I have a 1975 E-Rude tiller <br />Model#25553B <br />Serial #E0002586.<br /><br />My trouble is simple: some muton head over tightened the #2 spark plug now that cylinder is not holding compression. Solution is simple right just install Helicoil. Well I do have the luxury of a full machine shop at my disposal but I have never bought a Helicoil. What size do I need to accomadate the champion plug J6C. Also is there a chance the stainless steel may overheat and cause pre-mature combustion? Is there a better solution than the Helicoil? I understand that this is the popular method of thread repair. <br /><br />Please just help, Duck season in Michigan is not that far off and well my back up motor is a 1.2HP Eska looks kina silly clamped to my 16foot boat blind.