Rick is absolutely correct, spoilers have very little to do as speed brakes by generating drag... Speed brakes is the name given (generally) by Boeing...
At times I criticize the terminology used in England about some aircraft components - "undercarriage" - for gear, is one example - but often, England uses much more accurate terminology... example, spoilers (or speed brakes) are often referred to as "lift dumpers", love that wording, as it really means what they do. Most of the drag comes from flaps rather than spoilers.
Rick, what I often do on long runways on the 747, is NOT TO ARM spoilers before landing, to get that "smooth landing" which impresses so much passengers as to this superior "master pilot"... arming speed brakes makes that touch down so hard on the 747 (deploy with gear geometry position) whereas the spoilers in manual deploy with the thrust reverser levers... and all landings are extremely smooth... try it, if your old man allows that
I assume it is equivalent in your 767...?