Not worth the effort. Spend your time ( and save your money ) making the stock system work more efficiently. It’s not very complex.

If you want all the latest tricks and technology don’t start with an engine conceived in the 50’s designed in the 60’s and produced in the 70’s. In fact Electric cars already are here.

 

In Theory EFI is superior to carbs. The problem is all the hours required to sort out the program. Modern systems are. Self learning but require valid inputs. Digital inputs not analog. The biggest problem is the crank trigger. Not far behind is Is the compound input from two throttle bodies.
Those issues have been solved on the 6.0 liter but Due to the reliability and high demand buying a 6.0 liter has gone from a few hundred dollars to many thousands of dollars.I digress.
Carbs
The stock manifold is good right up to the point where it curves down to pick up heat from the exhaust manifold. If you chop off the downturn portion weld a little extension and with a carb mounting plate You can pick up over 20 horsepower. Advance the timing to 40 degrees+ ( depending on what fuel you’re using) there is another 10 horsepower for a total of 30. That’s on a stone stock engine. SU. HD8’s don’t add that much to a stock engine but as you get up over 400 horsepower really start to help.

There is one other way, the Stock EFI manifold can be modified to take 3 SU 1&1/2 inch carbs per side. ( 6 total ) By cutting open the face the throttle body is mounted on. welding a piece of aluminum angle on. and then making carb openings. The injector holes need to be carved out and replaced by a aluminum plug contoured to that shape. That will yield the highest output.

Now what’s so great about SU carbs? First there are plenty around used and affordable. Second the needle selection is great since there are so many different applications. Third E85 is worth at least a 10% power gain and the higher the compression the greater the power gain.
E85 sells for 60-70 cents a gallon less than premium and has a much higher octane.* there is no free lunch though, you will use more of it.
In addition it runs cooler and cleaner so you won’t get Deposits built up on the back of the intake valves.

 

OK if street cruising is your goal realize just how heavy that car is. Just like you don’t see many overweight track stars you won’t see many big Jaguars at the front of the pack on track days.
That luxury and comfort is heavy. Just pick up a seat from one. Now pick up a racing seat! That 40 pound difference is just a tiny start.
You can add 100 horsepower to the car and you’ll barely feel it. You get the weight down to 3000 Pounds and even with stock horsepower you’ll feel it a lot ( and yes feel and hear it as well)
You want fast? Buy a cheap modern car with a turbo.
Accept the fact that while this car will do 150 mph it will not quickly accelerate to that speed unless you lighten it.

 

Well if you cheat then anything is possible.

 

Search car-parts web site for prices here in the states.
The problem with using the BMW transmission is adapting it to the Jag. It used to be you could find a rusted XKE series 3 with a manual gearbox and just use that but not anymore. There is an outfit here in the states that has a bellhousing for a T5 that directly bolts on. But making an adapter to fit a Chevy bell housing and a Jaguar is really straight forward. The locating pins center everything and all you need to do is make a spacer plate if I could figure out how to transfer pictures I’d show you one.

 

I'll assume you are using a desktop computer, not a phone to post messages. If so, then at the bottom of the last message in a thread, you'll see the "Quick Reply" blank box and under that are two options: Post Quick Reply or Go Advanced. Click on Go Advanced. See the photo below:



The header above the blank box should now have changed from Quick Reply to Reply to Thread. In the header find the paperclip symbol and click on that. Photo below:




Then you'll see a cloud like image and an option to "Browse your Device" click that, and it brings up a windows explorer box. Navigate to where ever you have stored the photos on your computer (it might be worth making a folder on your desktop or somewhere that is easy for you to find and copy and paste the photos into that folder first). Once you have clicked on the photo you want, click the open button at the bottom and it should take you back to the cloud page with your photo(s) displayed. Then click upload in the top corner and it will place your photos into the message at the position where you had the cursor last.

I have combined the arrows below for both the browse and upload buttons. Once you have done that, click the Submit Reply button at the bottom and you're done. If you want, click Preview Post button and it shows how the final message will look. You can use that to see if the photos went where you intended for example. Hopefully this helps!

 

Thanks for trying to help a real Luddite. No I’m using an I phone and typically away from home. My wife works from home for a bank and you can’t believe the security in the home computers. It’s worse because of the department she works for. I do have my own computer but it’ cannot be connected to anything. I even have to unplug it when away.

 

Hi
just put a v8 4.2 sc jaguar engine in,we can get them all day long, here in the uk,
and you can fit manual 6 speed box,
and its 400 bhp out of the box

 

What do you do for the ECU? I was under the impression the factory one would not work as a stand alone system.

 

here in the uk,you can get an emerald k6 ecu stand alone that will run it ok.

 

I contacted emerald about that when I was considering converting my defender from an asthmatic 3.5 to a the jag 4.2 however I decided against it as I can convert it to run a bmw 335d engine/box which I think would suit it more.



Spoiler
I watched the driftworks series in which Craig converted his 4.3 aston to run a chevy lt4 and have contacted emerald and they said they'd be able to run an ls/lt in an x350...
though that project will only begin once my defender and xjs are finished.

 

whilst it's a lovely engine, I've been craving a v12 for a couple of years and now that I have one I'm not going to let go so easily

 

This is the jag in question She needs full restoration but the underside is solid! Hence the perfect excuse to remove the engine and get to work on it. Ive read that the v12 liners can be removed and bored to 96mm, are there any chevy/ford pistons that could be used? If that takes me upto 5.8 litres. I should add that the machining wont cost me anything. What power should i expect to make with the addition of cams and pre he heads, that is in addition to the modifications detailed by Mguar?

 

[QUOTE=Mguar;2247984]
Use the early distributor. 1980 or newer.

Why do you like the early distributor? I thought the pre HE and HE distributors were about the same except for the pick up coil. On my pre HE, the plastic pickup mounting was deteriorated with age. No such problem on my 83 HE. Is the advance different?

 

Based on the dyno tests I have seen from the TWR cars, leave the cams alone, and you'll probably max out at around 330 hp. They found the biggest improvement was going to 6.0 litres, that worked much better with the existing cams and valves. A 15% displacement provided a 27% power increase by doing a longer stroke. They found that the intake runners actually needed to be reduced in size by 3-4mm on the 5.3 and that produced a torque increase. That's part of the reason the longer stroke 6.0 worked well, it was better suited to the existing cam and valve size.

Yeas ago AJ6 Engineering made cams that were milder than the factory ones and produced more torque in the 5.3

If you can find one, I'd just do a swap for the factory 6.0, that will be most of the gains you can get already in a pre-engineered package.

 

Interesting project, good luck with it. I think you will find that just converting to a manual transmission and installing the higher geared rear end will wake the car up a lot.

 

Why would you do that? Sure you’re keeping Jaguar all Jaguar but you’re trying to make a tired old gal into a race horse.
Why not keep the old gal what she is. That V12 is a noble engine and will comfortably make 400 horsepower, probably for less than the engine swap will cost.

 

I agree that a 6,0 liter engine is a good engine, better than the 5.3. But they have gone up in cost enough that I can’t afford one anymore. Plus they are still stuck with those pollution control heads. And while I Still have several sets flatheads. I don’t have the $1500-$2000 a good set of Cosworth pistons Would cost to make them work. I’ve got some early distributors and I’m pretty sure I can retrofit one. But then we have to deal with the intake.
Oh sure leave it stock and grab the computer etc. but Yawn. Been there, done that.
Jaguar knew what they were doing. And yes the stock cams really work better than race cams for the street where you’re hauling a big fat overweight car designed to carry 4 fat old men and golf clubs around. Taking it up to and over the redline with an automatic is really a waste. There are a lot of newer turbo charged sedans around that will get off the line faster for a whole lot less money. Buy some thrifty electric car for transportation

But every red Blooded male should Learn the art and skill of racing. Have the thrill of driving a V12 to the limit on a race track. Feel that thing scream at 150+ mph and then dive inside of the Corvette under braking stealing the line away. Pull into the pits after the checkered Flag and share the joy of racing your friends at the absolute limit of your talent and the cars ability.
That to me is the very definition of a Sports Car.

 

If I wanted a street car, that’s what I’d do. A T5 or T56 and a later rear end with the outboard brakes. Maybe if you want Some 17’s. ( but keep the Kent wheels)

 

OK my choice has been this setup for since 2007, easy DEPENDABLE and awesome when hood is open!
makes 550hp and 750 ft,lbs.stock factory, starts in at 1500rpm carries to 4500rpm , a reprogram of ECU gets , NO taking the engine apart, 650hp, and 800torque!
with some small fuel changes and reprogram can make close to 1000hp , smooth quiet , dependable!
there were some of these around but seems other people have the same ideas!
but what an EYE catcher it would make, did in mention would get over 30MPG , in an XJS , engine actually weighs less than Jag V12!

V12 twin turbo , whats NOT to like?
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