here you will find every basic thing about spark plug

1. SPARK PLUG

2. What is a spark plug ?
• It is a device for delivering electric current
from an ignition system to the combustion
chamber.

3. PARTS
• TERMINAL
• SHELL
• RESISTOR
• INSULATOR
• CENTRAL ELECTRODE
• GROUND ELECTRODE

4. • TERMINAL
It is the part on which the high voltage from
the ignition coil is connected.
• RESISTOR
Used to eliminate the electrical or radio
interference.

5. SHELL
• Shell is designed with a thread that screws
into the combustion chamber.
• Acts as an earth point.

6. INSULATOR
• Function is to provide mechanical support and
electrical insulation for central electrode.
RIBS -
• It is designed to lengthen the distance
between upper insulated terminal and earth
shell as much as possible.

7. CENTRAL ELECTRODE
• It is connected to the terminal .
TYPES
• Nickel copper alloy
• Platinum
• iridium

8. Nickel copper alloy
• Allows the plug to heat up and also dissipate
heat quickly.
• but it subject to corrosive degradation.
• Diameter of central electrode - 2.5mm.
• service life - 20000 miles

9. PLATINUM
• Excellent corrosion resistance.
• Does not conduct electricity as Nickel copper
alloy.
• Diameter of central electrode – 1.1mm
• Service life – 100000 miles

10. • IRIDIUM
• Good conductor and six times harder than
platinum.
• Diameter of central electrode – 0.5mm
• Service life – 60000 miles

11. GROUND ELECTRODE
• Is welded on to shell.
• Made up of same material
of shell or coated with platinum.
• The shell may have one or more
ground electrode (current can
choose a least resistant path).
• Some have grove.

12. PRINCIPLE OF GROVE
• It forces the spark to occur at the outer edge
of central electrode.
• Easier to ignite the mixture
• The voltage required to produce spark is
reduced.

13. TYPES OF SPARK PLUG
• HOT PLUG
• COLD PLUG
• Main difference is length of electrode
insulator tip.
• Longer insulator tip makes the plug hotter

14. HOT PLUG
• Has the ability to retain heat at the plug tip.
• Used in lower compression engine. This
means the spark plug will heat up easily and
reach its optimal operating temperature.

15. COLD PLUG
• Has very short heat path so any retained heat
will dissipate much faster.
• Used in high performance engine to resist the
heat produced in the combustion chamber.

16. • What happens when the spark plug selected
for an engine is -
too cold ?
heat range is too high ?

17. • If the spark plug is too cold carbon deposit will
start to develop between central electrode
and shell it makes a ground path for the
current to flow.
• If spark plug heat range is too high then
abnormal pre ignition may occur.
• Leads to - miss firing
melting of spark plug electrode
piston damage…

18. THANK YOU