If the bores are not well oiled, it can be pretty stiff to turn over. Squirt a pump or two from your oil can into each bore and turn the crank 2 or 3 revolutions then try again (with the plugs out). Depending upon bore finish, I've had several that were stiff enough to get my attention, but I would guess somewhere in the 40 ftlb range at most.
Mark
Mark