MK X with XJ-6 S2 Engine and Auto Trans?

Is it possible to utilize the XJ6 S2 engine and trans (Model 65) into the engine compartment of a MKX? I mean will it fit without trans tunnel modification? Has anyone done such a conversion?
Yes I know the driveshaft will probably need length adjusting.
Will use the Tri Carbs and manifold from a 4.2 Mk X.
I plan to utilize the Crossmember engine mount brackets from a 420G as well as steering box.
Trying to foresee the myriad of problems I can expect.
The alternator and A/C compressor mount would be a plus.
Positive to Negative earth changes.
Waterpump distance to radiator?
Already know about the oil filter head and have located a head that a spin on filter tips into the block vertically.

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yes & no.

I have a S2 XJ engine in my 420G, retained the original BW8.

A BW12 will fit, therefore, so should a BW65

later S2 had the later viscous coupler…afaik, this will not fit…i used the original VC

to make everything fit, I had to swap alt to low mount, used S1 alt mount for a 70A Lucas Universal…clearance is very tight…<10mm

for the A.C compressor I used S1 XJ brackets, its a work of engineering, and you would be very lucky to find original brackets from a MKX-420G-S1 XJ

A Sanden to York adaptor plate is then bolted on

speedo is electronic, grab the XJ or other electronic speedo

  • to - earth is easy to do

I presume you must have read my writeup on this job, as you must know the camshaft oil feed pipes are different and an adaptor is needed

  • edit…You would probably have the Harrison compressor fitted to a S2 XJ…do you intend to keep that, or go with the original style, either York, or a Sanden in place of York ?

I have not read your write up but would like to. Can you provide the link.
As far as parts availability all I have access to are.
MK X 3.8 & 4.2. (No 420g) and XJ6 series 2&3.

Keep in mind the Model 65 gearbox (and Model 66) were just at their limit of suitability for the 4000 pound car with 4.2 liter engines and made worse with the 2.88 final drive that US cars came with in Series III cars. Jaguar had many warranty issues with this gearbox over the years. Might, however, work better with a 3.07 or 3.30 ratio, Daimler DS420 limos (admittedly much heavier) came with a GM400 gearbox behind the 4.2 liter XK engine to address this issue.

is your car LHD or RHD?..steering column limits options on RHD

The respondent JKHM is the fellow that put XJ front & rear end in as well, last heard of he had a late model Jag engine & trans he was going to put in

My car is a LHD. The oil filter head is from a XJ6 S2. 1976/1977.

That gives you better options for oil filter style.

in any case, its pays to take numerous measurements

The main issue you may face is to adapt the oil pressure sender unit, if you use the MKX filter head. On RHD, the steering column is right in the way, meaning it was easiest to use what I had, which was adapt the original filter head

for LHD you can (apparently, according to the linked thread), fit a side mount XJ filter head, with a stubby filter, or a down pointing one

imo, an upward pointing one runs the serious risk of fouling throttle linkage parts

The MK2 oil filter housing bolts straight on to the XJ6 block , and the cam oil feed pipe lines up very nicely

Various steering parts are different, 3.8 vs 4.2, and I am fairly sure you need them

Draglink, ends, tie rod, ends & bracket, and Idler box are all different part nums

The draglink ends have a different size taper

crossmember needs a hole drilled & tapped (I think)

Have you got an entire front end from a 4.2MKX or 420G ?

I do have the entire front suspension to a MK X 4.2.
I also have what appears to be a 420G front suspension with the motor mounts attached .The steering box on it is locked up and it’s missing the LH tie rod end and link tube. Hopefully the steering box from a 4.2 MK X will transfer.
After considering multiple transmission options I now believe utilizing a Borg Warner Model 8 or preferably a Model12 (420?) will be the simplest route, not having to fight modifications to linkages etc. The only hurdle with the old BW transmissions is finding someone knowledgeable enough to rebuild it properly. Parts have improved/changed and it will take someone familiar with the changes to properly rebuild it for the long term. Anyone with recommendations for a rebuilder would be appreciated.
I’ll also probably utilize a 4.2 engine with all the cooling system components from it as well.
It will be an interesting experiment to try and configure the car into a usable daily driver.
If anyone has traveled down this path any and all input will be greatly appreciated. I plan to document and photograph the process for future enthusiasts and post it when complete.
For now ,hopefully this thread will help some as well.

sounds like you have exceptional access to parts, and know what you are doing
The CD of Parts Manuals is essential

afaic, the 4.2 MKX Adwest and other steering linkage parts are a direct swap for the 420G

The BW8 is very similar to the BW12, but the later trans has a much better kickdown system, they were fitted mainly to S1 XJ… Both share internal kits with a Ford FMX

The problem is the hard parts, they are all slightly different, and many NLA as new parts
I have a couple of spare BW8 for my vehicle

fyi…here is a post I did recently…if you want to understand the steering box these videos are great, same design used in many Landrovers