Harmonic Balancer Removal

My puller rod is smaller, and works to bottom out inside the bore of the crank just fine.......grade 8 bolts through the puller to the balancer, and I should think that it would come off.........

But it won't............

Do I need an impact wrench on the puller? I really didn't want to pull the radiator if I didn't have to........not enough room for my impact.....I'm afraid I'm gonna snap the puller..........IT'S THAT TIGHT.

Normal? Not? Should I use a claw puller instead of the bolt-up?

And what's this about an installer.........? Why is an installer used ? What purpose does it actually serve ?