Well, my Belair was still not running right, wouldn't start and began backfiring again. After going back to basics and checking lots of things, it turns out that the timing was way off. Perhaps as much as 40-50 degrees. That was causing the starting difficulty, backfiring and engine running hot. The cause of the timing problem is a misaligned harmonic balancer. I set the motor on TDC and made a new alignment mark on the balancer and redid the timing. After doing that, I turned the key and the motor started immediately and runs very well.
Now the question becomes, why is the harmonic balancer that far misaligned? Could I have the wrong HB on the motor. The motor is I6 250 and maybe the HB is for a 235? Would a 235 HB fit on a 250? Or could the HB have slipped on the shaft? Sheared off the key pin? I'm going to pull this current one off and replace it and want to get the correct new one.
Thanks again to everyone for the help.
