Dave
I have installed a 2.1 crank in a 1.9 block but it took some clearancing
so the rods would clear the case. that can be a problem as the bump that
needs to be clearanced is for the head stud. when you grind and open the
blind hole for the stud this could allow anti freeze to seep into the
crank case. I epoxyed the hole to seal it before I assembled the
engine.  you will need to use the 1.9 main bearings to match the case
the main bearing journals sizes on both cranks are the same . the second
oil pressure switch hole will need to be taped . the intake air
distributor will also need to be modified because to fit the case.
Bob Donalds
Boston Engine
http://www.bostonengine.com
"All Rights Reserved."

Can I use a 1.9 short block as a core to start building up a new 2.1
engine
                        for an '86?
                           Are they basically the same? Any major
differences that need to be
                        addressed?
                                         Thanks
                                    David