Where does fuel enter the carb in this photo? I'm guessing where the arrows are, but am clueless lol

 

pretty much just below the two tubes there. if you give a little pull/push on the throttle linkage (other side of the carb), youll acctually see fuel squirt in there. just keep your head a back, somtimes it shoots out pretty far.

 

Also don't use a bic to see it. Unless you need to lighten up the eyebrows a little lol.

 

It actually enters in quite a few places. The first is the idle circuit at the bottom of the barrels, under the throttle baldes. Intake vacuum is always drawing fuel from there. When you start to open the throttle a transfer slot(which gets it's fuel from the same path as the idle circuit) is uncovered and delivers a bit more fuel. Those boosters that stick out are the primary fuel source for the barrels when you drive or operate under power. Since they do most of the "work" they're often refered to as the main metering system or the mains etc. You also have the accelerator pump that delivers fuel above the boosters when you open the throttle(only in the front barrels on a vacuum secondary). Those main boosters are the workhorse of the carb though, if they don't work properly then the car will never run right. Holleys use a power valve for enrichment as well, which usually comes on after the transfer slot and before the boosters(if it's tuned properly). If any "higher level" system is on, then they're all on, ie if the boosters are delivering fuel, so is the power valve, and the transfer slot and the idle circuit. They all have to work together and at the right time in order for the carb to get good power/mileage and have good throttle response.