The company that rebuilt my balancer was who told me to heat it. 180 to 200 degrees is normal operating temperature, how it that going to melt any rubber? A cold crank and hot balancer is enough difference for it to slide on.
I have since drilled and tapped my crank, but still heat the balancer before installing it. I changed camshafts this summer, and after two previous installs of the balancer, it was still very tight coming off.
