Bob:
I WOULD NOT even consider retapping to the 8 by 1.00 mm size.
You're dealing with cast iron here, which doesn't take threading
real well. A tap will just cut out more material making things
worse. If it were mallable iron or steel, the proper tool would
be a RETHREADING tap. This doesn't cut but forces the material
back into it's original position. However, I know of no source
for rethreading taps in metric. Also, forcing cast iron ack into
shape doesn't work as cast is quite brittle. Follow the advice
of others and helicoil the bad ones.
Hello out there in MG land. Does anyone know were I could get
the 8 by 1.00 rethreading tap and die?
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