I just made a tool to install the harmonic balancer with the engine in the car. I made it out of 3/4 X 16 threaded rod 6 inches long, 3 nuts and 2 washers large enough to cover the hole in the balancer. I welded the end nut to rod, then had to weld 3/4 in washer to a 1 inch washer to make it large enough, 2 ea.
Just put the dampener on crank, and thread the rod into crank by hand until it stops, it doesnt need to be tight. Just hold the welded jut with 1 wrench and turn the other nut. It goes on with no effort at all.
The third nut I use to keep it together while in the tool box. The this can also be use to hold a degree wheel using both adjustable nuts.
I was able to get the dampener on with the radiator still in the car.