Ok guys. I think I've given up on repairing my dropped valve seat, as I have been offered a complete running 94 XJ12 with the 6.0. I know some of you have done this swap, and I'm wondering what you encountered. I'm not really wanting the 5 speed like several of you guys have done, but the 4 speed auto with lockup seems a great idea, and being a old time hot rodder kinda guy with an affection for Jags, I've always believed that the only substitute for cubic inches is more cubic inches.

Thanks for putting up with my incessant inquires.

I have the 89 Marelli car with the dropped valve seat.

 

Please document the hell out of this. Considering the same swap.

 

supecharghedtr6,

Is it an XJ40 or an x300 car? The ecu is different on the 2 cars. I don't know if the same problem exists on the V12 x300, but the AJ16 x300 ecu is linked to its security system, so you have to fool the ecu into thinking it's still in an x300 when you transplant it into an XJS. As I said, I don't know if the same problem exists on a V12 x300, but maybe something to be aware of.

Good luck

Paul

 

I am pretty sure it is a XJ40.

 

Got the donor car today. It is a 94 XJ12. It is very very complete. So far, the only thing I see missing is the top plastic cover on the engine.

Do any of you have a wiring diagram for one of the cars?

 

 

anyone ever notice the HE engines drop valve seats more often than pre-HE engines!

HE runs very hot combustion temps in the exhaust valve area of the infamous May swirl chamber!, it is called the Fireball for a reason.

a little more useless info!

 

I think that HEs drop more ( if they indeed really do ) because there are simply more of them. My friends Series III XKE dropped one at idle only after slightly overheating once. I asked my friend who's a Jaguar mech this very question and he said IHO that's not the case, they all can potentially do it based on the Aluminum head and steel seat and the amount of heat/cool cycling the engine does.