According to the table below, the cylinder heads of jaguar 240 (SP) are identical to the jaguar 340 from 1967-68, to the jaguar 420 from 1966-68 and to the jaguar XJ from 1968 to 1973.
I would like to be sûre that this design is exactly the same (except camshafts of course)
I have a Jaguar 240 and would like to buy a cylinder head to entrust to a reconditioning workshop. The goal is to do a standard exchange and keep mine in its condition.
As Jaguar 240s are rare, I would like to know what type of cylinder head I can buy without fear. To be sure it fits my engine.
In advance thank you for advices
best regards
Jean-Sébastien SEGUI
FRANCE
The unique engine number is stamped at the front of the head in the valley between the cam covers. The 240 and 340 models used the same prefix, so they all start with 7Jxxxxxxx. If your objective is to find another 240 head, look for one mwith that same prefix. The factory part number is located on face of the cylinder head on the intake side. It’s not generally easily read on a complete engine while it’s in the car.
You could use the later XJ6 head , from the fuel injected Engine , has bigger valves , just need to block off the 2 extra waterways at the back of the head
I may well be wrong here, but I believe not all 340’s received the SPH; indeed a road test of the 240 pointed out that the 3.4 340 engine was unchanged from the previous Mk2. Did Jaguar perhaps use up the remaining B Type heads on the 340 until stock ran out?
Either way, it’s easy enough to identify; B Type heads have the spark plug at the rear of the front (6) combustion chamber whereas the SPH has the plug at the front of the chamber
I think your find it was more the other way around , bolted the SP head on to use up the stock , same as fitting the slim bumpers , from the Daimler , to use up stock .
Every thing I have read points to the 340 having the SP head !
Hi Jean
I have done some work on the straight port heads fitted to the 240/340 and can say that normally there is no number stamped on the front of the head as per other Jaguars.
If you buy another head it will be obvious that the inlet manifold is different from the B type head
in that, the studs are in a different position and the water ports are different
The head you need without alterations will also have the rev counter drive on the rear of the inlet
camshaft drilled to take 3 Allen screws to hold the rev counter transmitter, In my opinion, you should buy a 240 or 340 head
Your engine number will be found above the oil filter housing on the block (7Jxxxx-8or9)
I think that would be best, as it usually has the correct engine number for your car stamped in the cylinder head valley at the front, which should match the number stamped on the Data Plate (and engine block)
You can make the other heads fit, as far as I know, but there may be some slight issues
In addition, its quite likely the “other” head may need a rebuild anyway due to age & wear
The only thing that may change my mind is if I lucked on a rebuilt head, going cheap, and you have been told yours needs a complete expensive rebuild, (which it may do anyway, most I see now seem to have excessive valve seat recession )
Bonjour, Jean-Sébastien et bienvenue au Jag-Lovers
You have a 240. These were introduced in 1967 along with the 340 and had the same plain aluminium colour SP head as other Jaguar cars of this period for all capacities. They had no engine number stamped on so you can either use any blank SP head up to about 73 when the drillings behind the inlet cam changed and later the extra water passages appeared. You could even remove the number and paint from any earlier SP head (e.g. from a post 61 E-Type or MkX head etc.). So you can buy any post-67 pre-73 XK head and nobody would know, although you might need to polish the front of later heads which were left rough.
You don’t mention tuning, just being able to refurb a spare and keep your original. You can fit your 240 cams to any SP head but if you want to have an easy exchange you should rebuild a head complete with its own cams and suitable clearances, depending whether they are parabolic or earlier type. All SP head cams are 3/8" lift and perform the same.
The Coventry Foundation (www.coventryfoundation.org) has a nice 2.4 tuning book free as a .pdf, but a 240 has HD6 carbs and an SP head so it already gives as much power as a Stage 2 or 3 tuned 2.4 Mk1 car.
They sent me a copy but I only know how to attach jpegs.
The engine has never been changed. Normally all the serial numbers are original. Indeed I cannot not see any inscription on the cylinder head SP. According to your message, it is normal.
I didn’t know that all the car models mentioned by PeterCrespin had the same cylinder head and the same camshafts.
I contacted Conventry foundation about the 2.4 tune book. However I need to check about the French rules. I understood that we were not authorized to modify the power characteristics of the engine without going through a certification service. But, there are some recent new rules regarding classic cars.
Sorry, this is not strictly relevant to your issue, but may be of interest anyway. The naievety of youth! As a matter of perspective, at this time, my annual salary was $1600, and I had recently paid $1300 for my 3.4 Mk1. Naturally I did not proceed. A few years later I paid $100 for a complete, minus carburettors, 3.8 Mk10 engine. This was (naturally) pre-internet times and being “in the know” paid dividends. When buying my my E Type, all candidates were found via “friends of friends”, none were advertised.
As an aside, had I purchased a 3.8 head, I presume it would have come unstamped, which would no doubt cause much discussion on this forum.
