Purring Big Cat: 1973 Jaguar XJ12

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When it was originally released in 1972, the XJ12 presented the Jaguar engineers with a multitude of challenges, and most of these were concerned with preventing the original V12 engine and many of its ancillaries from melting due to heat that the engine generated. Their efforts met with some success, but more than one owner over the ensuing years has consigned that engine to long-term service as a boat anchor and had their XJ12 converted to small-block Chevrolet power. That conversion has been completed on this car, and it is now looking for a new owner. Located in Glendale, California, it is listed for sale here on eBay.

Every time that I see an XJ12, I can’t help but think how much I’d like to own one, and this one looks really nice. The body and paint look first rate, and the chrome and trim also look really good. These are quite a deceptive car because it’s not until you stand beside one that you realize just how low the whole car actually is. This low height doesn’t impact upon passenger comfort, but it really helps the car to cut through the air with a minimum of wind resistance.

It’s under the hood where common sense prevails with this Jaguar. The original V12 engine was always a tight squeeze in an XJ12, in spite of the designers protesting that the car was designed for that engine. Cooling was one of the greatest challenges, and it led to the use of a complicated radiator to keep the engine cool, and even the installation of a thematically-controlled fan specifically to keep the battery cool. That has all gone now, with this XJ12 being powered by a small block Chevrolet engine. The 350ci fuel-injected engine is backed by a GM 4L60E transmission. The owner says that the car runs and drives really well, with plenty of power to spare. Power steering, power brakes, and air conditioning are also fitted, and all work really well.

The interior. Life in the lap of luxury. The only word to describe it is immaculate. You get new leather upholstery, a new headliner, all of the timber has been restored and refinished, and the Jaguar has been fitted with a CD player with a USB port. It goes without saying that the car is also fitted with power windows. The owner says that everything in the car works, with the exception of the speedometer, which needs servicing. I guess it wouldn’t be a Jaguar if there wasn’t a minor glitch somewhere!

The XJ12 was one of those luxury cars that battled to hold its value and a large part of the problem that caused this was hidden away under the hood. The cooling of the original engine was so marginal that it caused a multitude of problems, and these had a major impact on reliability, and ultimately, on the resale value of the car. Today, it is not unusual to find XJ12s that have undergone the same conversion as this car selling for higher prices than original cars. The owner has set a BIN price of $10,700, but the option is there to make an offer. At that price, I really don’t think that it will be long before this car is off to a new home.

Auctions Ending Soon


  1. Coventrycat

    Oh yes! Yes! Yes! Thanks for the digital centerfold.

    Like 4
  2. redwagon

    Silver on red a classic combination that is not seen very often anymore. It would really stand out with redline tires. My 2 cents.

    Just curious does anyone know the hp, torque and weight specs on both the original v12 engine and the current small block chevy 350?

    Like 4
  3. MikeG

    No V12, sad….

    Like 4
  4. Beatnik Bedouin

    Redwagon, the SBC is lighter than both the XK-series six and the V12, makes more HP, requires a lot less fettling and is far more reliable.

    Adam, I’m sure you could find an XJ6 in Australia that you could convert to a V8…

    Like 3
    • Redwagon

      Thanks Beatnik, I figured the SBC would weigh less and be more reliable, good to know it also produces more HP. Torque may be lower (or not) but I’ll bet it makes for a beautiful cruiser.

      Looking again that red leather interior is stupendous.

      Like 6
  5. DonaldCanada

    This is no longer a Jaguar!

    Like 12
    • That AMC Guy

      Indeed. You’ll actually be able to drive across a mall parking lot without the engine overheating or the ignition system shorting out.

      Like 20
  6. Brian

    This one is a ’74 series 2. 73 would have the taller grille, and a ’75 would have bigger bumpers with the turn signals relocated.

    Like 5
  7. Sam61

    Great looking find!

    May I offer a couple editorial corrections:

    1) All Jaguar models present Jaguar engineers with challenges.

    2) It wouldn’t be a Jaguar without a major glitch somewhere…usually several.

    Like 8
    • Tirefriar

      Sam, that’s an old timer’s view of Jaguars. More modern Jags especially after the launch of x300 chassis have been very reliable. The AJ16 4.0 normally aspirated and supercharged were the best in line 6 cyclinders Jaguar ever built and one of the best I6 engines on the market. Every luxury car (with exception of Toyota Lexus has major issues, especially as they age. Very few cars would be able to match the grace of the Jag’s XJ lines.

      This is a nice example especially with a working A/C. Non working speedo could mean an issue with adapting a cable to transmission speedo drive but plenty of aftermket GPS based speedometer options available to remedy that although I would think that making the a/c function as part of the conversion would be more difficult than figuring out how to adapt a speedo drive. This one is a bit pricey unless you are specifically looking for a classic XJ model. For this same amount of scratch you can easily find 95-97 or 98-2003 XJR that will give you much better bang for the buck. Engine alone does not a car make, and the suspension of X300 and X308 chassis are much more superior to what this aging cat has to offer.

      Like 5
      • Ron W.

        Maybe some of us old timers just want to preserve cars and trucks as
        they were made for future generations. Own a 1986 original XJ-12 and there are ways of cooling any car/truck engine compartment and not destroy it.

        Like 0
  8. Mountainwoodie

    We had a ’72 XJ6 ( I think it was a ’72…small bumpers) in ’79 and ’80. Quietest car I ever drove with the classic dark green over tan interior. Blew it up on the 405 in LA……actually blew a head gasket but still…and two gas tanks! Just a beautiful car……on the bucket list would be a 2 door ’75-’76 with a sunroof.

    Like 4
  9. UK Paul 🇬🇧

    Love the interior…

    Like 4
  10. Johnny Gibson

    Chev power is not such a bad thing, always liked the look of these. One car on the block we were not allowed to apply the dealer sticker on the back windows so nobody knew where it come from when the tow truck picked it up off the side of the road.

    Like 5
  11. h5mind

    Back in the 1980’s my girlfriend’s Dad was thinking about picking up a second-hand XJ12 Jag. He mentioned the idea to his regular mechanic, who replied, “Who hates you so much they would sell you a 12 cylinder Jaguar?”

    Like 5
  12. ClassicCarFan

    Sorry, I’m with MikeG….no V12, no point anymore.
    Yes, a car of this vintage with the original V12 is going to be a labor of love to keep running healthy, but unless the engine was completely wrecked the knowledge is out there these days to get around the challenges of these engines.

    I always felt these were possibly the most beautiful 4-door sedans ever made.

    Yes, I get it, the Chevy 350 is cheap, lighter, provides good power…etc etc, but the whole point of this car was the silky-smooth exotic V12. You can keep this one. .

    Like 3
  13. wuzjeepnowsaab

    While I’m not one of those that always screams out “SBC” everytime I see a vntage car with vintage drivetrains, these old Jags with small block Chevy mills make a lot of sense. You get the reliability of the SBC (and it rains parts out of the sky) plus the uncompromised luxury of this era XJ’s

    When these 12’s were new, they were marvelous to sit and stare at, smooth as a milkshake when started and purred when driven. But they were fraught with issues…bad issues…that had them parked a lot. And come on…you can’t turn your nose up at an American mill in a Brit car. What about Jensen’s or the many manufacturers that used American drive trains?

    This ebay Jag is gorgeous!

    Like 1
  14. John

    $3500, max. Sorry, but a “lumped” Jag is rarely wanted.

    Like 2
    • Tirefriar

      The car is probably worth close to $3500 without the engine. However, I do agree that converted Jags are nowhere near the asking price here. I would say anywhere from $5k-$7k, depending on what its really worth to the seller. I would be a player closer to $5k though. Converted Jags are not worth much with an SBC, no matter how nice they are.

      Like 0
  15. tompdx

    I have owned many Jaguars, including V12s, and have found them to be very reliable. I had a ’76 V12 XJS that was my daily driver in the Air Force in Tucson AZ and it only overheated once. Of course, it sucked a valve seat when it did and I was down for a few weeks when I took the right head to a machine shop, but it was a cheap fix.

    I have a ’76 XJ12L in my garage now and it is an absolute joy to drive. Perhaps I am used to tinkering on these cars, but they are honestly not difficult to work on. I would never consider pulling the original power plant. It totally destroys the character of the car.

    Like 4
  16. Brue

    My family has a 73 XJ-12 when I was in high school and university. The smoothness of the engine was totally amazing. I often balanced a coin on the running engine. Not a huge amount of torque off the line but get it going and it was like having a jet engine pushing you. So amazingly smooth.

    We had the car for over 10 year and 150K miles. It never broke down, not once and that was after we had 200K on the engine and chassis. Luxury in spades for the time and really good even today. Over time the varnish on the wood on the tops of the doors will crack and fade but that is a weekend fix.

    With the SBC engine 4K max for a sale price. Almost certainly less than the cost of the interior. As for that engine just replace the carbs with some proper webber carbs and you can easily top 400HP and I have seen 500 at the wheels of a friends. We kept ours stock as 120 was easy enough to hit if you were not paying attention. My mothers tickets were proof of that. You can not tell the difference on the interior from 65 to 100 mph on a good highway. That she was a head nurse was the only thing that kept her from going to jail I think.

    These are not delicate cars, the Merlin engine used in a Mustang Fighter is not delicate either but both require specific care. Do not give it that care and you have a money pit on your hands. This true of many of the better cars of then and now.

    The bad reputation is largely from those that wanted the style and performance on a budget that was far too small. Otherwise from experience it was people that maintained cars only when they broke. I can assure you it makes no difference if it is a Ferrari, BMW, Mercedes Or Jaguar you break a V-12 and it will be expensive. I know that the present owner of our car is restoring it and we have put him in contact with those that will know what they are doing so it has many more years to provide pleasure.

    Last thought these can be fuel swilling monsters. Go fast enough you can see the fuel gage move in real time. Now they only show one of the two tanks at a time but WOW. I have never seen another car do that. I have seen a P/W-R-2800 empty a 50 gallon tank on a test bed and a Merlin engine do the same with about the same speed but still WOW.

    Like 0
  17. Gay Car Nut

    Lovely looking car. I remember when Jaguars looked like this. I’ve always found this way more attractive than the XJS that was also being produced.

    Like 0

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