Download Spark Plugs

Spark Plugs
Used to conduct secondary (high voltage)
ignition into combustion chamber for the
purpose of igniting the air/fuel mixture.
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Three main parts
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Threaded shell
Means to remove and insert spark plug
 Seal the combustion chamber
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Center electrode
Conducts high voltage
 Provides air gap for spark to jump
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Ceramic insulator
Insulates voltage going down center electrode
 Conducts heat
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Spark Plugs
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3 Steps to selecting a high performance plug
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Shell Design
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Physical dimensions of threads
Seat design
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Gasketed (Remember to use gasket!
 Indexing plugs
Tapered seat (mostly Ford)
Electrode and gap designs (draw on board)
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Surface Gap “V” Gap
Retracted “R” Gap
Regular Gap
Cut-Back Ground Electrode
Angled “A” Gap
Fine-Wire Electrodes
Projected Nose “Y” Gap
Spark Plugs
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Heat range selections (draw on board)
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“Relative temperature” of the core nose
Heat dissipation from firing end to cooling system
“Cold” plug
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Transfers heat rapidly
Avoids overheated plugs
Use to avoid detonation
If too cold won’t burn off deposits
“Hot” plug
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Slower rate of heat transfer
Avoids fouling
Longer core nose
If too hot will cause detonation or melt
Spark Plugs
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Heat range considerations
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Air/fuel mixture
Spark advance
Compression ratio
Fuel types
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Pump gas
Nitrous
Super or turbo-charging
When modifying a stock engine
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Heat range will primarily be what you are changing
Does not give you extra power, keeps you from losing power when driving under heavy
load for long periods of time
Normal change will be 1 or 2 heat ranges colder. Unusual to go hotter.
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Too cold and plugs will foul during normal driving.
Fouling is the build-up of deposits
Heat range has absolutely nothing to do with cold-start
Spark plug gap.
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Turbo applications with stock ignition may require closer gaps.
Don’t be afraid to play with gap. It’s free but won’t give you any power.
Spark Plugs
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Spark plug types
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Platinum
Iridium
Multiple electrode/ground
U-Groove
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Spark jumps to sharp edge
Spark plug gimmicks
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I wish I had no morals, I’d be rich
Split fire
Pulse plug
E3
If they seemed to work in your car, it was because there
was something wrong with your existing plugs.
Spark Plugs
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Installing
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Anti-sieze
Silver Cadmium plating
Black oxide
Zinc Chromate
Tips on removing stuck plugs
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Try to gently remove
Spray penetrating oil around base of plug
Rock back and forth
Slowly apply additional torque
May be wrong plugs