Upgrading from 3.9 to 4.0 shortblock

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Author Message   Neil Buchelt (Neil_b) New Member Username: Neil_b Post Number: 1 Registered: 09-2003 Posted on Friday, October 03, 2003 - 07:22 am:    Has anyone upgraded the 3.9 shortblock with the 4.0 shortblock? I would be using the same heads, etc. off the 3.9. From my understanding, there shouldn't be a problem with it, however, I was just looking for a few opinions. Thanks Neil   Geoff 93 RRC (Geoff) Member Username: Geoff Post Number: 120 Registered: 11-2002 Posted on Friday, October 03, 2003 - 09:07 am:    There was a guy on the Rovers North board that recently did it, so you might try posting over there. Basically the 4.0 crank is a little longer to fit the serpentine front engine cover. If you have the v-belts you will need a spacer behind the crank pulley. The bolt pattern for the heads uses less bolts (the bottom row not used). The bolts are stretch type too so get new ones. You will need the revised head gaskets. Other than that I believe its a straight bolt on. Post your experience/results when you get a chance.