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IGNITION TIMINGIGNITION TIMING
Man, did that feel Man, did that feel like 40,000 Volts!!!like 40,000 Volts!!!
IGNITION TIMING FACTORSIGNITION TIMING FACTORS
Ignition timing is how early or late Ignition timing is how early or late spark plugs fire in relation to spark plugs fire in relation to position of engine pistonsposition of engine pistons
Ignition timing must vary with engine Ignition timing must vary with engine speed, load and temperaturespeed, load and temperature
Must be advanced at times and Must be advanced at times and retarded at other timesretarded at other times
METHODS OF IGNITION METHODS OF IGNITION TIMINGTIMING
DISTRIBUTOR CENTRIFUGAL DISTRIBUTOR CENTRIFUGAL ADVANCEADVANCE
DISTRIBUTOR VACUUM ADVANCEDISTRIBUTOR VACUUM ADVANCE ELECTRONIC (COMPUTER) ELECTRONIC (COMPUTER)
ADVANCEADVANCE
IGNITION TIMING IGNITION TIMING COMPENSATES FOR BURN COMPENSATES FOR BURN
TIMETIME
CENTRIFUGAL ADVANCECENTRIFUGAL ADVANCE
VARIES IN DIRECT VARIES IN DIRECT RELATION TO ENGINE RELATION TO ENGINE RPMRPM
CENTRIFUGAL FORCE CENTRIFUGAL FORCE THROWS WEIGHTS OUTTHROWS WEIGHTS OUT
ALLOWS SPARK TO ALLOWS SPARK TO HAPPEN SOONER TO HAPPEN SOONER TO ALLOW ENOUGH TIME ALLOW ENOUGH TIME FOR COMBUSTION TO FOR COMBUSTION TO TAKE PLACE ON POWER TAKE PLACE ON POWER STROKE.STROKE.
FIG 5-34
VACUUM ADVANCEVACUUM ADVANCE
Provide advance at Provide advance at lower engine lower engine speeds and part speeds and part throttle operationthrottle operation
Matches timing to Matches timing to engine loadengine load
Controlled by Controlled by venturi vacuum or venturi vacuum or manifold vacuummanifold vacuum
FIG 5-35
ELECTRONIC SPARK ELECTRONIC SPARK TIMINGTIMING
Distributor does not have a Distributor does not have a centrifugal or vacuum advance centrifugal or vacuum advance mechanismmechanism
Uses engine sensors as inputs to Uses engine sensors as inputs to computercomputer
You must disable spark advance You must disable spark advance when setting base timing on when setting base timing on computer controlled carscomputer controlled cars
DISTRIBUTORLESS DISTRIBUTORLESS IGNITION SYSTEMIGNITION SYSTEM
ENGINE FIRING ENGINE FIRING ORDERORDER
REFERS TO REFERS TO SEQUENCE SPARK SEQUENCE SPARK PLUGS FIREPLUGS FIRE
CAST INTO INTAKE CAST INTO INTAKE MANIFOLDMANIFOLD
EACH ENGINE WILL EACH ENGINE WILL HAVE DIFFERENT HAVE DIFFERENT FIRING ORDERFIRING ORDER
MUST USE DURING MUST USE DURING TUNE-UPTUNE-UP
FIG 5-3