The 'E' Type Forum

I have just spent a week taking the head off my engine. Each stud had to come out first and some of them are about three feet long! They disappear somwhere down into the bowels of the motor and were caked with carbon, rust and sundry other muck. When I put it back together I would like to make the head removable next time. Is there a solution to this? Like drilling out the holes in the head? Plating the studs so they don't weld themselves to the aluminium? Any offers? Japanese engines don't do this!

This is what happens when people don't use inhibited antifreeze! Unfortunately, you have discovered one of the joys of the long stud block, although welding themselves to the head is less usual than is the case with V12s. What sort of state are the studs in? If they are pitted/corroded then there is no option but to renew them, and getting them back in and all to the requisite height can be a real pain, because the holes into which they screw often are filled up with crud which can be really hard, like granite, and correspondingly difficult to remove . It is mandatory to remove every core plug, which will give access to these areas, and never replace the core plugs until all threads have been chased with a tap ( a lot of people weld a tap to an old stud for this purpose ) and the studs have been securely and accurately put back in position with the heights carefully checked . A chemical wash of the block by an engineering shop may help. Note also that one of the studs is a greater diameter at the block/head interface level, so as to provide a dowel to locate the head. This IIRC is fitted to the second position from the front on the exhaust side of the engine

Thank you - this is most useful advice, especially as I've never worked on one of these engines before. I wondered what that lump on the one stud was for!
The car is from S Carolina and obviously never had antifreeze, since one of the core plugs has a very large hole in it!
I wouldn't even consider re-using the old studs after the punishment they had getting them out - they're all a bit bent & buggered and feeling a bit sorry for themselves now. Surprisingly I managed to get them all free by chopping one of the head nuts in half to make a half-nut plus a lock-nut. The studs were all nice and tight in their threads, and broke free with a reassuring jolt. 'Great' I thought. Then the fun began. I ended up spinning them with a ratchet gun while levering them up from underneath the nut while the whole engine was hanging by the stud from an engine hoist. Then bashing them back down again & repeating the process a dozen times while pouring my patent mixture of ATF and acetone down the hole.
Why did they use such long studs? I have seen longer ones in a Rover K Series - a very clever little engine that is built up like a layer cake; there is a 'ladder frame' on top containing the upper camshaft bearings, a ladder frame at the bottom containing the lower main bearings, and in between you have the head and the block, and the whole lot is squeezed together with great long bolts that run between the two ladder frames. The idea is that unlike most blocks, there are no tensile forces at work. Very clever. But once you take the head off, you can't turn the engine over because it all distorts!
Back to the Jag, like a fool I didn't loosen the pulley nut while the engine was in the car. Normally I just put a socket & bar on the nut & hit the starter. Lack of forward planning there. The good news is that the engine internals look very good indeed. Bloody heavy engine, BTW!

Hugo : the change to the long stud block took place in about early 1968 . The reason, I believe, was that by plugging the studs into the ( very substantial ) crankcase area rather than the ( quite thin) top of the block area the stresses were more evenly distributed given that the top of the block was less substantial in the 4.2 compared with the earlier engines because of the increased bore

Removing your pulley should not be too difficult. First straighten the lock tabs on the centre bolt, lie the engine on its right hand ( i.e intake ) side with the sump off , put a stout block of wood between a crankshaft web and the block side, and undo. I find my most useful tool is indispensible for this - a 3 foot length of steel pipe which goes nicely over the socket wrench!

PS you may need a friend to stand on the block to prevent it moving

So the Long Stud block is a better design - that makes sense - at least something is going in my favour!