I installed a New Johnson Pump 10-24915-01 on my 95 454 bravo merc so that I could remove the merc unit. After I started the motor the pump moves a lot during 800rpm. It doesn't move like the shaft is bent Mind you that I had this motor out and took my time cleaning the mating surface on the pulley to ensure a flat fit. There is no way to center the pump exactly to the pulley due to oversize holes on the pump assembly. I don't want to ruin the pump or destroy my main bearings. Is this normal or is there a better way to center these style of pumps?

I centerterd mine on twin SBC's. I had to get a model of the Johnson pump that had the same size mounting holes as my crank pulley. They both run smooth and true.

Do you have the support bracket installed holding the pump housing?

the holes align to pulley and yes I have the stability arm attached. The holes are just .030" larger than the bolts. I was looking at machine a bullet but I can't imagine I should have to.