I wouldn't advise reusing any head, rod, or main bearing cap stud
unless necessary. And then, I would never reuse one that I hadn't
installed new or they were factory installed. You never know if some
PO used them over, and if so were they properly torqued. Bolts have a
certain amount of "spring" in them and the proper torque will stay
below that elastic limit of the fastener. If the bolt was ever
tightened over its elastic limit the slight stretching deteriates its
tensile strength. It will no longer be able to withstand the tension
it was designed for.
Cut threads on fasteners are not as good as rolled threads. A thread
"rolled" into the shank is similar to forging in that it changes the
orientation of the material making it stronger. Cutting threads can
cause weak areas if the die is not dimension correctly, or leave an
improper "lead" where the threads blend into the unthreaded shank.
Rather than wire brushing studs, I glass bead them to remove scale and
also help stress releave them. Glass beading new ones might be
overkill, but it can't hurt either if the they are properly cleaned
afterwards.
I, too, had problems getting good head studs from MG suppliers. So
when we rebuilt two different TD engines we converted the head studs
to bolts. The rod bolts were out of some 1970s Ford V8 and the head
bolts were from a Datsun L18 engine. We installed Keensert inserts in
the block's deck to better handle the use of bolts rather than studs.
Blake
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