Ignition And Starter System 2

Question 1

Ignition systems

Answer 1

Supply an electrical spark in the cylinder at the right time to ensure efficient combustion

Types
Battery
Magneto (high or low tension aka voltage)

Question 2

Battery ignition

Answer 2

Requires battery or alt/gen for system to operate
Used in cars not a/c

Question 3

Magneto system

Answer 3

Independent of the a/c electrical system (requires engine to be turning over)
Heart is the magneto itself
Magneto uses principle of electromagnetic induction to generate low voltage and convert to high voltage to provide a spark

Question 4

Electromagnetic principles

Answer 4

If a conductor is moved through flux or flux is moved over conductor a voltage will be induced in conductor
Magnetism= electricity
When current flows through conductor it creates a magnetic field

Question 5

Rotating magneto

Answer 5

Permanent magnet mechanically rotated by engine
Primary coil near magnet gains low voltage from rotating magnet
When field created by primary Coil collapses the secondary coil with more turns gets high voltage current
High voltage used to provide spark

Question 6

Magneto components

Answer 6

Magneto switch (earthed when off)
Breaker points ( interrupt current in primary coil timed by rotating cam)
Capacitor (condenser) adds to sudden collapse of primary circuit and prevents arcing across breaker points when open also stores electricity to jump start primary coil

Rotating cam (attached to magneto drive shaft opens points each time spark is required at cylinder)
Rotor (attached to secondary coil, rotates half crankshaft speed lime camshaft, directs hot current to correct cylinder terminal on time)

Magneto (source of high voltage )
Distributor (directs spark to cylinders)
High tension leads (carry current to spark plugs from distributor)
Spark plugs

Question 7

Magneto types

Answer 7

High tension low tension
Shuttle type: fixed magnet rotating coil
Polar induction: fixed magnets and fixed coils plus soft iron rotor
Rotating magnet: fixed coil and rotating magnet

Question 8

Ignition harness (high tension leads)

Answer 8

Seperate leads bound together
Stranded copper or stainless steel wire with rubber or silicone insulation
Sheathed in metal braiding or conduit to prevent radio interference
Tough plastic on outer braid
Current at 20000v
Chafing and heat cracking lead to rough running

Question 9

Spark plug

Answer 9

Central electrode
Metal body
Ceramic insulation
Shielding to prevent radio interference

Question 10

Starter motor

Answer 10

Electrical power from battery
Activated by STSRT POSITION
Small current energises solenoid which completes circuit between battery and starter motor

Cockpit warning light on when motor is engaged
If starter motor remains engaged shut down engine (can’t handle high rpm’s)

Question 11

Rotary ignition switch

Answer 11

During startup only left magneto is active
Both position turns on right

Having only one magneto on should decrease rpm

Question 12

Magneto checks

Answer 12

Live mag and dead cut check at engine idle 650-700 rpm

Run up checks 1800-2000 rpm
Max 175 drop max diffference 50
If accidentally select both let the engine die

Question 13

Impulse coupling

Answer 13

Wound spring fitted to one magneto
Provides sudden acceleration of rotating magnet increasing voltage created
Effectively retards ignition timing allowing for engine to turn over