Caburettor

Question 1

Approximate standard fuel to air ratio

Answer 1

1 unit of fuel per 12 units of air

Question 2

Approximate lean and rich mixture ratios

Answer 2

Lean - 1:20
Rich - 1:8

Question 3

The name of the valve in the carbutter that’s connected to the thrust lever

Answer 3

Throttle butterfly valve

Question 4

Accelerator pump

Answer 4

Prevents weak-cut from increashing the throttle rapidly, preventing the lag

Question 5

Idling jet

Answer 5

A small chamber that is being used when on low RPM’s, since there’s not enough pressure to force the air/fuel mixture through the main jet

Question 6

If climbing higher (or high temparatue) where the air is less dense, the fuel/air mixture will be? (too rich / too lean)

Answer 6

too rich
The air molecules are less

Question 7

Two types of mixture controls

Answer 7

Needle
Back suction

Question 8

An over-rich mixture will cause

Answer 8

• Loss of power
• High fuel consumption
• Fouling the spakr plugs
• Formation of carbon from unburnt fuel

The extra fuel can also cool the engine by evaporation

Question 9

An execssive lean mixture will cause

Answer 9

• High cylinder head temps
• Detonation

Question 10

Detonation

Answer 10

Explosive combustion of the unburned fuel/air charge in the cylinder
Can be caused by too high temparatures

Question 11

Detonation causes

Answer 11

• Lower fuel grade
• Time-expired fuel
• Over-lean mixture
• Over-heated engine

Question 12

If detonation is suspected, you should:

Answer 12

• Enrich the mixture (as excess fuel can act as a coolant)
• Reduce pressure in cylinders by throttle back
• Increase airsped to assist in cooling

Question 13

Pre-ignition

Answer 13

The uncontrolled firing of the fuel/air charge be fore the spark ignition

Question 14

Prevent of pre-ignition

Answer 14

Correct fuel and operating limits

Question 15

Carbuerttor ice types

Answer 15

• Impact ice
• Fuel ice (can occuer at high temp 20 -30 with 50% relative humidity)
• Throttle ice (on the throttle valve, mostly when low throttle)

Question 16

Carbuteror icing most likely to form when the temp is between ____ and ____ and relative humidity is ____

Answer 16

-10
20
high

Question 17

Symptombs of carburettor ice

Answer 17

• A power loss
• Rough running

Question 18

When turning on carb. heat, since the heated air is less dense, what can we expect?

Answer 18

10-20 percent loss of power

Question 19

Why should you avoid carb. heat on the ground

Answer 19

The air is not filtered

Question 20

Advantages of fuel-injection instead of carburetter

Answer 20

• No fuel ice
• Imrpvoed control of ratio
• Fewer maintenance
  -Instant acceleration (no lag)
• Increase engine fficieny