Can dual pivot brakes replace single pivot without mods

[simongt]

If your ' old tourer ' is old enough to have had 27" wheels, you may have to fit long reach brakes, as if you are fitting 700 rims, the diameter is a bit less than the 27" and you'll end up with the blocks digging into the tyre walls. Had to do this with an early '80s Dawes Fox I upgraded to 700 rims which had the original Weinmann sidepulls.