I have a rough idea of how to install a lintel on an existing wall (to
make a new opening) using strong boys and needles. I don't have such
tools and thinking of adopting another method:
1) use a angle grinder to cut out some mortar (about 60%) where the
lintel is going to be installed
2 install one of those Catnic steel lintel "L" shaped or
similar....the lintel won't seats completely as the old mortar is
still on place but it should work fine.
3) take out the bricks to create new opening
4) finish job by installing a proper lintel just under the L shaped
one (making sure the top row of bricks is wider than the opening in
order to accomodate the new lintel). The L shaped one can then be
removed (useful for the next installation).


For most jobs point 4 would not be necessary. Furthermore, if access
to the other side of the opening is not an issue it would be possible
to install another L shaped lintel on the other side for extra
security.

How does it sound? Isn't that neater than using Strong Boys and
Needles?
Constructive criticism welcomed.