Multiple XJ8 owner here, nervously dipping toe in Lyons-era Jags. Am seriously contemplating purchase of Series II XJ12C. Part of my "due diligence" is mapping out my likely expenses.
Am I correct in understanding this era V12 fuel injection is no longer supported, most have been switched over to late Series III hardware?
In the same vein; I find several I6 swaps in this Forum, supercharged and NA, but have not uncovered a later V12 swap. Has anyone swapped out the 5.3 for a mid-90's OBDII V12 drivetrain?
- Doable?
- Can be done with difficulty?
- Don't bother?

 

Well.......I owned the same car your talking about from the original owner with the v12 .
That car had an original 26,000 miles coupe white with a black vinyl roof.
It was a money pit then and that's 15 years ago.
YOUR KILLING YOUR SELF FOR A 5,000 CAR.......
Just mho.
gtjoey1314

 

Very few have been switched over to series 3 hard ware becasue there were very few series 3 V12's to begin with.

ODB2 is 1996 on. Very few 1996 V12's were made and OBD2 swaps are far more difficult then earlier swaps becasue OBD2 monitors more systems like EVAP and there is more stuff to transplant to complete a successful swap.
The best V12 swap is from a 1995 XJ12 sedan. Still ODB1 and stand alone non integrated fuel management system is very swapable.

The early V12 fuel injection system is quite rudimentary and has no less than 40 high pressure hose clamps. With the dist sitting lower than the fuel rail fuel leaks and fires are quite common.

Like everything else there are fixes for all this. Modern hoses and OEtinker claps can greatly reduce the chance of a leak. But the early V12's are very fuel thursty and with a 7.8:1 CR They struggle to make 250HP these days.

As for a Later V12 swap, I believe some time in the mid 80's the XJS got a newer ORING fuel rail that is far less prone to fires. Also these engine would be HE and are far less fuel thursty and would be a good low cost candidate for a swap. But you'd need a complete XJS donor vehicle.

V12 swaps are difficult but not impossible. I've got one with a T56 past the planning stages as all the parts have been collected. The Jag V12 is very swapable into a sedan if you have a complete donor XJS... it's a very doable project mostly bolt in with very few modified parts. A late 80's XJS V12 would be more at home in a sedan. They offer high levels of refinement and with the 2.88 gears offer a sedate/relaxed driving experience. That's perfect for a cruiser. And there is the reason your dont see more of them, someone who has the skills and goes through all the effort is most likely looking for a more spirited driving experience from the time invested.

 

 

icsamerica, I miswrote. I meant to inquire into suitability of X300 V12 drivetrains for swapping into Series II XJC12's. I should've just asked; "What would be the best source of reliable and supportable Jag V12 FI or carburation for a Series II V12?"
Perhaps I've been misinformed, and it is possible to get new components which make this generation of V12 reliable. If so, I stand ready & willing to be thoroughly & completely informed via the well-honed keyboards & touchscreens of the Jaguar Forum Legion. Or something...

I am hoping to make this an actual road-tripper cruiser, not just a coffee-meet & car show artifact.


gtjoey, this car was delivered in silver, & has been stored inside for decades. (in multiple states!) So may not be the car you experienced.


gmoodyii, as the sale is not completely consummated I'm refraining from spraying too many details across the e-landscape. While I am willing to use recycled pieces/parts for much of the required restoration (especially body) I am much less adventurous when it comes to electrical or fuel systems. So will attempt to source rebuilt, reman or new parts for those area's


Thanks all for the responses! Am interested in any other Series II V12 engine & fuel system thoughts. What's been published you found most useful when maintaining these?

 

Not that I'm aware of...at east not the 'most' part. Maybe some?

The older Opus ignition system is/was a bugaboo....but there are workarounds. Uprated components or swapping to Crane or similar aftermarket ignition. Or perhaps the later Lucas CEi could be used? In dunno. It was a decent system.

The early V12 fuel injection was weird....or it seems that way to me. I suspect most or all of the unique parts are long gone....but I'm not well versed on the Series II V12s.

An alternative....not an ideal one in all respects, but still an alternative....would be swapping in a latter "HE" 5.3 V12 with the entire ignition and fuel injections systems. The HE has a bit more power and is much easier on gasoline. In terms of labor intensity, technical difficulty, and expense it shouldn't be too hateful. And XJS would make a great donor car, as mentioned. The "HE" variant, though having its own faults, is well supported in terms of parts and technical info. If you learn the quirks....they're all well documented....they can be reliable. But it takes some effort to make 'em that way and keep 'em that way.

I took a Series III XJ6 and turned it into an XJ12 using an "HE" 5.3 V12. Fun project, good result. Having a donor car on site, which I did, makes a big difference.


Cheers
DD

 

Good summation.

If *horsepower* is a prime consideration then a Jag V12 isn't the way to go unless you have very deep pockets. A V8 swap would be the better choice.

Cheers
DD