Hi guys, I have a 77 xj12 that has a turbo 400 in it, can anyone please tell me if this box is the same as a normal th400 or is the case or bell housing modified to suit the jag, can it be used behind a Chev is what I mean. Cheers.

 

NO, different trans to block bolt pattern!

but there do have an adapter plate, that is what i use ,Summit racing parts!

just so long as you are sure its a 400, not Borg Warner trans!

some 1977 cars had one or the other!

i personally use a Chevy GM 700R4, it has 4 speeds and overdrive 4th!

 

thanks ronbros, yeah i thought there might be a difference, im confused though, does the trans have a chev pattern and there is an adaptor plate needed for the v12 or is the trans drilled to suit the v12 and you need an adaptor to use behind a chev... i am selling the box and probably engine when i get it out of car and want to know if a chevy owner can use it. it is definitely a th400, has product of gm on pan and is right shape.

 

if it is a Jag V12 trans then it would have little use for a chevy engine, sell it for core to a trans shop! they use some of the H duty internal parts, aluminum case goes to scrapeyard.

if you are using a Chevy engine then there are many T400 that bolt right up to engine! (recommend a chevy 700R4, much better driving trans).

i other words chevy and V12 have different bolt patterns.

 

let me say what i did ,1978 Jag V12 engine mated to a 1990 Chevy 350 van 700R4 trans.

bought an adapter plate that had the GM chevy bolt pattern,from Summit racing parts, most important was the GM dowel holes, plate slipped right on the jag engine dowels(this lines up the center of crank to center of trans converter).

a lot of people are not aware that Jag used the GM dowel placement on the 1978 onward engines, most likly for ease of case manufacturing.

you will have to drill and counter sink to match the jag block bolt pattern, was very easy to do give a little loose for slight miss alighnment,counter sink wedges it in place!
bolts are available at most fastener stores.

also from summit was the small GM converter to crank adapter (something like a throwout bearing part), it needed a slight mod ,but cant remember,22yrs ago!


driveshaft is aluminum single piece,GM HD joints.

 

Hi ronbros, yeah that would be a great conversion, i had an early rangerover that i put a th700 behind and it was terrific. my info request was mainly to know what it might be worth, i am about to put the engine and trans up for sale. I am looking to make my xj12 a manual, 5 speed, not sure of engine yet, i don't want a chev as everyone else will have one. I might go for a modular 5.4 lt ford v8. the computer side of that is all that is holding me back...might be way to complicated to get it to run.

Dean

 

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that would be an interesting conversion, the 5.4 Ford engine nice, be easier to use the Ford ECU computer, it would run the engine and trans both!
with the Ford harness to hook things together

maybe pointless to use a 700 behind the ford, you would need a TCU to control the trans. seperate from the ford computer!

all doable but more work tuning both units to get along with each other!