Hey guys, never owned a jag before but I found a 1990 jag xj 12 vanden plas (it also has a badge saying MCL- not sure what that is or if it is a jag thing or not!). This thing had a wiring fire under the dash on the passenger side and has not ran in two years. I looked (albeit not closely) but I did not see any signs of fire damage either inside the cab or under the hood. When the fire guys tried to get to it the banged up the passenger side fender while trying to get in before trying the hood latch. It can be mine for real cheap! Even if I do not attempt to "fix" whatever the problem is, I would like to know more about it. Can someone tell me some power ratings on these v12's? Is it an aluminum block or is it iron? What about the rear end (axle ratio and transmission types)? It is a sexy looking car in a nice dark blue. Oh well, enough rambling, that is my introduction the being a jag enthusiast/owner. Thank you for your input.

 

Hi Velder, welcome to the site!
The stock V12's ran around 300bhp, depending upon the pollution controls that sapped 20 horse off the top. Removal of the extra mufflers and resonators and installing a better exhaust system are rumored to free up to 30-35 horses. Both the block and the heads are aluminum, but the engines are steel sleeved and are pretty rugged. However they don't like to overheat, so as long as that is taken care of they hold up pretty well.
I'm not sure what the XJ12 has for gears, but the XJS had a posi-rear end with a ratio in the upper 2's (they were trying to squeeze better mileage) and I believe your car will have the GM TH400 transmission.

 

is the xj12 more desired than say the 6? Obviously by way of wow factor the twelve is far cooler but are the 6 cyl cars of more value?

 

In the Ser III body style, which is what we're talking about here, the V12, by most accounts, is more desirable and valuable than the 6 cylinder. For some it was the most desirable body/engine combination made by Jaguar and even those who don't entirely agree will admit that it was a magnificent car by most any measure.

A superb example will have a much higher market value than a six cylinder car. An average or poor example...much easier to find...isn't worth much if any more than a six cylinder car in equal condition.

Only about 10% of the Ser III production had the V12 egnine so they're a bit rare.

Cheers
DD

 

is this something I need to ship to a different thread or can I ask some more question? BTW, I have read on here about the reliability of the over heating issues on those engines, and I understand that they have a gm 400 tranny in them. Is it plausible to yank the big 12 out in favor of a small block chevy v8 with a carb or standalone injection?. I know it probably would not do much for purest value but do you then have a more trouble free ride? BTW, can someone point me to good used sheetmetal people (ie. pass. side fender, possible hood)? Thank you guys so much for your help already. I appreciate it a great deal.

 

Lots of guys install V8s.

In most cases a V8 replaces a V12 only if the V12 has been damaged by overheating, as the repair expense is so high.

A well kept, basically sound condition the V12 can be made reliable for less money and effort than installing a V8, IMHO. Fuel hoses, cooling system service, radiator cleaning, etc. Plus, it does nothing to address reliabilty/repair issues with the rest of the car.

I had a V12 for years. It was about the only part of the car that DIDN'T need any repairs beyond routine servicing :-)

The 400 transmission used behind the V12s will not bolt up to any other engines due to the Jag-specific bolt pattern.

Getting back to your original posting I'll say that buying an old Jag that hasn't run in two years is risky, as you probably realize. I visualize a seriously big money pit here to be honest. But if you're a decent DIY guy with a few thousand in cash you could end up with a really nice car.

Or just go buy one in really nice condition and save a ton of money and agrravation :-)

Cheers
DD

 

the price is right. really right. ultimately I am gonna consider what it would need to fix- whole with v12or sbc, but I am also very much interested in a rear diff outta one of these cars to make like a trike chopper. I do not want to irritate the purest and talk on here about cannibalizing one of these cars but that would make a nice rear axle on a chopper. This guy is offering it to me for a hundred bucks. Instead I offered to airbrush his fuel tank on his '80 something Honda bike to which he agreed.

 

Can't go wrong for a hundred bucks.

If it's a nice, no rust car you might wanna try to get the V12 running before swapping a V8.

If it was a really nice car then the purists would (and should) howl but if it's a just another clapped out, rusty, non-running, neglected Jag nobody will care.

Cheers
DD

 

...imagine a trike with a V12....LOL!

 

Welcome to the forum Velder,

That sounds like an interesting and challenging project you are contemplating.

I hate to be a party pooper, but, if you want to continue the discussion please take it over to the XJ12 section.

 

ya man that is the plan, already had someone point to the right page. And yes a v12 trike would be killer.

 

$100.00 I don't think you go wrong. Good Luck

 

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