Some thread repairs don’t work because they can’t take the torque required for a head bolt, and others leak coolant through the insert itself if you do try to use them. Some engine builders “vee” out the cracks, weld them up, and deck the block, but that’s a time-consuming process that doesn’t always work out as planned.

Engine builders can make a permanent repair by using the Spiralhook thread repair insert made by Lock-N-Stitch, Inc. It’s easy to install with a drill, a tap, a spot face tool and a file or a deck machine. They will take the required torque; they don’t leak coolant through the threads and they eliminate the crack forever.

For more information about Spiralhook thread repair products, visit www.locknstitch.com.