I have a rocker arm in my '03 Century Custom that has stripped out the head. I tried to tap it and helicoil it but unfortunately the tap went sideways. I am thinking that I may be able to drill and tap it out to a larger size. My question is, can I tap this out to a larger size and use an m10 1.25 helicoil with an m8 1.25 helicoil. If not, is there a way for me to do this.

  • Try something like an EZ-Lock. The insert is solid and larger than an Helicoil. As long as you drill straight and there's enough meat left in the boss, it should be just peachy. Commented Mar 29, 2017 at 1:06
  • One option is to use a keysert, as shown in this question.
    – Zaid
    Commented Mar 29, 2017 at 2:09

1 Answer 1


I don't know how you held the tap or drill for your first effort, but you should use a drill press and mount the head such that the boss you need to work on is perpendicular so that whatever insert you plan to fit goes in correctly this time.

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