Anyone know or can direct me to info on difference between V12 Borg-Warner and TH400 attachment points? I now have an inoperable V12 attached to a BW trans in a 1975 XJ12. Am planning to swap inop V12 for a rebuilt 1977 V12.

Was led to believe '77 V12 was mated to a TH400, originally in an XJS.

As the '77 V12 no longer has its trans, I cannot confirm what the OEM trans was.

IF this block was mated to a TH400, will it bolt to the Jag XJ BW? Splines & stub shaft fit? BW appears to have a separate torque converter. The non-Jag TH400's I've worked with appear different in front.

Yes, I have looked at John's Car site, and spoken to many other folk. And not heard the same thing twice.

I realize no one sez much nice about the mid-'70's Jag BW, but I'd like to get this car moving in as few steps as possible. I have plans to upgrade the transmission, but would like to conclude this endless car chapter with an operable car. A V12 engine swap is a large enough adventure for me at this time.

Anyone either know the answer or where to find it?

This post may also show up in the XJS threads.

Thank you in advance for your collective wisdom!

 

I had a look at the Jaguar Classic Parts website, and they do list different part numbers for a stripped engine depending if they are for the BW transmission or GM - so there obviously is some difference.

The transmission section of the XJ12 parts book says the BW is up to engine number 7P32897, the GM trans after those engine numbers. If you find the engine number on your 77 and see if it is above or below that break point and then you'll know what trans should fit.

If the 77 engine is from an XJS, the BW->GM break point is engine number 8S7016. GM after number 8S7017.

Scans of the parts catalogues are here: https://parts.jaguarlandroverclassic...le-information

 

From what I found about that way back in the late 80's, before all this technology. Shade tree and beer, lotsa beer.

Fitting a TH400 engine to a BW12 car.

BW12 and TH400 to block =, same, BUT the dowels are in different places, I removed the dowels and moved on.
Crankshaft hole is going to mess with the brain, that's where the beer comes in. The BW12 is a hole (like a manual trans unit), the TH400 is a female "dome". I simply made a "dome" spacer thing with a hole to mimic the BW12 crankshaft, moved on some more.

Thats all I remember, but that car is still a daily driver, so I did well me thinks.