Does anyone know if a 1997 740 motor will fit in a 1995 840ci.

It will bolt right in but the engine would have to be converted to OBD1 or the electronics in the car adapted to the OBD2 engine.

Will the old electronics just bolt right up to the new engine? Say if you just used the new engine without any older electrics? Basically using the bare new engine, Heads and block.

The old crank damper needs to be used and a bracket built for the crank position sensor. Need the '95 sensor.

A new cam position trigger needs to be fabbed and a spacer fabbed for the sensor. Need the '95 sensor.

A '95 water pump and thermostat with housing needs to be substituted for the later model water pump with electronically controlled thermostat.

All of the temperature sensors from the '95 swapped over along with all of the other sensors like the knock sensors under the intake manifold. I am pretty sure that all of the plugs are different. At least "many" are different.

The emissions plumbing is virtually the same. The fuel rail is probably different. I know the '97 540 is. Injectors are the same though.

You need to be careful to not get a Vanos motor (IIRC mid '98) because conversion of one of those would have to go the other way to OBD2.

And the list probably goes on from here with little things that don't quite work the same but I think I got the bigger stuff.

Good to know TerryY, Thanks!