Converting a Pre HE XJS to a 6-litre?

[Finlandese]

My 1978 XJS has a fatally wounded engine. I might have the possibility of aquiring a 6-lite XJS engine with fuel injection and the 4L80E transmission. Has any one else done a this swap to pre-he and would I be stupid to do this swap?

[rougemont]

If you have a complete donor 6.0 litre car then its reasonably straight forward, just a case of swapping everything over, and I mean everything as you would really be re-shelling a 6.0 litre car into a pre he body. About the only thing a late 6.0 car shares in common with the early cars is the number of cylinders! The transmission tunnel may need some modification as that GM 4l80e is a huge (and very heavy) box and I think the late facelift cars had a modified tunnel.
I went down a similar path but with a 6.0 litre xj40 into a series 3, to cut a very long story short ended up ditching the gm4l80e in favour of a 5 speed manual and reverted to the non cat Lucas ignition set up.

[Finlandese]

Thank you for your reply. It seems that the best solution might be the manual transmission conversion to a pre-he engine.

[tortop45]

Why would you put in a less powerful engine ?.........