Industrial Spark Plugs

Reliability of operation for gas engines

With over 115 years in spark plug development, Bosch is one of the leaders in spark plug manufacturing. Thanks to its close cooperation with engine manufacturers, Bosch has gained outstanding know-how – concerning components such as spark plugs as well as the sophisticated interactions inside the engines. Due to this expertise, Bosch is able to provide a comprehensive Aftermarket range of spark plugs suiting almost any engine – including older units.

The range of industrial spark plugs for stationary engines features innovations such as the continuous-wave laser-welding and innovative precious-metal electrodes for high reliability and long service life.

Learn more about Industrial Spark Plugs

M14 industrial spark plugs


Short code	7339	7322	7321
Type	WR 3 CII 360	FR 3 CII 360	FR 3 KII 332
Type number	0 242 255 533	0 242 255 518	0 242 255 511
Wrench size	20,8 mm (13/16”)	16 mm (5/8”)	16 mm (5/8”)
Thread	M 14 x 1,25 mm	M 14 x 1,25 mm	M 14 x 1,25 mm
Thread length	19 mm (3/4”)	19 mm (3/4”)	19 mm (3/4”)
Precious-metal center electrode	Iridium	Iridium	Iridium
Precious-metal ground electrode	Iridium	Iridium	Platinum
Electrode gap	0,3 mm (0,011”)	0,3 mm (0,011”)	0,3 mm (0,011”)
Resistance	6 kΩ	6 kΩ	6 kΩ
Adjustable electrode gap	Yes	Yes	No

Gas-powered Co-Gen power plants and stationary power generators provide economically generated heat and electricity right at the place where they are needed the most. This can, for instance, be at schools, swimming pools, hotels, hospitals or production facilities. Featuring high quality, Bosch industrial spark plugs to ensure reliable operation of gas engines.

Benefits:

First-class ignitability for high performance due to specifically developed precious-metal alloys at the center and ground electrode
Outstanding engine protection due to nickel-plated housing and thread
Hassle-free spark plug replacement due to factory-set electrode gap
High wear resistance due to a highly heat-conductive center electrode
Reliable thermal characteristics due to heat-shrink assembly

Technology

The SAE terminal
receives high voltage from the ignition leads and passes it on to the center electrode.

The insulator
isolates the center electrode from the housing thus preventing flashovers.

The connector
transmits the high voltage to the resistor.

The spark-plug housing and thread
connects the spark plug and cylinder head.

The resistor
lowers the spark plug’s spark current and the electromagnetic radiation.

The center electrode
with heat-conductive copper core it reaches the operating temperature quickly. It protects against thermal overloads, corrosion and spark erosion.

Electrode gap
The spark gap between the center and ground electrodes.

The seal ring
seals the spark-plug housing against the cylinder head, prevents leakages and balances different expansion rates.

The ground electrode
influences the service life and heat dissipation.

Workshop tip

Reduced fitting times thanks to proper installation techniques

Replace the whole set at once

The operating conditions of an engine’s individual spark plugs are very similar – as it becomes apparent by their similar wear behavior.

Experience has shown that replacing the whole set of spark plugs is cheaper than having to replace them one by one.

Fast and correct fitting

1. Select the matching industrial spark plug from the range of products.

2. Screw in the industrial spark plug by hand until it is seated tight at the cylinder head.

3. Then, use a torque wrench to tighten the industrial spark plug applying the torque specified.

Thread: M14 Torque: 20 – 40 Nm

Thread: M18 Torque: 50 – 70 Nm

Why to use Bosch seal rings for M18 industrial spark plugs

Seal rings significantly contribute to safety

The seal rings used by Bosch feature minimal dimensional deformation, but they are highly elastic, thus preventing the spark plug from loosening during operation.

In case a spark plug is removed and reinstalled, the seal ring is to be replaced. For this purpose, Bosch recommends using only Bosch seal rings.

Type Number M18 (7305/7306/7308) seal rings - 1 240 280 055

The Bosch re-gapping tool is a professional tool for accurate readjustment of the electrode gap of Bosch M18 Iridium industrial spark plugs.

Type Number: 0 986 600 001

Application

During their operation, industrial spark plugs wear off as the electrode gap increases. This results in misfires. Bosch Iridium M18 industrial spark plugs were developed in such a manner as to allow electrode regapping by means of the Bosch re-gapping tool.

Simply readjust industrial spark plugs using the Bosch re-gapping tool:

1. Place the cleaned M18 industrial spark plug into the socket. Make sure, the spark plug housing is properly positioned at the pattern inlay while the back of the ground electrode faces out.

2. Push the lever all the way to the stop and keep up the pressure for a period of time.

3. Release the pressure from the lever and carefully remove the regapped spark plug from the socket.

Check your spark plugs:

Spark plugs are wearing parts. Their functionality should be checked regularly. The following failures might point at a defective spark plug:

Loud combustion noises before reaching the operating temperature
Unevenly running warm engine
Loss of power
High spark-plug resistance
Need for increased ignition voltage
Increased fuel consumption

Benefits

Increase in service life of industrial spark plugs due to accurate readjustment of the original electrode gap.

Reduced service times and costs thanks to its easy operation.

Safe application thanks to integrated force limitation: Prevents overbending of the ground electrode or pushing out the center electrode.