Xj40 valve cover difference

I just installed a rebuilt head on my 94 xj6 but noticed that the bolt holes for valve cover are different on the new head from old head. Is there an explanation for this?

Was the replacement head definitely from a AJ6 engine and not a AJ16? Just a thought.

My mistake, it was for a Aj16. I guess it will still work I would just have to get another valve cover.

That will be a magnesium one. Not sure if that will be compatible with the spark plugs? The AJ16 has coil over SP.

The 1994 cam covers look like that. The cam cover has 13 bolts holding it down, not seven as in early models. Also the oil filler cap is located on the cover, not outboard.
That isn’t for an X300, it is an XJ40 unit, looks just like mine.
Your replacement head was from a pre-1994 car possibly?

Yes after researching it does appear that it is from an earlier model, the problem is if I get a valve cover it will not have an oil fill, so would it be possible to install an oil filler tube like earlier models?

OK, crazy thought - it would be slow going but you could add oil via the dipstick tube, couldn’t you?

I could if all else fails in previous forums people say that there is a blanking plate on the block where the filler tube would go on earlier model.