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Basic Ignition

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2 CircuitsPrimary & Secondary

• Primary can have the following parts

• 1. Battery

• 2. Ignition Switch

• 3. Resistor

• 4. Coil

• 5. Triggering devices

• 6. ECU electronic control module

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Secondary

• Secondary can have the following parts

• 1. Spark Plug wires or Secondary wires

• 2. Spark Plugs

• 3. Distributor cap

• 4. Rotor

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Primary circuit 8-16 volts

flow through this section

• 1. Battery12.6 volts produced

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Primary circuit

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Ignition Switch

• key has different positions;

• accessory, (power to radio and other accessories but none to the ignition)

• off, (No power going to any terminal)

• on, (power to all accessories and the ignition)

• start, (battery voltage to start the car)

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Resistor• Reduces voltage from 12 to 9-10.5 volts

• Ballast resistor heats up at low engine speed when flow of current in primary circuit is longer this lowers current flow at high engine speed when duration of current flow is less. often the resistor cools down allowing more current flow

• Not used on most new cars

• Ford may use a resistor wire

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Resistor Problems• Ballast resistor on cars can go bad. If it does car

will start and will stall when the key is returned to the on position. Chrysler cars with the 4 prong resistor below had a lot of problems with this. It can happen with any car.

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Coil

• construction

• soft iron core

• primary windings 200 turns # 18 gauge wire

• secondary windings 22,000 turns # 38 gauge

• coil is hermetically sealed - made air tight

• oil cooled, (it is filled with oil) if dripping oil, the coil will need to be replaced soon.

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Different types of Coils

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• 12 volts in 30,000 + volts out

• Step up transformer

• When current flows magnetic field is developed

• quick clean interruption of current field collapses the magnetic field

• What interrupts the field is a triggering device (Points, old cars, most new cars use a reluctor or a slotted wheel.

Coil

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• Purpose is to take 12 volts and induce 30,000 volts or more into the secondary circuit two primary terminals one positive (+) and one negative (-) one secondary terminal for coil wire.

• The positive side could have several names on it; Pos, Bat, +

• The negative side could have several names on it; Neg, Dist, -

Coil

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• Both sides are really a positive terminal (both have voltage there) but one side is closer to the battery side and one closer to ground.

• Polarity of second terminal determined by battery ground if negative ground then the negative terminal is connected to distributor, positive to battery, positive side.

• If hooked up backwards car will still run but picture on scope will be upside down.

Coil

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Triggering devices• Contact Points Used before 1975

• used to connect and disconnect current flow in primary circuit

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Triggering devices

stationary point

moveable breaker point

breaker arm spring

rubbing block

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• parts of

• stationary point - connect to ground

• moveable breaker point - connected to insulated side

• rubbing block - opens and closes points by a cam lobe.

• breaker arm spring - pushes points together

• point gap is measured when the rubbing block is on the highest part of the cam lobe .018 - .022

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Things that go bad with points

• 1. rubbing block will wear out you can readjust about every 10,000 miles

• 2. Point face that transfers the electricity will be bad in about 10,000 miles if you file clean you will remove the thin coat of tungsten steel (about .003) and their life will be short lived. Need to be replaced.

• Points will burn up, to prevent it install a condenser.

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• Cam Angle can also be called degrees of dwell or dwell angle

• it is the number of degrees the points are closed

• to decrease dwell you increase gap

• to increase dwell you decrease gap

• If you don’t know what to set the dwell at a number to make it run is below

• 28 - 32 8 cylinder

• 40 - 45 6 cylinder

• 49 - 55 - 4 cylinder

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Dual points

• adjust each set of points separately by putting a piece of thin cardboard or paper in the other set adjust on a V8 to about 24-26 degrees Then pull out the paper and check for the total dwell should be about 34-36 degrees.

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Dual points

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Condenser

• construction

• two sheets of foil

• separated by layers of insulation

• one side insulated one side grounded

• holds charge so points can open and not burn

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• condenser capacities

• A condenser is rated about .20 microfarads if working right the points will still wear but the face will not be excessively pitted. If the condenser capacity is to high it will wear on one side if to low it will wear on the other side of the points

• If the condenser is not tighten down it will arc

• usually we always replace the condenser whenever we replace the points.

Condenser

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Trigger wheels

• Most new cars use a trigger wheel can be called a reluctor or pole piece. They have one tooth for each cylinder of the engine.

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Trigger wheels

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Trigger wheels

• The reluctor lines up with a pickup coil as it turns around, this changes the magnetic field in the pickup coil. When the magnetic field changes it changes the current flow in the pickup coil and that is noticed by the ignition control module or ECU electronic control module.

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Hall and optical

• Some cars use a Hall effect pickup that use a slotted wheel or a tab that passes by a permanent magnet.

• Some cars also use a optical pickup very expensive too replace and can quit if dirt or debris blocks the path of the little light.

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ECU electronic control module

• The brain box of electronic ignition

• explain how primary system works?

• Draw out a ignition system.

• distributor turns at one half crankshaft speed explain ?

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• This is a ford if the car runs for less then 30 minutes and dies and you have no spark this is probably the problem.

• Different color plastic on bottom helps ID the box

ECU electronic control module

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Secondary Circuit Secondary or Spark Plug wires

• Spark plug wires

• insulation 7, 8, 9,10mm wire size

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Secondary wires Thanks Kingsborne

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Spark Plug wires

• Do a visual Inspection are the wires

• Brittle (Hard break easy)

• Oil soaked

• Chafed or worn against a part

• Is the boot torn or ripped

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Spark Plug wires• Measure the resistance of Spark Plug wires

• resistor or resistance wires- carbon impregnated 4,000 to 10,000 ohms per foot

• solid core 0 ohms used on some race cars

• Some new wire sets have metal running through them and have about 500 ohms resistance

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Spark Plug wires• silicone - high heat hypalon

• boots terminals 45, and 90

• Some wires cannot be removed from the cap

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Spark Plugs see other Power points on spark plugs

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Distributor cap• distributes spark from center tower to spark plug

terminals

• construction carbon rod, outer terminals anti flashover grooves

• non conductive material

• different colors no real problem clear caps are for show cars will not last as long on street cars

• lugs in spark plug towers Brass and copper the best aluminum OK

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Distributor caps

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Things to watch for;

• carbon Tracts - trace of carbon that spark follows to ground

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• cracks - When cap cracks the spark will follow the crack to ground

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• water spots - White spots inside of cap sign that the cap is breaking down

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• broken center carbon rod

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• Green corrosion inside of spark plug or coil towers (Poor connection)

• White Corrosion on towers

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• build up of corrosion on spark plug lugs on inside of cap

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• How often should you replace a Distributor cap. When it has any of the mentioned problems or If you inspect and do not feel it will take the customer to his next tune-up replace it.

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Rotor

• carry voltage from center to side terminal

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Firing order• spark plug wires arranged in cap the way

cylinder fires in either cc or ccw direction

• go through fire order handouts

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Firing order

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Basic timing

• use a basic strobe light

• vacuum advance unhook and plug

• rpm low enough so centrifugal advances is not kicked in

• read the instructions on how to do, some wires need to be unplugged or jumped on some engines

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• know where the marks on fly wheel or vibration damper are

• clean up if you cannot read them

• known what they mean (2, 21/2, 3, 5 degrees, which one is zero)

• hook timing light to # 1 and time engine(some engines are timed to different cylinders)

Basic timing

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Basic timing• If you can not hook up the timing light to the

#1 Cylinder on a V engine like a 350 take the firing order and stack the first 4 numbers on top of the second 8 and time it on the first one on the bottom set.

• 1 8 4 3

• 6 5 7 2

• In other words time it on #6

• It still fires on #6 but you can time it there

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Basic timing

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Basic timing

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The End

For this coil and this cap