72 dart 318 starting sequence
At idle and off-idle fuel flows from the bowl to the intake because of the difference in pressure.
Another way to think about it is the pistons moving down create a vacuum under the throttle plate.
When the choke plate (not shown) is nearly closed, that increases the pressure difference and reduced the air mass density.
The action of opening the throttle does actuate the mechanical pump shot. So that's why pumping the throttle is sometimes useful when the intake is completely dry. But with a flooded carb is counter productive.
Opening the throttle and choke fully and holding during starting results in nearly the same pressure at the idle port as in the fuel bowl (atmospheric) .
Air comes in and mixes with the excess fuel sitting in the intake and cylinders.
There's some MTSC sessions on how carbs work here
Master Technician Service Conference - Chrysler's Training for Mechanics
Look at Carb Fundementals in either 1966 or 1970
What happens is both the throttle and the choke are held open. This results in air but no additional fuel flowing into the intake.
At idle and off-idle fuel flows from the bowl to the intake because of the difference in pressure.
Another way to think about it is the pistons moving down create a vacuum under the throttle plate.
When the choke plate (not shown) is nearly closed, that increases the pressure difference and reduced the air mass density.
The action of opening the throttle does actuate the mechanical pump shot. So that's why pumping the throttle is sometimes useful when the intake is completely dry. But with a flooded carb is counter productive.
Opening the throttle and choke fully and holding during starting results in nearly the same pressure at the idle port as in the fuel bowl (atmospheric) .
Air comes in and mixes with the excess fuel sitting in the intake and cylinders.
There's some MTSC sessions on how carbs work here
Master Technician Service Conference - Chrysler's Training for Mechanics
Look at Carb Fundementals in either 1966 or 1970
