Jaguar V8 Kit

Our basic philosophy on engine conversions is very simple: use as many standard, off-the-shelf components as you can, and a minimum number of “special” parts. Using standard parts makes for a more reliable, cost effective, and easier to maintain conversion, and these are typically the primary goals a Jaguar owner considering an engine conversion. Also, using more standard parts makes any conversion appear more like a factory installation- clean, tidy, and well executed.

Since GM, and Chevrolet, have spent hundreds of millions of dollars over the years developing a variety of parts for their cars that were both tremendously reliable and manufactured at a reasonable cost, why not take advantage of that?? When I did my first Jaguar conversion 15+ years ago, this scheme made the most sense to me, and it has stuck. Now as a supplier, I offer the Suncoast kit, and in addition, a host of other conversion components, all developed by us (Jaguar Specialties), to make these conversions even better. Our approach is still the same- use an absolute maximum number of "off-the-shelf" GM parts, and a minimum number of special, conversion-specific pieces. And the kit is supplied in that manner- only the parts that are truly unique are included. All of the rest that is needed for the swap is outlined, by manufacturer and part number, in the conversion manuals. What this means to the end user is that your initial cost for the kit is very low, and your ability to easily obtain key replacement parts in the future is maximized. Basically the kit includes only the parts the end user either couldn't buy or have easily made at his home location. These kit parts are truly the only engineering intensive components to the conversion, and are indeed the pieces best left to the professionals familiar with the swap. The real payday of this philosophy is that in the end, your final bill for the kit, and the other generic parts required to finish the conversion will actually cost less than the heavily advertised "all inclusive" kits. I have personally converted several cars of my own over the years, and regardless of carburated or fuel injected configuration, this has been found to be true. And the cars converted this way have a more professional, factory appearing installation- which should not be a be a huge surprise as they use 95% OE GM parts!!!

All of our components can be purchased individually, or grouped together as you need them, depending on your requirements

Applications:

All 70-87 XJ6, 75-78 XJ6C, 73-79 XJ12, and all XJS cars.

Engine and transmission options:

Engine- Any 69-97 Generation 1-2 Chevy Small Block, 265-400 cubic inches, carburetor, TBI, TPI, or LT1

Transmission- Turbo 350, Turbo 400, T700R4, 4L60/4L60E, or T2004R

The kit allows you to install any 1969 and up carbureted or fuel injected Chevrolet 265-500 cubic inch small block V8 (up to and including the late model LT1 engines), and Turbo 700R4/4L60E (automatic overdrive) transmission into your Jaguar . I recommend using the T700R4, as it has the best (steepest) first gear of the three transmissions listed (so it offers the best low end pull), and it also has an overdrive 4th gear that allows for lower engine speeds on the freeway. The overdrive feature is especially important for the earlier 70-79 sedans and 76-80 XJS as they were factory equipped with 3.31 to 3.54 rearend ratios. These higher (numerical) gear ratios cause unnecessarily high engine speeds (RPM) on the freeway (with a 3 speed transmission), and the overdrive 4th gear of the T700R4 reduces that to an acceptable level. This gives you longer engine life, reduced noise, and best of all, improved fuel economy. As an example, my own 1987 Vanden Plas sedan with a 305 TPI engine and T700 R4 transmission has routinely achieved greater than 22 mpg at 75mph. If you would prefer to use a T350 or T400 transmission, the kit can be provided that way.

Weight:

Weight reduction is one added side benefit of the small block Chevy V8 conversion. A typical XJ6 will lose about 50-75 lbs when converted to small block V8 power. A V12 XJS will lose over 300lbs (!!) with a small block V8 conversion. This is a huge drop in weight primarily on the front wheels, and the conversion manual outlines how to accommodate that change with very inexpensive custom replacement front springs)

What is included in the basic kit:

Left and right front engine mount adaptors
Rear crossmember
Conversion manual (model-specific; 70-79 XJ6, 80-87 XJ6, or XJS)

Transmission Option Items

Rear transmission mount adaptor (required only for T700R4/4L60/4L60E and T350)
Transmission Shifter Package (to mate Jaguar shifter to GM transmission- all models)

Conversion manual:

Each kit comes with a model-specific conversion manual that covers the V8 installation from start to finish. Each separate section of the manual covers: engine/transmission mounting, electrical, cooling, power steering, driveline, air conditioning connections, speedometer, calibration, and much, much more. There is no aspect of the conversion that is not covered in the respective manuals. There are three different manuals (70-79 XJ6, 80-87 XJ6, and all XJS), as each of the installations is slightly different. Each manual also includes the all important parts list for the conversion- these are the off-the-shelf parts described above, that are available anywhere, including your local auto parts store, and of course, the internet. These parts include: the radiator, rubber engine and transmission mounts, molded radiator hoses, oil pressure and water temp senders, speedometer calibration parts (gears), cooling fan and shroud options, and even some OE references for driveshafts. It's very comprehensive.

TPI manual:

For those of you considering using Tuned Port Injection (available on GM cars from 1985 onwards), we also offer a manual on how it install, tune, and troubleshoot this type of induction in a Jaguar conversion, or any car. It is absolutely essential, and comes in very handy as you go through the installation. If you would like more information on this manual, please E-mail me.

General Electrical/Wiring Information:

In addition to the conversion kits, Jaguar Specialties offers several different wiring products to make your conversion reliable and trouble free:

1) Basic engine wiring harness- 74-87 XJ6, 74-79 XJ12, and 76-92 XJS. This is a plug-in replacement for the factory engine harness with connections for tachometer, oil pressure gauge, temp gauge, oil warning light, coil power (or power to distributor module), AC compressor clutch control, alternator field, and transmission kickdown (if used). The harness is beautifully manufactured from 90º C wiring (hi temp) with a molded matching (Jaguar) plug. The wiring itself is 60” long from the plug, and is speciall color coded for the different functions (and a color code chart is provided)

2) LT1 Speedometer interface- when doing an LT1 conversion (94-97), there is no mechanical provision on the transmission to drive the Jaguar speedometer. Jaguar Specialties offers a custom designed and manufactured electronic interface box that takes the LT1 PCM (computer) speedometer output signal and converts it for use by the Jaguar speedometer. Installation is simple, and the unit has an external adjustment screw to accommodate differential ratio changes, and tire size variations

3) VATS bypass unit- All 88 and later TPI, TBI, and LT1 GM engines incorporate an anti-theft circuit in the engine computer (called VATS- Vehicle Anti Theft System). A special module in the car relays a signal to the computer that allows the engine to start. This module is part of the dash typically, and not usually provided with the donor engine when delivered to the customer. If the computer does not receive this proper signal, the engine will not run. One workaround is to program this out of either the Chip (TPI/TBI) or the computer itself (LT1), both of which are expensive options, likely to run several hundred dollars. Another option is to use the Jaguar Specialties VATS bypass module. This unit, smaller than a pack of cigarettes, fits under the dash, and when energized with ignition power, provides the proper signal to the GM computer. And it is very inexpensive- under $50. Using this approach preserves the factory anti-theft system, which can be used by the Jaguar owner- a kill switch can be utilized in the VATS unit power lead to immobilize the car. Simple, neat, and reliable.

4) Tachometer calibration unit- Your Jaguar tachometer will need to be recalibrated for the V8 engine. Details of how to do this yourself are in the “Tech Tips” section of my website. However, for those customers who prefer not to remove and disassemble an XJS cluster, or remove the XJ6 tach from the dash, we offer an external unit to do the same thing. It is a small unit, ½ the size of a pack of cigarettes, and simple to wire.

Recommended conversion parts for different Chevy engines

The following section gives you my recommendations on the parts required to do a top quality conversion, and the lists are broken out by engine type (and Jag model, to some degree)

Carbureted Chevy V8-

Basic V8 Kit

Shifter package

Transmission mount adaptor (T700R4 or T350 only)

Power steering hose set

Fan shroud

Exhaust header set

Basic wiring harness (74-87 XJ6, 74-79 XJ12, and 76-90 XJS)

TBI/TPI Chevy V8-

Basic V8 Kit

Shifter package

Transmission mount adaptor (T700R4 or T350 only)

Power steering hose set

Fan shroud

Exhaust header set

Basic wiring harness (74-87 XJ6, 74-79 XJ12, and 76-90 XJS)

LT1 Chevy V8-

Basic V8 Kit

Shifter package

Transmission mount adaptor

Power steering hose set

Fan shroud

Exhaust header set

Basic wiring harness (74-87 XJ6, 74-79 XJ12, and 76-90 XJS)

LT1 Speedometer interface

VATS Bypass

Other Upgrades/Repairs to do before/while doing your conversion:

If you’re planning to do an engine conversion on your Jaguar, there are several other important upgrades you may want to consider doing at the same time. The key here is that once the (original) engine is out (and before the new one goes in), you’ll have virtually unlimited access to the engine compartment, front suspension, steering, etc., Here are a few of the items I always attend to at this point:

1) Polyurethane steering rack bushing upgrade: It’s no secret that the stock Jaguar rubber rack bushing are a terrible design, and fail easily in the environment of the engine compartment (oil, heat, etc..,.). If the bushings in your car are still the original style (rubber), change them. Changing the bushings to the firmer polyurethane greatly improves steering feel and response, and cures that “wandering” feeling. I always upgrade my cars to polyurethane rack bushings, a part we carry as well (see the suspension page). While it is possible to do this even after the car is all assembled, the best time is when you can access the rack from above- it will cut the time of the job in half. The parts are so cheap, don’t pass on it. Also, take a peak at your steering rack boots- replace any with cracks or splits.

2) Front subframe mounts: These are the 4 mounts (2 in front, and 2 in the rear) that support/attach the front subframe to the car. Due to the age of these cars, and the amount of oil, road sludge, and other crud that they are exposed to, they frequently are bad. It’s easy to tell if yours need replacing: look for any rubber sections soaked with oil, cracks or splits in the rubber, and any evidence of the rubber separating from the metal surrounds. These are cheap and easy to replace, and are a simple job when the engine is out.

3) Front sway bar upgrade: The idea here is that if you’re going to the effort and expense of upgrading your Jaguar to a more powerful and responsive V8, you may want to pay a little attention to the car’s handling characteristics as well. The stock front sway bar of the XJ6 sedans is very small, and even the larger stock sway bar on the XJS could use improvement due to the extreme (300lb) weight loss going from V12 to V8. If you’ll ever be interested in improving the handling of your car (and you should), now is the time to do it, while the engine is out. If you look at the way the front sway bar is installed on XJ6 and XJJS cars, you’ll know why I bring this up. It’s sandwiched basically between the front subframe and the body, and doing the sway bar swap with the engine in the car is basically a 2-3 hour job, which is a royal pain in the behind. However, with the engine out, it can be done in 15 minutes. So keep this in mind as you plan your project- it’s well worth considering, and is a small expense compared to your total outlay in the project. The return is worth the effort many times over.

Chevy Big Block Conversion:

The mount set will also work with 396-502 Big Block engines and the above listed transmissions. If stump pulling power is your thing, please Email me for more details on the Big Block conversions

More information:

I'd be happy to discuss any aspect of the V8 conversion with you-please feel free to Email me. Please take a look at the attached pictures to get a feel for what the conversions are like. Also please be sure to check out our unique V8 conversion and other products for Jaguar XJ cars on the other pages.

What’s possible?? Here are some pics of both my cars and customer cars built with Jaguar Specialties parts:

89 XJS Convertible with carburated 350