Rolls-Royce Phantom III - helical inserts for exhaust manifold

	The bolt holes for the exhaust manifold attachment had been damaged by the insertion of various incorrect bolts. A drill guide was made from a piece of 1" square mild steel bar to ensures that the holes were widened in line with the originals. The correct bolt is 1/4" BSF thread with a reduced head to avoid overtightening. The holes were widened to 6.6mm and then tapped at 26tpi to take the new inserts to a depth of 3/4".
	The following two pictures show the helical insert being screwed into place. The collar on the tool must be adjusted to butt against the top of the insert to ensure that it does not 'jump' as it is wound into the new thread. When fully home it is important to snap off the winding tang at the bottom of the insert - if this is not done the bolt may push the insert and possibly strip its thread.

	Helical insert in place and roughly half a turn below the outer face to avoid snagging. Each hole was tested with a bolt to ensure that no errors had occurred. Much easier to rectify on the bench if the need arises.