Shown Below is a typical billet metering block, seen from the side that mates to the main body. This particular model does not utilise a power valve, nor does it have a place to do so - essentially, it is a race-only calibration. From this side, you can visually locate all of the tuneable orifices including emulsion, idle feed restriction, and intermediate discharge.

• Idle feed restriction controls the amount of fuel that mixes with the air from the idle air bleed. Decrease the orifice size to lean out the idle mixture - increase it to richen the mix.
• Intermediate discharge controls the amount of fuel/air mixture that is supplied to the intermediate pull-over tubes located in the main body.
• Emulsion orifices control how much air (supplied from the high-speed air bleed) is allowed to enter the main well of the metering block and ultimately feed the booster venturi.