I ask because i have bought a head (That comes with new gaskets) with the intent of painting and replacing the current head and gaskets. Now when i bought it locally online i knew it was for a 4.2 XJ6 of course but it didnt occur to me to check the year, because when i showed up and saw a clearly-early-70s jag in their yard, i began to have doubts about compatibility. So tell me, 1.) What year is this head from (Guess), 2.) Will it work in a 1984 XJ6? I visually compared it to the current head and saw only one, small difference. Any help on this?






(Sorry in process of painting it)

 

I know that the Ser III 4.2 heads used bigger valves.

Others will chime in with more

Cheers
DD

 

Doug is correct , the series 3 uses 1 7/8 inch inlet valves which are a lot bigger than the exhaust valves. Also on the top of your cylinder head you have large niuts , on my UK spec Series 3 head they are plugs. Your cam covers are definitely not series 3 as the jaguar name is part of the casting. On Series 3 cam covers this area is flat and appropriate Jaguar or Daimler stickers are put on.

 

Doug and Steve confirm the major change in heads. The larger inlet valves were first used on the engines for the 1954 D-type cars for Le Mans.

The head will bolt straight on to your '84 engine, but might not give as much power as you might like.

 

Will the head gasket that came with it work though or no? That would be inconvenient if it didnt

 

How much of a power decrease are we talking though? And so it would work without issue? Just thinking.. current head isnt in best shape. but i could sell this if i had to

 

 

sorry to thread jack, but.

This is the first time Ive seen a quality picture of a head gasket.

Not a lot of material between the cylinders... (no chance of boring up to 5.0L)

those Valve/ Cam. covers are awesome looking, I'll have to source a pair for myself some day.

 

Thanks, as much as id like to keep them white i know it wont stay that way for long in the engine bay haha. Gonna do the whole head Blue with the lines on the covers (And the "Jaguar" badge) in white.

And yeah im really hoping this head gasket will work. And if i have to sell this head it will be hard not knowing the year i reckon

 

I just remembered that that the later slotted blocks need holes drilled in the cylinder head at each end of the slot so the coolant can circulate. If you have an '84, it should have a slotted block. Earlier blocks had horizontal coolant passages machined in them via the bores, then covered by a liner. It was a spatchcock, (Jaguar were rather fond of them), and meant most blocks cracked between the bores, unfortunately.

 

So this gasket wont work?

 

Bumpppp someone please tell me

 

I think the gasket is OK, but check the coolant passages on the new head, with the existing one, and also check the gasket against new and old heads to see what is different. Also check old and new gaskets too.