What pump is it, if a LUCAS/CAV it is a doddle, and will make a HUGE difference, mine went like stink and did a indicated 112mph after a fiddle, was a n/a 1.8 diesel escort(mk4), also still did 55mpg, took all of 5 minutes to do.
Look on the front of the pump and see if there is a big hex shaped cover about the size of a 50p piece ?
tabetha