1998 Johnson Evinrude EC 50 thru 70 HP 3-Cylinder Service Manual, Page 55Get this manual
Heli-Coillnserts and Installers
Use these Heli-Coil inserts on all models to repair damaged threadsThe installation kit consists of drill, tap, and insertion toolsmm spark plug inserts are specially made for use in aluminum cylinder headsDo not use substitutes
INote The 14
Installation Instructions 1Drill to adequate depth using drill size supplied with kit2Use Heli-Coil tap supplied with packCheck thread size on shank to make certain proper size is used3Screw insert onto mandrel until tang is fully engaged in driving contour4Screw insert into tapped holeTop of insert must be onequarter to one-half turn below top surface5The tang must be removed to allow full passage of screw into the insertThe tang may be broken off cleanly at the notch in the bottom coil with punch or rod having diameter that just fits into the assembled insertMake sure that the punch or rod has square end (no chamfer)Place punch or rod into assembled insert until it rests on tang Holding tool squarely, strike it sharply with hammer