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XK ENGINE MODIFICATIONS The below is in response to a number of private enquiries about....


The Block.
A complete blueprint would be beneficial, not necessary, but helpful. The factory tolerances were terrible even in the best of cases. Add to that the wear over 50 or so years and there's room for improvement. First, make sure you have a good block. Magnaflux the bearing saddles. Check for cracks in the bores etc. If all is well then you can start spending money. I would make sure the block deck is parallel to the centerline of the crank to start off.
You may need to align hone. Some people align hone, some align bore. Smokey Yunick hones and that's good enough for me. Once that dimension is achieved you will be able to bore and hone the cylinders with accuracy. Using a grinder, clean all the flashing marks off the block, both inside and out.
You can buy pistons "off the shelf" from any number of sources or have them custom made. There is very little price difference but great flexibility as to size and CR. Forged or cast, there are advantages to both. Forged are stronger at high RPMs, cast's are more dimensionally stable. Once you have the pistons then it is time to bore and hone. When honing, use a crosshatch pattern and make sure that your shop will bore/hone to each piston. Not the standard 20 or whatever over across the board. If possible use a surface plate. BHJ makes them, ask your shop.
Make sure all surfaces are flat, the oil pan, timing chain cover, etc., and make sure there are no sharp edges anywhere on the block.
Have the rods resized, ensuring that the big and small end are within tolerances. Rebush the small end as a matter of course and hone to fit the pins.
Grind away all forgeing/casting marks on the crank and bring a good crank to a good crank grinder that has a good crank grinder and have him grind the journals if necessary. Radius the oil holes and chamfer the edges. Have the shop order bearings, do not economize on the bearings. Retap all the threaded holes using a "cleaning tap," you don't want to remove metal if necessary. Chamfer the top of the holes, you don't want the top threads pulling up into the gaskets.
Paint outside of block after a cleaning that would embarrass most surgeons. 15 dollars worth of spray carb cleaner, some liquid Dawn dish soap, a bunch of clean lint free rags, HOT water, and some compressed air will be the best investment you can make for the longevity of the engine. Mask off all machined surfaces before painting using body shop masking tape..... the solvent resistant kind. Some people will paint the inside of the block with GE's Glyptal to aid oil flow down to the sump. You need a very clean block otherwise the paint may flake off and.....
Now the block is done. Cover it with a plastic trash bag and tie it. I put a few moth balls in there to absorb moisture. The above is a BRIEF synopsis of what to do. There is no way to translate years of experience that your machinist and or engine builder may have into a few emails. Later will talk about the head and misc. parts.
All this work may seem like overkill, and to some extent it is, but the need to lessen a failure should be at the top of everyone's list. It is no fun to pull and redo an engine for want of saving a few dollars (Pounds, Franc's, Lire, etc.). The XK power plant is probably one of the most reliable engines made in history. By careful assembly and workmanship behavior one can have an engine that will outlast the owner in many cases. It DOES require "going the extra mile" and to assume nothing. Make your shop PROVE to you what was done. They have the mics and gages. Have them show you EVERY dimension and take notes. Cost. Costs very. Big help Ron....... but, boring and honing should be about $30-40 a cylinder, align hone about $150. Crank grinding about $150. or so. Surfacing the head surface on the block about $50. All that grinding of casting flash...... free, YOU can do it with a small grinder and some abrasive rolls.
I would be willing to stand corrected on any and all of the above. No ego involved, just the dissemination of correct information.
ANY QUESTIONS ? Post them as others are probably interested in the answer also.

- Ron Duncan

As a companion piece to my previous post.

With VERY few exceptions stay away from "Foreign Car Repair" places. This DOES NOT include people like Larry Schear, etc., whose reputations speak for themselves, and speak very well too. But to the people who hang a shingle that says Jaguar, Mercedes, etc., repairs....
Think NASCAR when you want machining work done. Look through a magazine called "Circle Track" for recommendations on good shops. The magazine is interesting from a number of perspectives. The main one is getting work done. Most foreign car places use the "excuse" method of repairing. "We couldn't get the part as only one person in England makes it and he's on holiday with his wife and won't be back for three months, and he's got a backlog."
The "Good Boys" do it a little differently.... "Well, we started late Saturday night after the old lady went to bed and we found that we needed a valve so we called Billy Bob and he opened his shop but all we found was a Dodge 318 valve. We had to cut it down a little so it fit the after-market Chevy heads but we did that and all it took was 3 cans of Bud before we were finished." "We dropped the engine in before the pizza guy came and got him to help install the radiator before his next delivery" My experience with Foreign car places and some "specialists" is that one is going to pay a lot of money for mediocre work. Boring and honing is a simple process if set up correctly on the right equipment.
I've also noticed the "British Car Tax" when purchasing parts from various "specialty" suppliers. For example...... Bearings. All bearings have a part number that is crossed referenced to all other manufacturers. Look at the number and call your local bearing supplier and see how much you can save over the people who advertise in Hemmings and or have the catalogs with the copies of the factory parts book as sales pages. Same with valves..... TRW makes most, if not all, of the valves for any car. Need a sodium filled valve for Porsche 356 S90 ? No problem, it's an off the shelf item. Same with Manley in the USA. Blank forgings, cheap. Bring 'em to your machinist and an hour later you have a set of valves. Total cost about $12 each, in stainless.

- Grumpy Ron Duncan

Hey Ron -
Great write-up... thanks! I eagerly await the next installment.
Ed Mellinger


It is all very true and very well written. Congratulations on insisting that the whole job be done thoroughly and correctly. It is certainly not overkill. Cutting corners through stupidity or false economy is only one thing, expensive in the long run.

Best regards, Christian Hueber

Hey - ol' Grumpy Ron - thanks for the write-up on XK modification. I am entering that phase of 59 FHC restoration and much appreciate your comments. Planned to do something like that anyway but it is conforting coming from a professional and if I can find no adequate shop to handle the jag, I will yell "loud" for Larry.. Bob Harty Seattle 59 FHC 835808. again, Ron thanks.


Make sure you have a good head, crack test. Or better yet X ray and pressure test. But before that hot tank it. BE CAREFUL, make sure your shop knows that the head is aluminum. Put it in the tank for iron and you won't have a head left in the morning.
Deburr the casting flanges and lightly (repeat many times) play around in the water openings. All the years of who knows what being pumped throughout the car has caused corrosion in the water passages. Blocked passages will lead to over heating in extreme cases.
Make sure that the surface is both flat and parallel to the cam centerlines. CC the combustion chambers and match the intake ports to the gasket to the manifold.
On the exhaust manifold make sure the openings on the manifold are slightly larger than the ports. The is to avoid the spent gases from flowing back in. Replace all the valve guides with maganese bronze and do a 3 or 4 angle valve job. Size the cam followers to the openings, I would cross hatch the bores to aid in oil retention. Retap all the holes and use a die to go over the threads.
Once all the machine work is completed do a trial assembly. Correct any problems and then paint, mask off the machined surfaces. Polish the cam covers to your liking, but make sure that the gasket surface is flat also. New springs that have been prepped by placing a piece of emery paper, that has been sprayed with WD 40 on a flat plate of glass. Rub the springs in a figure 8 pattern to flatten the bottom and top surfaces, that will aid in both seating and more importantly heat transfer. Make sure the stems on your new valves are round. Use new keepers as a rule. Clean everything yourself. It's your engine and you're responsible. I coat all machined surfaces with a light wipe of 10W oil if it is going to be sitting a while.

Your choice depending upon usage. I wouldn't go over a 280 for street use, even that's pushing it. Make sure that your cams are good. The best way is to use a "cam doctor" by Audie Technology. Find Audie, call them, and ask who they sold one to in your area. call them and explain the situation. Do the same when you get your cams back from Isky, Kent, Piper or whoever. They make mistakes too sometimes. Again, it's your engine and you're responsible. Same with cleaning. Coat with Moly if they are to be stored for a while.
- Ron Duncan


Been reading your "How to" on engine rebuild prep and heve agreed completly and wholeheartedly.
This morning you posted a bit on "Heads"....again, all the right stuff.....except........While you can X-ray an aluminum head, the usual method for finding hidden cracks is to have the head ZYGLO'd. This is a erie green glowing liquid that will make even a hairline crack stand out like the Royal Gorge. Much better than X-ray. Everything you have detailed out to the list about the engine/head rebuild should be looked at as the least you should do for your powerplant....includes a balance job as well.

- Charles Bishop #677556


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