One friend asked me to post this threat, is very desesperate with his 97 LT1, so here we go:

He purchased a balanced 383 stroker kit from speedomotive (hub and flexplate were included, not pulley), after the kit installation, his motor start to vibrate at 2000 rpms and decreasing the vibrations while increasing the rpms. The guys from speedomotive says that the kit was balanced, anyways, he is sending back the kit for double check, but in case that is not the balancing, what could be?

thanks in advance..

 

any help....