Carter Thermoquads ~ 'More General Information'
too much emulsion can fatten up the fuel curve from idle to 40% throttle opening.
too much high speed air bleed can lean the fuel curve beyond 50% throttle opening.
the secondary air bleed is down into the secondary main well, it's filled with fuel, so when air is first sucked into it upon secondary opening, it acts like an accelerator pump, the air pushes the fuel out initially.
many phenoms can occur at sustained WOT in a carburetor, and can be counter-intuitive, i.e. opposite of what's expected, such as the accelerator pump passage can pull air reverse and act like an air bleed. or it can continue on pulling fuel if the check valve or ball doesn't function or is missing.
the idle jet tube can flow air in reverse and become an air bleed, because it's connected to the rear facing idle air bleed down in the primary rod area cavity, in the lid, and the air bleed in the top angled backwards. the diminishing bleed in the venturi prevents this by pulling fuel into the venturi instead, when the idle discharge port/transfer slots turn off at WOT.
on the secondary side, the air bleed tube is just that, an air bleed. but that cross drilled little hole in the bottom of it, below float level, creating 2 little holes, those are emulsion holes.
a TQ carb by design has no primary emulsion holes drilled anywhere just for that specific purpose, like a Holley metering block. the air bleeds themselves emulsify the fuel, in the idle/off idle circuit at part throttle, and inside main metering nozzle passages in the lid.
a carb that's been fiddled with by a tuner, can have too much emulsion, the result will be globs of air and fuel coming out of the nozzles or discharge tubes, in a chaotic manner, instead of a steady atomized stream. like when you turn on your kitchen or bathroom spigot after installing a new hot water heater, and there's air in the pipes, what happens. it sputters, rattles, carries on until all the air is pulled through and discharged. but if there's too much emulsion in the carb circuit, it never goes away. the car falls on it's face, and the tuner is jetting up, down, all over and never can really iron it out. even putting rich jets in, it may act like it's still lean sometimes. the plugs will be black but it acts lean like it's running out of fuel, or vice versa.
Spreadbore carbs like the TQ and Qjet use 2 different delivery systems. The primary has a venturi, the secondary has a discharge tube. Each type reacts different to pressure/vacuum change. The secondary discharge tube senses airflow at 1:1 ratio as pressure/vacuum increases, and fuel flows in direct proportion to the air. The main jet alone will provide the right amount of fuel, with minimum air bleed/emulsion.
The primary booster venturi doesn't flow 1:1, it flows in a straight line as pressure/vacuum increases. The actual airflow curves towards a horizontal flat line. So the booster venturi needs an air correction system/emulsion to allow the booster signal to follow airflow. Emulsified fuel is just the result of the air correction.
too much emulsion can fatten up the fuel curve from idle to 40% throttle opening.
too much high speed air bleed can lean the fuel curve beyond 50% throttle opening.
the secondary air bleed is down into the secondary main well, it's filled with fuel, so when air is first sucked into it upon secondary opening, it acts like an accelerator pump, the air pushes the fuel out initially.
many phenoms can occur at sustained WOT in a carburetor, and can be counter-intuitive, i.e. opposite of what's expected, such as the accelerator pump passage can pull air reverse and act like an air bleed. or it can continue on pulling fuel if the check valve or ball doesn't function or is missing.
the idle jet tube can flow air in reverse and become an air bleed, because it's connected to the rear facing idle air bleed down in the primary rod area cavity, in the lid, and the air bleed in the top angled backwards. the diminishing bleed in the venturi prevents this by pulling fuel into the venturi instead, when the idle discharge port/transfer slots turn off at WOT.
on the secondary side, the air bleed tube is just that, an air bleed. but that cross drilled little hole in the bottom of it, below float level, creating 2 little holes, those are emulsion holes.
a TQ carb by design has no primary emulsion holes drilled anywhere just for that specific purpose, like a Holley metering block. the air bleeds themselves emulsify the fuel, in the idle/off idle circuit at part throttle, and inside main metering nozzle passages in the lid.
a carb that's been fiddled with by a tuner, can have too much emulsion, the result will be globs of air and fuel coming out of the nozzles or discharge tubes, in a chaotic manner, instead of a steady atomized stream. like when you turn on your kitchen or bathroom spigot after installing a new hot water heater, and there's air in the pipes, what happens. it sputters, rattles, carries on until all the air is pulled through and discharged. but if there's too much emulsion in the carb circuit, it never goes away. the car falls on it's face, and the tuner is jetting up, down, all over and never can really iron it out. even putting rich jets in, it may act like it's still lean sometimes. the plugs will be black but it acts lean like it's running out of fuel, or vice versa.
Spreadbore carbs like the TQ and Qjet use 2 different delivery systems. The primary has a venturi, the secondary has a discharge tube. Each type reacts different to pressure/vacuum change. The secondary discharge tube senses airflow at 1:1 ratio as pressure/vacuum increases, and fuel flows in direct proportion to the air. The main jet alone will provide the right amount of fuel, with minimum air bleed/emulsion.
The primary booster venturi doesn't flow 1:1, it flows in a straight line as pressure/vacuum increases. The actual airflow curves towards a horizontal flat line. So the booster venturi needs an air correction system/emulsion to allow the booster signal to follow airflow. Emulsified fuel is just the result of the air correction.