Can the harmonic balance come loose?

cudavert said
It could very well be the crank pulley loose on the harmonic. It happened to me in my parents' Caprice wagon with a 454 when I was a teenager. Heard a rattle now and then, and you know I was always taking that sucker to redline every other minute.

Then one day I sent that crank pulley right up into the fan and radiator. Watch out.....check it out before you keep driving it.
Click to expand...

I built a 454 for a 71 Monte and had the water pump shaft shear off while i was under the hood revving it!!! Only 8 lives left now.....

Ported 396 heads , 10:1 KBs , 550ish roller Comp , RPM intake msd 6al / distributer and headers. My 340 would have eaten it ! My first and last venture into chebbies! Could have been lack of experience with them..but still