ISO INTERNATIONAL STANDARD 3412 Third edition 1992-12-15 Road vehicles Screened and waterproof spark-plugs and their connections : Types 1A and 1B Véhicules routiers - Bougies d'allumage blindées et étanches et leurs connexions—Types1Aet1B Referencenumber ISO 3412:1992(E) Copyright International Organization for Standardizatior No reprodu d without license from IHS Not for Resale ISO 3412:1992(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 International Electrotechnical Commission (lEC)onallmattersofelectrotechnicalstandardization. circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the memberbodies casting a vote. International Standard ISO 3412 was prepared by Technical Committee IsO/TC22,Roadvehicles,Sub-CommitteeSC1,lgnitionequipment. Thisthird editioncancels andreplacesthesecond edition plugs. Annex A of this International Standard is for information only ISO1992 by any means, electronic or mechanical, including photocopying and microfilm, without per- mission in writing from the publisher. InternationalOrganizationforStandardization Case Postale 56 · CH-1211 Geneve 20 · Switzerland Printed in Switzerland nal Organization for Standardization Not for Resale INTERNATIONAL STANDARD ISO 3412:1992(E) Road vehicles -- Screened and waterproof spark-plugs and their connections Types 1A and 1B 1Scope ISO 1919. ISO 2345 and ISO 2346. The dimensions of the bore and the thread in the cylinder head shall This International Standard specifies the main charac- conformtothecorrespondingstandards. teristics of screened and waterproof spark-plugs of Details not specified are left to the manufacturer's types 1A and 1B and their connections, for use with spark-ignition engines. choice. 2 Normative references 3.2 Connection The following standards contain provisions which, Dimension limits of the 5/8-24 UNEF connection throughreferenceinthistext,constituteprovisions thread shall be as specified in table 1. of thisInternationalStandard.At thetime of publi- cation, the editions indicated were valid. All standards are subject torevision,andparties to agreements Table 1 based on thisInternational Standard areencouraged Dimensions in millimetres to investigate the possibility of applying the most re- cent editions of 'the standards indicated below. Connector Members of IEC and ISO maintain registers of cur- Plug thread Dimension thread rently valid International Standards. Class 2A Class 2B IsO 1919:1988, Road vehicles M14x1,25spark- max. 15,844 Major not specified plugs with flat seating and their cylinder head housing. diameter min. 15,662 15,875 ISO 2345:1987. Road vehicles - M18 x 1,5 spark- plugs with conical seating and their cylinder head max. 15,156 15,318 Pitch housing. diameter min. 15,055 15,187 IsO 2346:1991, Road vehicles — M14 x 1,25 com- pact spark-plugswithflatseatingandtheircylinder max. 14,546 14,986 head housing. Minor diameter min. not specified 14,732 3 Requirements The connectors for this type of spark-plug shall have a 5/8-24 UNEF-2B thread and a hexagon of 19 mm 3.1 Spark-plugs with tolerance h13 across flats and with a width acrosscornersof21mmmin. Dimensions of types 1A and 1B spark-plugs shall be as indicated in figures 1 and 2 respectively. Moreover, the connector fitted to the spark-plug shall provide good watertightness, good electrical contact All dimensions below the line A-A shall conform to the and good screening to radio-electric radiation. dimensions and t