Hammering the balancer on is how many many balancers have been installed over the years. I have done it myself. Is it wrong, no, not really. Is it the best way, no not really. Hammering them on does have the potential of messing with the crank thrust bearing. That is not to say that hammering them on always damages the thrust bearing, or commonly damages the bearing, only that there is the potential. So if that is all that is available, that is what you will do to get it reinstalled.

The better way if you can swing it is to drill the snout of the crank for a bolt. A couple of people have come up with tools to do that job with the crank out of the motor or in the motor if you have the room or can take enough stuff apart to make some room. Here are two examples:

https://www.12bolt.com/store/p164/C...ixture_235_261_283_327_194_230_250_.html

https://mrhotrod6.com/products/235-...-tap-fixture-tool-kit?variant=1142530609

Then you can install the balancer with a harmonic balancer tool like so:

https://www.jegs.com/p/Moroso/Moros...lation-and-Removal-Tools/751803/10002/-1

Also allows the install of a bolt to affirmatively hold the balancer to the crank snout. A little extra prevention on these old motors.

If you are stuck using the traditional hammer method, use a block of wood and a large hammer, checking your progress with the water pump pully to help determine alignment and seating against the crank gear so you can limit the number of hammer wacks to just what is needed.

Mike