will a b16 crank fit in a b18 block??????

 

Yes, but the deck height of the two blocks are different. If you use the B16A crank you will need longer rods.

 

its been done buy a few h-t members but it is a pain you need custom lengh rods and the pins on the pistons need to be upsize by like 6 .
best thing for a b16a if you want more cc would be to go with a 1.7 gsr crank and gsr rods with your b16 pistons perfect fit and will raise up your displacement and compression ratio.