Hi to alls
I would like to know if it's possible to mount a Jaguar Type E 4.2 l cylinder head on a Jaguar MK2 3.8l engine block ?
If this is true, what precautions should be taken ?
Regards
Gérard

 

Yes, but it depends on the age of the head. After about 1968, 2 extra coolant passages were added at the rear of the block and head. If you use those on an earlier block, the holes in the head will needed to be plugged.

Also note that an E Type has what is called a straight port head, and the Mark 2 uses a B Type head. The positions of the intake ports and stud locations are different, so the intake manifolds are not interchangeable. You may be able to get a later XJ6 2 carb intake manifold to use in a Mark 2, but I don't know if it will fit in the engine bay - it probably will, but I can't say for certain that it will. All XJ6 cars used the straight port head.

The 3 carb manifold from an E Type will not fit without doing some cutting/welding modifications to the body for clearance.

 

The B type head with twin SU HD6's is good for low end torque if you have an automatic transmission. If you have a 4 speed manual then you could see improved performance from straight port E type head, but as pointed out above, the E type manifold with 3 SU HD8's will not fit in engine bay.
It has a 12* down slope from cylinder head to the carb, then a 10* up-slope from the carb's to the air intake intake. This is for hood clearance on XKE. On sedan you have interference with wheel well when using the E type manifold.
You may get the clearance you need by using the 3 carb. manifold from a 420G or Mark 10 engine which will fit E type head. These manifolds have a 7* up-slope from the cylinder head. The performance improvement comes from the better air flow from the 3 carb. manifold, not the bigger SU HD8's carbs. If you used 3 SU HD6's, they would not reach max piston lift, before you got to red-lined RPM.

If you have the E type head overhauled before you install it, you could get more performance by installing the larger intake seats & valves and more aggressive cams. An XJ6 S3 cylinder head has the larger intake valves, but you must address the rear water hole misalignment as mentioned above. There are details on how to do it on this forum or Jag Lovers, I read it many years ago. Found it attached below.
Use the head gasket as required for the original block.

If you install a 2 carb. manifold from a XJ6 (4.2 engine) "E-type" head on a 3.8 Mark 2 engine, you would have to be on a dynamo-meter to notice any improvement.
Rgds
David

 

The last Mk2 cars, the 240 and 340, used straight port heads. I think they used the same twin carb manifold as the 420 and XJ6, but with the smaller bore carbs. A few 340s had 3.8 engines and at least one of those had a straight port head. By many accounts, the 340 with SP head is faster than the 3.4 Mk2 with B type head, but it's not clear how much of that is due to the engine or some weight loss in the body.

For myself, I have a SP, big valve head from a series 3 XJ to into my 3.4 Mk2 at some time in the distant future. Since my car is gaining metal to stiffen and strengthen the body, it's not likely to be lighter than standard.

 

The full race "SP" E-type head was rare and developed for racing. The performance target would be in the upper 1/3 of the RPM range, needing the 4 speed gearbox to access potential.
You can still get the upgrades. See the detail of the build at this website:
https://www.thorntonrestorations.com...linder-head-sp
Rgds
David

 

Thanks to alls for yours pertinent answers
Regards
Gerard

 

It's wandering off Gérard's original question, but the best source of info on the factory racing E type engines is Peter Wilson's book 'Strictly no admittance!' If I had the cash to build something similar today, I'd go to Rob Beere. He's a very nice and honest person to communicate with, very knowledgeable, and is the source of most of the parts that other people use.