Ignition SystemsPurpose: to produce a high voltage surges, delivered at the correct time and the correct spark plug for different operating conditions.

! Review of the Magneto Ignition System !

Creating the Magneto Ignition !

Important Measurements and Adjustments !

! Armature Air Gap !! Breaker Point Gap !! Spark Plug Gap !

The Complete Magneto Cycle

a) – Magnet approaches the armature, lines of force cut across the windings , causing current flow in the primary circuit.

b) – Electron flow creates a magnetic field around the windings.

c) – Piston arrives at TDC on the compression stroke, breaker points open

d) – Primary circuit is broken causing the magnetic field to collapse very FAST!

e) –Collapsing lines of force cut across the secondary winding, causing HIGH electrical current to be induced in the circuit

f) – High electron current causes a spark to jump across the spark plug gap.

Ignition SystemsPrimary Circuit

Similar to Magneto “No Magnet” a battery provides current flow!

Operation:Parts:

- battery

- ignition Switch

- resistance unit

- primary windings

- contact points

- breaker Cam

- condenser

- Setting point gap,“Dwell” the time the points remain closed

Ignition SystemsSecondary Circuit

Operation:

Similar to Magneto“Except Multiple Cylinders” `

Parts:

- battery

- ignition Switch

- resistance unit- secondary windings- distributor cap- rotor- secondary wires- spark plugs

Ignition SystemsIgnition Timing

- ignition does not occur @ TDC !

“ Initial Timing “

- ignition occurs before TDC, measured in degrees

0 TDC

180 BDC

10 BTDC

o

o o

Crankshaft Angle

Ignition SystemsIgnition Timing

Sometimes Initial Timing is not good enough !

#1 – under RPM Conditions

#2 – under Load Conditions

- not enough time for full power @ TDC, therefore ignition must occur prior to initial timing

- to rich a A/F mixture for full power @TDC, therefore ignition must occur prior to initial timing

“ Centrifugal Advance “

“ Vacuum Advance “

“ DEMO on Sun Dist Simulator “

Ignition SystemsElectronic Ignition

- early Electronic Ignition systems are very much the same as point ignition systems except for one thing.

“ No Points “- points are replaced with electronic components to open and close the primary circuit.

- interruption from the armature through the magnetic fields created by a magnetic pick up sends signals to the control unit which opens and closes the primary circuit, therefore creating and collapsing the magnetic field.

Ignition SystemsElectronic Ignition

“Advantages” “Disadvantages”

- no points, less moving parts- no adjustment required- parts last longer- higher spark voltages- better gas mileage

- electronic

Ignition SystemsAdvance Electronic Systems

“ Distributor less Ignition ““ Direct Ignition “

Ignition Systems

DEMO: Tune Up on a Budget !