clear plugs, use them for setting/observing the true running fuel level, then remove them and install the brass plugs, seems the current grade of clear plastic plugs are not fuel friendly, I tend to think it's the mfg's choice in plastic, as I have some clear plug sets in several of my cars that are over 3 decades old, still intact/removable and still visible, although those sets are Moroso and not Holley, but I've had feedback from others that the Holleys are junk, so don't run with them, granted the factory method is fine for setting the fuel levels, but the clear site plug will allow you to see how the fuel level "behaves" after an actual run in the vehicle, rather than just observing a stationary idle condition watching the fluid dribble out the fill hole


The Moroso pn# is 65226, the "new" Holley GLASS site plugs (PN# 26-112) require you to drill/tap the fuel bowl to install these, the AED brand plastic plugs sold are very poor quality, I'd recommend the Moroso's for testing/calibration use

Mike