Mark V6 Conversion

GM power for a Jaguar Mark classic, this John's Cars conversion places a Chevrolet 90? V6 and GM transmission into your Jaguar Mark I or II Sedan. The S-types and 420 (not 420G) also benefit from this V6 conversion. The car runs very well with the Chevy V6, is approximately 150 pounds lighter and requires no suspension modifications.

Which Marks are compatible with this conversion?

The Mark conversion kit is compatible with all Jaguar Mark I and II Sedans. The S-types and 420 (not 420G) also benefit from this conversion. This conversion kit will not fit any E-Type nor early Sedans.

Which GM motor and transmission do I need?

The Chevrolet 90? V6 (200-229-262 [4.3L]) was made from 1978 to 98 (today) and looks like the V8 Chevrolet except with two less cylinders. The distributor is in the rear, but beware, not all Chevy V6’s with rear distributors are 90?! This kit is not suitable for the 60? Chevy 2800-V6 nor the Buick V6 with the distributor in the front. The mounts in this kit will not work with a V8. I reviewed V8 motors for this conversion and do not recommended them due to the tight engine compartment and limited radiator area. Every V8 car I’ve seen has cooling problems even without air-conditioning. The Buick V6 does not fit well and the small displacement 60? V6 motors are not up to the task.

A GM 5-speed manual, T350 automatic or T700 overdrive transmission can be installed. I strongly suggest an overdrive transmission – don’t scrimp on this. The savings on fuel economy and engine wear and tear will quickly pay for any additional cost now. To install an automatic transmission into an early manual shift car requires widening the transmission tunnel 2" on the right side (sheet metal modification only), a 6-12 hour job depending on your skills.

T700 Notes: All T700's have torque-convertor lockup and it must be hooked up to prevent damage to the transmission. John's Cars offers ELECTROLOCK™, the simple set-up to lock-up a T700 torque convertor for maximum fuel economy. Very easy to install – no drilling, tapping or machining required. For T700 transmission to 1992 (not 4L60E). The kit can be installed with the transmission in the car.

What is included in the Kit and how much does it cost?

Mark V6 Kit

T350 Automatic Kit^{1, 2}	$745.00
T700 Automatic Kit^{1, 2}	745.00
5SP Standard Kit^{1, 2}	745.00

Headers (Shorty Style)		$250.00
Tachometer Recalibration³		250.00
Repair Clock³		125.00
Electrolock™		95.00

1 Add $100.00 for Fuel injection V6.
3 Add $25.00 if not a JCI conversion.

The conversion kit includes:

right and left engine mounting brackets (stock GM engine isolators are retained)
transmission crossmember and mount
automatic transmission shift linkage
temperature adapter
oil pressure fittings
speedometer hookup and calibration (not FI)
radiator and heater hoses and plumbing
necessary hardware for mounting the V6
information and procedures for wiring, throttle linkage, etc.
freight paid in the continental USA.

You may purchase via PayPal. But you will get better customer service and sometimes lower prices by ordering via telephone at (214)426-4100.

Anything else?

Exhaust Manifold: The only difficulty of this swap is the left side exhaust manifold – it will not clear the steering. However, we have a shorty set of headers. Some GM manifolds can be cut and re-welded to clear. RHD Marks must use headers, please call.

LHD Mark: You have to drill two (3/8") holes in the frame rail for the engine mount. RHD Mark please call.

Gauges: I can modify the generator style tachometer to read accurately using a modern electronic movement (retaining the original face) for $250.00. It will not function otherwise. Please include $125.00 (average cost) if you wish to have the clock repaired at the same time. I offer this tachometer calibration service for approximately my cost to my kit customers. If your conversion is not a JCI conversion, add $25.00. Electronic speedometer drives for Fuel Injection V6’s are also available.

Other: The GM automatic pattern is P-R-N-D – it may not match your Jaguar pattern. I do not supply a parts/fix for this.

How do I order?

Complete the information on the Mark Conversion Order Sheet, sign and send it in with certified funds or money order. No COD, no credit cards, and no personal/company checks. No exceptions! KITS in STOCK and shipped upon receipt of funds. Kits are not returnable. Especially important are the original transmission type, speedo number, tire size, rear axle ratio, plus year, model, etc. Before ordering, be sure your engine is a Chevrolet 90? V6.

The Mark Conversion Order Sheet is a JPEG image (about 185K each) so it will take a minute or so to load. Print it out from a Laser, LED or ink-jet printer only – dot matrix printer will be useless. Make sure your print margins are set to .50 inches or it may not fit on a page.

Read our Customer Testimonials to hear what our customers think about us and our products.

If you have any questions, please call or email them to markv6@johnscars.com. Prices subject to change without notice.

Mark Parts & Spares

John's Cars does not stock parts for the Mark Series except suspension and brake parts that are common with the later XJ Sedans and that giant leaping kitty on the bonnet. Check out our XJ parts page for more details.