Jerry's suggestion on using a C clamp or ball joint press is the way to go. WAY less chance of cracking the block than hammering on it.

Heating MIGHT reduce the chances of cracking while hammering, but not worth the chance, IMO.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.