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Street Sleeper Fun: 1974 Jaguar XJ12


Barn Finds has been an interesting place here as of late. Several of our readers have expressed an interest to see less rusty cowls and project cars that are both super-rough and equally overpriced, and are looking for cars that are a little closer to turn-key condition. Here’s one that might fit the bill. This 1974 Jaguar started out life as an XJ12, but has been converted to small block Chevrolet running gear. It’s offered for sale here on craigslist in St. Louis, Missouri for $5,800, but is apparently located several hundred miles away, in Springfield, Missouri.


The seller says it runs and drives great, says the conversion was professionally done, and the power plant is a GM Goodwrench crate engine, with low miles. He also says it has dual exhaust, sounds good, and is an attention-getter, wherever he goes.


The other engine photo shows a GM-style Frigidaire compressor, and we can assume the trouble was taken to install it, with the thought of having working air conditioning in mind, although he doesn’t specifically say whether it’s ready to go or not.


The single interior shot provided shows an interior that appears to be clean and very well maintained, with light color and handsome wood trim and steering wheel, but I’d sure like to see a few more photos of the driver’s seat and other important areas. It looks like a fun car, and it looks like I could just hop in and drive away. I think this is an awesome, tasteful car, and the price seems reasonable for what it is, how good it looks, and the work that has been done to it. Do you agree? It left the factory with 12 cylinders, but that number has been reduced by one third. What’s your opinion on that?


  1. Avatar photo grant

    Ok, so I get why people do this, but… is a chevy 350 the answer to everything? A friend of my father had one of these back in the 90’s, the V12 made a very nice noise as I recall.

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    • Avatar photo The Walrus

      I was the proud owner of a 1983 Jag XJS for a time. The 12 Cylinders do make a very nice noise indeed, when they fire. Drove the car less than 1000 miles and broke down more than a dozen times. Worst engine ever. I’m no Chevy fan, and I think the 350 is often misused. Outside of the mechanicals (they use GM automatics) the rest of the car is so beautiful… I think this is the best possible application of non-original GM powerplants. What those in the know say about the 12 cyl Jaguar engine is that it was 12 cylinders too many for the Jaguar engineers…

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      • Avatar photo Ross W. Lovell

        Greetings All,

        Walrus, British Leyland was more responsible for those issues with their cost cutting measures. The credo of BLC back then was to share/combine components so as to save costs. This meant that the two sensors, both the same but one more expensive, this cheaper was use and the pricier one no longer utilized. Sometimes this worked, other times you found out the more costly one had a higher temperature range that it could work IN, not on while the extra heat caused the cheaper to fail.
        Knowing the cost of everything and the value of nothing.

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  2. Avatar photo Charles

    I drove a conversion like this many years ago when this conversion was common. The 350 really woke these cars up! Also got to drive the car with the original engine before it failed and the GM crate engine was installed. The OE 12 cylinder was supper smooth when sorted, but they could not keep it running. One has to remember that in the 70’s and 80’s one of these cars in non-running condition had no value, and it costs considerably less to install a new crate 350 and all the related items then to rebuild or replace the original engine. A well executed conversion made sense in those days as these cars were known to have reliability issues Once converted to a small block GM and related components allowed one to own a low maintenance higher performance version of a Jaguar. It is not that the small block 350 is the answer to everything. The GM engine is cheap to buy, cheap to run, reliable, and has good factory support, and unlimited aftermarket support. It’s easy to see how they end up in all sorts of vehicles.

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    • Avatar photo ydnar

      There is/was a shop in Dallas called John’s Cars. They specialized in these conversions and did a great job. The only people that did not like the conversions were the Jaguar purists.

      The XJ-12’s and XJS’s I believe are still very cheap to buy, this may be the next car to go into “bubble phase”.

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  3. Avatar photo Glen

    I don’t know how complicated it would be, but I’m wondering if BarnFinds could set-up an option system. The readers would choose a level of condition that the vehicles are in, and only receive emails that match ( more or less) what they desire. I enjoy seeing everything, so I’m fine the way it is, but I can see both points of view. I have no idea as to whether that is something easily done or not, but it’s just a thought I had. None the less keep, up the excellent work!

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  4. Avatar photo Donnie

    Chevy 350 s are the greatest and most boring engine that there is people put them in every thing .

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  5. Avatar photo leiniedude Member

    Great looking ride! Price seems reasonable to me. Not to familiar with the crate motors, Is the 350 decal on the valve covers for horsepower, cubes or both?

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  6. Avatar photo Birdman
    • Avatar photo David Member

      Thanks for sharing! That is loads of fun!

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    • Avatar photo Marty Member

      I am definitely a Roadkill fan. Both episodes that feature the Draguar are excellent.

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    • Avatar photo Mark-A

      Exactly what I was thinking when I saw the Advert! The Draguar Mk2!! 😊

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  7. Avatar photo dj

    It’s not a Jaguar anymore. Me and my dad did the conversions in the 80’s and bought the parts from John’s Cars. I guess that’s why I can’t stand doing this to these cars. If you want a four door 350 powered car, buy an Impala or Caprice.

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  8. Avatar photo duke

    narrow minded amricans- the v-12 rules

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    • Avatar photo The Walrus

      Have you ever owned one? Seriously, worst contraption ever!

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  9. Avatar photo Charles

    The 350 crate engine is a basic universal replacement engine designed for passenger cars and light trucks. Current prices are around $1900.00, and it makes about 225 HP. It’s a dependable V8, nothing wild or high performance, sort of the Briggs and Straton of car engines. The 350 that my co-worker installed in his Jaguar was a high performance version with 400 HP.

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  10. Avatar photo jim s

    i would rather see it on the road with the incorrect motor then parked, parted out or junked with the correct motor. i do wish it had been converted to manaul transmission also. interesting find.

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  11. Avatar photo 64 bonneville

    johns’ cars, also known as broken kitty is still in business. they advertise in the Jaguar section of hemmings motor news every month. they do have the best conversion kits , which are totally complete, down to the nuts, bolts, and washers. also their GM tranny conversions can’t be beaten.
    My personal preference is to see a jaguar, no matter what year, on the road, than sitting waiting for the rustman to take it away. I also believe the jaguars built before Ford bought it, are much better cars, however the ford technology, did help make the late models much more drivable and easier to maintain.

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  12. Avatar photo piper62j

    Never could take to these cats.. Electrical and body problems… Ugh!! 350 or not..

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  13. Avatar photo Ross W. Lovell

    Greetings All,

    I’m the owner of several pre 82 Jaguars as well as a 1934 SS1 Tourer, LOVE THESE!!!!!!!

    John’s has one of the nicest, most complete kits that includes plugs for mating the compressor to the Jags harness for one reason. Wondering if it’s a Quarterbreed with the Jaguar transmission or the other version that uses a GM 700R4 with overdrive.

    Jaguar V12’s………what can I say? When running the are like electric motors, nothing smoother. Don’t ever overheat one they’ll drop valve seats far too easy. Overheating is not helped by the temperature sensor being located on the bank of cylinders closest to the water pump as opposed to the other bank which will be cooked long before the sensor shows this………the reason? TA DA, the American market reversed the UK version with the sensor in the right place to accommodate USA harness differences. Yepp, that’s British engineering.

    Always been amazed by the introduction of the V12 as it was completed under the watchful eyes of the bean counters that ran the British Leyland Group. If the tooling hadn’t been so far down the pipeline it would have been shelved.

    Have one here currently had originally planned on a Ford 5.0 or newer, but will go with the Chevrolet version since Ford sold Jag.

    Ford dragged Jaguar into the 20th century. I do mourn for the loss of the V12 but that engine along with the XK had pretty much run to the end of its design.

    V12’s used to be cheap but many getting used up for racing. Try rebuilding one to just stock without the ability to print money. Very few are getting rebuilt. Aluminum heads bond well to the steel block. Hylomar sealant around liners tend to brittlize and clog up the cooling system. There’s a lot of reasons to look for an alternative when the need arises.

    Just getting a good distributor cap right now is ridiculous. Subaru coil packs and a crank trigger is the hot setup because of OPUS ignition issues.

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  14. Avatar photo Mark E

    Always thought one of these would be great as a summer DD and this one’s only about 5 hours away, but we’ve got one too many cars already right now…

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  15. Avatar photo Reg Bruce

    @Ross W. Lovell:
    Got a 1992 XJS V12 that makes me nervous.
    Where can I find more information about the Subaru coil packs and crank trigger set up?

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  16. Avatar photo johnforsman

    In the 80s I had friends who bought Jags. The joke among them was,”Always buy two, then one can be working.”

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  17. Avatar photo Ross W. Lovell

    Greetings All,

    Walrus, own two V12’s one, an HEvin an XJS and the other in an XJ-C V12. I don’t count the XJ-12 Sedan which is getting something American put under the hood. Sure to annoy some of the fellow Jaguar Club Members.

    Reg Bruce…rossw.lovell@yahoo .com. Or check the Archived E-mail at the Jag-Lovers web site. If you haven’t read Kirby Palms book/ it can be downloaded. Should be required by EVERY owner of a V12. Lots of tweaks, and things to look for during ownership. If that doesn’t help you my e-mail will, but get the book and read it.

    When distributor caps started being made somewhere else, quality went to hell, necessitating the crank trigger, the coil paks were Subaru as the were compact, might be something more compact nowadays.

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  18. Avatar photo Dean

    This was also a common conversion here in New Zealand back in the 80s. Turned a great car in to a reliable great car. As the chev motor was lighter than the jag they tended to sit a bit high in the front like this one. A friend of mine bought one that had been converted and the previous owner had added lead to the front to add weight. These days after market springs are a lot easier to get.

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  19. Avatar photo Ross W. Lovell

    Greetings All,

    Dean, you telling me they can figure out how to get the new engine sorted out but not how yo change spring rates or lose a coil, or are they thinking they will go back to the Jaguar engine ……..some day?

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  20. Avatar photo Paul

    As a british owner of a ’78 Daimler Sovereign I read this post with interest. Now, I’m not averse to the idea of V8 conversions generally – I’ve owned a number of modified cars over the years and a buy the argument that these Jags are a total pain in the arse in terms of reliability.

    But I’ll say this: who buys a ’70s Jaguar and then complains that it leaves you roadside occasionally in some kind of electrical tantrum? It’s a bit like booking waterskiing lessons and then complaining because you get wet. These cars were not from an era of British engineering quality to be proud of – an irritating fact that helped render many of these cars beyond economic repair over the years and has thus led to so many being scrapped.

    Which leads me to wonder whether preservation is the better bet now. It’s not the ’90s any more, when these cars were the price of a cup of coffee and a V8 would be a preferred option next falling into disrepair through lack of use.

    If you saw a Mk2 or Mk10 with a small block Chevy you’d weep and want to swap it back. These XJs are finding their feet now as collector’s cars and even if they were a bit, well, shit they are still magnificent to drive if well looked after. And all the better for being kept original.

    And let’s try our best to ignore those chrome wheel arches…

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