There seems to be quite a few 4.0 still out there running with high miles. What are the differences between the 4.0 and the 4.6? Is it just the same engine with a touch more displacment? Obviously, the 4.6 may attain the same longevity its just not old enough to be there yet.
thanks.

 

The difference is in the guts.
Same block and heads.

 

So, they did not reuse any of the internal parts?

 

This will answer your question better than I.

http://www.roversnorth.com/store/c-598-lower-end.aspx

 

Thanks. Actually there is a good bit of overlap, pretty much all the same bearings and timing chain parts. The real difference is in the piston assembly and connecting rods, which you would expect being the extra displacment.

 

Don't forget the crank shaft.
It also uses a different cam which some install in their 4.0.

 

does it produce torque lower in the rpm range?

 

So my question is can I put the 4.6l timing cover on my 4.0l and just update the crank shaft sensor and stuff?

 

You should be able to swap it right over, no need to update the crankshaft sensor (but I think you mean camshaft sensor, which shouldn’t need to be changed either).

 

As for the different engines, there is an option to change the vehicle tune for Cruise Control: