I see I have a broken off bolt on the front of the engine block. The block is out and bare. I've centered it pretty well, started at a 3/16 drill and am now at .221 dia drill. Minor diameterof a 5/16-18 thread is .250 so I'm really close and can see tops of some internal threads. I've drilled thru the bolt but the cast iron hole is still a blind hole. I soaked it in PB Blaster over night so it could leach in from on top of the bolt and from the bottom up. I heated up the block, tapped in an easy out and it won't let go. SO. Should I use a helicoil, or a time-sert to repair this? I'm not sure what is the better method. I'm open to suggestions.