Brake Question-H.A.C.

This stand for HUGE American
Car. I'm going to change the
brake fluid on the 70 Impala,
as it has no viscosity, and is
black as swamp water. After I
drain the master with a turkey
baister, and add the new
fluid, I will go for the wheel
cylinders. The car has power
brakes, so my question is,
while bleeding the wheel
cylinders, car running, or not
running?

TIA,
Brad

Check out the new British Cars Forum:
http://www.team.net/the-local/tiki-view_forum.php?forumId=8