Module 7 Ignition System Flashcards
What is the purpose of a continuity check test on an ignition?
Checks for continuity of the lead from the distribution cap to the spark end
what check is done on the ignition lead to test the integrity of the insulation
isolation check ( ignition lead leakage text)
what is the number 3t indicate on an ignition lead?
ignition lead goes to the top of cylinder #3
what are the main two terminal ends sizes
5/8 - 24 and 3/4 -20 (thread and pitch)
which terminal is the most common
3/4-20
what are the two main electrode type for A/C spark plugs
massive electrode and fine wire
what type of electrode type would least prone to lead deposits
fine wire
when removing your spark plugs for servicing you should put them in a number tray, why?
the visual inspection of the of a spark plug reveals much about the efficiency of the combustion
excessive oil found on a spark plug could be result of?
- extend engine shut down -idling
- damage piston
- worn or faulty piston rings, valve guides, etc.
- new engine still in break-in period
excessive lead deposits appears as
hard bead-like deposits in the firing cavity of a spark plug
how are the lead and carbon deposits removed from the spark plug firing end?
vibrating tool
what is the manufacture primary reason for numbering spark plugs
plugs are designed for specific engines
a spark plug with a long nose insulator is a ?
hot plug-to be used in a cold engine
what is the purpose of the resistor in a shielded spark plug for an aircraft engine
minimize electrode erosion
when are the electrodes of a spark worn out?
when the electrodes are half size of their original size
what will occur if the spark plug gap is excessive
the intensity of the spark will be incorrect leading to difficulty to starting
you should always rotate the spark plugs positions when reinstalling them, why?
to equalize plug wear , rotate from top to bottom and next in the fired order.
before installing spark plug one should?
lubricate the threads and change the bronze gasket
when reinstalling a spark plugs, torque to specified torque using a _____ sided deep socket
six
if you where given a task of doing a spark plug change, describe how you would after removal: clean, and service them and reinstall them
text book servicing 8-101 thru 8-106
there are 2 magnetos checks an engineer should carry out after ignition work ?
- live magneto check
- magneto drop check
the purpose of the magnet in the magneto is to?
provides magnetic lines from of flux-flow from north to south
what is meant by the term “full register” position
when the magneto poles are aligned with the pole shoes (magnet field is stronger)
the clearance between a roting magnet and the pole shoes must be as little as possible because?
the air is not a good conductor of the magnetic flux
why laminated pole shoes used magnetos
- to reduce eddy currents
- keeps the magnetos cooler and boost efficiency
with reference to the magneto, magnet zero is the
point at which the poles between pole shoes are centered between poles shoes
the magneto coil has ______ and ______ winds
primary and secondary
in respect to the electrical flow, what are the difference between the primary and secondary coils
primary= low voltage -high amperage
secondary=high voltage -low amperage
what is the function of the distributor rotor
conducts the high voltage to out put pulses
what is the speed of the distributor rotor to engine RPM
one half engine crankshaft
function of the distributor block ?
when the finger of the distributor aligns with the electrode, voltage is transfered to the respective spark plug
what it will cause distributor flash over ?
moisture or carbon tracking
the numbers on the magneto block adjacent to the ignition wire indicates?
the firing order of the magneto (LH or RH rotation)
what is the function of the contact breakers
to open and break flow of electricity in the primary coil
what is a cam follower
the nylon piece which rides on the cam to open and close the contact breakers points
how is the breaker cam lubricated
by felt oiler pad
the condenser used in conjunction with magneto points is connected by?
parallel
when you have burned and pitted points in a magneto the part most likely to cause this is?
the condenser or capacitor
beside preventing with arching of points , the condenser is used for what purpose?
it assist (hastens) the rapid collapse of the primary
on installations of a magneto on an engine, the magneto should be set at
fire #1 cylinder-red tooth in window engine set before TDC on the compression stroke
why does magneto ignition system require and auxiliary starting system?
because the coming speed of the magneto is 100-200 RPM , and the spark is to advanced and will cause kick back during starting
an impulse coupling will increase the rotational speed of the magneto and:
retard the spark to TDC to prevents kick back
if an impulse coupling breaks, the magneto will?
fired in a retard position TDC during normal operation
an shower sparks ignition system uses a set of retards breakers to:
retard the ignition timing to TDC to prevent kickback during starting
due to the difference in exhaust gas scavenging and difference in temperature distribution, some manufactures prescribe a:
staggered ignition- ie. degrees and 22 degrees
why is the trailing electrode necessary in some booster coil magneto distributors?
to prevent kick back during starting
why do spark plug wires have a heavy insulation?
to prevent leakage of high tension current
why are the ignition leads shielded
prevents high frequency electromagnetic waves ( radio interference)
