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I found nothing too difficult with the V12, I helped maintain and repair one for a friend for quite a few years. Which I ended up buying in 2019.
Plenty of help available here, especially in the XJS forum (X27)…next forum down from this one.
Biggest issue is all the "know it all" mates etc that have fiddled with them.
That 1975 could be the last of the Carby engines, or the 1st of the Infected engines.
Carby versions require a special amount of luv.
The EFI are simple, reliable, and just do what they do well.
The wiring, in the engine bay, will be the killer. I rewired all mine from day 1, never looked back.
Our S2 XJ12 EFI is @ 655000kms, and as made. It is DRIVEN, hard, and loves the fuel, maybe, but not as bad as some claim.
It is on its 2nd trans (BW12), 3rd Alternator, OE radiator, recored in 1995, Crane Ign System (the Opus fitted was dead), Sanden A/C compressor. The rest is as made in 1976.
Had many 6cyl, awesome in their own right, but the V12 is just a special thing. Had a few of them also.
The rest of the car, suspension, etc etc is the same basically as your S1, some upgrades to brakes etc, but the basics are there.
It will only be a garage nightmare if you let it be.
The majority of our Jaguar V12 experts are to be found in XJS forum. That's the best place to ask for owner's opinions and advice on the engine. *
I only had one brief interlude with a 1973 XJ12 Series I in 1974 following on from a 1972 Daimler Sovereign 4.2. The fuel consumption on the early V12 was frightening as a daily driver and I went back to an XJ6 in less than a year. Even when relatively new, the cooling and ignition systems were temperamental.
Graham
*I wrote this before seeing Clarke and Grant's posts.
Last edited by GGG; Sep 20, 2021 at 04:10 AM.
Reason: Add * comment
I own a few odd ball machines because they gained a bad name for one reason or another and resale plummeted. All have been great buys.
Which has always been one of the 'plus' factors with old Jags. You can buy 'em for peanuts, relatively speaking. But prices on old cars are rising, even old Jags. Before long I'm afraid they won't be the bargain they used to be.
Anyhow.....
I'm on my second V12 and I think they're great. If you already have some decent DIY tinkering experience under your belt, can work slowly and patiently, and have no objection to learning some new things, owning one isn't all that bad at all....as old cars go. It's actually quite satisfying. My present V12 is my daily driver.
If you'll be paying out-of-pocket to maintain one, well, those better be deep pockets.
I have had a lot of the V12 cars (Series III) - the V12 engine is an absolutely silky gem. Problems? Very few. The fuel injected version (which is more economical) tends to be hard on the ignition module in the amplifier -very, very easy to replace. It is a standard, not expensive, GM part (D1906); the fuel hoses must be pliable to the touch and if not, they must, MUST, be replaced...hmmm...what else? In general, extremely reliable.
I have had a lot of the V12 cars (Series III) - the V12 engine is an absolutely silky gem. Problems? Very few. The fuel injected version (which is more economical) tends to be hard on the ignition module in the amplifier -very, very easy to replace. It is a standard, not expensive, GM part (D1906); the fuel hoses must be pliable to the touch and if not, they must, MUST, be replaced...hmmm...what else? In general, extremely reliable.
That is exactly the reports that I was hoping to hear.
It seems that if maintained by someone with the knowledge of their basic operation, the V12 is a thing of beauty.
Well said sov211! My first Jag was a 72 E-type coupe. V12 of course. I rebuilt that entire car, even though it was in great shape when purchased. Using basic hand tools and a cold Canadian garage, it took 3 years, but what rewarding years they were. There can never be a more satisfying experience than spending an afternoon balancing those 4 Strombergs. When you finally hit that sweet spot with the mixtures and the idle smooths to silk, the grin from ear to ear has to be seen to be believed.
I never had anything but joy from that car, especially from the engine and I still miss it after 23 years. And that grin just gets larger each time someone say's "Can I see the engine" and you open to reveal what all those "Ooooh's" and "Aaah's "are about. Spectacular and simple to work on.
I was an Engineer at DeHavilland Aircraft in those days, and when rebuilding the differential accidently discovered that the pinion bearings were the same Timken part number as those fitted to the main landing gear of the DHC-6 Twin Otter!
Appart from fuel consumption and mechanics running away, screaming, are they that much beyond a backyard mechanic?
There is one for sale locally and I am sorely tempted. '75 Series Two. Looks very honest.
I would love a BIG Cat, but only if she is going to be able to stretch her legs and not be the Nightmare in my shed.
Please only first hand experience comments and not just what you have heard about the V12.
I own a few odd ball machines because they gained a bad name for one reason or another and resale plummeted. All have been great buys.
Cheers.
I have a 1986 XJS V-12 but my V-12 had its' last days. I am currently in the process of putting in a L2 400hp 6-speed manual. I was looking to overhaul the V-12 but just too much money and I have always had trouble with it. The engine I am dropping in will have more hp with a lighter payload.
The GM LS2 if from 2005 and the LT2 from last year. If they aren't better in some way than an engine from half a century ago, then GM should close their shop. On the same basis, you could replace the rest of the car with a modern Corvette...
Don't be offended, I do see your logic, but still somehow old cars go nicely with their old engines.
When people are looking at my car, I don't wait for them to ask to see the engine. Some people aren't interested enough to ask. So I ask "Do you want to see the engine?" And they humor me and say "yes". And that's when I get the ooohs and aaahs. They didn't expect to see that level of mechanical ART. And mine's only a 6-cylinder!
The GM LS2 if from 2005 and the LT2 from last year. If they aren't better in some way than an engine from half a century ago, then GM should close their shop. On the same basis, you could replace the rest of the car with a modern Corvette...
Don't be offended, I do see your logic, but still somehow old cars go nicely with their old engines.
I would have put another V12 in but I didn’t want to take the chance of putting the issues back in. With the L2 I will have a lot more options with mechanics if needed. At least now it will run as fast and smooth as it looks.
How bad are the 12 pots, really?
