7mm helicoils are available, I've used them before. You need to take some care in increasing the size of bolt holes, particularly around water jackets. -- Mike > I wonder if this would be a good time to change bolts to 8mm (can you > even get 7mm Helicoils)? Would dramatically increase fastener options. > BTW: metric Helicoils probably have to be mail ordered. Could convert > to 5/16" from any parts house if you don't mind mongrelizing car. > > Only one time in my life have I drilled straight through a bolt. > Didn't even have to re-tap hole. Only one time. Every other time have > been off center enough to Helicoil or tap to next larger size. > > Once you get a threaded hole, another option would be converting bolt > to stud and a nut. Am seriously considering taking my intake manifold > off AGAIN to do that while my own internal water pipe bolts not > frozen. Have found source of stainless steel 7mm drill rod and nuts. > > Bill Robertson > #5939