I just aquired a European market '85 XJ6 with a 3.6L six & 5 speed trans. It is currently not running needing a new head gasket & possible head rebuild. I have a chance to buy an 86k mile good running '88-'89 3.6L six out of an XJ6 for a great price, so I need to find out if this motor will go into my XJS? Does anyone have any info on this?

 

It is the same engine but i cannot say for sure the mounting is the same. I would guess that it is a drop in. Those heads are very easy to fix, why not just pull the head and repair it? I can't imagine a whole engine is cheaper than repairing the existing head. As far as an answer to your question, I think it would be the same mounting therefore fits.

 

Weren't the Euro motors significantly more powerful due to emissions restrictions in the states?

I would lean towards repairing the head.

 

I do not know about this. I do not have any horsepower figures for either motor. Anyone know about this

 

Pretty sure the Euro motors were at least 20 horses & torque up, but I'll defer to the experts. If none chime in within a week, I'll research the figures myself and post here.

 

Unless im mistaken your 85 has an xj type motor,which dates back to the late 40s. The xj40s came out in late 1987 and is a complete different casting. That being said if the bell housing will fit then you should be able to swap them. Then the only problem will be with the electronics. If it was me id rebuild the head and leave it stock.