Digital BW, The Print

Hi all,

I'm brand new to digital printing.  I have an Epson Stylus 780 and 
have finally calibrated it to the point where I can get pretty 
accurate colour prints.  

My question is, is there any way, other than a separate set of grey 
inks to get good B&W prints?  When I try to use just the black ink, 
it comes out VERY grainy.  Obviously the colour inks produce a 
noticeable cast.

I apoligise if this is an old question.  I tried to search through 
the archives but couldn't find an answer.

Thanks,

Ben