Yup if you have a Pro billet distributor they will
1. cross fire with a start retard at any more than 10 deg retard. (I guess not as bad on huge GM hel distributors??)
2. if it starts and stalls you have to turn key all the way off or it's still in no retard mode.
3. go back to light springs and be happy "I DID" .
I use light mopar springs on an MSD pro billet as MSD chev springs are too stiff. I just want the mechanical advance to start and full advance after.