Let's take some time together and let me explain just what we do and why we do it. First of all, we completely disassemble and clean the engine. The "top half" is basically the cylinder head, it's aluminum as is the front timing chain cover and the oil pan (XKE I, II ). Aluminum cannot be acid dipped for cleaning because the acid will dissolve the aluminum. Therfore, these pieces and a few internal pieces have to be cleaned by hand. We bead blast all the aluminum parts and inspect for cracks and corrosion problems at this time. The antifreeze/water combination used to keep the engines from freezing and overheating, causes a potential hazard to all the aluminum parts it comes in contact with.

The antifreeze/water solution, mostly because of the "tap" water used, is corrosive to the aluminum. (So, by the way, we fill our engines with permanent antifreeze and distilled water to prevent future damage.) Quite often we have to "weld" the water jacket area of the cylinder head to correct the damage (caused by corrosion) to insure a good head gasket or intake manifold seal. The water pump attaches to the front timing chain cover and about 50% of the time we end up replacing the front timing cover because of the corrosion and pitting also caused by the previous antifreeze/water solution.

The cylinder head is responsible for letting the air in and out of the engine. "How" it lets the air in, "How Much" air it lets in and "How" it lets the air out is what is important. First of all we want the air to flow as easily as possible so we "port and polish". " Porting and Polishing" is the term for the machining the inside of the aluminum cylinder head. Since the cylinder head is "cast" it has some rough edges and surfaces inside where you can't see.
These areas, in addition to being enlarged to their maximum and matched in size from cylinder to cylinder, are made very, very smooth. This procedure allows the fuel/air mixture to flow easily without restriction.
Remember we are trying to get the air in and out as quickly and efficiently as possible. ( All "race" car engines are designed this way.)

The cylinder head has (2) valves per cylinder, one to let the air in (intake) and one to let the air out (exhaust).
The camshafts are responsible for the operation and timing of the valves. In other words, they tell the engine when to inhale, how long to hold it, and when to exhale. We have tried several different styles of camshafts and have found some that we are extremely excited about.

These camshafts provide a smooth idle yet have the kick that make most grin. An unbelievable amount of power between the speeds of 35 and 90 mph., gives you the power to pass and smile or even laugh out loud. Because our engines rev faster than most, we "up" the valve spring pressure holding the valves in place to assure a good, tight, precise fit. Since our engines take such a "deep breath" and "hold it" as long as possible - the tappets became a little noisier because of the new geometry involved with these camshafts. We now use a shorter tappet to eliminate most of the valve noise - it corrects the geometry problem. As a precaution, we also use the latest style valve guides which have a little clip to hold them in place - just in case one should loosen it won't slide down into the engine.

The valve guide is a brass cylinder pressed into the aluminum cylinder head used to guide the valve as it moves up and down. Also, because of the engines "big breath" the camshafts cause the valves to open further than before, so we use a shorter valve retainer at the top of the valve so as not to collide with the valve guide.

Another common Jaguar problem is the "tappet guides". They are steel sleeves pressed into the aluminum head to guide the tappets. Since aluminum and steel expand at different rates under heat, the tappet guides can slide out of their bore and attack the camshafts (usually on the exhaust side). We install special steel plates to hold the tappet guides in place so as not to do any cylinder head or camshaft damage in the future.

The camshafts are fitted to the top of the cylinder head and rotate as the engine turns. The bearings which allow the camshafts to turn freely are replaced, but we also check the area in which the bearings are installed to make sure they are aligned - this is called " line boring". Sometimes the cylinder head can get warped from the overheating, or it may have been machined years ago to cure a head gasket leak, but what about the camshaft bearing area on the other side? When something changes shape or warps, don't both sides change? Of course. So the camshaft area could be too tight from previous repairs. This can cause oil starvation, needless wear, and of course noise. We check and line bore every cylinder head carefully. We also make sure that both the intake and exhaust valves close all the way. If we don't then there would be a leak and the cylinder would be useless ( no compression). In other words if we took a deep breath and let it out at the same time we wouldn't be able to hold it. The cylinder needs to hold air so that it can be compressed. (ie.. compression)
There is a small disc that fits on top of the valve under the tappet beneath the camshaft ( this is called a valve shim). We custom grind this disc to assure the proper clearance between the top of the tappet and the bottom of the camshaft. Then we know that the valves close when they're supposed to be closed. This is called valve adjustment, and is very critical for engine performance.

After we've finished all the machine work, we disassemble again and sand and polish the front of the cylinder head to a high gloss, and paint the appropriate color and portions of the head, top, bottom, and sides so it looks as good as it works. We photograph all work for your records and record the specs and stats for further reference and service.