[dirtyjim]

I've seen starter bolts snapped and nose cones broke from kickback. I've never seen a busted block firsthand. back 30 years ago when I was a teenager and raced a 72 c10 with a 454 we would run the ignition on a toggle stitch and get the engine spinning before turning the ignition on to prevent kickback when you was running high compressing and a lot of ignition timing. the ignition boxes and efi available now can retard the ignition timing during startup so its no longer needed