The XK Engine

by Norman Garrett

I had the good fortune to own a Jaguar XK-E back in the ’70s, when you could find them for hundreds of dollars, not tens of thousands. Mine was a ’66 coupe, British Racing Green over green leather. It was languishing outside of an import car repair shop, like so many imports of the day, waiting on parts, or money, or both to fix it. I found it unlocked and scrounged up a piece of mail in the glovebox with a name and address on it. A quick trip to the white pages and I had the owner on the line. It was two weeks before tax time, and I could hear a baby screaming in the background, no doubt born since the E-Type had been left at the repair shop. He told me it was in for exhaust repairs, and that he had been waffling about investing any more money into the car. After a few minutes of polite conversation, I asked him if he would sell it to me. He told me to make him an offer.

“How about $500,” I said. (This was 1978.) “There’s no way I could sell it for that,” came the response. Disheartened, I felt the momentum of the deal ebbing away. This guy must know what he has. “How about $600,” came his counteroffer. And that is how I got my first Jag at the age of 19. Dad hooked our trusty tow rope to the back of his Buick Electra, and we dragged one more dead British beast home, me using the emergency brake to keep from ramming him at each turn and intersection.

Decades later I still long for that car, which was sold for some long-forgotten justification only a few years after I got it back on the road. Aside from the wonderful shape of that car’s lines, I miss the engine the most. Its wonderful throaty baritone sound, the way it stretched out under the hood like some polished piece of art, which, to my mind, it is. So, I found myself dangerously browsing an online marketplace for no particular reason, and I ran across a Jaguar Mark II for sale in a town about two hours away. Of course I had to consider it, for at least a moment, and in the description were the words “spare engine.” An immediate plan sprung up in my head: While I don’t have room for another vehicle in my garage, an.engine,well that’s another thing altogether… hmmm.

A quick message to the owner started a conversation about what it would take to pry the spare engine out of his hands. I asked if the engine turned over with a wrench (to make sure it was not seized—I figured I could work with the rest if the cylinder bores were okay). I asked for some up-close photos. It looked like a good candidate for bringing back to life, and it was so appealing even just as a hunk of metal to me personally. A reasonable number of dollars was agreed upon, and I set myself in motion to pick up the hunk of British steel, bronze, and aluminum. I had no real plans for what I might do with it once I got it, but I knew that the experience of rebuilding it and polishing it up would be a great distraction for my mechanical bent. Much more entertaining than anything on any screen. Plus, my students would love to see it run on the university’s dyno once it was put together. I wanted them to hear that baritone roar and fall in love with it as I did when I was a young man.

A quick drive across state lines and my inspection began. The engine was not frozen-up, as promised, and it was largely complete with carburetors, manifolds, starter, etc. The aluminum cam covers were only slightly corroded and would polish up nicely. A look inside the oil cap showed a relatively clean cam with no oil sludge or scars on the one lobe I could see. The deal was done, and we loaded the lump onto my trailer. The seller turned out to be as deep a Brit car fan as I was, with a large backyard shop housing the Jag Mark II from the listing, plus a Lotus Europa, as well as a race-prepped Lotus 7, a couple of true Minis, and a Bugeye Sprite E-Production race car. Kindred spirits from the start. I resisted asking about the price on anything else he wanted to sell, and drove away with a new Jag project, albeit partial. On the way home I contemplated what to do with the engine once I got it running. Man-cave coffee table art? No, this engine deserved to spin and to make noise and heat as it was intended to. Engine transplant? I had a few candidates in storage such as a Bugeye Sprite (probably too large), an MG TD (now that would be interesting), and a final-year Spitfire (that could be very interesting, someone stuffed a 3.8L engine into a Midget once…).

Back in my shop, I started the most-satisfying disassembly of the 3.4L engine. The serial number (and the internet) tells me it is most likely from a 1962 Mark II. I discovered that it had domed pistons with a 0.50″ flat surround around the dome, which means it should be the 9:1 compression ratio. Only a few Mark II engines were built this way. The cylinder head has a “-8” suffix, so it is a normal 8:1 compression ratio head, so it must have been special order to get the high compression domed pistons. Lucky me.
After decades of working on Brit cars, I knew to be very careful not to strip any fasteners as I started my disassembly. Copious.dopings of PB Blaster plus some patience (waiting overnight) rewarded my efforts with nary a single stripped bolt or nut. Lots of Zip-lock freezer bags later, I had the cylinder head off and the pistons and bores exposed.

The aluminum cylinder head came off without too much fuss, but only after dealing with the wonderfully British dual cam chain drive that Harry Weslake devised in one of his many moments of brilliance. Knowing that the camshafts were the “shim and bucket” type, and that the cams would have to come off every 10k miles or so, Mssr. Weslake created a very clever way to “park” the cam sprockets on a front hanger, allowing the camshafts themselves to be removed and replaced easily. Brits have always led the world on clever mechanisms, and this is a shining example of this craft.

Despite being aluminum, the cylinder head was not particularly light to carry, but wrestling it onto my workbench gave me a clear view of a wonderful combustion chamber staring back at me, born from a drawing board 70 years ago. With a smooth semi-hemispherical shape with two ample valves and a near-centrally located spark plug, this design cannot be improved upon by much in the modern world. In fact, other than a second.spark plug, the chamber looks very similar to Dodge’s much-lauded modern Hemi engine. Weslake knew his basic principles.

As was taught to me by a dirt track racer back when I was a boy of ten, I ran my fingernail up each exposed bore in the engine block and was delighted to not detect even the slightest ledge in the zone where the piston rings don’t drag—a very good sign. The piston tops were only slightly carboned, with an appropriate layer of around one eighth of an inch. Sure, it was a sedan’s engine and probably mated to an automatic transmission, so the lack of “Italian tune ups” to decarbonize the chambers can be forgiven.

Popping off the oil pan gave me further warm feelings for this particular example, plus some wonderment on how the engine’s bottom end was designed. There was no oil sludge to contend with, and the pan was free from debris or unwanted matter. The large crankshaft is supported by seven large main bearings, and each cylinder’s.bore has a boxed cast iron chamber surrounding it, as if it were six separate engines cast together. Stronger than a bridge, and invariably stable. Alas, it is also why this engine weighs as much as four average men, and twice as much as a modern V-6 from the current Jaguar fleet.

Each piston slid out easily and showed no adverse wear on the major thrust side of the skirts. The rings themselves were stuck solid in their lands, the one tell-tale that this engine had been sitting for a long time. I was saved the dreaded “cast iron ring rusted to an iron cylinder” plague that comes with many stored engines, so the moisture had been kept from this engine over the years. Thank you, previous owner(s) for making my life much easier. A quick hone and some new rings should bring this short block back to life.

For the cylinder head, I stripped it fully down and bead blasted the exterior. The valves, both intake and exhaust, looked very good and will respond nicely to some light grinding followed by lapping. The head itself has alloy seats pressed into the aluminum base metal and these, likewise, will machine-down well with a triple-angle valve cut. The guides turned out to be in great shape, even the exhaust.guides which tend to wear more (higher temperatures affecting the oil and the oiling itself), so they do not need to be changed. The coolant passages look very clean, considering their age.

After removing all the pistons and rods, I used a micrometer on the exposed connecting rod big end journals and once again was pleasantly surprised to find them within factory tolerances, with an acceptable surface finish.

Likewise, the main journals are in great shape, again thanks to the oil-mindedness of the previous owners. Some pipe cleaners through the oiling holes and the crank will be good to go. The rear seal is of the funky “rope” type, which I will address at some level. I am not too worried about authenticity or concours judges, but balk at the prices charged for the full-on modern lip seal conversions. Most of my cars leak oil, so I may knowingly create another “rust proofing” assembly with this engine.

I spent a good hour on the Moss Motors website, shopping like a lottery winner to get what I needed for the refreshing/rebuild of the XK engine. New bearings, seals, piston rings, gaskets plus some miscellaneous hardware and I’m good to go for the re-assembly after some machine work. Stay tuned for the progress report in the next issue.

To be continued… Part 2: The Assemblage