Carburettors vs Fuel Injectors

Question 1

What are carburettors?

Answer 1

A device in petrol engines used to mix air and fuel to create a combustible mixture (carburetion)

Question 2

What are barrels and how do they function?

Answer 2

Tubes or passages through which air flows.

Air is drawn in, creating a pressure drop (Venturi effect) that draws fuel into the airstream

Question 3

What are the benefits of having more barrels on a carburettor?

Answer 3

• Used in bigger engines with higher performance
• Increased air flow
• Improved throttle response
• Increased power at higher RPMs due to better fuel delivery

Question 4

What is an updraft carburettor?

Answer 4

• Manifold is above the carburettor
• Fuel and air enter from below and are drawn upwards

Question 5

What is the downdraft?

Answer 5

• Manifold is below the carburettor
• Air and fuel enter from above
• Most common in engines

Question 6

What is a sidedraft manifold?

Answer 6

Air and fuel enter from the side of the manifold

Question 7

What is the role of the idle system?

Answer 7

Provides sufficient fuel for smooth idling when the engine runs at low speed

Question 8

What is the role main metering system?

Answer 8

Ensures an economic mix of fuel and air

Question 9

What is the role of the accelerator system?

Answer 9

Provides a boost in fuel during acceleration.

Question 10

What is the role of the power enrichment system?

Answer 10

Provides a boost in fuel added to the mixture when more power is required

Question 11

What is the role of the float system?

Answer 11

• Provides a constant supply of fuel to the idle, main metering, accelerator and power enrichment systems
• Controls the fuel level in the float chamber (bowl) to ensure a consistent fuel supply to the engine
• When fuel level drops, float drops and valve opens
• When the fuel level is correct, float rises and valve closes