This is not meant to be a how-to; I am not a professional nor an expert. This is a chronicle of my attempt to replace a blown head gasket on my XK engine. I took a lot of photographs as a memory aid, and a lot of my notes here are to help me as I attempt to put it all back together.
Warning: this section is rated R for moderate profanity, and I will take the Lord's name gratuitously and in vain. If that sort of thing offends you, do not proceed.
The background: In 1949, Jaguar introduced their XK engine, which is a straight six, dual overhead cam with a steel block and an aluminum head. For more on this, check out the Wikipedia article.
They loved this engine so much that they continued to manufacture it in various sizes for the next 40 years. They put them in both their killer sports cars and their big four-door luxury sedans (saloon in England).
The last version was the 4.2 liter, which is what I've got. My car is a 1984 Vanden Plas (it was badged as the Daimler Sovereign in England). It's fitted with the last head, the "straight port" type. Even though the heads vary over the years, and mine has fuel injection instead of carbs, electronic ignition (albiet with distributor) and various smog parasites, it's largely the same engine as the one from my father's old XK120.
In fact, I bought the car partly because when I went to look at it, I took the Old Man along for his opinion. We popped the hood and looked it over and he said, "I recognize that engine. We can work on that." He'd had two XK120s, and he'd rebuilt the engines and knew them well.