4.2l head doesn't seem to fit!

[snmarshall816]

Hi - looking for some help here. Just taken off the head of my 4.2l 2+2 E type 1968. And whilst the head gasket fits the block correctly, it doesn't fit the head as can be seen in the photo. This means that the car has been running with the head not fully aligned with the cylinder bores and as can be seen in the photo, combustion has been taking place partially on the cylinder head face. This clearly can't be right, which makes me think it might be the wrong head for a 4.2? Anyone got any ideas?

the number appear to read WM7286 and P30077BE on the head - any help much appreciated!

[piman]

Hello Snmarshall816,

from memory, when Jaguar expanded the XK engine to 4.2 litre they had to move the bore spacing to be able to increase the borees to the necessary size. However they did not alter the head casting so the combustion chambers misalign with the bores.

Perhaps someone elese can verify this?

Alec

[snmarshall816]

Thanks very much for this - if true I find this incredible. But it would in many ways explain things. If anyone else has any further information that would really help

[iRS]

Hi, I'd give our technical adviser a quick call - number in the magazine. He will know instantly. I seem to remember him writing something in the magazine recently about cylinder heads.

[snmarshall816]

thanks will do!

[3.8etypephil]

Hello Snmarshall816,

from memory, when Jaguar expanded the XK engine to 4.2 litre they had to move the bore spacing to be able to increase the borees to the necessary size. However they did not alter the head casting so the combustion chambers misalign with the bores.

Perhaps someone elese can verify this?

Alec

Absolutely correct, and the reason that the 4.2 doesn't breathe as well as the 3.8.