gm hei no spark?

Ok. Summit is sending me a new one . i do enough business. No problems there. ..... It is a pro form 66990... No spark from coul wire in block cranking with cap on. I removed distributor. And spun by hand with kry on with new gm hei set up. Shot one hell of a spark... Spinning fast good.... Went slow seamed spuratic? When pushing up on distributor shaft ad in car slowly seamed like hit and miss... Put in old mopar unit. And spun fast sparks good. Better pushed up slowly spining too. Possible distributor grounding out when installed in block? Something i friend possibly suggested. ... Any one seen this. Type of issue?