GM Turbo 400s on Jaguar V-12 had a unique bolt pattern. It would be better to to buy an adapter from John's and install a newer GM trans. I would ditch the fuel injection and go for the carbs, especially for the sound! I wold also ditch the Lucas ignition and use an aftermarket one. With some bucks you could use a 6.0 crank for more power.
You can contact Lonnie at his web site, he is the Builder of "The RUNAMUCKA", it has a Jag V-12 with carbs on it, he can answer all your questions about that engine. It also has the late Jag ignition two wire distrubutor which is similar to the GM HEI unit. Here is his web site link: http://www.lonniesplace.com/specialtyproducts/
Here is the source for all info Jag related - http://jag-lovers.org/ Dig into the discussion archives http://forums.jag-lovers.org/ , maybe sign up on the list that is most informative for you. The racing list does not have a lot of activity, but posting a question there will usually get you an answer.
Why don't you blow me? You've added NOTHING to the thread other than childish profanity. The guy asked about the easiest way to have a carbureted XJS. The FACT is that the easiest, most effective, lightest, and fastest way to have a carbureted XJS is to have an American V8 under the carburetor. If you don't like the 350, others have used 454s and even Cad 500s to good effect. Hope that stick up your ass doesn't hurt too much when you sit down.
Jag V-12: Cool factor: High. Lucas the Prince of Darkness and 4 late-model Zenith Strombergs, with all the fun late-carb features like air-bypass, together: Cool factor still high. Hassle factor also high. Run Factor is low. It's a complex motor, and the late ZS's are more complex as well. I've had my E-type for 15 years. It's got a 4.2 6cyl. with a pair of ZS's. What the heck - if you're up for a challenge, go for it! Great looking motor. Pete
Having owned several XJS's back in the early 80's just a couple of comments. Everything on these is complex in fact the injection was probably one of the easier and more reliable parts of the whole thing. Also have you factored in running costs because believe me you hand is never out of your pocket. I can remember a 800 mile trip costing over $300us in fuel back in 85 when gas was cheap. A sweet running well seviced one can be a lovely engine but a neglected tired example will be a nightmare.
There are several reasons for using the v12. 1. Everyone around here thinks that every small block chevy is worth gold because #2 everyone has a small block chevy in their car. #3. A v12 is badass. Period. I have taken several avenues to get to the point I am at now. It originally started out with a ford 460, but it wouldn't fit the frame. Then a small block chevy, and all I got was minimum $250 for a pile of shit with no tranny. Then it was a flathead 8ba, but the engine was locked up. Then it was a small block ford, an aluminum slant 6, an olds 215? all aluminum. Then I came across the jag, and I can buy the whole car for what I would have in the same motors that every other vehicle would/ could have. After reading some of the posts here, I don't think that this is the motor I am looking for in this vehicle, simply because of the weight of the combo. I appreciate all vehicles, I am not trying to bust anyones balls about using whatever motor they used, or for what reason they used it. I just want to know more about the jag because I think it would be a badass motor to have in a hotrod. Thanks for everyones replies, any more info would be great. Thanks again, Rick
I congratulate you on the use of a different motor for the project. The Jag V12 will be a bit more difficult than a BMW or Mercedes V12, however they do look cool and have the GM bolt patern on the back side. Problems with EFI are usually simple, either a bad sensor, bad injector, bad fuel pump, bad relay, blown fuse etc. The chances of the ECU going are actually quite low as this is the most hardened part of the system. However, if you can not get the factory EFI up and running, I would strip out the factory ECU and go aftermarket. Most likely a Stage IIb from 034. Javad and crew are playing with odd installs every day and will give you a hand. http://www.034motorsport.com/index.php?cPath=22 You retain the driveability of EFI with additional power available by being able to tune to any modifications such as low restriction air cleaners and open exhaust Plus, if you understand suck, squish, bang, blow and can add a few electrons in there EFI is easier to tune than carburation because you command how much fuel and spark advance at a given RPM and load. (you can easily add a blower / supercharger as well) Carburation at best is a compromize and optomized for only idle or WOT.
Frizi, you never did tell us what you were planning on putting this in - knowing that might help with alternative suggestions.
If you're looking for an offbeat DOHC type engine for which carbureted intakes are available, why not look at a Caddy Northstar? They were designed to be 300,000 mile engines (between rebuilds), and they appear to be just that. There's a wealth of knowledge out there on how to swap them into north/south configurations using Chevy S-10 parts. http://www.chrfab.com/ They have single 4-barrel and tunnel ram intakes, cam covers to either look like a vintage Ford Indy engine or a Hemi, etc. And good running ones can be had used for a decent price. Pretty lightweight, too.
Nice unit the NorthStar, but the question was more info on V12 Jag units, so here goes, Big old bus, depending on trim level 3900lbs typical, and not slow, every Jag I have ever known would easy hit a ton plus on demand, effortless, more than enough power . So If you stick the V12 in a lighter car it will darn near fly. Ok the large mass at the front of the car will not make for the sharpest corning ever, In fact I would go as far as to say that on the roads where I live I would seriously not want to drive anything which was as bad as such a plan is likely to be. But in a straight line, a Jag V12 in a light body should be rapid, and it will sound fantastic, great noise a 12 ( Flat 12 Ferrari boxer is a personal fav, or 917 Porsche ) It's going sound crisp, the way European stuff often does. As Scott says the EFI gives you driveablity, and is suited to still work with breathing improvements, where a carbed motor will have you spending hours trying to get the right combo of jets and air correctors. Given a choice of engines while I might not first be going for a V12, certainly injectted would sway me, makes life easy. Injection has allways been the ultimate cool, And this lump comes with it fitted as stock, ok the pipe work wants replacing with some tricker Goodridge and the wires want some braid slid over them and clipping back some it all looks neat, and a few other minor changes and it will look like the race inspired injection system it's suposed to. The whole car is coming it at a reasonable price so you should be able to sell the axle and a load of parts and see a chunk of the price of the motor back. Chances are if it does not currently go it's only the pump died or the connecttor to ether the throttle pot or the crank sensor needs pulling apart cleaning and stuffing back together, there is very little to go wrong, and reliabilty good. I have a Hemi on the bench at the momment it's only a little one for a change, but I got to say I am seriously thinking of an EFI set up to fit it, I see it as being a way to get the Hemi look of having one while still being able to afford the gas, but I know a lead right foot can soon take care of any dreams of miles per gallon in double figures. It's not unusual to find old Jags which have done huge mileages, I have pulled them apart after hundreds of thousends of miles, to find very little wear, typically the body rots away long before the engine fails. I say to people that every one knows what's inside a ford, coz we have all had to rebuild one, diffrence with a Jag, few people have ever looked inside one, there was no need, engines are as near bullet proof as you can get, oil pressure can run scarey low on very tired examples but seemed to still go, and don't rattle bad or anything too horrid. It's a Herron head motor, chamber in piston, heads are effectively flat. Like a traditional Diesel engine, simple, good for making reasonable torque. Can't think of any think else to say about it.
Early Jaguar V-12s are the desirable Heron head. Rick has the later HSE version which was tuned for emissions and "fuel economy". HSE V-12s came on line in 1981. Of the HSE models, the, '91 through '96 (I believe those are the years) 6.0 are the best, with Motronic ignition and fuel injection. Personally, I would fabricate a manifold for six two barrel Holley carburetors. You (he says simplisticly) would just need to tune them for 326 cubic inches of displacement!
If you don't want the engine, grab it for the front and rear suspension and other bits to use. All that stuff is sellable on Ebay too. Except the engine and trans, they don't seem to sell.
Wow see what I mean about not getting to see inside, Carnut is right, early V12's are the only Heron head variant, I have never seen inside the later HE, but I have just looked at a picture which shows a flat top piston and the strange combusion chamber/exhaust valve pocket arrangement, and read a bit which suggests that this chamber shape was designed to work with the Lucas system. I got to admit that as I say I had never looked inside the later motors, just assumed they were the same, and I was wrong ! There seemed to be no shortage of upgrade kits for these motors, 'The Driven Man' and others list a bunch of stuff to address any hp increase desired. As I have said several times I would be sticking with the EFI ( because it's easy once you get your brain round it ) and just modifying the throttle bodies/manifolds, which is one of the many things that 'The Driven Man' also suggests as being an area to target, though they had in mind keeping everything under the stock hood line, rather than a tunnel ram with a bug catcher hat, but we are talking detail here. Anyway, bottom line is what it's all about, and you are saying that the whole car comes for less than you are going to get even a motor alone out of anything else, so there is little to deside here, you might as well buy the Jag, which will give you an engine and trans and a pile of other stuff which will sell or come in for something
jag v12s are bulletproof. Good choice. Early carb manifolds are available as these were used on etypes and other early v12s. Or cut the airboxes and weld on a plate for any carb you want. Lose the air injection and plug the holes with 1/4 inch nail anchors one inch long. Get a distributor from an earlier motor. Don't forget to free the siezed centrifugal advance as that is one that caused problems. Adapt any tranny you want as the dowel pins are in stock chevy locations. Good luck and pm me if you have other questions.
oh yes you want the HE engine not the earlier preHE. HE motors have high compression and a swirl head. Much higher up and they burn lean. Just like a vortec chevy head. The HE head is also called a May head. You need the whole motor as the pistons are different.
Here is a shot that may be of some use, it is of a car over here racing.It has carbs and what looks like a home made inlet manifold.
Ya gotta love those drag strip pics...roll bar...guard rails.....just like the US in the 50's... Oh, sorry, this is about the marvelous Jag v-12... .
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