I would like to get the crankshaft out before I pull the engine from the frame.  I have pistons out and timing gear cover off, and main bearing bolts slightly loosened.  

Question is will the crankshaft come out if I remove the main bearings?  Or are there bolts in the back of the crankshaft?  I have oliver parts and service books, and I&amp;T. But in the books I only see dowels engaging the back of the crankshaft and not sure about bolts.

Thanks.