How would you classify a magneto system, (how is it powered?)
uses a self contained AC generator for a power source.
What are the 3 indivudual circuits in a Magneto
What does the magnetic circuit consist of?
rotating magnet, pole shoes, pole shoe extensions and a iron core
Why is the soft iron core laminated?
To prevent eddy currents
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
What does the Primary circuit consits of?
- pri windings
- breaker points
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
What position of the magnet will cause the highest current flow?
when mag is in neutral
Define E-GAP, when does it occour
lines of flux are sustained until ten degrees after neutral
Where does the current flow in the primary circuit?
Points open, pri field collaspes and induces current into the secondary field
What are the components in the secondary circuit?
- sec windings and distributor
- spark plug
- igintion windings
What type of power come out of the secondary circuit?
high volts low current,
When is max flux achieved?
at full registar
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
the time the points are open
As breaker points wear they will open early and close late, this is refered to as?
(in degrees) when does E-GAP occour?
10 deg after null
(In deg) when does Null occour?
What is the position of the magnetic rotor when the change of flux is the greatest?
When you turn the iginition off, what position is the switch in?
closes the switch
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)
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
Name two internal adjustments when the distributor is mounted?
- -Check the gap of the contact points
- -check that points open at E-Gap
what would cause the points to deviate, open sooner, close later?
How many igition pulses per rotation would a 2 pole mag have?
Name two functions of the capacitor?
- -prevents arching
- -accelerating field collapse
When magnetic poles are aligned with pole shoesits called the?
full registar position
When rotating mags are perpendicular to the poles shoes its called the ?
Neutral position, no lines of flux pass through the coil
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
What is the function of retard breaker point?
Delays igition until TDC during engine start
A healthly secondary voltage pulse requires a mag speed of 100 to 200 RPM is refered to as what speed?
the Coming in speed
Name three starting systems?
- Shower of sparks
- booster coil
Name 2 benifits of the Impulse coupling?
- -boost ignition spark
- -retard ignition timing
What type of starting system (momentarly) increase the mag RPM at start up to get a better spark by using centrifugal force?
What type of ignition system uses a induction viberator?
Shower of sparks
What type of ignition system has a main finger and a trailing finger?
How is the magneto rotation referenced?
looking at the drive end
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
Name 3 possible ways to set the timing on any mag?
- -timing marks
- -timing hat and plug
- -Time rite tool
What is Shane's prefered method of timing?
Spinning timing hat while butt plug is deep inside cylinder
When is a mag drop test done?
- -after mag has been internally timed, and engine is up to temp
What is the expected RPM drop during a mag drop test?
How much RPM difference should there be between both mags?
- -no more than 50rpm
What rpm would you preform a live mag check?
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
What type of system was develpoed to combat flashover at altitude?
Low tensile system-mags are pressurized
How are mags pressurized in the low tensile system?
takes manifold pressure and pumps it into mag
Position of mag rate of static flux change is the greatest?
rate of resulatant (primary circuit) flux change is the greatest?
name two ways to find the crank position without using the notch on the flywheel?
how is retard timing achieved with retard points?
Shower of sparks
Why is the mag grounded during start?
so it won't spark and cause kick back during start
How is spark timing returned to proper advanced timing after stat switch is released?
retard point circuit is opened
How do you check dwell?
by a feeler gauge
why would you need to fine tune engine to mag timing?
becasue of gear lash
Point of greatest change of flux is?
Null-because of change of direction of flow
Name the four components of the ignition lead?
- metal shielding
What does braided shield leads protect against?
- radio noise
- high voltage pulses
What are 5 reasons silicon rubber used for?
- moisture protection
- anti chafe
- current leakage
- low friction penetration, easy to clean
what are the two different sizes of ignition leads ?
- Slick-5 mm
- Bendix-7mm (less flexible)
What are the two different centre conductor sizes?
- solid coil
- straight stranded
what are the two basic spark plug thread sizes?
What are the three parts to an aviation spark plug?
- steel shell
- ceramic insulator
- centre electrode
name the two types of spark plugs ?
- massive-2 to 4 ground electrodes
- fine wire- platinum or uridium, centre electrode is silver
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
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%
Name three different methonds of cleaning a spark plup?
- viberating pencil
- glass bead
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