Qualified shops will tell you to budget about $20,000 for the typical Chevy swap. It’s not as simple as it sounds even with a kit.
Your XJS could be as much as 45 years old by now and wiring that age is flaky. But you will need a different transmission as well. While the GM turbo 400 is used on both Chevy’s and Jaguar V12, the casting is different. It’s not the Buick, Cadillac or Chevy design it’s unique to Jaguar.
Do be prepared for a much rougher running engine. A V8 ( any brand) has a second order harmonic the V12 doesn’t. Access to spark plugs is also harder the engine compartment is narrow and most spark plugs are on the side under the exhaust manifolds unlike the Jaguar where they are on top.
Power wise the V12 is really powerful. It doesn’t seem that way compared to pre 1973 ratings which are gross or Advertised power. After 1973 the Chevy 350 was rated at 160 horsepower and the Chevy 454 was rated at 230. Jaguar is 262 so 32 more horsepower than a 454
If EFI complexity is your concern it’s understandable. Plus no OBD2 to plug in and have it tell you what’s wrong. Thats common to all engines of the era.
You can switch it back to carbs. Either use the two 4 barrels ( like Holley’s)if you’re willing to modify the hood. Or use the stock 4 Strombergs that are lawn mower simple.
That will cost you power though. About 17 horsepower and much worse fuel mileage.
If you ever take a V12 apart. You will be amazed at how strong and durable it is. The crankshaft is a heavy duty forging as are the connecting rods. The rings last forever as do the valves etc.
yes there are some small things different like you need to put a few drops of oil in the distributor annually and there are two radiator caps.
But all the bolts are American sized. ( the British taught us about inches)
In fact there is much about the Jaguar that isAmerican made.

 

I see this thread was started 13 years ago and has just seen it's second post. Mguar has given his opinion, but I will see if there is more activity generated here before I post.

Dave

 

Mguar, I disagree. I gather you have never owned a converted car. Yes, for a top of the line conversion with a new engine and transmission maybe be that much, but, come on. I own an original Series III and a converted one. They are both fine, fun to drive cars but the conversion is way, way less expensive to maintain. I'll let Dave get into the details.

Jeff

 

This could shape up to be an interesting thread.
So much I can say on this topic, but like Dave, I will hold back! ( for now) only thing I will say, is that I am nowhere near 20k on my swap!

 

Would anyone consider putting anything other than a GM LS these days?

 

I was gonna say there's nothing to be discussed that hasn't already been discussed before. Until this :

I still think the 350 TPI is perfectly viable choice. There's nothing wrong with 'em. They're just old skool nowadays. Actually, considering that the LS engines are now so commonplace in engine-swap cars it might be sorta cool to go against the grain

Cheers
DD

 

Alabbasi,
My advise before choosing an engine would be to come to grips with why you want to "lump" and what the car will be doing afterwards that will get your juices pumping. After that, I think the small block engines from GM, FORD, and CHRYSLER will all bring a smile to your face, but some will cost more because they're not as common or popular. When I decided to build my last-ever auto project, I was looking for anything that I could put a more powerful engine in without it being obvious. I looked at a couple of TR6's I think (little cars that looked like a door stop), a couple of Volvo 242's and then I saw this XJ6 in Craig's List and went to look at it......the rest is history. Point being, I knew I wanted to put a big engine in something and that it would scare the crap out of me if I let it, or idle through town to the coffee shop if I wanted it to. The small block Chevy engine is a natural for this Classic sized Jaguar, in my opinion. I'm talking about the "old school" small block that ended in the late '90's.

If you would like to go racing, the LS style engine might make more sense, but do your homework first. I think getting one would be pretty easy, but the small parts and pieces are what make or break a conversion like we're talking about. Conversion kits for the LS can be had from specialty vendors and make the job so much easier and professional looking. Our Series 1,2,3 Jags are "analog" vehicles, meaning the only thing being controlled by that mysterious metal box is the fuel injection (Series 3 only, I think) Everything else is just battery/ground and wiring. Mating the two isn't too difficult if the donor engine/trans retains it's original PCM and wiring harness.

After having mine completely apart and then putting it back together, I think the Series cars are best suited to cruising the highways at 100mph all day long, with complete confidence. To do that, a well built small block and mating auto trans is the perfect setup. Keep in mind, the old school SBC can easily produce 400hp if you want to build it that way. That's well into commonly available LS territory, and cheaper.

If you follow my Alaskan XJ6/LT1 thread, there are a few pictures of the engine installed, I don't think you could ask for a more natural looking engine/car combination. I my opinion. As far as cost, that's like asking "how long is a piece of string?". You can change plugs in a running junk yard special, have your next door neighbor (or you) with the welder make something to attach the engine to the car, hook up a battery, hook up a gas line and turn the key. $1000 or less. I have about $10,000 in my engine/transmission and all the bits and piece needed to make a good conversion. There are some of you out there who have just changed your mind concerning my sanity, but damn it Mildred, this is my last one. I have another $10K in the total rebuild (not restore) of the car, yup.

I saw a YouTube the other day where a young man spent some quality time putting a SBC in his (dad's) ride-on lawn mower, nice job too. Piece of wire in hand for the throttle and it would jump pretty good for 10' or so, he could only drive it on his lawn and it was very hard to steer. So, you can put any engine you want in any vehicle you want, but the best one is the one you can afford and have confidence working with while allowing the car to do what you intended. You'll save a ton of $$$$ if you are mechanically inclined.

Good Luck, we're here to help if you need it.

Dave

 

That's exactly what I have! An Old School (Very olde school) 350 with carbie, that even though probably only a fraction of the power of your LS engines, still has quite enough to get me into trouble, or idle sedately through WalMart parking lot (turning heads, I might add).

Once in a while I have to "blow the carbon off the valves" just to see if it will get out of hand if I'm not paying good attention.
So far, So good......

I have no doubt about your sanity, Dave! Absolutely none!
(';')

 

People say that the old school carb V8 is easy to band aide if you are ever stuck but I disagree the new LS V8's are so rock solid and trouble free I really would not recommend going old school. The modern LS V8's are jus so trouble free and more quiet, smooth, and more power. I have upgraded my 3.8s with an aluminum block/head LS1 and put well over 200,000 miles with no issues. When you use a SBC carb the value of the car will drop as most people do NOT want those engines in any car now. People want the ease, power, reliability of a modern V8 not the old school V8's. The modern LS is lighter, more reliable, no cold start issues, no issues due to changing altitudes, way more power, smoother, and you just put gas and go. I have had many real offers to buy my car for way more than I put into it but I now realize why the LS swapped cars sell so much more than the SBC carb cars do is that they are way more pleasurable to drive and doing a good quality swap does take a lot of time and effort so I really do not want to start all over If you are really into old school V8's go ahead but do not expect to sell that car no matter how nice you do the swap for much money as everyone wants a modern V8 like an LS.

 

Except that it's not anymore. You can walk into just about any junk yard and find a cast iron LS engine from a truck that was running and under warranty for around $600. They've been in continuous productoin since 1999..

Modern fuel injection, 4 speed automatic (or 6 speed manual if you choose), modern fan controller for electric fans, serpentine belt, modern alternator, modern a/c compressor all controlled a factory GM computer that you can talk to via OBD2. The availability of parts pretty much everywhere at low cost. Power and torque, better fuel economy, reliability.

It's a good option if you want a driver. I've been kicking the same idea around for my Jensen interceptor. The block has a crack and those engines run hot in that bay. An LS would have all the benefits that I listed above. I had a 78 XJ12C with a lump which I sold when I bought my V12 coupe. I did not consider it as a nice car to drive although it was reliable. That's why I sold it, although in hindsight, I should have kept it and did this swap.

 

In your shoes I wouldn't either. But I think I'll keep what I have.

Speaking strictly for myself, I didn't get this car as in Investment and I don't think very many people in here did.

I have no plans to sell it any time soon. If that time does come eventually, I'll take what I can get, because the *Value* of any item is exactly what someone is willing to pay for it, not necessarily what the Seller thinks they should get. So I'll probably keep Driving the Wheels Off ( and Thoroughly enjoying it) until the Goon Squad takes it away from me.
(';')

 

I’m sure not a purist. I turn street cars into race cars. Which means I’m really serious about going fast.
However I’m cheap. Too cheap to waste money without serious improvement.
Nor am I blind to the flaws or shortcomings of Jaguars. In fact, I’m sure I know better than most.
The V12 Engine itself is impossibly stout. You really have to screw it up to ruin it. Neglect and ham fisted doesn’t always do it!!!!
Like carbs? OK you can buy a nice manifold that will take a pair of Holley’s. Like EFI? The original is pretty good, capable of delivering 1250 CFM stock! Replace the intakes and you’re over 1600cfm.
Run a pair of Turbo’s? Sure, won’t hurt the bottom end that can easily take 1000 or more stock!
I’m going Vintage racing with mine. Up against Big Block Corvettes. 427 Cobra’s ( admittedly rare)
Mustangs and Camaro’s.
You know what? They are cheaper to race than all of those. Not by a little but a lot. The prime reason is that V12.
Now a brief word about the early Cast Iron six. Designed during WW 2 while on the roof watching for fires during the Battle of Britain 🇬🇧 it’s old. Lasted a long time. From WW2 until 1987 but it has a long stroke (4.17) which makes piston speed impossibly fast. 300 horsepower is about it unless you are willing to spend a fortune to get another 50+ horsepower out of it. But that old six gives 454 Corvettes a real run for their money in an XKE.
Jaguar also made a modern all aluminum Six with 4 valves per cylinder. The GM Atlas is directly patterned after it. And those in stock form with a simple turbo are really blasting up the drag strip. ( optional on the Jaguar version is a supercharger which is actually as fast as the V12
Let’s use Net horsepower figures for a bit. Those are as an engine is installed in the car with smog and mufflers etc. yes take the smog off and horsepower goes up. ( surprisingly little now days) and mufflers do cost horsepower. Especially a car designed to be luxury. If you do nothing more than deal with those. You’ll pick up nearly 90 horsepower. Add that to the stock 262 and we are at 350+
Now, modifications. Well running on French pump gas (86 octane) the V12 made 700+ horsepower for 24 hours during the mid 80’s. And over 835 in the Listers. Yes it won LeMans twice to add to Jaguars other 3 wins.
Budget. I’m running a stone stock carbureted one next year I’ll be making slightly over 400 hp to sort out the chassis. Then I’ll spend around $2000 ( yep 2000) to get it to 650 in an XKE I’ll easily take big block Corvettes but even in the XJS I should be competitive.

 

Jeff, due respect because you sound intelligent and hard working. How much time do you have in doing your swap? I believe you said you had about $10,000 in parts etc? How many hours? Now multiply that times shop rates. Are you now at or over the $20,000 I mentioned? Yes, you’re probably like me in that you enjoy that time.
Look I know you probably spent a decent chunk of money dealing with delayed maintenance issues etc. but that’s going to be true in any older car.

 

I didn't say the old 350 TP was the optimal choice, nor most popular choice nowadays, nor most modern. Nor cheapest; nor easiest to find. I said the old 350 TPI was a viable choice. Viable means capable of success; sustainable; it'll do the job satisfactorily. The old 350 most definitely is a viable choice; I wouldn't be in too big of a rush to disparage it. Many lumpers used this engine very successfully and were very happy with the results and their decision. And unless they've been re-lumped, those cars are still running around today with happy owners. A lot of people still like those old engines.

Cheers
DD

 

You’re also seeing some Jaguars de-lumped. First I noticed it was a XJC ( the two door sedan ) which is rare had the Chevy tossed away and a V12 installed. ( most XJC’s were 6 cylinders )
But I saw an XJS where that’s being done and regularly hear of XKE’s doing it.
How many? Well with the strength of the Jaguar market I’m sure more and more. XKE’s are well over $185,000 for rather ordinary ones in fine shape. While English XJS’s in nice shape are strong $35-45,000 here in America we’re around $20-25,000 while some convertible V12’s exceed that.
Check Junkyards and running V12 engines with a warranty are less than $1,000. Makes sense.

 

Alabbasi,
All the attributes you mention are exactly what I wanted in the car I'm building, that's why I chose the Chevy small block LT1, it is the most modern of the old school SBC. It has every single feature on your list, including OBD2 from 1996 to the end of it's run (in 1999 I believe). In addition, the cooling system was redesigned to cool the heads first which allowed for 10.4 to 10.8 compression ratio on good pump gas.

If I were building another type of car or had a different purpose for this car, I might very well choose the LS. There is one member here who has swapped a Ford 460 big block in his.

The power train you choose to go with is entirely up to you, I only recommend you educate yourself on all of the "moving parts" that are involved in a Series conversion. If you are good with a wrench and have a shop to work in, it's not an impossible undertaking, but it is tedious and hard at times. If you farm the whole project out it will be much more expensive and you'll want to choose the shop wisely. Again, good luck.

Dave

(Modern fuel injection, 4 speed automatic (or 6 speed manual if you choose), modern fan controller for electric fans, serpentine belt, modern alternator, modern a/c compressor all controlled a factory GM computer that you can talk to via OBD2. The availability of parts pretty much everywhere at low cost. Power and torque, better fuel economy, reliability.)

 

If you want all of those attributes just replace the 5.3 with the 6.0 V12 ( it’s bolt in swap) it has all of that. and includes the 4 gear or overdrive transmission. It will cost a little less for the engine. Yes Chevy’s sell for more than Jaguar V12. And has similar power to the first LS Chevy’s
If you want more power you can do the same things to the Jaguar that you do to a Chevy. The Camshafts (2) take about 1/2 the time swapping a cChevy camshaft does because they are on top and you don’t have to pull the belt, water pump, vibration damper, timing cover, Remove the lifters, pushrods rocker arms and reassemble them.
Jaguar has a mount you slide over to hold the timing chain sprockets and then just unbolt the camshafts. Then just put everything back together.
The ease of putting 5-6 speed manual transmission is amazing. Well yes you have to get under the car and remove the automatic eyes. But it’s all straight forward work. The alignment dowels in a Chevy align the crankshaft etc all you need is a little adaptor than can be made in a few hours.

About 3-4 hours work.

 

Or………

let this topic go! Always ends up bad.
if you own the car, you can do what you want to it, helll, cut out the floor and use it like the flintstones, for all I care,
GGG shut it down on the xjs forum already, I don’t go around telling everyone that they need to pull the jag engine and put In a Chevy , I also don’t want to be told that I shouldn’t have put a Chevy engine in, that’s not what these forums are
about! Nothing useful comes from
these threads, !

 

Darren. The subject has been discussed with respect and an intention to inform. Not every member has read or will read. I don’t read all the postings here, I’m sure you don’t either.
I for one try my best to inform.
The interesting part is the misperceptions about lumping there are.