I’m betting you are using an 8.00
Harbor Freight pulley puller instead of a good harmonic balancer install, puller tool. Once you use one you won’t go back.

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time