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4.2 engines

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Not all are the same. The E type started with less displacement than 4.2. (3.8) It evolved to a 4.2 displacement in the 60s but somewhere along the line between carbureted versions and fuel injected versions the block was significantly changed. The fuel injected versions have a "steam galley" in the block, between the cylinders and with the head studs ending under the added galley in the lower level of the block. The head studs are much longer than previous versions of the XK block. They also have a nasty habit of severe corrosion in the steam galley if the owner chooses to use water instead of a mixture of water and antifreeze. I have encountered several cases of this failure with the stud actually rusting or breaking in two pieces while trying to remove them. Most of the E type blocks that I have worked on had studs the terminated in the top of the block where you normally expect them to be. I do not know when and why the steam galley configuration was incorporated into the design. If any one can add to the discussion, I would be interested. I have never bothered with the historic details but I suspect there was a good reason. Probably had to do cooling demands of the reduced space in the block of the 4.2 liter.
 
I'm quite interested as im trying to source an additional engine. I've been told the early 80's xj engine (early fuel injection) is the best head to get? some thing about flow and valve size in the head? these engine are quite plentiful now and fairly cheap, do you think it makes sense to by one as a backup for the original engine in my car?

I'm interested in building a hot street motor for the car and saving to original motor from abuse

thoughs anyone?
 
Go for it!! The XK block is a great piece of work. I think the only differences between early and later heads is the early ones, 1980, did not have air pump injection ports.
 
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