ISO 22977:2005

INTERNATIONAL ISO
STANDARD 22977
First edition
2005-07-15

Road vehicles — M12 x 1,25 spark-plugs
with flat seating and 14 mm bi-hexagon
and their cylinder head housing
Véhicules routiers — Bougies d'allumage M12 x 1,25 à siège plat et bi-
hexagonal de 14 mm et leur logement dans la culasse




Reference number
ISO 22977:2005(E)
©
ISO 2005

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ISO 22977:2005(E)
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ISO 22977:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Interna-
tional Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an Interna-
tional Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 22977 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 1, Ignition
equipment.

© ISO 2005 – All rights reserved iii

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INTERNATIONAL STANDARD ISO 22977:2005(E)

Road vehicles — M12 x 1,25 spark-plugs with flat seating
and 14 mm bi-hexagon and their cylinder head housing
1 Scope
This International Standard specifies characteristics of M12 × 1,25 spark-plugs with flat seating and 14 mm
bi-hexagon and of their cylinder head housings, for use with spark-ignition engines.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated refer-
ences, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 68-1, ISO general purpose screw threads — Basic profile — Part 1: Metric screw threads
ISO 261, ISO general purpose metric screw threads — General plan
ISO 965-1, ISO general-purpose metric screw threads — Tolerances — Part 1: Principles and basic data
ISO 965-3, ISO general purpose metric screw threads — Tolerances — Part 3: Deviations for constructional
screw threads
ISO 4095, Aerospace — Bihexagonal drives — Wrenching configuration — Metric series
ISO 14508, Road vehicles — Spark-plugs — Terminals
3 Terminals
The spark-plug terminal may be either the solid post or the threaded type as described in ISO 14508. A spark-
plug with threaded terminal on which a nut is applied shall respect the dimensions specified for spark-plugs
with solid post terminals (see Figures 1 and 2).
4 Dimensions and threads
4.1 Spark-plug reach
The spark-plug reach shall be according to Table 1 (see Figures 1 to 4).
© ISO 2005 – All rights reserved 1

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ISO 22977:2005(E)
Table 1 — Spark plug reach
Dimensions in millimetres

a
Y
A E
B
Type of reach
+ 0,3
max.
Tolerance of A+E ± 0,2
– 0,8
Normal
12,7 21 11,7
0
Long 27
19 18
Extended long 1,5 … 6 31
Extra long 0 34,5
26,5 25,5
Extended extra long 1,5 … 6 38,5
a
It is intended to specify E more definitively in future revisions of this International Standard.

4.2 Gasket
When the spark-plugs have been tightened with a torque of 25 Nm, on threads that are clean, smooth and dry,
the gaskets shall be 1 mm to 1,6 mm thick. If the gasket thicknesses are different, a corresponding adjustment
to dimensions A, B and Y shall be made.
...