Identifying a cylinder head

[Peter B.]

Hello,
found a car that is very attractive, but the engine is not from an e-type. Number starts with 7F..., found out that is for a 420. Now I would like to know what else has been changed, ancilliaries look all good and e-type like, but I?m not sure abpout the cylinder head. No engine number on it, just one casted marking "HV 231". Can anyone identify if this is a e-type head or a 420, or something else? Or does this make no difference at al?
Many thanks
Peter

[christopher storey]

Provided the head is from a 4.2 engine, it makes not the slightest difference. All 4.2 heads are straight port heads, recognisable by the front sparking plug being next to the front wall of the head, as opposed to earlier heads which have a large gallery plug at the front

[Peter B.]

Hello Christopher,
head looks like the one I had on my 2+2, and as you said, front spark is close to front wall of the head. Cam covers are ripped, but doesn?t matter, manifolds look as well as they should, when on an e-type. Was wondering if there were supposed to be some differences in the water cooling parthways, but when its is the same, then that should be ok.
Many thanks
Peter

[Dawnpatrol]

Hi Peter,
You might be thinking of a series 3 XJ head (eng number not stamped on the front) which is also straight port but has extra water ways at the back of the head. If you have one of these then the two holes will have been or need to be tapped and a plug srewed in to blank off if fitted to an earlier block like yours. If the back of the head overlaps the back of the block significantly then it could be a series 3 head, you could check with a mirror on a stick.
Advantage of the series 3 head is that it has larger inlet valves.
Also I think but not sure, that the series 3 head doesn't have the tappings for the tacho geny on the inlet cam.
All the best,

Mike