>into the case or what?  Right now, they seen real tight.  #4 fits just snug, 

Real tight? Just snug?  I wish I had my sensory appartus there to help you
out.  They have to fit into the case quite snuggly (like, this helps...) 
They shouldn't be so loose that they would fall out of the case if you
tipped it to one side.  They hae to be tight, because they have to stay
put.  Torquing the case halves together further seats the main bearings
into their seats. 

When you put them in, does it feel like your are jamming a square peg into
a round hole?  Or do they go in, but there is just a "fingernail" edge that
won't go in unless you press really hard?  Don't bang on them!  Just press
hard with your fingers.  I'll admit that I did LIGHTLY tap on my main
bearings with a rubber mallet (bearings covered by a cloth).  But I won't
recommend this, because I made this one up as I went along (while
rebuilding my engine) because it felt like the right thing to do.  I never
heard of anyone doing this.  My rebuilt engine runs well.

Don't forget those damn pegs!  If you don't get those little dowels into
the case halves, and line up the holes on the back of the main bearings
with those pegs, you'll never get the case halves together!  Putting them
in will seem like something is not right, like something is too tight.  So
watch it!

Those dowels are VERY important.

Wolfram

"Measure twice, cut once."