4.2 engines

[norman m. macleod]

I am commencing the restoration of a 1967 2+2 FHC which according to the chassis number would appear to be a late Series I, about mid 1967. The engine which came with it is not the original, and seems to be a Series II, about 1969. Not that this is of much more than academic interest, as theengine, on preliminary stripping, has major corrosion in the block water jacket, with 2 of the long head studs corroded and immovable, one has sheared off by the efforts of a previous owner. I have an offer of a 1981 Sovereign 4.2 motor (currently runs well....still in car....!) My question is, can the head/block/crank/etc be fitted into the car without any fitting problems...will the bell-housing/gearbox from the e-type fit straight onto it, are the engine mounts the same, etc,etc. I have a totally rebuilt set of triple HD8's plus manifold, etc, will this bolt straight on after I throw away the injection stuff from the Sovereign. What other problems are there...? I am given to understand that the Series III head breathes better than the early XK heads (Des Hammill et al...) Is there a major difference in the camshaft profiles..? Any comments or advice would be greatly appreciated......I do appreciate it won't be at the forefront of the originality stakes, but beggars can't be choosers, and the Sovereign is almost free......
norman m. macleod
Western Australia

[christopher storey]

Norman : there is absolutely no difficulty in making the swap . All XK engines are virtually interchangeable. You will have to change the sump and the pickup pipes , the flywheel if the donor is automatic, and the spigot bush in the rear of the crankshaft , and you may need to change the oil filter housing and the engine mounts, but these are straightforward changes. The manifold should bolt straight on, but you need to check that all the water passages mate up. If they do not, the solution is easy with either removal or fitting of blanking plugs as appropriate . However, be warned that you may be merely swapping one set of corrosion problems for another, since all the long stud engines suffer from corrosion of the studs , and in some ways , better the devil you know!

[norman m. macleod]

Hi Christopher,
Thanks for your prompt response, looks like an option then.....I appreciate your ccomment on the corrosion problems of all the long-stud engines, I was hoping that the Sovereign engine, being almost 15 years younger, and having a known service history, might be a better bet.....however, nothing is for sure....! Have you or anyone else got any comment on the camshaft profiles....? Or maybe I can use the e-type cam in the "new" engine...? Any other or further comments/advice would be much appreciated.......
Thanks again,
Norman.

[christopher storey]

The cam profiles changed in about 1970 to a parabolic style which was supposedly quieter, using bigger valve clearances . Either type of cam can be used on any 4.2 engine and gives effectively the same performance with the same lift and timing, but it is important to identify the cam you are using so as to identify the correct valve clearance. The part no. is engraved on a small flat ground on the rough surface of each shaft. The embossed nos. ( something like MC20889) are merely casting numbers and tell you nothing. Someone else may be able to remember which cams have a four hole front flange as opposed to a two hole flange, but I cannot remember which is which!