This happened to me.

Educated guess at my issue:
-k1 crank has a radius edge vs 90* on factory crank. Where the timing gear butts up to the crank.
-maybe the bolt wasn't torqued properly with locktite

Fix:
- install factory 6.1 pin in jones cam
- chamfer the timing gear
-lots of locktite and torque


-'02 Dodge Viper Ex-World Challenge racecar
-'73 Duster, 6.1 based 392 hilborn hemi, tko600, full floater rear 9", Hellwig custom bars, viper brakes, built for road course