Any opinions out there about which v12 should/ could go back into my 77 xjc12?
Since all the Ecu components are gone as is original v12 I have a clean slate. My ultimate desire is a six speed to go with my eventual v12 but probably automatic initially.
So I’ve considered buying every type of xj 12 from a carbureted 74 to a 96 x305. I have not pulled the trigger on any donor yet as they have either been to nice to demolish or so poorly maintained it casts doubts on the engines longevity. I am not really sure where I want to go. Opinions? Winning concours not a concern just think it deserves a v12.
When you say ‘donor’ I presume you are referring to a donor car.
In the USA, at least, the XJS would be the most likely source…due to sheer numbers. Relatively few sedans were sold here with the V12… but tens-of-thousands XJSs were. Especially early 80s-early 90s “HE” 5.3 variants. This would probably be the easiest way for you to accomplish your goal.
Personally, I’d avoid an older carbureted engine. Seems like a retrograde step to me.
A 6.0 V12 would be nice owing to the fact that that it packs a lot more wallop than the 5.3. But, that might not be a big factor to you, I dunno.
Cheers
DD
1 Like
The X305 V12 might get a little tricky. The engine management system is pretty thoroughly integrated into various sub-systems. What’s your tolerance and ability for sorting the details?
Cheers
DD
1 Like
Thanks for input. Would any 6.0 physically fit? No great or any mounting issues? Is there a slightly less integrated 6.0 available ? Certainly can’t reprogram computer but cutting wires within my ability. Lol
Surely not in my repertoire of :expertise"
But, in a way. As I did the swap that you plan to undo !!!
Reverse thinking !!
First. Omissions!!! A poor way to think, but needed. OK for your jurisdiction , Yes. But not so on others? The latter lowers opportunity to selll , should you choose and a lessor value!
Did the 77 come with EFI? If so, that seems the less complex.
As far as I know, the V12’s mentioned are physical the same. Bolt in is the “easy” part
Chedk out Doug’s posts. His swap of a V12 into a bay formerly housing the 6 are informative.
And hopefully your PO did not mess things up to bad on the swap you plan to undo. I did not and a reinstall of a DOHC is feasible. Wires the main obstacle.
Carl
is this a newly acquired 77 XJc? the reason why I’m asking is because there is or was one for sale, that was lump(ified) SBC that I had my eye on and kinda still do.
If you really want to do this, here is the source for your engine and all the trimmings.
Good luck,
Phillip
Yes Where was the one you were thinking about located?
Similar one on eBay now plus a xjc6.
Washington State, Good for you!! I love the coupe’s I’d almost give up my '74 Short Wheel Base XJ6 for it. The significance of the short wheel base is up until recently, I was aware of only 3 left - now possibly 5. Four for sure, the other is their parts car.
Cyderman,
you probably should find out whether you want to restore your car to its original state or whether you want just your individual favorite. If it was my car I’d probably make up my mind considering the state of the rest of the car. Is it unmolested or already butchered? Is there any history?
Maybe the easiest way to source a true donor would be coming to Europe and find a good running example with a rusted out body.
For ease and documentation I’d go for a HE 5.3 as used in XJ sedans till 1992. Even if not the climax of this engine’s development it will give the SWB coupe plenty of go.
Good luck and keep us posted
Jochen
Thanks. This one was brought to my attention last time they ebayed it. Went from $1000 to $3000 in one bid by new bidder. Since it’s on market again they either got scammed or just want $3000 as reserve. Either way it’s to far away for me to see if engine anything more than future furniture. Plus I would have to pay additional $1000 to ship. Then I would have two similar ones but ••••••is there another way?
If you are interested in just the motor, I have two v12’s from 74 XJs that I probably won’t be using. I know the first one ran before I pulled it but was low on compression. The other turns but I did not try to get it running since the car was a parts donor for the first one. The first one is a resto mod that will be getting a GM transplant. Please be nice about that. I’m located in Montana.
1 Like
Thanks for reaching out. I might be depending on cost. I am in Oregon so a doable three day weekend. Unless your next to the Dakotas.
No judging, who knows where I’ll end up. My son has a ls1 in an 83 xj6. Go like crazy but wiring always an issue I fear. Still sorting.
Mark Bailey
I’m in Helena and I’m not looking to make a bunch of money on these.
TONY,
Please notice the license plate on this. It enjoys it’s LT1 power and dependability to the nines.
Phillip
NICE. I have a 75 coupe but planning to keep the v12 going in that one.
That is one beautiful car. Love the new vinyl roof also… Mine has been removed and i keep dreaming of cans of flat black spray.paint. The only thing that scares me about vinyl is the idea the roof may disappear underneath it. Thanks for the picture . Very motivating.