What drill size to drill out for helicoils?

[ZenkaiRacerDsM]

Hi I just got my helicoils in (size M8x1.25) for the head studs. What size drill bit do I need to use to drill out the stripped threads in the head?

 

[dave99gst]

i take it , that it wasnt a kit ? they norm come with a drill bit. i would imagin it says inthe packaging somwere

 

[TSiAWD666]

You don't need to drill them out if the hole is already there with just stripped threads. Just use the tap.

 

[92GSXman]

21/64, that's what came in my heli-coil kit.