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How would you classify a magneto system, (how is it powered?)
uses a self contained AC generator for a power source.
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What are the 3 indivudual circuits in a Magneto
- Magnetic
- Primary
- Secondary
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What does the magnetic circuit consist of?
rotating magnet, pole shoes, pole shoe extensions and a iron core
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Why is the soft iron core laminated?
To prevent eddy currents
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what is position A, B and C?
- A- full registar
- B- Null
- C- full registar but the lines of flux are running opposite to pos A
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What does the Primary circuit consits of?
- pri windings
- breaker points
- condensor
- cam
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What is the function of the condensor in the primary circuit?
- prevents arching when points are coming apart
- accelerates the collaspe of the primary field
- radio noise filter
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What position of the magnet will cause the highest current flow?
when mag is in neutral
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Define E-GAP, when does it occour
lines of flux are sustained until ten degrees after neutral
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Where does the current flow in the primary circuit?
Points open, pri field collaspes and induces current into the secondary field
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What are the components in the secondary circuit?
- sec windings and distributor
- spark plug
- igintion windings
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What type of power come out of the secondary circuit?
high volts low current,
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When is max flux achieved?
at full registar
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Why do we need such high voltage in the sec circuit?
to jump the gaps in the distributor and the gap at the spark plug
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Define dwell
the time the points are open
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As breaker points wear they will open early and close late, this is refered to as?
Drifting
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(in degrees) when does E-GAP occour?
10 deg after null
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(In deg) when does Null occour?
0 deg
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What is the position of the magnetic rotor when the change of flux is the greatest?
E-Gap
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When you turn the iginition off, what position is the switch in?
closes the switch
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How is voltage induced into the sec. coil?
points open, pri field collaspes, induces voltage into sec windings, sec windings are tighter (so they produce higher voltage)
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How is Voltage induced into the primary circuit?
rotation of permanent magnet causes change in flux which sends high current, low voltage into the pri field coil
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Name two internal adjustments when the distributor is mounted?
- -Check the gap of the contact points
- -check that points open at E-Gap
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what would cause the points to deviate, open sooner, close later?
Drifting
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How many igition pulses per rotation would a 2 pole mag have?
2
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Name two functions of the capacitor?
- -prevents arching
- -accelerating field collapse
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When magnetic poles are aligned with pole shoesits called the?
full registar position
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When rotating mags are perpendicular to the poles shoes its called the ?
Neutral position, no lines of flux pass through the coil
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What is the angle of the magnetic shaft when the breaker points open?
E-Gap, point where there is the greatest amount of field stress
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What is the function of retard breaker point?
Delays igition until TDC during engine start
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A healthly secondary voltage pulse requires a mag speed of 100 to 200 RPM is refered to as what speed?
the Coming in speed
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Name three starting systems?
- Impulses
- Shower of sparks
- booster coil
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Name 2 benifits of the Impulse coupling?
- -boost ignition spark
- -retard ignition timing
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What type of starting system (momentarly) increase the mag RPM at start up to get a better spark by using centrifugal force?
Impulse coupling
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What type of ignition system uses a induction viberator?
Shower of sparks
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What type of ignition system has a main finger and a trailing finger?
Booster coil
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How is the magneto rotation referenced?
looking at the drive end
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Where are two places to line up the mag on a lycombing the engine ?
- -notch on starter to notch on flywheel
- -line up flange mark to crank flange split mark
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Name 3 possible ways to set the timing on any mag?
- -timing marks
- -timing hat and plug
- -Time rite tool
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What is Shane's prefered method of timing?
Spinning timing hat while butt plug is deep inside cylinder
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When is a mag drop test done?
- -after mag has been internally timed, and engine is up to temp
- -1800RPM
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What is the expected RPM drop during a mag drop test?
How much RPM difference should there be between both mags?
- -25-150RPM
- -no more than 50rpm
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What rpm would you preform a live mag check?
600 (idle)
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Explain what is done on a live mag test and what the purpose of the test is?
- -quickly go from both on to both off and back to both on again(momentary shut down)
- -test is done to ensure that the engine won't start while you are working on it
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What type of system was develpoed to combat flashover at altitude?
Low tensile system-mags are pressurized
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How are mags pressurized in the low tensile system?
takes manifold pressure and pumps it into mag
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Position of mag rate of static flux change is the greatest?
Null
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rate of resulatant (primary circuit) flux change is the greatest?
E-Gap
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name two ways to find the crank position without using the notch on the flywheel?
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how is retard timing achieved with retard points?
Shower of sparks
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Why is the mag grounded during start?
so it won't spark and cause kick back during start
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How is spark timing returned to proper advanced timing after stat switch is released?
retard point circuit is opened
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How do you check dwell?
by a feeler gauge
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why would you need to fine tune engine to mag timing?
becasue of gear lash
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Point of greatest change of flux is?
Null-because of change of direction of flow
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Name the four components of the ignition lead?
- conductor
- insulator
- metal shielding
- silicone
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What does braided shield leads protect against?
- radio noise
- high voltage pulses
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What are 5 reasons silicon rubber used for?
- moisture protection
- anti chafe
- current leakage
- low friction penetration, easy to clean
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what are the two different sizes of ignition leads ?
- Slick-5 mm
- Bendix-7mm (less flexible)
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What are the two different centre conductor sizes?
- solid coil
- straight stranded
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what are the two basic spark plug thread sizes?
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What are the three parts to an aviation spark plug?
- steel shell
- ceramic insulator
- centre electrode
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name the two types of spark plugs ?
- massive-2 to 4 ground electrodes
- fine wire- platinum or uridium, centre electrode is silver
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how are sprak plug broken up into different classifications?
- by reach-depending on the thickness of the cylinder head, shorter the reach the lower the proformance
- Hot plugs-cermanic insulator doesn't contact metal
- Low compression- cooler running engine
- Cold plug-contacts metal to disapate heat quickly
*higher compression, hotter running engine, cooler plugs are required
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What are three visual inspections that can be preformed on a spark plug?
- lead fouling
- carbon fouling
- centre or ground electrodes are worn up to 50%
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Name three different methonds of cleaning a spark plup?
- degrease
- viberating pencil
- glass bead
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How are spark plugs to be rotated on an engine when servicing?
top to bottom, lead deposits then rotate to the next cylinder in the firing order for electode wear
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