Howdy.

I have the opportunity of someone giving me a jaguar V12 and turbo 400 after they cannibalized an XJ12 for a hot rod. My XJ6 is fine and dandy so i don't want to swap it in there. However I also have a 1957 Mercury Meteor in good nick, and I really like the idea of taking the 312 Y block out of that to use as a backup motor for the Thunderbird, and putting the V12 in the Meteor.

However obviously this means i don't have the jaguar EFI analogue computer junk. My first thought is to convert it to Carbs, but its my understanding that the cam and combustion chamber on HE motors do not like carbs at all. I wouldn't mind converting it to an aftermarket universal EFI setup like the holley sniper system, but I simply don't know enough about EFI to know how reasonable an endeavor that is.




My car isn't in nearly as good a shape as this, so originality is out the window. However i don't think space is going to be an issue as the car is significantly bigger than my XJ. Nor is weight, as the car weighs no more than 3700 pounds, which is less than the 4000 pound XJ it came out of.

Just wondering if anyone had an experience on swapping the EFI, or aftermarket EFI setups in general and could offer some advice.

 

What year Jag is the engine from?

The 80s versions in particular had a pretty rudimentary FI system, not really integrated into the electrical architecture of the car; basically a stand-alone set-up.

Get an ECU and harness from a donor car, hook everything up, and away you go. Or, eliminate some non-essential functions along the way, if desired.

Cheers
DD

 

Dude says 85.

Frankly i'd like to avoid the stock anologue computer setup if at all possible. I'd like to get a little more mosey out of it, and I don't like the bundle of wires as thick as my arm going to the big mystery box in the trunk.

 

The ECU's after 1980 are actually digital. No matter what EFI setup you go with you'll be dealing with a thick bundle of wire, unless you go canbus and a fiber optic network. That you'd have to create and program from scratch though. The OEM Jaguar EFI system actually works quite well and would certainly be the easiest way to go. It's basically apply power, ground and a vacuum line and you're up and driving.

The semi plug and play aftermarket EFI systems like the Holly and Edelbrock will really only work with a downdraft V8 manifold, they won't work with the V12's manifold and there isn't a manifold possible because the distributor is in the center of the V. Making a coilpack distributorless ignition is possible, but you'll be making your own printed circuit boards and programming an ECU to do it. Possible, but not easy.

I have done a Megasquirt conversion to a 1966 S Type and it's a tremendous amount of work. The documentation is approximately 1500 pages long and you will have read and need to completely understand all of it by the time you can get the car to 80% of an OEM systems drivability. I've spent 7 years working on and off on it and it's about as good as a carb, which is to say not that great. Certainly not as good as the starting and drivability of an 85 V12 stock EFI system.

The V12 was always designed for EFI right from the beginning, but the first 4 years were carbs as the EFI supplier pulled out at the last minute and the carbs were a stopgap until an EFI system could be found. The V12 carb engines had the dubious distinction of being the first cars in Britain to need air injection to cope with the after start emissions because of the need to massively overfuel to get the engine to start. You lost about 50hp with carbs vs EFI too.

By far, the easiest, cheapest, best drivability and best power is to use the stock EFI system, as it's almost plug and play. I'd get the car running with that and then do further modifications down the road, but in the meantime you can drive and enjoy the car,

 

Oh is it digital? I was basing my assumptions on my 79 XJ6.

Is it possible to flash or otherwise tune it then?

My other reason for wanting to ditch the stock setup is the concern of width. I'll have miles more vertical space to work with, but i'm unsure as to the horizontal space between the splash panels, whereas the carbed setup is a much more laterally compact package.




Plus, imagine slapping a big ol' ed roth teir scoop on that. Can't say that wouldn't look great.

 

If you proceed with the swap please post plenty of pictures. Good luck.

 

It's not possible to flash in the conventional sense, I believe a new chip has to be written and burned and then put on to the board. Possible if you know the language the code is written in, but not easy.

The V12 is a 60 degree V and V8's are 90 degrees, so it should be a similar sort of space. Although saying that, I'm not familiar with the width of American V8's to compare. Do you have the engine to measure your engine bay to see if it would fit?

I hadn't seen a manifold like that before, I'd hate to balance and tune those carbs! Or pay for it at the pump either...

 

The manifold is a marine application, there's a video of one running here. Was hoping they'd be more common but i can't find any for sale.


I don't have the car yet, it belonged to my late great uncle in Edmonton, who bought it new. Property's being liquidated at some point in the near future and a member of the family who wanted to come here for the summer anyway was going to trailer it over.

I do have the thunderbird with a Y block in it to compare motor dimensions. But the thunderbird is a much smaller car, so engine bay of the Mercury is a mystery until it's here. I'm assuming ill have to doghouse the firewall slightly, though it's possible i wont due to the absence of the mechanical fan and shroud.

I have no doubt the motor itself will handily fit if it fit into an E type or XJ, however i have a hunch that those intake manifolds and their lovely long runners will be a problem.

As for the ECU, again i would like to get a little hustle out of it for the sake of it being a hot rod. I'll also be removing all of the appliances apart from power steering and the alternator too, i'm not sure how fickle that stuff is in regards to affecting the ECU's assumptions

So my interest in the carb setup is a combination of the runners, the possibility of modification and plain old fashioned simplicity and familiarity with american carbs over a german mystery box.

 

I quite understand about using carbs from yuor own comfort and understanding point of view. You should be aware, though, that getting more power out of an HE V12, over stock is not possible by chipping, screwdriver tuning etc etc. An HE USA C/R V12 without all the emissions stuff should be about 280-290 BHP (real DIN BHP not advertising BHP!) if you use larger throttle bodies and an unrestrictive 2.5 inch diameter exhaust system. There is no more to be had after that without changing the heads to pre-HE and using pre-HE pistons. Carbs will in no way change this basic fact, which is a function of the heads' lean burn configuration with a heavily shrouded exhaust valve.
On the plus side, 280 BHP is loads more than your Mercury had when new!

 

The Canadian spec engine was 262 hp. In 1985 the only accessories would have been power steering, AC and alternator, Canadian cars did not have air injection. The only real emissions equipment are the catalytic converters.

I had a 1992 Series III V12 and the converters were damaged and mostly plugged and I replaced them with the European downpipes with no cats. I didn't do a before and after dyno run, but I could detect no difference in performance or fuel consumption between good cats and none, so I don't think the cats are restrictive.

Regarding more power, it depends on how you drive. Below approximately 5500-6000 rpm, the only way to gain power for a specific engine to to add displacement. Once you get into the 7000-7500 RPM stage then there a number of things you can do, but the automatic transmission won't survive those speeds, and the cost to get the extra power will be well into 5 figures, maybe 6. Very little of it will be off the shelf bolt on parts either. The only relatively simple way to gain power is to change the Canadian spec 11.5 compression pistons for European 12.5:1 pistons, that will get you an extra 35hp.

 

That Meteor is a 57 Ford in different rim. As i recall, it had no emsion equipment, certainly not air injection!!

A very capable engine. More than a couple in our family.

I am impressed with the idea of two four barrels atop the V12...

Heck Jay Leno's Merlin powered RR uses 6 Webbers up top.

Carl

 

I guess i'm used to modifying big dumb unoptimized american V8's where you can quadruple the output with less than 1000 dollars of bolts ons. I've seen people do Turbo 12's, which seems wild on 11 or 12-1 compression ratios. Is there much space for porting on those heads?

Regardless, I guess i'll just get the motor and make it fit.

Yeah, canadian fords and mercuries had rebadged counterparts. The idea was that the population density of canada wasn't strong enough that every town had a ford and mercury dealer, so now they could sell fords at mercury dealers, and mercuries at ford dealers.





Just wrapping up my canadian built '49 F3 hot rod right now, which also had a mercury counterpart, which existed until about 1960. I think the meteor was equivalent to the same year Crown Victoria.

There were equivalents to this from other car builders, such as Pontiac Acadians, the ford Frontenac falcon the later Dodge Polaras (such as my '66 with the american Fury II dashboard) etc.

I think Ed Edd 'n Eddy put it best:

 

The V12 is quite different from the American V8s, basically Jaguar didn't leave power on the table unlike the V8's. Consider that when the HE came out in 1982 it was more powerful than a Ferrari and the fastest car with an automatic you could buy. As an example in 1982 the Euro version 5.3 V12 was 299hp and a Ford 5.8 was 140 hp. The Ford 7.5 only managed 202 hp and when it was injected in the late 1990's it only came up to 235hp.

Porting basically does nothing, and if you're not careful can very easily destroy the power. The cams and ports are actually oversized already for the 5.3, it's possible to gain torque by reducing the intake runners size by 3-4mm. The cams and valves work better with the 6.0 version, they kept them the same and gained 27% more power from a 15% displacement increase, and shifted the torque peak downward to a more usable range for a street car.

Pretty much any gains from the V12 will be had at high (5500+) RPM for race type applications, there is very little to be had for a street car. I have seen dyno runs showing the incremental changes made for a race engine, and the race engines can show large gains over 6000 rpm, but generally lose power over the stock engine under 5500 rpm.

 

Well i guess i'll have the truck for going real fast.

Fingers crossed that those lovely manifolds clear.

I'm assuming the 12 runs at 30 psi with a return line like my XJ6. I doubt they anticipated that with the '57s fuel tank.

 

The cams are virtually identical. Slight modification to deal with ramp up in order to fix a problem caused by worn machinery.
The distributor Is modified to provide much less advancement 17 degrees compared to 38. In the earlier.
That’s real good news I’ll cover later.

To make it simple. With carbs all you need is switched 12 volts for the coil. The coil triggers the tach. Use a Jaguar tach ( and gauges ) for ease.

Yes the Strombergs will need different needles. They are available. You can do one slight modification and pick up 30 extra horsepower.
a couple others and pick up 20 more.

But the really great option is E85. Because that can have octane around 100 depending on actual ethanol content. The timing can be significantly advanced. Every degree advanced yield up several extra horsepower.
But you need to enrich the fuel mixture at the same time. Up to 40% more fuel.
A quick and dirty solution is 4 SU carbs HD8’s. With UM needles.
Some slight welding required.

 

But not cheap, HD8's have become very expensive now. Last set of 3 I saw was around $3500.

 

Buying a “set” is the expensive way. The HD8’s were used on a variety of cars usually in pairs. Shopping for singles is easier on British EBay. Prices are then reasonable. I’m not sure if there is a simpler carb to rebuild than a SU. Plus there are video’s and books to help if you need them.
Everything still seems available.

But first you need to find an early carb manifold. Or lacking that be prepared to rework the Fuel injection manifold. By cutting the plenum open, welding an aluminum angle on the face with openings for 3 inch &1/2 SU’s. Then you’ll need to cut out the injection nozzle holes and weld in a plate to cover those. then spend some time grinding to make everything smooth and decent looking.
Yes you will need 6 inch &1/2 SU’s. Much cheaper carbs and very readily available.

Even with the early carb manifold you’re not free from welding. The stock manifold has a dog leg at the end where it goes down to pick up heat from the exhaust manifold. If you cut that off straight and put a plate to mount the carbs you’ll make 30 more horsepower than stock. Considering the Fuel injection only made 20 more horsepower that’s not a bad deal.

Carbs will not get the fuel injections mileage. But you’re building a hot rod. Not an economy car.

 

The V12’s dimensions are as follows. Length from back to front is 35 inches. You can remove two grooves of pulleys and save another inch.
height from bottom of the pan to top of the engine is 25 inches. Another inch or so for the throttle tower.
and 22 inches wide at the exhaust manifolds.
That’s often less than an in-line 6 cylinder. With the intake on one side and exhaust on the other.
Carbs or fuel injection will add to that. But if you follow my instructions not by any significant amount.
Those are quick and dirty measurements done with a tape measure and eyeball alignment.

A few other points. Spark plugs are right up on top easy to get. Not buried down under some hot manifold so you’ll have room for a park bench on either side of the engine. ( slight exaggeration )

Second. Throw the stock A/C compressor in the trash. It’s big , heavy, ugly as sin, and it trashed up an otherwise beautiful engine.
If you must have A/C buy a compact Sanyo and hang it off the side. Same with the giant bus sized
Alternator. There are plenty of much more compact and efficient one wire alternators.

Finally don’t be fooled by hype and advertising. 262 DIN net horsepower is a lot of power.
The 450 horsepower engines were Advertized or Gross horsepower. They lied to you. Plain and simple. They subtracted the power it took to drive the water pump and accessories even the oil pump was factored in and then they adjusted for air density and other conditions to unrealistic amounts. That was on the dyno unmuffled etc. Not installed in the car power. Like modern ratings.

When everybody changed over to SAE net or DIN net the Chevy 454 went from 400+ horsepower to 230 horsepower. Yes less than Jaguar. Fords big engine went to 210.

The same applies to aftermarket parts. Headers, carbs manifolds etc. In a word, Dyno’s can be and often are fudged. Make a minor entry for air density and the same part can show more power.

 

There is a good 3 part series on the stock EFI For the V12 on U tube. Watch it a few times and you’ll see the stock system isn’t junk. Relatively easy to fix.
It’s nice to have someone explain things to you.

 

The JagV12 is 22 inches wide at the exhaust manifolds. It’s 35 inches from the back of the block to the front of the pulleys. You can deduct an inch if you remove 2 of the 4 pulleys. And it’s only 25 inches tall ( plus an inch or so for the throttle tower.
Except for length You’ll have enough room for a pair of park benches on the side. ( kidding)
The carbs themselves are a wonder of simplicity. They make a typical 4 barrel look like a Byzantine nightmare in comparison. About as complex as the carb on your lawn mower.

Once you throw away that big ugly heavy inefficient A/C compressor and the plumbing associated with it
you’ll start to see the beauty of that engine. Plus the fuel injection gets seriously simpler. With all the room in your engine compartment you won’t need to air condition the fuel lines. ( honestly).
throw away that giant bus sized alternator too there are plenty of much smaller one wire alternators out there.

Don’t be so quick to toss the fuel injection. There is a three part series on U Tube that explains it all and then it’s much simpler. Even understandable . I’ll admit the factory could have done a nicer job of running lines and hoses. So you do it.