1. Ignition Systems
Purpose: 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 !

2. Creating the Magneto Ignition !
Important Measurements and Adjustments !
! Breaker Point Gap !
! Armature Air Gap !
! Spark Plug Gap !

3. 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.

4. Ignition Systems Primary Circuit Operation: Parts: - battery
Similar to Magneto “No Magnet” a battery provides current flow!
- ignition Switch
- resistance unit
- primary windings
- contact points
- breaker Cam
- condenser
Setting point gap,
“Dwell” the time the points remain closed

5. Ignition Systems Secondary Circuit Operation: Similar to Magneto
“Except Multiple Cylinders” `
Parts:
- battery
- ignition Switch
- resistance unit
- secondary windings
- distributor cap
- rotor
- secondary wires
- spark plugs

6. Ignition Systems Ignition Timing “ Initial Timing “
- ignition does not TDC !
- ignition occurs before TDC, measured in degrees
0 TDC
180 BDC
10 BTDC o
Crankshaft
Angle

7. Ignition Systems Ignition Timing
Sometimes Initial Timing is not good enough !
#1 – under RPM Conditions
- not enough time for full TDC, therefore ignition must occur prior to initial timing
“ Centrifugal Advance “
#2 – under Load Conditions
- to rich a A/F mixture for full therefore ignition must occur prior to initial timing
“ Vacuum Advance “
“ DEMO on Sun Dist Simulator “

8. Ignition Systems Electronic 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.

9. Ignition Systems Electronic Ignition “Advantages” “Disadvantages”
- no points, less moving parts
- electronic
- no adjustment required
- parts last longer
- higher spark voltages
- better gas mileage

10. Ignition Systems Advance Electronic Systems
“ Distributor less Ignition “
“ Direct Ignition “

11. Ignition Systems
DEMO: Tune Up on a Budget !