…that could be fun…
I like those types of findings. Not knowing where you’re located, but the XJ12’s (Series II and Series III) here in the US are diamonds. I had the opportunity a bout 3 years ago to pick up one in Canada; but it got away from be before I could find the time and get a trailer to go get it. It’s pretty much an two day round trip from where I live.
I’m still looking for an XJ12. but I’m gonna have to sell something first.
V12 engine repair ain’t cheap.
Many, many years ago a full overhaul was in the $10,000 range.
Much more common is dropped valved seats…much less involved than a full overhaul but it was still $5000+ if both heads needed to come off…probably much more now.
And finding a capable and willing repair shop is part of the struggle
In the old days, when a basic, low-tech V8 conversion might’ve been as low as $2500 or so and the cars were only worth $5000…well…you get the idea
Cheers
DD
To have a V12 built properly like it came from the factory or better (built by one of the original factory Jaguar engine builders) you’re looking at $16,000.00 providing heads, crank are in decent shape.
and a decent running sbc is a few hundred bucks. then their is the time for the rebuild. finding a decent engine builder is one thing, waiting on his list is another! as doug pointed out, it isn’t practical to spend that on a car only worth half as much and wait 6 monthes to drive it!
I’m worried that I’ll be asked to de-lump it, yes. I don’t relish the task. First, I envision a huge time sponge. Second, working on cars like this is very nerve jangling…especially heavy work like hailing engines in and out… There are no inexpensive mistakes
Cheers
DD
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You either love a marque, Doug - or you lump it…
Frank
xj6 85 Sov Europe (UK/NZ)
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That’s the quandary: on the car pictured below purchased below for $800 complete, albeit as a non-running car at time of purchase. (first expense was $60 to tow to my house)
There is no wisdom in spending anything like $16k plus the ancillaries to make it a V12 again.
Some people may question that estimate of a more than proper rebuild at $16k. To those who have not gone down that path I would suggest they take a look at the long list of specialty tools listed in the Jaguar repair manual. Finding someone who actually has all of those long out of production tools is one thing, finding someone with those tools who actually knows how to properly use them is another thing in itself. That is the great conundrum of XJ12’s when they go from splendid to bad - how much do you want to bruise your wallet for V12 bragging rights on a car with modest market value?
Some cars, like vintage Ferraris, are a different equation in which spending $200k restoring a lumped version with good history will still see the owner getting more than that back when the car next goes to auction. Sourcing an era correct vintage Ferrari V12, rebuilding it and collecting all the ancillaries, will probably check in somewhere between $60k to $80k.
Its only money, and each of us gets to determine how much we are willing to spend/contribute to preserving automotive history. Meanwhile I say we should all enjoy the beauty of our cars with no apologies for cars like mine that were lumped a couple of decades ago by a retired postal worker - who never let go of his dream car even long after he could only look at it in his garage.
You still know she is a cheap tart, jrinam - but sure ready to roll…
Frank
xj6 85 Sov Europe (UK/NZ)
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Very true, enjoying our cars is the most important part! And what a sad story about the previous owner of your car, who could only drive it for a few thousand miles before becoming to ill to drive it 
Right.
On the other hand, though, there ARE alternatives.
I ‘lumped’ my 1985 XJ6…with a Jaguar V12.
Using a very rusty V12 donor car with a very sweet running engine I was able to turn my XJ6 into an XJ12 with all factory parts. The engine looks like it was born there, naturally, and I have what I’ve long wanted…a Series III V12.
In my case the donor car was given to me, gratis, but I’m sure it could’ve been purchased for less than $1000. Probably much less. Good used V12s are out there, cheap…with or without the rest of the car. This may not have been the case decades ago, though, when your car was lumped.
Personally I have no objection to lumping. But if lumping is a sin the lumper can’t really play the “it was cheaper” card nowadays and expect absolution. Better to just be honest and confess that you wanted a V8 all along
Cheers
DD
Good for you Harald!
Beautiful X300! and you got the magnificent 6.0 V12 to boot! score!
I have the feeling I have seen this V12 hot rod. Is that in the Haynes Motor Museum in Sparkford?
I’ve always looked down my knows at lumps; be it Jag, Ford, Chevy or the like.
if you want more go, then keep the powerplant within, at least an option spec of what the car’s model year.
If the car came with a V12, (and are so inclined) then make it so. V12’s can be acquired pretty cheaply. the caveat is getting one with the proper block coding to match the year of your XJ. Then there’s getting the proper FI module & wiring harness, for that year V12, or the manifold & carbs for an early Series II, there are companies that re-cast these parts, and others that sell rebuilt SU carbs (especially in the UK). The SU’s aren’t particularly expensive the recast manifolds, on the other hand are, and will set you back about $3,500.00.
For me, and my conundrum
I would love to have an series III XJ12, but sadly I don’t.
I have 2 Series III XJ6’s and a spare matching year '85 V12 (50,000 miles on it) with the ECU and wiring harness and transmission in storage. I picked up for $400.00 on craigslist from a parted out XJS. I could lump one of my XJ6’s to an XJ12 but then it would be a lump (this kind of goes against the above paragraph. Not to mention it’s a proper pfaff to retro fit one. It’s essentially a complete running gear replacement. and stripping of the interior for the wiring,
So if you were so inclined, putting the car back to an XJ12 is very doable, and can be done for under $2,000 and gobs and gobs of (your) time.
The $16k is for a expert V12 rebuild. The most of parts for these engines aren’t hugely expensive. The cost goes up because there’s just a bunch of them aka 12 pistons, 12 liners, 24 buckets, 24 springs, 24, valve guides, 24 valves, 12 injectors. I think you get my point. As for the special tooling, most can be made with a bit of ingenuity; some aren’t necessary, but just make the job 1000 times easier. If you watch ebay, you can find the special tools; at a reasonable rate.
With a whole lot of patience, due diligence of monitoring scrappers, Craigslist, this forum sale website, ebay, offerup and the like, You CAN get the bits necessary to put the car back the way it was at a very reasonable rate.
For what ever its worth
M
Here is where the V12’s out of rusty XJ’s go:
Or
I suppose anything is possible, although if I pieced together everything from the fuel pumps forward (the Jag electric fuel pumps were entirely deleted when my car was lumped) and the ancillaries for $2000 all I would expect is a running but tired V12 engine and BW transmission of lackluster performance. If I dropped $2000 on my low mileage lump I would expect more than 400 fun horsepower.
Its an individual decision: spend countless hours acquiring all the big and little bits to make it a V12 again, and countless more hours getting it all assembled and properly running - or spend very little time and money and get to enjoy driving it pretty much the way it is lump and all.
From what I know of stock unworked Jag V12’s is that they usually pull ~ 250hp +/- on the engine dyno - which is pretty much the same as a garden variety 350 SBC. Yes I know a Jag V12 can be hopped up - but it really becomes the work of a specialist vs. the lazy Saturday of installing aftermarket heads and a roller cam in my primitive SBC.
OH MY GAAAWD! How terrible, to desecrate a T-bucket, and lump it with a British V12!!
All T-buckets should ONLY have Ford flathead engines in them!
The horror!!
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That’s a lose, lose situation depreciated the T bucket and the v12;
I don’t know if you watch ed the 2nd video, but if you notice you can hardly tell the V12 is running. It’s so smooth.
There is no stopping back woods engineering - there will be no wasting of the good bits of former luxury cars
The shortage of an odd wheel is no impediment
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That’s the gist of the disagreement, Thomas - love of garden variety horse power versus love of thoroughbreds…
Frank
xj6 85 Sov Europe (UK/NZ)
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One of the things about the V12 that Jaguar got right was that it had a certain amount of snob appeal (Jaguar new car buyers have expectations of prestige) along with bragging rights in the era. Cylinder multiplication has been left behind by technology ala XJ220’s V6, and today many 4 cylinder cars out perform vintage Jaguars - thank goodness you can hold your head high knowing that those bangers lack a V12. Meanwhile market prices for XJ6 and XJ12 are perpetually stuck in the basement and are eclipsed by same year VW bugs at auction.
I had nothing to do with the lumping of my XJ12, but I’m certain it will be the most fun $800 car I have ever purchased. Sadly for Jaguar lovers I am certain that when I go to car shows and have the hood up that 95% of the spectators will see a couple of the Jaguar badges that I am fitting to new chrome valve covers
and they will think its a Jaguar engine. Of the 5% who recognize what it is they will be mostly interested in talking about performance. Jaguars are odd cats anywhere within a five hour radius of my home. The people most anguished by cars like mine will be found on the Internet - but if I get a live one at a show its going to be fun!